PH-Responsive Polymer Microspheres: Rapid Release of Encapsulated Material Within the Range of Intracellular PH Financial Support Was Provided by the NSF (Cooperative Agreement No. ECC9843342 to the MIT Biotechnology Process Engineering Center), the NIH (GM26698), and the Department of the Army (Cooperative Agreement DAMD 17-99-2-9-001 to the Center for Innovative Minimally Invasive Therapy). D.M.L. Wishes to Thank the NIH for a Postdoctoral Fellowship (NRSA Fellowship No. 1 F32 GM20227-01). Scanning Electron Microscopy and Confocal Microscopy Images Were Acquired by William Fowle at the Northeastern University Center for Electron Microscopy. Dr. David Putnam, David Ting, and Tommy Thomas Are Thanked for Helpful Discussions

Angewandte Chemie (International Ed. in English). May, 2001  |  Pubmed ID: 11353487

Stomach-specific Anti-H. Pylori Therapy. I: Preparation and Characterization of Tetracyline-loaded Chitosan Microspheres

International Journal of Pharmaceutics. Mar, 2002  |  Pubmed ID: 11879743

The main objective of the study was to develop a stomach-specific drug delivery system to increase the efficacy of tetracycline against Helicobacter pylori. Chitosan microspheres were prepared by ionic cross-linking and precipitation with sodium sulfate. Two different methods were used for drug loading. In method I, tetracycline was mixed with chitosan solution before the simultaneous cross-linking and precipitation. In method II, the drug was incubated with pre-formed microspheres for 48 h. The cumulative amount of tetracycline that was released from chitosan microspheres and the stability of the drug was examined in different pH medium at 37 degrees C. Microspheres with a spherical shape and an average diameter of 2.0-3.0 microm were formed. When the drug was added to the polymer solution before cross-linking and precipitation only 8% (w/w) was optimally incorporated in the final microsphere formulation. When the drug was incubated with the pre-formed microspheres, on the other hand, a maximum of 69% (w/w) could be loaded. Thirty percent of tetracycline either in solution or when released from microspheres was found to degrade at pH 1.2 in 12 h. The preliminary results from this study suggest that chitosan microspheres can be used to incorporate antibiotic drugs and may be effective when administered locally in the stomach against H. pylori.

Localized Delivery of Paclitaxel in Solid Tumors from Biodegradable Chitin Microparticle Formulations

Biomaterials. Jul, 2002  |  Pubmed ID: 12059022

Paclitaxel (Taxol)-containing chitin and chitin-Pluronic F-108 microparticles were formulated as biodegradable systems for localized administration in solid tumors. The microparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and swelling studies in phosphate-buffered saline (PBS, pH 7.4). Lysozyme-induced degradation and in vitro release of paclitaxel was examined in PBS at 37 degrees C. The percent change in tumor volume was used to assess efficacy of the Formulations after local administration in murine Lewis lung carcinoma model. FT-IR confirmed higher degree of acetylation in chitin microparticles from the starting chitosan sample and the SEM showed that the chitin-Pluronic F-108 microparticles were significantly more porous than chitin microparticles. Due to higher porosity, chitin-Pluronic microparticles were able to imbibe higher swelling medium and degraded much faster in the presence of lysozyme than chitin microparticles. After 48 h. 51% of incorporated paclitaxel was released from chitin-Pluronic microparticles as compared to 28% from chitin microparticles. In vivo studies in Lewis lung carcinoma-bearing mice showed that the tumor volumes after 6 days using paclitaxel-loaded chitin and chitin-Pluronic F-108 microparticles was 458 and 307 mm3, respectively. In contrast, the tumor volume was 997 mm3 for the untreated control. The results of this study show that chitin and chitin-Pluronic F-108 microparticles are biodegradable drug delivery systems that can be useful for localized delivery of paclitaxel in solid tumors.

Intratumoral Administration of Paclitaxel in an in Situ Gelling Poloxamer 407 Formulation

Pharmaceutical Development and Technology. May, 2002  |  Pubmed ID: 12066574

In order to examine the efficacy of paclitaxel (Taxol, Bristol-Myers Squibb) after administration locally at the tumor site, we have developed a thermo-reversible gelling formulation in poloxamer 407 (Pluronic F-127) solution. Paclitaxel was incorporated in poloxamer 407 [20% (w/w)] at 0.5- and 1.0-mg/mL concentrations. The in vitro release studies were carried out in phosphate-buffered saline (pH 7.4) at 37 degrees C. Control and paclitaxel-poloxamer 407 formulations were administered intratumorally at a dose of 20 mg/kg in B16F1 melanoma-bearing mice. The change in tumor volume as a function of time and the survival of treated animals were used as measures of efficacy. Poloxamer 407 solution undergoes a reversible sol-gel transition when the temperature is raised to above 21 degrees C. In vitro paclitaxel release from poloxamer 407 gels was very slow (only 6.1% after 6 hr) probably due to the poor aqueous solubility of the drug. Significant enhancement in the anti-tumor efficacy was noted following intratumoral administration of paclitaxel-poloxamer 407 formulation. The initial tumor growth rate was delayed by 67% and the tumor volume doubling time was increased by 72% relative to saline control. In addition, more than 91% of the tumor-bearing animals that received paclitaxel in poloxamer 407 gel survived on day 15 post-administration as compared to 58% in the control group. The results of this study show significant benefit of paclitaxel for solid tumor when administered locally in an in situ gelling poloxamer 407 formulation.

Long-circulating Poly(ethylene Glycol)-modified Gelatin Nanoparticles for Intracellular Delivery

Pharmaceutical Research. Jul, 2002  |  Pubmed ID: 12180540

The objective of this study was to develop and characterize long-circulating, biodegradable, and biocompatible nanoparticulate formulation as an intracellular delivery vehicle.

Biodegradable Poly(epsilon -caprolactone) Nanoparticles for Tumor-targeted Delivery of Tamoxifen

International Journal of Pharmaceutics. Dec, 2002  |  Pubmed ID: 12433441

To increase the local concentration of tamoxifen in estrogen receptor (ER) positive breast cancer, we have developed and characterized nanoparticle formulation using poly(epsilon -caprolactone) (PCL). The nanoparticles were prepared by solvent displacement method using acetone-water system. Particle size analysis, scanning electron microscopy, zeta potential measurements, and differential scanning calorimetry (DSC) were used for nanoparticle characterization. Biodegradation studies were performed in the presence and absence of Pseudomonas lipase in phosphate-buffered saline (PBS, pH 7.4) at 37 degrees C. Tamoxifen loading over different concentrations was analyzed by high-performance liquid chromatography (HPLC) and the optimum loading concentration was determined. In vitro release studies were performed in 0.5% (w/v) sodium lauryl sulfate (SLS) containing PBS at 37 degrees C. Cellular uptake and distribution of fluorescent-labeled nanoparticles was examined in MCF-7 breast cancer cells. SEM micrographs and Coulter analysis showed nanoparticles with spherical shape and uniform size distribution (250-300 nm), respectively. Zeta potential analysis revealed a positive surface charge of +25 mV on the tamoxifen-loaded formulation. Being hydrophobic crystalline polyester, PCL did not degrade in PBS alone, but the degradation was enhanced by the presence of lipase. The maximum tamoxifen loading efficiency was 64%. Initial burst release of tamoxifen was observed, probably due to significant surface presence of the drug on the nanoparticles. A large fraction of the administered nanoparticle dose was taken up by MCF-7 cells through non-specific endocytosis. The nanoparticles were found in the perinuclear region after 1 h. Results of the study suggest that nanoparticle formulations of selective ER modulators, like tamoxifen, would provide increased therapeutic benefit by delivering the drug in the vicinity of the ER.

Poly(ethylene Oxide)-modified Poly(beta-amino Ester) Nanoparticles As a PH-sensitive Biodegradable System for Paclitaxel Delivery

Journal of Controlled Release : Official Journal of the Controlled Release Society. Jan, 2003  |  Pubmed ID: 12526819

The main objective of this study was to develop and characterize a pH-sensitive biodegradable polymeric nanoparticulate system for tumor-selective paclitaxel delivery. A representative hydrophobic poly(beta-amino ester) (poly-1) was synthesized by conjugate addition of 4,4'-trimethyldipiperidine with 1,4-butanediol diacrylate. Poly-1 (M(n) 10,000 daltons) nanoparticles were prepared by the controlled solvent displacement method in an ethanol-water system in the presence of Pluronic) F-108, a poly(ethylene oxide) (PEO)-containing non-ionic surfactant. Control and PEO-modified nanoparticles were characterized by Coulter counter, scanning electron microscopy (SEM), zeta potential measurements, and electron spectroscopy for chemical analysis (ESCA). Polymer degradation studies were performed in phosphate-buffered saline (PBS, pH 7.4) at 37 degrees C. Paclitaxel loading capacities and efficiencies were determined and release studies were performed in Tween)-80 (0.1%, w/v)-containing PBS at 37 degrees C. Control and PEO-modified nanoparticles, labeled with rhodamine-123, were incubated with BT-20 cells to examine the uptake and cellular distribution as a function of time. PEO-modified nanoparticles with an average size of 100-150 nm and a positive surface charge of 37.0 mV were prepared. SEM analysis showed distinct smooth, spherical particles. The ether (-C-O-) peak of the C(1s) envelope in ESCA confirmed the surface presence of PEO chains. Polymer biodegradation studies showed that almost 85% of the starting material degraded after 6 days. The maximum paclitaxel loading efficiency attained was 97% at 1.0% (w/w) of the drug. Paclitaxel release studies showed that approximately 10% was released in the first 24 h, 80% after 3 days, and the entire content was released in approximately 5 days. After 1 h of incubation, a large fraction of the administered control and PEO-modified poly-1 nanoparticles was internalized in BT-20 cells. Results of this study demonstrate that PEO-modified poly-1 nanoparticles could provide increased therapeutic benefit by delivering the encapsulated drug to solid tumors.

Chitosan-based Gastrointestinal Delivery Systems

Journal of Controlled Release : Official Journal of the Controlled Release Society. Apr, 2003  |  Pubmed ID: 12711440

Chitosan, a natural polymer obtained by alkaline deacetylation of chitin, is non-toxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for the development of conventional and novel gastrointestinal (GI) drug and gene delivery systems. The objective of this review is to summarize the recent applications of chitosan in oral and/or buccal delivery, stomach-specific drug delivery, intestinal delivery, and colon-specific drug delivery. The use of chitosan for targeting of drugs to each of these sites in the GI tract is illustrated by examples supported by in vivo studies. Chitosan appears to be a promising material for GI drug and gene delivery applications as many derivatives and formulations are being examined.

Cellular Uptake and Concentrations of Tamoxifen Upon Administration in Poly(epsilon-caprolactone) Nanoparticles

AAPS PharmSci. 2003  |  Pubmed ID: 12713275

In an attempt to increase the local concentration of tamoxifen in estrogen receptor positive breast cancer cells, we have prepared and characterized poly(epsilon-caprolactone) (PCL) nanoparticle formulation.

Stomach-specific Anti-H. Pylori Therapy. II. Gastric Residence Studies of Tetracycline-loaded Chitosan Microspheres in Gerbils

Pharmaceutical Development and Technology. Aug, 2003  |  Pubmed ID: 12901691

This study examines the gastric residence of chitosan microspheres and the local tetracycline concentrations following oral administration in gerbils. Chitosan microspheres were prepared by ionic cross-linking and precipitation with sodium sulfate. Gastric retention studies were performed by administering radioiodinated [125I] chitosan microsphere suspension in the nonacid-suppressed and acid-suppressed states. At different time points, animals were sacrificed, and the radioactivity in tissues and fluids was measured with a gamma counter. Local tetracycline concentrations were measured using chitosan microspheres loaded with tritiated-[3H]-tetracycline. The radioactivity, measured with a liquid scintillation analyzer, was used to determine the microg of drug per gram of tissues or fluids under nonacid-suppressed and acid-suppressed states. Microspheres with a spherical shape and an average diameter of 2.0-3.0 microm were formed. After 2 hr in the fasted stomach, approximately 10% of the administered dose remained. The microspheres were predominantly found in the colon after 6 hr of administration. There was no detectable radioactivity in the small intestine, plasma, urine, liver, and kidneys. Additionally, acid suppression with ranitidine did not influence the gastric residence time of chitosan microspheres. To our disappointment, tetracycline concentration profile in the stomach from microsphere formulation was similar to the aqueous solution. Also, there was no significant difference between the stomach tetracycline concentrations in the nonacid-suppressed and acid-suppressed states. The drug was predominantly found in the colon and urine samples after 6 hr. Tetracycline could not be detected in the plasma, small intestine, liver, or kidneys. Results of this study show that chitosan microspheres prepared by ionic cross-linking do not provide a longer residence time in the fasted gerbil stomach. The tetracycline concentration profile in the stomach, following administration in microsphere formulation, was similar to that of aqueous solution. Lastly, acid suppression did not influence the gastric residence time of chitosan microspheres or tetracycline concentration profiles.

Enzyme Immobilization in Novel Alginate-chitosan Core-shell Microcapsules

Biomaterials. May, 2004  |  Pubmed ID: 14738858

Alginate-chitosan core-shell microcapsules were prepared in order to develop a biocompatible matrix for enzyme immobilization, where the protein is retained either in a liquid or solid core and the shell allows permeability control over substrates and products. The permeability coefficients of different molecular weight compounds (vitamin B2, vitamin B12, and myoglobin) were determined through sodium tripolyphosphate (Na-TPP)-crosslinked chitosan membrane. The microcapsule core was formed by crosslinking sodium alginate with either calcium or barium ions. The crosslinked alginate core was uniformly coated with a chitosan layer and crosslinked with Na-TPP. In the case of calcium alginate, the phosphate ions of Na-TPP were able to extract the calcium ions from alginate and liquefy the core. A model enzyme, beta-galactosidase, was immobilized in the alginate core and the catalytic activity was measured with o-nitrophenyl-beta-D-galactopyranoside (ONPG). Change in the activity of free and immobilized enzyme was determined at three different temperatures. Na-TPP crosslinked chitosan membranes were found to be permeable to solutes of up to 17,000Da molecular weight. The enzyme loading efficiency was higher in the barium alginate core (100%) as compared to the calcium alginate core (60%). The rate of ONPG conversion to o-nitrophenol was faster in the case of calcium alginate-chitosan microcapsules as compared to barium alginate-chitosan microcapsules. Barium alginate-chitosan microcapsules, however, did improve the stability of the enzyme at 37 degrees C relative to calcium alginate-chitosan microcapsules or free enzyme. This study illustrates a new method of enzyme immobilization for biotechnology applications using liquid or solid core and shell microcapsule technology.

Stomach-specific Anti-H. Pylori Therapy; Part III: Effect of Chitosan Microspheres Crosslinking on the Gastric Residence and Local Tetracycline Concentrations in Fasted Gerbils

International Journal of Pharmaceutics. Mar, 2004  |  Pubmed ID: 15019073

The main objective of the present study was to examine the effect of chemical crosslinking of chitosan microspheres on the gastric residence and local tetracycline concentrations following oral administration in fasted gerbils. Radioiodinated [125I] glyoxal-crosslinked chitosan microsphere suspension in deionized distilled water was administered for the gastric residence studies. At different time points, the animals were sacrificed and the radioactivity in tissues and fluids was measured. Stomach tetracycline concentrations were determined using tritiated-[3H]-tetracycline-loaded crosslinked chitosan microspheres. The radioactivity, measured with a liquid scintillation analyzer, was used to determine the microgram of drug per gram of tissues or fluids. After 2 h in the fasted stomach, approximately 10% of the non-crosslinked chitosan microspheres remained. On the other hand, 17% of the crosslinked chitosan microspheres remained in the fasted stomach after the same time period. The microspheres were predominantly found in the colon after 6 h of administration. There was no detectable radioactivity in the plasma, urine, small intestine, liver, and kidneys. Tetracycline concentration profile in the stomach from the crosslinked microsphere formulation was higher than that of the aqueous solution and the non-crosslinked microsphere formulation. While the area-under-the-curve (AUC(0.5-->10 h)) for tetracycline solution and non-crosslinked chitosan microspheres was 447.3 and 358.2 microg h/g of tissue, respectively, the AUC(0.5-->10 h) for the crosslinked chitosan microspheres was 868.9 microg h/g of tissue. The drug was predominantly found in the colon and urine after 6 h of administration. Results of this study show that chitosan microspheres prepared by chemical crosslinking provide a longer residence time in the fasted gerbil stomach than either tetracycline solution or microspheres prepared by ionic precipitation.

Poly-N-acetyl Glucosamine-mediated Red Blood Cell Interactions

The Journal of Trauma. Jul, 2004  |  Pubmed ID: 15280744

Investigations were performed to assess the effect of poly-N-acetyl glucosamine (p-GlcNAc) fiber slurry-mediated hemostasis by interactions with red blood cells.

Biodistribution and Targeting Potential of Poly(ethylene Glycol)-modified Gelatin Nanoparticles in Subcutaneous Murine Tumor Model

Journal of Drug Targeting. 2004  |  Pubmed ID: 15621684

In order to develop a safe and effective systemically-administered biodegradable nanoparticle delivery system for solid tumors, the comparative biodistribution profiles of gelatin and poly(ethylene-glycol)(PEG)-modified (PEGylated) gelatin nanoparticles was examined in subcutaneous Lewis lung carcinoma (LLC)-bearing female C57BL/6J mice.

Cellular Interactions and in Vitro DNA Transfection Studies with Poly(ethylene Glycol)-modified Gelatin Nanoparticles

Journal of Pharmaceutical Sciences. Jan, 2005  |  Pubmed ID: 15761942

In order to develop a systemically administered safe and effective nonviral gene delivery system, cellular interactions and plasmid DNA transfection with poly(ethylene glycol)-modified (PEGylated) gelatin nanoparticles were examined. The DNA-containing nanoparticles were prepared by a controlled water-ethanol solvent displacement method. The nanoparticles were characterized for particle size, surface charge, and DNA loading, release, and stability. For cellular interaction studies, the control and PEGylated gelatin nanoparticles, complexed either with colloidal gold for transmission electron microscopy or loaded with rhodamine-dextran for fluorescence confocal microscopy, were incubated with NIH-3T3 fibroblast cells. At different time points, the location of the nanoparticles in the cellular environment was investigated. Furthermore, a reporter plasmid expressing the enhanced green fluorescent protein was encapsulated in the control gelatin and PEGylated gelatin nanoparticles for in vitro transfection studies. DNA-containing nanoparticles were prepared in the size range of 100-500 nm, with an average of 200 nm. PEGylated gelatin nanoparticles, with a slight negative surface charge, could stably and efficiently encapsulate plasmid DNA. Both transmission electron microscopy and confocal microscopy images showed that the gelatin and PEGylated gelatin nanoparticles rapidly entered the cell through nonspecific endocytosis followed by vesicular transport in the cytosol. Almost 100% of the administered gelatin and PEGylated gelatin nanoparticles were internalized in NIH-3T3 cells within the first 6 h of incubation. A large fraction of the administered nanoparticles was found to be concentrated in the perinuclear region of the cells after 12 h. Green fluorescent protein expression was observed after 12 h of nanoparticle incubation and remained stable for up to 96 h. Flow cytometry results showed that the DNA transfection efficiency with gelatin and PEGylated gelatin nanoparticles was 43% and 61%, respectively, after 96 h. The results of this study illustrate that PEGylated gelatin nanoparticles were rapidly internalized by the cells through nonspecific endocytosis and remained intact in the cytosol for up to 12 h. In addition, the DNA-encapsulated PEGylated gelatin nanoparticles were found to efficiently transfect cells in culture.

Poly(ethylene Oxide)-modified Poly(epsilon-caprolactone) Nanoparticles for Targeted Delivery of Tamoxifen in Breast Cancer

International Journal of Pharmaceutics. Apr, 2005  |  Pubmed ID: 15778064

This study was carried out to evaluate and compare the biodistribution profile of tamoxifen when administered intravenously (i.v.) as a simple solution or when encapsulated in polymeric nanoparticulate formulations, with or without surface-stabilizing agents. Tamoxifen-loaded, poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were prepared by solvent displacement process that allowed in situ surface modification via physical adsorption of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock polymeric stabilizer (Pluronic). The nanoparticles were characterized for particle size and surface charge. Presence of PEO chains on nanoparticle surface was ascertained by electron spectroscopy for chemical analysis (ESCA). In vivo biodistribution studies were carried out in Nu/Nu athymic mice bearing a human breast carcinoma xenograft, MDA-MB-231 using tritiated [(3)H]-tamoxifen as radio-marker for quantification. PEO-PCL nanoparticles with an average diameter of 150-250 nm, having a smooth spherical shape, and a positive surface charge were obtained with the formulation procedure. About 90% drug encapsulation efficiency was achieved when tamoxifen was loaded at 10% by weight of the polymer. Aqueous wettability, suspendability, and ESCA results showed surface hydrophilization of the PCL nanoparticles by the Pluronics. The primary site of accumulation for the drug-loaded nanoparticles after i.v. administration was the liver, though up to 26% of the total activity could be recovered in tumor at 6h post-injection for PEO-modified nanoparticles. PEO-PCL nanoparticles exhibited significantly increased level of accumulation of the drug within tumor with time as well as extended their presence in the systemic circulation than the controls (unmodified nanoparticles or the solution form). Pluronic surfactants (F-68 and F-108) presented simple means for efficient surface modification and stabilization of PCL nanoparticles to achieve preferential tumor-targeting and a circulating drug reservoir for tamoxifen.

Tumor-targeted Gene Delivery Using Poly(ethylene Glycol)-modified Gelatin Nanoparticles: in Vitro and in Vivo Studies

Pharmaceutical Research. Jun, 2005  |  Pubmed ID: 15948039

To develop safe and effective systemically administered nonviral gene therapy vectors for solid tumors, DNA-containing poly(ethylene glycol)-modified (PEGylated) gelatin nanoparticles were fabricated and evaluated in vitro and in vivo.

Poly(ethylene Oxide)-modified Poly(beta-amino Ester) Nanoparticles As a PH-sensitive System for Tumor-targeted Delivery of Hydrophobic Drugs. 1. In Vitro Evaluations

Molecular Pharmaceutics. Sep-Oct, 2005  |  Pubmed ID: 16196488

A representative poly(beta-amino ester) (PbAE) with biodegradable and pH-sensitive properties was used to formulate a nanoparticle-based dosage form for tumor-targeted paclitaxel delivery. The polymer undergoes rapid dissolution when the pH of the medium is less than 6.5 and hence is expected to release its contents at once within the acidic tumor microenvironment and endo/lysosome compartments of cells. PbAE nanoparticles were prepared by solvent displacement method and characterized for particle size, charge, and surface morphology. Pluronic F-108, a triblock copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), was blended with PbAE to induce surface modification of the nanoparticles. In vitro cellular uptake of tritiated [(3)H]-paclitaxel in solution form and as a nanoparticulate formulation was studied in MDA-MB-231 human breast adenocarcinoma cells grown in 12-well plates. We also examined the intracellular degradation pattern of the formulations within the cells by estimating the drug release profile. Cytotoxicity assay was performed on the formulations at different doses and time intervals. Nanoparticles prepared from poly(epsilon-caprolactone) (PCL) that do not display pH-sensitive release behavior were used as control. Spherical nanoparticles having positive zeta potential ( approximately 40 mV) were obtained in the size range of 150-200 nm with PbAE. The PEO chains of the Pluronic were well-anchored within the nanomatrix as determined by electron spectroscopy for chemical analysis (ESCA). The intracellular accumulation of paclitaxel within tumor cells was significantly higher when administered in the nanoparticle formulations as compared to aqueous solution. Qualitative fluorescent microscopy confirmed the rapid release of the payload into the cytosol in the case of PbAE nanoparticles, while the integrity of the PCL nanoparticles remained intact. The cytotoxicity assay results showed significantly higher tumoricidal activity of paclitaxel when administered in the nanoparticle formulations. The cell-kill effect was maximal for paclitaxel-loaded PbAE nanoparticles when normalized with respect to intracellular drug concentrations. Thus, PEO-modified PbAE nanoparticles show tremendous potential as novel carriers of cytotoxic agents for achieving improved drug disposition and enhanced efficacy.

An Approach to Heterobifunctional Poly(ethyleneglycol) Bioconjugates

Bioorganic & Medicinal Chemistry Letters. Dec, 2005  |  Pubmed ID: 16236512

A family of differentially substituted poly(ethyleneglycol) building blocks has been assembled from commercially available material. Their utility is demonstrated by formation of amino acid conjugates, image contrast agents, gold nanoparticles, and functional antibody conjugates. Application in the cellular trafficking of antitumoral agent conjugates is expected.

Poly(ethylene Oxide)-modified Poly(beta-amino Ester) Nanoparticles As a PH-sensitive System for Tumor-targeted Delivery of Hydrophobic Drugs: Part 2. In Vivo Distribution and Tumor Localization Studies

Pharmaceutical Research. Dec, 2005  |  Pubmed ID: 16254763

This study was carried out to determine the biodistribution profiles and tumor localization potential of poly(ethylene oxide) (PEO)-modified poly(beta-amino ester) (PbAE) as a novel, pH-sensitive biodegradable polymeric nanoparticulate system for tumor-targeted drug delivery.

Preparation and Evaluation of Thiol-modified Gelatin Nanoparticles for Intracellular DNA Delivery in Response to Glutathione

Bioconjugate Chemistry. Nov-Dec, 2005  |  Pubmed ID: 16287238

To enhance the intracellular delivery potential of plasmid DNA using nonviral vectors, we have developed thiolated gelatin nanoparticles that can release the payload in the highly reducing environment, such as in response to glutathione. Thiolated gelatin was synthesized by covalent modification of the primary amino groups of Type B gelatin using 2-iminothiolane (Traut's reagent). The degree of thiolation of the polymers ranged from 0 to 43.71 mmol of reduced sulfhydryl (SH) groups when the amount of 2-iminothiolane was increased up to 100 mg per gram of the biopolymer. Cytotoxicity evaluations carried out by the formazan (MTS) assay showed that the thiolated gelatin prepared with 20 mg and 40 mg of 2-iminothiolane (SHGel-20 and SHGel-40) per gram of gelatin had comparable cell viability profile to that of the unmodified gelatin. In vitro release studies of fluorescein isothiocyanate (FITC)-labeled dextran (mol wt. 70 000 Da), when encapsulated in gelatin and thiolated gelatin nanoparticles (150-250 nm in diameter), was found to be affected by the presence of glutathione (GSH) in the medium. The presence of GSH was found to enhance the release by about 40% in case of thiolated gelatin and about 20% in gelatin nanoparticles under similar conditions of temperature and GSH concentrations. Qualitative and quantitative analysis of transfection in NIH-3T3 murine fibroblast cells by the nanoparticles carrying plasmid DNA encoding for enhanced green fluorescent protein (EGFP-N1) was done by fluorescence confocal microscopy and fluorescence-activated cell sorting (FACS). Qualitative results showed highly efficient expression of GFP that remained stable for up to 96 h. Quantitative results from FACS showed that the thiolated gelatin nanoparticles (SHGel-20) were significantly more effective in transfecting NIH-3T3 cells than other carrier systems examined. The results of this study show that thiolated gelatin nanoparticles would serve as a biocompatible intracellular delivery system that can release the payload in a highly reducing environment.

Long-circulating Polymeric Nanovectors for Tumor-selective Gene Delivery

Technology in Cancer Research & Treatment. Dec, 2005  |  Pubmed ID: 16292881

Significant advances in the understanding of the genetic abnormalities that lead to the development, progression, and metastasis of neoplastic diseases has raised the promise of gene therapy as an approach to medical intervention. Most of the clinical protocols that have been approved in the United States for gene therapy have used the viral vectors because of the high efficiency of gene transfer. Conventional means of gene delivery using viral vectors, however, has undesirable side effects such as insertion of mutational viral gene into the host genome and development of replication competent viruses. Among non-viral gene delivery methods, polymeric nanoparticles are increasingly becoming popular as vectors of choice. The major limitation of these nanoparticles is poor transfection efficiency at the target site after systemic administration due to uptake by the cells of reticuloendothelial system (RES). In order to reduce the uptake by the cells of the RES and improve blood circulation time, these nanoparticles are coated with hydrophilic polymers such as poly(ethylene glycol) (PEG). This article reviews the use of such hydrophilic polymers employed for improving the circulation time of the nanocarriers. The mechanism of polymer coating and factors affecting the circulation time of these nanocarriers will be discussed. In addition to the long circulating property, modifications to improve the target specificity of the particles and the limitations of steric protection will be analyzed.

Formulation Optimization for the Nanoparticles-in-microsphere Hybrid Oral Delivery System Using Factorial Design

Journal of Controlled Release : Official Journal of the Controlled Release Society. Jan, 2006  |  Pubmed ID: 16338017

The tremendous progress witnessed in the field of biotechnology with respect to discovery of therapeutic and antigenic proteins has propelled the need for development of suitable oral delivery devices for these and other macromolecules. In this study, we report the encapsulation of fluorescein isothiocyanate (FITC)-labeled gelatin nanoparticles into poly(epsilon-caprolactone) (PCL) microsphere (nanoparticle-in-microsphere oral delivery system, NiMOS) by double emulsion like technique and the influence of variables such as polymer concentration in organic phase, amount of nanoparticles added as internal phase, and the speed of homogenization on particle size of NiMOS using a 3(3) randomized full factorial design. A statistical model with interaction terms was derived to predict the particle size of the hybrid system. The results from multiple linear regression analysis and Student's t-test revealed that for obtaining large particles of NiMOS, a high polymer concentration and low speed of homogenization was necessary. In contrast, to obtain particles of smaller size, high speed of homogenization was found to be very important. The mathematical model obtained was validated for prediction of particle size. The encapsulation of gelatin nanoparticles in PCL microsphere was confirmed by fluorescent microscopy. Based on the statistical model we were also successful in producing NiMOS of less than 10 mum in size, which could be used as oral delivery system for therapeutic and antigenic macromolecules.

Surface Functionalization of Gold Nanoparticles Using Hetero-bifunctional Poly(ethylene Glycol) Spacer for Intracellular Tracking and Delivery

International Journal of Nanomedicine. 2006  |  Pubmed ID: 16467923

For the development of surface-functionalized gold nanoparticles as cellular probes and delivery agents, we have synthesized hetero-bifunctional poly(ethylene glycol) (PEG, MW 1500) having a thiol group on one terminus and a reactive functional group on the other for use as a flexible spacer. Coumarin, a model fluorescent dye, was conjugated to one end of the PEG spacer and gold nanoparticles were modified with coumarin-PEG-thiol. Surface attachment of coumarin through the PEG spacer decreased the fluorescence quenching effect of gold nanoparticles. The results of cellular cytotoxicity and fluorescence confocal analyses showed that the PEG spacer-modified nanoparticles were essentially non-toxic and could be efficiently internalized in the cells within 1 hour of incubation. Intracellular particle tracking using a Keck 3-D Fusion Microscope System showed that the functionalized gold nanoparticles were rapidly internalized in the cells and localized in the peri-nuclear region. Using the PEG spacer, the gold nano-platform can be conjugated with a variety of biologically relevant ligands such as fluorescent dyes, antibodies, etc in order to target, probe, and induce a stimulus at the target site.

Multi-functional Polymeric Nanoparticles for Tumour-targeted Drug Delivery

Expert Opinion on Drug Delivery. Mar, 2006  |  Pubmed ID: 16506948

The use of nanoparticles as drug delivery vehicles for anticancer therapeutics has great potential to revolutionise the future of cancer therapy. As tumour architecture causes nanoparticles to preferentially accumulate at the tumour site, their use as drug delivery vectors results in the localisation of a greater amount of the drug load at the tumour site; thus improving cancer therapy and reducing the harmful nonspecific side effects of chemotherapeutics. In addition, formulation of these nanoparticles with imaging contrast agents provides a very efficient system for cancer diagnostics. Given the exhaustive possibilities available to polymeric nanoparticle chemistry, research has quickly been directed at multi-functional nanoparticles, combining tumour targeting, tumour therapy and tumour imaging in an all-in-one system, providing a useful multi-modal approach in the battle against cancer. This review will discuss the properties of nanoparticles that allow for such multiple functionality, as well as recent scientific advances in the area of multi-functional nanoparticles for cancer therapeutics.

A Review of Nanocarrier-based CNS Delivery Systems

Current Drug Delivery. Apr, 2006  |  Pubmed ID: 16611008

Drug delivery to the central nervous system (CNS) is one of the most challenging fields of research and development for pharmaceutical and biotechnology products. A number of hydrophilic therapeutic agents, such as antibiotics, anticancer agents, or newly developed neuropeptides do not cross the blood brain barrier (BBB) after systemic administration. The BBB is formed by the tight junctions at the brain capillary endothelial cells, which strictly control drug transfer from blood to brain. Drug modification, osmotic opening of cerebral capillary endothelium, and alternative routes for administration (e.g., intracerebral delivery) have been successfully used to enhance drug transport to the CNS. The use of nanocarriers, such as liposomes and solid polymeric or lipid nanoparticles may be advantageous over the current strategies. These nanocarriers can not only mask the BBB limiting characteristics of the therapeutic drug molecule, but may also protect the drug from chemical/enzymatic degradation, and additionally provide the opportunity for sustained release characteristics. Reduction of toxicity to peripheral organs can also be achieved with these nanocarriers. This review article discusses the various barriers for drug delivery to the CNS and reviews the current state of nanocarriers for enhancing drug transport into the CNS.

Role of Nanotechnology in HIV/AIDS Treatment: Potential to Overcome the Viral Reservoir Challenge

Discovery Medicine. Aug, 2006  |  Pubmed ID: 17234137

Insufficient concentrations and very short residence time of the anti-retroviral agents at the cellular and anatomical sites are among major factors that contribute to the failure of eradicating HIV from reservoirs and the development of multidrug resistance against antiretroviral agents. In recent years, nanotechnology-based drug delivery systems have shown remarkable ability to overcome many of the same anatomical and physiological barriers and deliver the therapeutic agents locally at the site of systemic diseases such as cancer.

Formulation and Physiological Factors Influencing CNS Delivery Upon Intranasal Administration

Critical Reviews in Therapeutic Drug Carrier Systems. 2006  |  Pubmed ID: 17341201

The treatment of central nervous system (CNS) disorders is particularly challenging because of a variety of formidable barriers to effective and persistent delivery of therapeutic compounds. This review discusses the potential of intranasal drug administration as a means to bypass a major barrier, the blood-brain barrier, and allow for direct delivery of drugs into the CNS. The article emphasizes physicochemical properties of intranasal drug formulations as well as relevant anatomical and physiological factors in intranasal delivery of drugs for CNS therapy. Published examples of intranasal administration of small molecular weight drugs, peptides and proteins, and novel formulations for delivering a broad spectrum of molecules are discussed. Finally, the article provides several strategies for effectively enhancing nose-to-brain transport of drug molecules through rational formulation design and optimization.

Nanoparticulate Drug Carriers for Delivery of HIV/AIDS Therapy to Viral Reservoir Sites

Expert Opinion on Drug Delivery. Sep, 2006  |  Pubmed ID: 16948557

Providing the optimum treatment of AIDS is a major challenge in the 21st Century. HIV is localised and harboured in certain inaccessible compartments of the body, such as the CNS, the cerebrospinal fluid, the lymphatic system and in the macrophages, where it cannot be reached by the majority of therapeutic agents in adequate concentrations or in which the therapeutic agents cannot reside for the necessary duration. Progression in HIV/AIDS treatment suggests that available therapy can lower the systemic viral load below the detection limit. However, on discontinuation of treatment, there is relapse of the infection from the reservoir sites and a potential for resistance development. This review discusses the aetiology and pathology of HIV, with emphasis on the viral reservoirs, current therapy of AIDS, and the opportunity for nanotechnology-based drug delivery systems to facilitate complete eradication of viral load from the reservoir sites. Literature-cited examples of drug delivery systems that are under investigation for the treatment of AIDS are discussed. The article also focuses on the future outlook and strategies for investigational drug formulations that use nanotherapeutic strategy for HIV/AIDS.

Intracellular Delivery of Saquinavir in Biodegradable Polymeric Nanoparticles for HIV/AIDS

Pharmaceutical Research. Nov, 2006  |  Pubmed ID: 16969696

This study aims at developing poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticulate system as an intracellular delivery vehicle for saquinavir, an anti-HIV protease inhibitor.

Improved Oral Delivery of Paclitaxel Following Administration in Nanoemulsion Formulations

Journal of Nanoscience and Nanotechnology. Sep-Oct, 2006  |  Pubmed ID: 17048539

Nanoemulsion formulations were designed for enhancing the oral bioavailability of hydrophobic drugs. Paclitaxel was selected as a model hydrophobic drug, which is also a substrate for the P-glycoprotein efflux system. The oil-in-water (o/w) nanoemulsions were formulated with pine nut oil as the internal oil phase, egg lecithin as the primary emulsifier, and water as the external phase. Stearylamine and deoxycholic acid were used to impart positive and negative charge to the emulsions, respectively. Nanoemulsions were prepared by sonication method and characterized for particle size and surface charge. The control and nanoemulsion formulations with tritiated [3H]-paclitaxel were administered orally to female C57BL/6 mice and the distribution of the drug was examined. The formulated nanoemulsions had a particle size range of approximately 90-120 nm (laser diffraction method) and zeta potential values ranging from -56 mV to +34 mV. Following oral administration, a significantly higher concentration of paclitaxel was observed in the systemic circulation when administered in the nanoemulsion relative to control aqueous solution. The absorbed drug was found to be distributed in the liver, kidneys, and lungs. The results of this study suggest that nanoemulsions are promising novel formulations that can enhance the oral bioavailability of hydrophobic drugs, like paclitaxel.

Biodistribution and Pharmacokinetic Analysis of Long-circulating Thiolated Gelatin Nanoparticles Following Systemic Administration in Breast Cancer-bearing Mice

Journal of Pharmaceutical Sciences. Feb, 2007  |  Pubmed ID: 17075865

The objective of the present study was to modify thiolated gelatin nanoparticles with poly(ethylene glycol) (PEG) chains and examine their long circulating and tumor-targeting properties in vivo in an orthotopic a human breast adenocarcinoma xenograft model. The crosslinked nanoparticle systems were characterized to have a size of 150-250 nm with rapid payload release properties in a highly reducing environment. Upon PEG modification, the nanoparticle size increased to 300-350 nm in diameter. The presence of PEG chains on the surface was confirmed by characterization with electron spectroscopy for chemical analysis. The in vivo long-circulating potential, biodistribution and passive tumor targeting of the controls, and PEG-modified thiolated gelatin nanoparticles were evaluated by injecting indium-111 (111In)-labeled nanoparticles into breast tumor (MDA-MB-435)-bearing nude mice. Upon modification with PEG, the nanoparticles were found to have longer circulation times, with the plasma and tumor half-lives of 15.3 and 37.8 h, respectively. The results also showed preferential localization of thiolated nanoparticles in the tumor mass. The resulting nanoparticulate systems with long circulation properties could be used to target encapsulated drugs and genes to tumors passively by utilizing the enhanced permeability and retention effect of the tumor vasculature.

Nanocarriers for Systemic and Mucosal Vaccine Delivery

Recent Patents on Drug Delivery & Formulation. 2007  |  Pubmed ID: 19075870

Over the past several years, immunization and treatment of infectious diseases has undergone a paradigm shift. Stemming from the vaccine research and development, not only a large number of disease-specific vaccines have been developed, but also enormous efforts have been made to improve the effectiveness of vaccines in order to provide optimal immunization. Introduction of nanotechnology and the development of nanocarrier-based vaccines have started to receive a lot of attention in order to provide effective immunization through better targeting and by triggering antibody response at the cellular level. Also, in the past several years, attention is placed on routes of vaccine administration in order to induce both mucosal and systemic immunity against the pathogen. Through judicious selection of the nanocarrier systems and the vaccine antigen, an optimal immunization and protection can be induced. This review article focuses on the patented applications of nanocarrier-based vaccine formulations and delivery. We have examined the United States patent literature to select inventions that specifically address this strategic approach for prevention of infectious diseases.

An Overview of Condensing and Noncondensing Polymeric Systems for Gene Delivery

CSH Protocols. 2007  |  Pubmed ID: 21357090

INTRODUCTIONSelf-assembling synthetic vectors for DNA delivery are designed to fulfill several biological functions. They must be able to deliver their genetic payload specifically to the target tissue/cells in a site-specific manner, while protecting the genetic material from degradation by metabolic or immune pathways. Furthermore, they must exhibit minimal toxicity and be proven safe enough for therapeutic use. Ultimately, they must have the capability to express a therapeutic gene for a finite period of time in an appropriate, regulated fashion. The DNA encapsulated in these vectors may be in a condensed or noncondensed form, depending on the nature of the polymer and the technique used for formulating the vector system. The whole process presents many barriers at both tissue and cellular levels. Overcoming these hurdles is the principal objective for efficient polymer-based DNA therapeutics.

Poly(ethylene Glycol)-modified Thiolated Gelatin Nanoparticles for Glutathione-responsive Intracellular DNA Delivery

Nanomedicine : Nanotechnology, Biology, and Medicine. Mar, 2007  |  Pubmed ID: 17379167

Poly(ethylene glycol) (PEG)-modified thiolated gelatin (PEG-SHGel) anoparticles were developed as a long-circulating passively targeted delivery system that responds to intracellular glutathione concentrations to enhance DNA delivery and transfection. Reporter plasmid expressing enhanced green fluorescent protein (EGFP-N1) was encapsulated in the nanoparticles. DNA-containing gelatin (Gel) and thiolated gelatin (SHGel) nanoparticles were found to have a size range of 220 to 250 nm, whereas surface modification with PEG resulted in particles with a slightly larger size range of 310 to 350 nm. PEG modification was confirmed by electron spectroscopy for chemical analysis (ESCA), where an increase in the ether peak intensities of the C1s spectra corresponds to the surface presence of ethylene oxide residues. In addition, the PEG-SHGel nanoparticles released encapsulate plasmid DNA in response to varying concentrations of glutathione (up to 5.0 mM GSH in phosphate-buffered saline, or PBS). The stability of the encapsulated DNA was confirmed by agarose gel electrophoresis. Finally, from the qualitative and quantitative results of in vitro transfection studies in murine fibroblast cells (NIH3T3), PEG-Gel and PEG-SHGel nanoparticles afforded the highest transfection efficiency of the reporter plasmid. The results of these studies show that PEG-modified thiolated gelatin nanoparticles could serve as a very efficient nanoparticulate vector for systemic DNA delivery to solid tumors where the cells are known to have significantly higher intracellular GSH concentrations.

Poly(ethylene Glycol)-modified Nanocarriers for Tumor-targeted and Intracellular Delivery

Pharmaceutical Research. Aug, 2007  |  Pubmed ID: 17393074

The success of anti-cancer therapies largely depends on the ability of the therapeutics to reach their designated cellular and intracellular target sites, while minimizing accumulation and action at non-specific sites. Surface modification of nanoparticulate carriers with poly(ethylene glycol) (PEG)/poly(ethylene oxide) (PEO) has emerged as a strategy to enhance solubility of hydrophobic drugs, prolong circulation time, minimize non-specific uptake, and allow for specific tumor-targeting through the enhanced permeability and retention effect. Furthermore, PEG/PEO modification has emerged as a platform for incorporation of active targeting ligands, thereby providing the drug and gene carriers with specific tumor-targeting properties through a flexible tether. This review focuses on the recent developments surrounding such PEG/PEO-surface modification of polymeric nanocarriers to promote tumor-targeting capabilities, thereby enhancing efficacy of anti-cancer therapeutic strategies.

Gastrointestinal Distribution and in Vivo Gene Transfection Studies with Nanoparticles-in-microsphere Oral System (NiMOS)

Journal of Controlled Release : Official Journal of the Controlled Release Society. Jun, 2007  |  Pubmed ID: 17475358

The aim of this investigation was to develop and evaluate a novel nanoparticles-in-microsphere oral system (NiMOS) for gene delivery and transfection in specific regions of the gastrointestinal (GI) tract. Plasmid DNA, encoding either for beta-galactosidase (CMV-betagal) or enhanced green fluorescent protein (EFGP-N1), was encapsulated in type B gelatin nanoparticles. NiMOS were prepared by further protecting the DNA-loaded nanoparticles in a poly(epsilon-caprolactone) (PCL) matrix to form microspheres of less than 5.0 microm in diameter. In order to evaluate the biodistribution following oral administration, radiolabeled ((111)In-labeled) gelatin nanoparticles and NiMOS were administered orally to fasted Wistar rats. The results of biodistribution studies showed that, while gelatin nanoparticles traversed through the GI tract fairly quickly with more than 85% of the administered dose per gram localizing in the large intestine within the first hour, NiMOS resided in the stomach and small intestine for relatively longer duration. Following oral administration of CMV-betagal or EFGP-N1 plasmid DNA at 100 microg dose in the control and test formulations, the qualitative results presented in this study provide the proof-of-concept for the transfection capability of NiMOS upon oral administration. After 5 days post-administration, we observed transgene expression in the small and large intestine of rats. Based on these preliminary results, NiMOS show significant potential as novel gene delivery vehicle for therapeutic and vaccination purposes.

Polymeric Nano- and Microparticle Technologies for Oral Gene Delivery

Expert Opinion on Drug Delivery. May, 2007  |  Pubmed ID: 17489649

Gene therapy refers to local or systemic administration of a nucleic acid construct that can prevent, treat and even cure diseases by changing the expression of genes that are responsible for the pathological condition. Oral gene therapy has significant promise for treatment of local diseases such as inflammatory bowel disease and for systemic absorption of the expressed protein therapeutics. In addition, efficient oral delivery of DNA vaccines can have significant impact in disease prevention. The use of polymeric gene delivery vectors promises the translation of this experimental medical concept into clinical reality. This review addresses the challenges and opportunities in the development of polymer-based nano- and microparticle technologies for oral gene therapy. Specifically, the discussion is focused on different synthetic and natural polymers used for formulating nano- and microparticle technologies and the use of these delivery systems for oral DNA administration for therapeutic and vaccination purposes.

Modulation of Intracellular Ceramide Using Polymeric Nanoparticles to Overcome Multidrug Resistance in Cancer

Cancer Research. May, 2007  |  Pubmed ID: 17510414

Although multidrug resistance (MDR) is known to develop through a variety of molecular mechanisms within the tumor cell, many tend to converge toward the alteration of apoptotic signaling. The enzyme glucosylceramide synthase (GCS), responsible for bioactivation of the proapoptotic mediator ceramide to a nonfunctional moiety glucosylceramide, is overexpressed in many MDR tumor types and has been implicated in cell survival in the presence of chemotherapy. The purpose of this study was to investigate the therapeutic strategy of coadministering ceramide with paclitaxel, a commonly used chemotherapeutic agent, in an attempt to restore apoptotic signaling and overcome MDR in the human ovarian cancer cell line SKOV3. Poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were used to encapsulate and deliver the therapeutic agents for enhanced efficacy. Results show that indeed the cotherapy eradicates the complete population of MDR cancer cells when they are treated at their IC(50) dose of paclitaxel. More interestingly, when the cotherapy was combined with the properties of nanoparticle drug delivery, the MDR cells can be resensitized to a dose of paclitaxel near the IC(50) of non-MDR (drug sensitive) cells, indicating a 100-fold increase in chemosensitization via this approach. Molecular analysis of activity verified the hypothesis that the efficacy of this therapeutic approach is indeed due to a restoration in apoptotic signaling, although the beneficial properties of PEO-PCL nanoparticle delivery seemed to enhance the therapeutic success even further, showing the promising potential for the clinical use of this therapeutic strategy to overcome MDR.

Paclitaxel and Ceramide Co-administration in Biodegradable Polymeric Nanoparticulate Delivery System to Overcome Drug Resistance in Ovarian Cancer

International Journal of Cancer. Journal International Du Cancer. Oct, 2007  |  Pubmed ID: 17557285

The objective of this study was to overcome drug resistance upon systemic administration of combination paclitaxel (PTX) and the apoptotic signaling molecule C(6)-ceramide (CER) in biodegradable poly(ethylene oxide)-modified poly(epsilon-caprolactone (PEO-PCL) nanoparticles. Subcutaneous sensitive (wild-type) and multidrug resistant (MDR-1 positive) SKOV-3 human ovarian adenocarcinoma xenografts were established in female Nu/Nu mice. PTX and CER were administered intravenously either as a single agent or in combination in aqueous solution and in PEO-PCL nanoparticles to the tumor-bearing mice. There was significant (p< 0.05) tumor growth suppression in both wild-type SKOV-3 and multidrug resistant SKOV-3(TR) models upon single dose co-administration of PTX (20 mg/kg) and CER (100 mg/kg) in nanoparticle formulations as compared to the individual agents and administration in aqueous solutions. For instance, in SKOV-3 wild-type model, more than 4.3-fold increase (p < 0.05) in tumor growth delay and 3.6-fold (p < 0.05) increase in tumor volume doubling time (DT) were observed with the combination treatment in nanoparticles as compared to untreated animals. Similarly, 3-fold increase (p < 0.05) in tumor growth delay and tumor volume DT was observed in SKOV-3(TR) model. Body weight changes and blood cells counts were used as measures of safety and, except for an increase in platelet counts (p < 0.05) in PTX + CER treated animals, there was no difference between various treatment strategies. The results of this study show that combination of PTX and CER in biodegradable polymeric nanoparticles can serve as a very effective therapeutic strategy to overcome drug resistance in ovarian cancer.

Synthesis and Evaluation of Tripodal Peptide Analogues for Cellular Delivery of Phosphopeptides

Journal of Medicinal Chemistry. Jul, 2007  |  Pubmed ID: 17580848

Tripodal peptide analogues were designed on the basis of the phosphotyrosine binding pocket of the Src SH2 domain and assayed for their ability to bind to fluorescein-labeled phosphopeptides. Fluorescence polarization assays showed that a number of amphipathic linear peptide analogues (LPAs), such as LPA4, bind to fluorescein-labeled GpYEEI (F-GpYEEI). LPA4 was evaluated for potential application in cellular delivery of phosphopeptides. Fluorescence microimaging cellular uptake studies with fluorescein-attached LPA4 (F-LPA4) alone or with the mixture of LPA4 and F-GpYEEI in BT-20 cells showed dramatic increase of the fluorescence intensity in cytosol of cells, indicating that LPA4 can function as a delivery tool of F-GpYEEI across the cell membrane. Fluorescent flow cytometry studies showed the cellular uptake of F-LPA4 in an energy-independent pathway and confirmed the cellular uptake of F-GpYEEI in the presence of LPA4. These studies suggest that amphipathic tripodal peptide analogues, such as LPA4, can be used for cellular delivery of phosphopeptides.

Role of Nanotechnology in Pharmaceutical Product Development

Journal of Pharmaceutical Sciences. Oct, 2007  |  Pubmed ID: 17688284

A number of new molecular entities (NMEs) selected for full-scale development based on their safety and pharmacological data suffer from undesirable physicochemical and biopharmaceutical properties, which lead to poor pharmacokinetics and distribution after in vivo administration. An optimization of the preformulation studies to develop a dosage form with proper drug delivery system to achieve desirable pharmacokinetic and toxicological properties can aid in the accelerated development of these NMEs into therapies. Nanoparticulate drug delivery systems show a promising approach to obtain desirable druglike properties by altering the biopharmaceutics and pharmacokinetics properties of the molecule. Apart from the advantages of enhancing potential for systemic administration, nanoparticulate drug delivery systems can also be used for site-specific delivery, thus alleviating unwanted toxicity due to nonspecific distribution, improve patient compliance, and provide favorable clinical outcomes. This review summarizes some of the parameters and approaches that can be used to evaluate nanoparticulate drug delivery systems in early stages of formulation development.

Nanoparticulate Carriers for the Treatment of Coronary Restenosis

International Journal of Nanomedicine. 2007  |  Pubmed ID: 17722543

The current treatment for coronary restenosis following balloon angioplasty involves the use of a mechanical or a drug-eluting stent. Despite the high usage of commercially-available drug-eluting stents in the cardiac field, there are a number of limitations. This review will present the background ofrestenosis, go briefly into the molecular and cellular mechanisms of restenosis, the use of mechanical stents in coronary restenosis, and will provide an overview of the drugs and genes tested to treat restenosis. The primary focus of this article is to present a comprehensive overview on the use of nanoparticulate delivery systems in the treatment of restenosis both in-vitro and in-vivo. Nanocarriers have been tested in a variety of animal models and in human clinical trials with favorable results. Polymer-based nanoparticles, liposomes, and micelles will be discussed, in addition to the findings presented in the field of cardiovascular drug targeting. Nanocarrier-based delivery presents a viable alternative to the current stent based therapies.

Poly(ethylene Oxide)-modified Poly(beta-amino Ester) Nanoparticles As a PH-sensitive System for Tumor-targeted Delivery of Hydrophobic Drugs: Part 3. Therapeutic Efficacy and Safety Studies in Ovarian Cancer Xenograft Model

Cancer Chemotherapy and Pharmacology. Mar, 2007  |  Pubmed ID: 16862429

The objective of this study was to evaluate the anti-tumor efficacy and lack of systemic toxicity of paclitaxel when administered in pH-sensitive poly(ethylene oxide) (PEO)-modified poly(beta-amino ester) (PbAE) nanoparticles in mice bearing human ovarian adenocarcinoma (SKOV-3) xenograft.

Cytotoxicity and Apoptosis Enhancement in Brain Tumor Cells Upon Coadministration of Paclitaxel and Ceramide in Nanoemulsion Formulations

Journal of Pharmaceutical Sciences. Jul, 2008  |  Pubmed ID: 17854074

The objective of this study was to examine augmentation of therapeutic activity in human glioblastoma cells with combination of paclitaxel (PTX) and the apoptotic signaling molecule, C(6)-ceramide (CER), when administered in novel oil-in-water nanoemulsions. The nanoemulsions were formulated with pine-nut oil, which has high concentrations of essential polyunsaturated fatty acid (PUFA). Drug-containing nanoemulsions were characterized for particle size, surface charge, and the particle morphology was examined with transmission electron microscopy (TEM). Epi-fluorescent microscopy was used to analyze nanoemulsion-encapsulated rhodamine-labeled PTX and NBD-labeled CER uptake and distribution in U-118 human glioblastoma cells. Cell viability was assessed with the MTS (formazan) assay, while apoptotic activity of PTX and CER was evaluated with caspase-3/7 activation and flow cytometry. Nanoemulsion formulations with the oil droplet size of approximately 200 nm in diameter were prepared with PTX, CER, and combination of the two agents. When administered to U-118 cells, significant enhancement in cytotoxicity was observed with combination of PTX and CER as compared to administration of individual agents. The increase in cytotoxicity correlated with enhancement in apoptotic activity in cells treated with combination of PTX and CER. The results of these studies show that oil-in-water nanoemulsions can be designed with combination therapy for enhancement of cytotoxic effect in brain tumor cells. In addition, PTX and CER can be used together to augment therapeutic activity, especially in aggressive tumor models such as glioblastoma.

A Review of Stimuli-responsive Nanocarriers for Drug and Gene Delivery

Journal of Controlled Release : Official Journal of the Controlled Release Society. Mar, 2008  |  Pubmed ID: 18261822

Nanotechnology has shown tremendous promise in target-specific delivery of drugs and genes in the body. Although passive and active targeted-drug delivery has addressed a number of important issues, additional properties that can be included in nanocarrier systems to enhance the bioavailability of drugs at the disease site, and especially upon cellular internalization, are very important. A nanocarrier system incorporated with stimuli-responsive property (e.g., pH, temperature, or redox potential), for instance, would be amenable to address some of the systemic and intracellular delivery barriers. In this review, we discuss the role of stimuli-responsive nanocarrier systems for drug and gene delivery. The advancement in material science has led to design of a variety of materials, which are used for development of nanocarrier systems that can respond to biological stimuli. Temperature, pH, and hypoxia are examples of "triggers" at the diseased site that could be exploited with stimuli-responsive nanocarriers. With greater understanding of the difference between normal and pathological tissues and cells and parallel developments in material design, there is a highly promising role of stimuli-responsive nanocarriers for drug and gene delivery in the future.

Poly(beta-amino Ester) and Cationic Phospholipid-based Lipopolyplexes for Gene Delivery and Transfection in Human Aortic Endothelial and Smooth Muscle Cells

Biomacromolecules. Apr, 2008  |  Pubmed ID: 18307309

Safe and effective nonviral gene delivery and transfection in primary human vascular endothelial cells (EC) and smooth muscle cells (SMC) has tremendous potential for cardiovascular diseases such as in the treatment of coronary restenosis. Using a combination of a cationic biodegradable polymer, poly(beta-amino ester) (PBAE), and a cationic phospholipid, 1,2-dioleoyl-3-trimethylammonium propane (DOTAP), we have engineered a lipopolyplex nanovector system that can transfect EC and SMC cells with reasonably high efficiency. For instance, upon addition of 1.0 microg DNA complexed in lipopolyplexes the transfection efficiency in SMC was 20% and in EC was 33%. The results of this study shows that PBAE-DOTAP-plasmid DNA lipopolyplexes are a promising nonviral vector system for gene delivery and transfection in EC and SMC.

Development of Novel Biodegradable Polymeric Nanoparticles-in-microsphere Formulation for Local Plasmid DNA Delivery in the Gastrointestinal Tract

AAPS PharmSciTech. 2008  |  Pubmed ID: 18446494

There is a critical need for development of novel delivery systems to facilitate the translation of nucleic acid-based macromolecules into clinically-viable therapies. The aim of this investigation was to develop and evaluate a novel nanoparticles-in-microsphere oral system (NiMOS) for gene delivery and transfection in specific regions of the gastrointestinal (GI) tract. Plasmid DNA, encoding for the enhanced green fluorescent protein (EGFP-N1), was encapsulated in type B gelatin nanoparticles. NiMOS were prepared by further protecting the DNA-loaded nanoparticles in a poly(epsilon-caprolactone) (PCL) matrix to form microspheres of less than 5.0 microm in diameter. In order to evaluate the biodistribution following oral administration, radiolabeled ((111)In-labeled) gelatin nanoparticles and NiMOS were administered orally to fasted Balb/C mice. The results of biodistribution studies showed that, while gelatin nanoparticles traversed through the GI tract fairly quickly with more than 54% of the administered dose per gram localizing in the large intestine at the end of 2 h, NiMOS resided in the stomach and small intestine for relatively longer duration. Following oral administration of EGFP-N1 plasmid DNA at 100 microg dose in the control and test formulations, the quantitative and qualitative results presented in this study provide the necessary evidence for transfection potential of NiMOS upon oral administration. After 5 days post-administration, transgene expression in the small and large intestine of mice was observed. Based on these results, NiMOS show significant potential as novel gene delivery vehicle for therapeutic and vaccination purposes.

Enhanced Mucosal and Systemic Immune Response with Squalane Oil-containing Multiple Emulsions Upon Intranasal and Oral Administration in Mice

Journal of Drug Targeting. May, 2008  |  Pubmed ID: 18446609

The objective of this study was to develop and evaluate squalane oil-containing water-in-oil-in-water (W/O/W) multiple emulsion for mucosal administration of ovalbumin (OVA) as a model candidate vaccine in BALB/c mice. Control and optimized OVA-containing W/O/W emulsion (OVA-Emul) and chitosan-modified W/O/W emulsion (OVA-Emul-Chi) formulations were administered intranasally and orally at an OVA dose of 100 mug. The mucosal and systemic immune responses were evaluated after the first and second immunization. The OVA-Emul formulations resulted in higher immunoglobulin-G (IgG) and immunoglobulin-A (IgA) responses as compared with aqueous solution. In addition, significant IgG and IgA responses were observed after the second immunization dose using the emulsions with both routes of administration. Intranasal vaccination was more effective in generating the systemic OVA-specific IgG response than the mucosal OVA-specific IgA response. Oral immunizations, on the other hand, showed a much higher systemic IgG and mucosal IgA responses as compared with the nasally treated groups. The results of this study show that squalane oil-containing W/O/W multiple emulsion formulations can significantly enhance the local and systemic immune responses, especially after oral administration, and may be adopted as a better alternative in mucosal delivery of prophylactic and therapeutic vaccines.

Enhancement in Anti-proliferative Effects of Paclitaxel in Aortic Smooth Muscle Cells Upon Co-administration with Ceramide Using Biodegradable Polymeric Nanoparticles

Pharmaceutical Research. Aug, 2008  |  Pubmed ID: 18480968

Using a combination of paclitaxel (PTX), and the apoptotic signaling molecule, C6-ceramide (CER), the enhancement in anti-proliferative effect of human aortic smooth muscle cells (SMC) was examined by administering in polymeric nanoparticles.

Modulation of Drug Resistance in Ovarian Adenocarcinoma by Enhancing Intracellular Ceramide Using Tamoxifen-loaded Biodegradable Polymeric Nanoparticles

Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. May, 2008  |  Pubmed ID: 18483388

To modulate intracellular ceramide levels and lower the apoptotic threshold in multidrug-resistant ovarian adenocarcinoma, we have examined the efficacy and preliminary safety of tamoxifen coadministration with paclitaxel in biodegradable poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles.

Multi-functional Nanocarriers to Overcome Tumor Drug Resistance

Cancer Treatment Reviews. Nov, 2008  |  Pubmed ID: 18538481

The development of resistance to variety of chemotherapeutic agents is one of the major challenges in effective cancer treatment. Tumor cells are able to generate a multi-drug resistance (MDR) phenotype due to microenvironmental selection pressures. This review addresses the use of nanotechnology-based delivery systems to overcome MDR in solid tumors. Our own work along with evidence from the literature illustrates the development of various types of engineered nanocarriers specifically designed to enhance tumor-targeted delivery through passive and active targeting strategies. Additionally, multi-functional nanocarriers are developed to enhance drug delivery and overcome MDR by either simultaneous or sequential delivery of resistance modulators (e.g., with P-glycoprotein substrates), agents that regulate intracellular pH, agents that lower the apoptotic threshold (e.g., with ceramide), or in combination with energy delivery (e.g., sound, heat, and light) to enhance the effectiveness of anticancer agents in refractory tumors. In preclinical studies, the use of multi-functional nanocarriers has shown significant promise in enhancing cancer therapy, especially against MDR tumors.

Multi-functional Nanocarriers for Targeted Delivery of Drugs and Genes

Journal of Controlled Release : Official Journal of the Controlled Release Society. Sep, 2008  |  Pubmed ID: 18538887

In this review article, we describe the different nano-platforms developed in our laboratory at Northeastern University in Boston, MA for the targeted delivery of drugs and genes. Special emphasis is placed on nano-platforms that offer opportunities for multi-functionalization to allow for targeted stimuli-responsive and/or simultaneous strategic delivery of multiple drugs, genes, as well as the combination of therapeutic systems with image contrast enhancers. Polymeric and lipid-based nanocarriers can provide versatile platforms for the delivery of multiple pharmacological agents, specifically to enhance therapeutic effect and overcome drug resistance in cancer. In addition, polymeric nanoparticles and nanoparticles-in-microsphere oral system (NiMOS) are useful for systemic and oral gene therapy, respectively.

A Model Predicting Delivery of Saquinavir in Nanoparticles to Human Monocyte/macrophage (Mo/Mac) Cells

Biotechnology and Bioengineering. Dec, 2008  |  Pubmed ID: 18553495

Modeling the influence of a technology such as nanoparticle systems on drug delivery is beneficial in rational formulation design. While there are many studies showing drug delivery enhancement by nanoparticles, the literature provides little guidance regarding when nanoparticles are useful for delivery of a given drug. A model was developed predicting intracellular drug concentration in cultured cells dosed with nanoparticles. The model considered drug release from nanoparticles as well as drug and nanoparticle uptake by the cells as the key system processes. Mathematical expressions for these key processes were determined using experiments in which each process occurred in isolation. In these experiments, intracellular delivery of saquinavir, a low solubility drug dosed as a formulation of poly(ethylene oxide)-modified poly(epsilon- caprolactone) (PEO-PCL) nanoparticles, was studied in THP-1 human monocyte/macrophage (Mo/Mac) cells. The model accurately predicted the enhancement in intracellular concentration when drug was administered in nanoparticles compared to aqueous solution. This simple model highlights the importance of relative kinetics of nanoparticle uptake and drug release in determining overall enhancement of intracellular drug concentration when dosing with nanoparticles.

Biodistribution and Pharmacokinetic Analysis of Paclitaxel and Ceramide Administered in Multifunctional Polymer-blend Nanoparticles in Drug Resistant Breast Cancer Model

Molecular Pharmaceutics. Jul-Aug, 2008  |  Pubmed ID: 18616278

In this study, we have investigated the biodistribution and pharmacokinetic analysis of paclitaxel (PTX) and the apoptotic signaling molecule, C6-ceramide (CER), when administered in a multifunctional polymer-blend nanoparticle formulation to female nude mice bearing an orthotopic drug sensitive MCF7 and multidrug resistant MCF7 TR (MDR-1 positive) human breast adenocarcinoma. A polymer-blend nanoparticle system was engineered to incorporate temporally controlled sequential release of the combination drug payload. Hereby, PTX was encapsulated in the pH-responsive rapid releasing polymer, poly(beta-amino ester) (PbAE), while CER was present in the slow releasing polymer, poly(D,L-lactide-co-glycolide) (PLGA) within these blend nanoparticles. When particle formulations were administered intravenously to MCF7 and MCF7 TR tumor bearing mice, higher concentrations of PTX were found in the blood due to longer retention time and an enhanced tumor accumulation relative to administration of free drug. In addition, the PLGA/PbAE blend nanoparticles were effective in enhancing the residence time of both drugs at the tumor site by reducing systemic clearance. Overall, these results are highly encouraging for development of multifunctional polymer-blend nanoparticle formulations that can be used for temporal-controlled administration of two drugs from a single formulation.

Improved Oral Bioavailability and Brain Transport of Saquinavir Upon Administration in Novel Nanoemulsion Formulations

International Journal of Pharmaceutics. Jan, 2008  |  Pubmed ID: 17651927

The aim of this investigation was to develop novel oil-in-water (o/w) nanoemulsions containing Saquinavir (SQV), an anti-HIV protease inhibitor, for enhanced oral bioavailability and brain disposition. SQV was dissolved in different types of edible oils rich in essential polyunsaturated fatty acids (PUFA) to constitute the internal oil phase of the nanoemulsions. The external phase consisted of surfactants Lipoid-80 and deoxycholic acid dissolved in water. The nanoemulsions with an average oil droplet size of 100-200 nm, containing tritiated [(3)H]-SQV, were administered orally and intravenously to male Balb/c mice. The SQV bioavailability as well as distribution in different organ systems was examined. SQV concentrations in the systemic circulation administered in flax-seed oil nanoemulsions were threefold higher as compared to the control aqueous suspension. The oral bioavailability and distribution to the brain, a potential sanctuary site for HIV, were significantly enhanced with SQV delivered in nanoemulsion formulations. In comparing SQV in flax-seed oil nanoemulsion with aqueous suspension, the maximum concentration (C(max)) and the area-under-the-curve (AUC) values were found to be five- and threefold higher in the brain, respectively, suggesting enhanced rate and extent of SQV absorption following oral administration of nanoemulsions. The results of this study show that oil-in-water nanoemulsions made with PUFA-rich oils may be very promising for HIV/AIDS therapy, in particular, for reducing the viral load in important anatomical reservoir sites.

Preparation and Loading of Gelatin Nanoparticles

CSH Protocols. 2008  |  Pubmed ID: 21356667

INTRODUCTIONThis protocol describes the synthesis of nanoparticles using the biopolymer gelatin and its derivatives, the loading of DNA to the nanoparticles by encapsulation and adsorption, and the estimation of entrapment efficiency. The steps involved in the preparation of nanoparticles by desolvation using ethanol are presented, as are the precautions to be taken during the encapsulation or adsorption of the payload.

Intracellular Trafficking Studies Using Gold-encapsulated Gelatin Nanoparticles

CSH Protocols. 2008  |  Pubmed ID: 21356668

INTRODUCTIONTrafficking of nanoparticles in cells is best carried out by encapsulation of electron-dense material (e.g., gold) in the nanoparticles and by visualizing them in the cell by transmission electron microscopy (TEM). This protocol describes the preparation of gold particles, their encapsulation in protein nanoparticles, culture conditions, and sample preparation for TEM.

Cell Transfection and Analysis Using DNA-Loaded Gelatin Nanoparticles

CSH Protocols. 2008  |  Pubmed ID: 21356669

INTRODUCTIONThis protocol describes cell-culture techniques for transfection using DNA-loaded gelatin nanoparticles. Also included are methods for qualitative analysis of transfection with fluorescence microscopy and quantitative analysis using a fluorescence-activated cell sorter (FACS).

Protein Nanospheres for Gene Delivery

CSH Protocols. 2008  |  Pubmed ID: 21356682

INTRODUCTIONNanoparticles have been widely used to overcome the barriers for drug delivery. Those prepared from natural polymers have a significant advantage over others prepared from synthetic polymers. This article outlines the advantages of gelatin for the preparation of nanoparticles and a method for preparing them. The uses of nanoparticles are also discussed. Cell trafficking can be studied using nanoparticles encapsulated with electron-dense material (e.g., gold); such particles are then visualized by transmission electron microscopy (TEM). DNA-encapsulated nanoparticles can be used for transfection and other methods of gene delivery. The qualitative and quantitative analysis of transfection studies is outlined briefly.

Epidermal Growth Factor Receptor-targeted Gelatin-based Engineered Nanocarriers for DNA Delivery and Transfection in Human Pancreatic Cancer Cells

The AAPS Journal. Dec, 2008  |  Pubmed ID: 19034673

Type B gelatin-based engineered nanocarrier systems (GENS) have been used over the last several years as a non-condensing systemic and oral DNA delivery system. In this study, we have modified the surface of GENS with epidermal growth factor receptor (EGFR)-targeting peptide for gene delivery and transfection in pancreatic cancer cell lines. GENS were prepared by the solvent displacement method and the EGFR-targeting peptide was grafted on the surface using a hetero-bifunctional poly(ethylene glycol) (PEG) spacer. Plasmid DNA, encoding for enhanced green fluorescent protein (GFP), was efficiently encapsulated and protected from degrading enzymes in the control and surface-modified GENS. Upon incubation with EGFR over-expressing Panc-1 human pancreatic adenocarcinoma cells, the peptide-modified nanoparticles were found to be internalized efficiently by receptor-mediated endocytosis. Both quantitative and qualitative transgene expression efficiencies were significantly enhanced when plasmid DNA was administered with EGFR-targeted GENS relative to the control-unmodified gelatin or PEG-modified gelatin nanoparticle systems. Based on these preliminary results, EGFR-targeted GENS show tremendous promise as a safe and effective gene delivery vector with the potential to treat pancreatic cancer.

Evaluations of Combination MDR-1 Gene Silencing and Paclitaxel Administration in Biodegradable Polymeric Nanoparticle Formulations to Overcome Multidrug Resistance in Cancer Cells

Cancer Chemotherapy and Pharmacology. Mar, 2009  |  Pubmed ID: 18618115

In this study, the effect of MDR-1 gene silencing, using small interfering RNA (siRNA), and paclitaxel (PTX) co-therapy in overcoming tumor multidrug resistance was examined. Poly(ethylene oxide)-modified poly(beta-amino ester) (PEO-PbAE) and PEO-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were formulated to efficiently encapsulate MDR-1 silencing siRNA and PTX, respectively. Upon administration in multidrug resistant SKOV3(TR) human ovarian adenocarcinoma cells, siRNA-mediated MDR-1 gene silencing was evident at 100 nM dose. Combination of MDR-1 gene silencing and nanoparticle-mediated delivery significantly influenced the cytotoxic activity of PTX in SKOV3(TR) cells similar to what was observed in drug sensitive SKOV3 cells. We speculate that the enhancement in cytotoxicity was due to an increase in intracellular drug accumulation upon MDR-1 gene silencing leading to an apoptotic cell-kill effect. Taken together, these preliminary results are highly encouraging for the development of combination nano-therapeutic strategies that combine gene silencing and drug delivery to provide more potent therapeutic effect, especially in refractory tumors.

Label-free Raman Spectral Imaging of Intracellular Delivery and Degradation of Polymeric Nanoparticle Systems

ACS Nano. Nov, 2009  |  Pubmed ID: 19863088

Novel optical imaging methods, such as Raman microspectroscopy, have been gaining recognition in their ability to obtain noninvasively the distribution of biochemical components of a sample. Raman spectroscopy in combination with optical microscopy provides a label-free method to assess and image cellular processes, without the use of extrinsic fluorescent dyes. The submicrometer resolution of the confocal Raman instrumentation allows us to image cellular organelles on the scale of conventional microscopy. We used the technique to monitor subcellular degradation patterns of two biodegradable nanocarrier systems-poly(epsilon-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA). Our results suggest that both drug-delivery systems eventually are incorporated into Golgi-associated vesicles of late endosomes. These processes were monitored via the decrease of the molecule-characteristic peaks of PCL and PLGA. As the catabolic pathways proceed, shifts and variations in peak intensities and intensity ratios in the rendered Raman spectra unequivocally delineate their degradation patterns.

Coadministration of Paclitaxel and Curcumin in Nanoemulsion Formulations to Overcome Multidrug Resistance in Tumor Cells

Molecular Pharmaceutics. May-Jun, 2009  |  Pubmed ID: 19278222

Development of multidrug resistance (MDR) against a variety of conventional and novel chemotherapeutic agents is a significant challenge in effective cancer therapy. Over the last several years, we have focused on a multimodal therapeutic strategy to overcome tumor MDR by enhancing the delivery efficiency to the tumor mass and lowering the apoptotic threshold by modulation of the intracellular signaling mechanisms. In this study, we have examined augmentation of therapeutic efficacy upon coadministration of paclitaxel (PTX) and curcumin (CUR), an inhibitor of nuclear factor kappa B (NFkappaB) as well as a potent down-regulator of ABC transporters, in wild-type SKOV3 and drug resistant SKOV3(TR) human ovarian adenocarcinoma cells. PTX and CUR were encapsulated in flaxseed oil containing nanoemulsion formulations. The results showed that the encapsulated drugs were effectively delivered intracellular in both SKOV3 and SKOV3(TR) cells. CUR administration was shown to inhibit NFkappaB activity and down regulate P-glycoprotein expression in resistant cells. Combination PTX and CUR therapy, especially when administered in the nanoemulsion formulations, was very effective in enhancing the cytotoxicity in wild-type and resistant cells by promoting the apoptotic response. Overall, this cotherapy strategy has significant promise in the clinical management of refractory diseases, especially in ovarian cancer.

Challenges and Opportunities in CNS Delivery of Therapeutics for Neurodegenerative Diseases

Expert Opinion on Drug Delivery. Mar, 2009  |  Pubmed ID: 19290842

With an increase in lifespan and changing population demographics, the incidence of central nervous system (CNS) diseases is expected to increase significantly in the 21st century. The most challenging of the CNS diseases are neurodegenerative diseases, characterized by age-related gradual decline in neurological function, often accompanied by neuronal death. Alzheimer's disease, Parkinson's disease and Huntington's disease are some examples of neurodegenerative diseases and have been well described in terms of disease mechanisms and pathology. However, successful treatment strategies for neurodegenerative diseases have so far been limited. Delivery of drugs into the CNS is one of the most challenging problems faced in the treatment of neurodegeneration. In this review, we describe the difficulties with CNS therapy, especially with the use of biological macromolecules, such as proteins and nucleic acid constructs. CNS therapeutics also represents a huge opportunity and examples of strategies that can enhance therapeutic delivery for the treatment of neurodegenerative diseases are emphasized. It is anticipated that with an increase in biological understanding of neurodegenerative diseases, there will be even more therapeutic opportunities. As such, these delivery strategies have a very important role to play in the future in the translation of CNS therapeutics from bench to bedside.

Delivery Strategies to Enhance Mucosal Vaccination

Expert Opinion on Biological Therapy. Apr, 2009  |  Pubmed ID: 19344280

Vaccines capable of eliciting cellular and humoral immune responses in tandem could provide prophylactic and therapeutic responses against infectious diseases and cancer. These responses can be induced systemically and at mucosal surfaces by activating the mucosal immune system, but rarely successfully due to challenges associated with mucosal delivery.

Doxorubicin Loaded Polymeric Nanoparticulate Delivery System to Overcome Drug Resistance in Osteosarcoma

BMC Cancer. 2009  |  Pubmed ID: 19917123

Drug resistance is a primary hindrance for the efficiency of chemotherapy against osteosarcoma. Although chemotherapy has improved the prognosis of osteosarcoma patients dramatically after introduction of neo-adjuvant therapy in the early 1980's, the outcome has since reached plateau at approximately 70% for 5 year survival. The remaining 30% of the patients eventually develop resistance to multiple types of chemotherapy. In order to overcome both the dose-limiting side effects of conventional chemotherapeutic agents and the therapeutic failure incurred from multidrug resistant (MDR) tumor cells, we explored the possibility of loading doxorubicin onto biocompatible, lipid-modified dextran-based polymeric nanoparticles and evaluated the efficacy.

Nanoporous Inorganic Membranes or Coatings for Sustained Drug Delivery in Implantable Devices

Advanced Drug Delivery Reviews. Mar, 2010  |  Pubmed ID: 19922749

The characteristics of nanoporous inorganic coatings on implants or on implantable devices are reviewed. The commonly used nanoporous materials, such as aluminum oxide (Al(2)O(3)), titanium oxide (TiO(2)) and porous silicon are highlighted with illustrative examples. The critical issues for sustained release systems are examined and the elution profiles of nanoporous coatings are discussed. The available data shows that these systems can be used effectively for sustained release applications. They satisfy the basic biocompatibility tests, meet the requirements of drug loading and sustained release profiles extending to several weeks and also are compatible with current implant technologies. Nanoporous inorganic coatings are well suited to provide improved efficacy and integration of implants in a variety of therapeutic situations.

Nanotechnology Solutions for Mucosal Immunization

Advanced Drug Delivery Reviews. Mar, 2010  |  Pubmed ID: 19931581

The current prevalence of infectious diseases in many developing regions of the world is a serious burden, impacting both the general health as well as economic growth of these communities. Additionally, treatment with conventional medication becomes increasingly challenging due to emergence of new and drug resistant strains jeopardizing the progress made in recent years towards control and elimination of certain types of infectious diseases. Thus, from a public health perspective, prevention such as through immunization by vaccination, which has proven to be most effective, might be the best alternative to prevent and combat infectious diseases in these regions. To achieve this, development of wide-scale immunization programs become necessary including vaccines that can easily and widely be distributed, stored and administered. Mucosal vaccines offer great potential since they can be administered via oral or intranasal delivery route which does not require trained personnel, avoids the use of needles and improves overall patient compliance and acceptance. However, it necessitates the implementation of specific immunization strategies to improve their efficacy. Application of nanotechnology to design and create particle mediated delivery systems that can efficiently encapsulate vaccine components for protection of the sensitive payload, target the mucosal immune system and incorporate mucosal adjuvants maximizing immune response is key strategy to improve the effectiveness of mucosal vaccines.

Sustained Drug Release from Non-eroding Nanoporous Templates

Small (Weinheim an Der Bergstrasse, Germany). Jan, 2010  |  Pubmed ID: 19967712

Nanoparticle-based Endodontic Antimicrobial Photodynamic Therapy

Journal of Endodontics. Feb, 2010  |  Pubmed ID: 20113801

To study the in vitro effects of poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with the photosensitizer methylene blue (MB) and light against Enterococcus faecalis (ATCC 29212).

Development and Validation of a Rapid Reversed-phase HPLC Method for the Determination of the Non-nucleoside Reverse Transcriptase Inhibitor Dapivirine from Polymeric Nanoparticles

Journal of Pharmaceutical and Biomedical Analysis. Jun, 2010  |  Pubmed ID: 20117900

The objective of this work was to develop and validate a rapid reversed-phase (RP) high-performance liquid chromatography (HPLC) method for the in vitro pharmaceutical characterization of dapivirine-loaded polymeric nanoparticles. Chromatographic runs were performed on a RP C18 column with a mobile phase comprising acetonitrile-0.5% (w/v) triethanolamine solution in isocratic mode (80:20, v/v) at a flow rate of 1 ml/min. Dapivirine was detected at a wavelength of 290 nm. The method was shown to be specific, linear in the range of 1-50 microg/ml (R(2)=0.9998), precise at the intra-day and inter-day levels as reflected by the relative standard deviation values (less than 0.85%), accurate (recovery rate of 100.17+/-0.35%), and robust to changes in the mobile phase and column brand. The detection and quantitation limits were 0.08 and 0.24 microg/ml, respectively. The method was successfully used to determine the loading capacity and association efficiency of dapivirine in poly(lactic-co-glycolic acid)-based nanoparticles and its in vitro release.

Augmentation of Therapeutic Efficacy in Drug-resistant Tumor Models Using Ceramide Coadministration in Temporal-controlled Polymer-blend Nanoparticle Delivery Systems

The AAPS Journal. Jun, 2010  |  Pubmed ID: 20143195

The development of multidrug resistance (MDR) is a major hindrance to cancer eradication as it renders tumors unresponsive to most chemotherapeutic treatments and is associated with cancer resurgence. This study describes a novel mechanism to overcome MDR through a polymer-blend nanoparticle platform that delivers a combination therapy of C6-ceramide (CER), a synthetic analog of an endogenously occurring apoptotic modulator, together with the chemotherapeutic drug paclitaxel (PTX), in a single formulation. The PTX/CER combination therapy circumvents another cellular mechanism whereby MDR develops, by lowering the threshold for apoptotic signaling. In vivo studies in a resistant subcutaneous SKOV3 human ovarian and in an orthotopic MCF7 human breast adenocarcinoma xenograft showed that the PTX and CER nanoparticle combination therapy reduced the final tumor volume at least twofold over treatment with the standard PTX therapy alone. The study also revealed that the cotherapy accomplished this enhanced efficacy by generating an enhancement in apoptotic signaling in both tumor types. Additionally, acute evaluation of safety with the combination therapy did not show significant changes in body weight, white blood cell counts, or liver enzyme levels. The temporal-controlled nanoparticle delivery system presented in this study allows for a simultaneous delivery of PTX + CER in breast and ovarian tumor model drug, leading to a modulation of the apoptotic threshold. This strategy has tremendous potential for effective treatment of refractory disease in cancer patients.

Targeting Stents with Local Delivery of Paclitaxel-loaded Magnetic Nanoparticles Using Uniform Fields

Proceedings of the National Academy of Sciences of the United States of America. May, 2010  |  Pubmed ID: 20404175

The use of stents for vascular disease has resulted in a paradigm shift with significant improvement in therapeutic outcomes. Polymer-coated drug-eluting stents (DES) have also significantly reduced the incidence of reobstruction post stenting, a disorder termed in-stent restenosis. However, the current DESs lack the capacity for adjustment of the drug dose and release kinetics to the disease status of the treated vessel. We hypothesized that these limitations can be addressed by a strategy combining magnetic targeting via a uniform field-induced magnetization effect and a biocompatible magnetic nanoparticle (MNP) formulation designed for efficient entrapment and delivery of paclitaxel (PTX). Magnetic treatment of cultured arterial smooth muscle cells with PTX-loaded MNPs caused significant cell growth inhibition, which was not observed under nonmagnetic conditions. In agreement with the results of mathematical modeling, significantly higher localization rates of locally delivered MNPs to stented arteries were achieved with uniform-field-controlled targeting compared to nonmagnetic controls in the rat carotid stenting model. The arterial tissue levels of stent-targeted MNPs remained 4- to 10-fold higher in magnetically treated animals vs. control over 5 days post delivery. The enhanced retention of MNPs at target sites due to the uniform field-induced magnetization effect resulted in a significant inhibition of in-stent restenosis with a relatively low dose of MNP-encapsulated PTX (7.5 microg PTX/stent). Thus, this study demonstrates the feasibility of site-specific drug delivery to implanted magnetizable stents by uniform field-controlled targeting of MNPs with efficacy for in-stent restenosis.

In Vitro and in Vivo Studies of Local Arterial Gene Delivery and Transfection Using Lipopolyplexes-embedded Stents

Journal of Biomedical Materials Research. Part A. Apr, 2010  |  Pubmed ID: 19569206

Gene-eluting stents can have profound impact in the treatment of coronary restenosis, especially when the encoded protein can re-endothelialize the arterial lumen. In this study, we have examined gene delivery in vitro and in vivo using poly(beta-amino ester) (PbAE) precondensed plasmid DNA-containing cationic liposomes or lipopolyplexes (LPP) immobilized on stainless steel meshes and stents using gelatin coatings. In vitro studies using LPP-immobilized on 50 mm round meshes using type A and B gelatin coatings showed that LPP were efficiently internalized in human aortic smooth muscle cells (SMC) over time, leading to green fluorescent protein (GFP) expression. Type B gelatin coating was found to be more effective in intracellular delivery and transgene expression efficiency and, as such, was used for stent coating. In vivo studies, carried out in iliac artery restenosis model in New Zealand white rabbits, also showed GFP expression in arterial tissues after 24 h of implantation. Based on these encouraging preliminary results, LPP-based formulations can serve as a safe and effective nonviral gene delivery system for effective treatment of coronary restenosis.

Brain Delivery of Proteins by the Intranasal Route of Administration: a Comparison of Cationic Liposomes Versus Aqueous Solution Formulations

Journal of Pharmaceutical Sciences. Apr, 2010  |  Pubmed ID: 19774660

The goal of this research was to evaluate the effectiveness of cationic liposomes for intranasal administration of proteins to the brain. Cationic liposomes were loaded with a model protein, ovalbumin (OVAL), and a 50 microg dose was administered intranasally to rats. In qualitative studies, liposomes were loaded with Alexa 488-OVAL and delivery was assessed by fluorescence microscopy. By 6 and 24 h after administration, Alexa 488-OVAL deposits were widely distributed throughout brain, with apparent cellular uptake in midbrain by 6 h after administration. In quantitative studies, liposomes were loaded with (111)In-OVAL, and distribution to brain and peripheral tissues was monitored by gamma counting at 1, 4, 6, and 24 h after administration. The highest brain concentrations were achieved at the shortest time point, 1 h, for both liposomal and aqueous OVAL. However, the liposomes yielded higher (111)In-OVAL concentrations in brain than (111)In-OVAL in PBS. Moreover, a 2 microg/microL form of liposomal OVAL yielded a higher percentage of dose in brain, and a lower percentage in stomach and intestines, than twice the volume of a 1 microg/microL preparation. Cationic liposomes may provide a novel, noninvasive strategy for delivery of neuroactive proteins to the brain for treatment of central nervous system disorders.

Nanotechnology Solutions for Infectious Diseases in Developing Nations. Preface

Advanced Drug Delivery Reviews. Mar, 2010  |  Pubmed ID: 19913580

Nanotechnology-based Systems for the Treatment and Prevention of HIV/AIDS

Advanced Drug Delivery Reviews. Mar, 2010  |  Pubmed ID: 19914314

The HIV/AIDS pandemic is an increasing global burden with devastating health-related and socioeconomic effects. The widespread use of antiretroviral therapy has dramatically improved life quality and expectancy of infected individuals, but limitations of currently available drug regimens and dosage forms, alongside with the extraordinary adapting capacity of the virus, have impaired further success. Alongside, circumventing the escalating number of new infections can only be attained with effective and practical preventative strategies. Recent advances in the field of drug delivery are providing evidence that engineered nanosystems may contribute importantly for the enhancement of current antiretroviral therapy. Additionally, groundwork is also being carried out in the field nanotechnology-based systems for developing preventative solutions for HIV transmission. This manuscript reviews recent advances in the field of nanotechnology-based systems for the treatment and prevention of HIV/AIDS. Particular attention is given to antiretroviral drug targeting to HIV reservoirs and the usefulness of nanosystems for developing topical microbicides and vaccines.

Inhibition of ABCB1 (MDR1) Expression by an SiRNA Nanoparticulate Delivery System to Overcome Drug Resistance in Osteosarcoma

PloS One. 2010  |  Pubmed ID: 20520719

The use of neo-adjuvant chemotherapy in treating osteosarcoma has improved patients' average 5 year survival rate from 20% to 70% in the past 30 years. However, for patients who progress after chemotherapy, its effectiveness diminishes due to the emergence of multi-drug resistance (MDR) after prolonged therapy.

Curcumin Enhances Oral Bioavailability and Anti-tumor Therapeutic Efficacy of Paclitaxel Upon Administration in Nanoemulsion Formulation

Journal of Pharmaceutical Sciences. Nov, 2010  |  Pubmed ID: 20845461

The aim of this study was to evaluate the effect of curcumin (CUR) in oral bioavailability and therapeutic efficacy of paclitaxel (PTX) administered in nanoemulsion to SKOV3 tumor-bearing nu/nu mice. Oral administration of the mice with CUR at 50 mg/kg for 3 consecutive days resulted in a down regulation of intestinal P-glycoprotein (Pgp) and cytochrome P450 3A2 (CYP3A2) protein levels. PTX, a Pgp and CYP3A2 substrate, was administered orally at 20 mg/kg in solution or nanoemulsion either as single agent or upon pretreatment with CUR at 50 mg/kg in tumor-bearing mice. Plasma AUC(0-∞) of PTX administered in nanoemulsion to CUR pretreated mice showed 4.1-fold increase relative to controls. Similarly, relative PTX bioavailability was increased by 5.2-fold, resulting in a 3.2-fold higher PTX accumulation in the tumor tissue. PTX administered in nanoemulsion to CUR pretreated mice also showed significantly enhanced anti-tumor activity. Preliminary safety evaluation showed that CUR + PTX combination did not induce any acute toxicity as measured by body weight changes, blood cell counts, liver enzyme levels, and liver histopathology. The results of this study suggest that combination of PTX and CUR, administered in nanoemulsions, could improve oral bioavailability and therapeutic efficacy in ovarian adenocarcinoma.

Non-viral ENOS Gene Delivery and Transfection with Stents for the Treatment of Restenosis

Biomedical Engineering Online. 2010  |  Pubmed ID: 20875110

In this study, we have examined local non-viral gene delivery, transfection, and therapeutic efficacy of endothelial nitric oxide synthase (eNOS) encoding plasmid DNA administered using coated stents in a rabbit iliac artery restenosis model.

A Review of Multifunctional Nanoemulsion Systems to Overcome Oral and CNS Drug Delivery Barriers

Molecular Membrane Biology. Oct, 2010  |  Pubmed ID: 20929336

The oral and central nervous systems (CNS) present a unique set of barriers to the delivery of important diagnostic and therapeutic agents. Extensive research over the past few years has enabled a better understanding of these physical and biological barriers based on tight cellular junctions and expression of active transporters and metabolizing enzymes at the luminal surfaces of the gastrointestinal (GI) tract and the blood-brain barrier (BBB). This review focuses on the recent understanding of transport across the GI tract and BBB and the development of nanotechnology-based delivery strategies that can enhance bioavailability of drugs. Multifunctional lipid nanosystems, such as oil-in-water nanoemulsions, that integrate enhancement in permeability, tissue and cell targeting, imaging, and therapeutic functions are especially promising. Based on strategic choice of edible oils, surfactants and additional surface modifiers, and different types of payloads, rationale design of multifunctional nanoemulsions can serve as a safe and effective delivery vehicle across oral and CNS barriers.

Preliminary Evaluation of a Nanotechnology-based Approach for the More Effective Diagnosis of Colon Cancers

Nanomedicine (London, England). Nov, 2010  |  Pubmed ID: 21128727

The goal of this research was to develop and preliminarily test a novel technology and instrumentation that could help to significantly increase the diagnostic yield of current colon cancer screening procedures. This technology is based on a combined fluorescence-optical coherence tomography (OCT) imaging, and topical delivery of a cancer-targeting agent.

Pharmacokinetics and Biodistribution of Lonidamine/paclitaxel Loaded, EGFR-targeted Nanoparticles in an Orthotopic Animal Model of Multi-drug Resistant Breast Cancer

Nanomedicine : Nanotechnology, Biology, and Medicine. Aug, 2011  |  Pubmed ID: 21220050

The aim of this study was to assess the biodistribution and pharmacokinetics of epidermal growth factor receptor (EGFR)-targeted polymer-blend nanoparticles loaded with the anticancer drugs lonidamine and paclitaxel. Plasma, tumor, and tissue distribution profiles were quantified in an orthotopic animal model of multidrug-resistant breast cancer and were compared to treatment with nontargeted nanoparticles and to treatment with drug solution. A poly(d,l-lactide-co-glycolide)-poly(ethylene glycol)-EGFR targeting peptide (PLGA-PEG-EFGR peptide) construct was synthesized for incorporation in poly(ɛ-caprolactone) particles to achieve active EGFR targeting. An isocratic high-pressure liquid chromatography method was developed to quantify lonidamine and paclitaxel in mice plasma, tumors, and vital organs. The targeted nanoparticles demonstrated a superior pharmacokinetic profile relative to drug solution and nontargeted nanoparticles, particularly for lonidamine delivery. The first target site of accumulation was the liver, followed by the kidneys, and then the tumor mass; maximal tumor accumulation occured at 3 hours after administration. Lonidamine-paclitaxel combination therapy administered via EGFR-targeted polymer-blend nanocarriers may become a viable platform for the future treatment of multidrug-resistant cancer. FROM THE CLINICAL EDITOR: In this study the biodistribution and pharmacokinetics of epidermal growth factor receptor (EGFR)-targeted polymer-blend nanoparticles loaded with lonidamine and paclitaxel were assessed. The targeted nanoparticles demonstrated a superior pharmacokinetic profile relative to drug solution and nontargeted nanoparticles, paving the way to new therapeutic approaches for multidrug-resistant malignancies.

Role of Hypoxia and Glycolysis in the Development of Multi-drug Resistance in Human Tumor Cells and the Establishment of an Orthotopic Multi-drug Resistant Tumor Model in Nude Mice Using Hypoxic Pre-conditioning

Cancer Cell International. 2011  |  Pubmed ID: 21320311

The development of multi-drug resistant (MDR) cancer is a significant challenge in the clinical treatment of recurrent disease. Hypoxia is an environmental selection pressure that contributes to the development of MDR. Many cancer cells, including MDR cells, resort to glycolysis for energy acquisition. This study aimed to explore the relationship between hypoxia, glycolysis, and MDR in a panel of human breast and ovarian cancer cells. A second aim of this study was to develop an orthotopic animal model of MDR breast cancer.

Development of EGFR-targeted Polymer Blend Nanocarriers for Combination Paclitaxel/lonidamine Delivery to Treat Multi-drug Resistance in Human Breast and Ovarian Tumor Cells

Molecular Pharmaceutics. Feb, 2011  |  Pubmed ID: 20942457

Multi-drug resistant (MDR) cancer is a significant clinical obstacle and is often implicated in cases of recurrent, nonresponsive disease. Targeted nanoparticles were made by synthesizing a poly(D,L-lactide-co-glycolide)/poly(ethylene glycol)/epidermal growth factor receptor targeting peptide (PLGA/PEG/EGFR-peptide) construct for incorporation in poly(epsilon-caprolactone) (PCL) nanoparticles. MDR was induced in a panel of nine human breast and ovarian cancer cell lines using hypoxia. EGFR-targeted polymer blend nanoparticles were shown to actively target EGFR overexpressing cell lines, especially upon induction of hypoxia. The nanoparticles were capable of sustained drug release. Combination therapy with lonidamine and paclitaxel significantly improved the therapeutic index of both drugs. Treatment with a nanoparticle dose of 1 μM paclitaxel/10 μM lonidamine resulted in less than 10% cell viability for all hypoxic/MDR cell lines and less than 5% cell viability for all normoxic cell lines. Comparatively, treatment with 1 μM paclitaxel alone was the approximate IC₅₀ value of the MDR cells while treatment with lonidamine alone had very little effect. The PLGA/PEG/EGFR-peptide delivery system actively targets a MDR cell by exploiting the expression of EGFR. This system treats MDR by inhibiting the Warburg effect and promoting mitochondrial binding of pro-apoptotic Bcl-2 proteins (lonidamine), while hyperstabilizing microtubules (paclitaxel). This nanocarrier system actively targets a MDR associated phenotype (EGFR receptor overexpression), further enhancing the therapeutic index of both drugs and potentiating the use of lonidamine/paclitaxel combination therapy in the treatment of MDR cancer.

Oral TNF-α Gene Silencing Using a Polymeric Microsphere-based Delivery System for the Treatment of Inflammatory Bowel Disease

Journal of Controlled Release : Official Journal of the Controlled Release Society. Feb, 2011  |  Pubmed ID: 20959130

The purpose of this study was to evaluate down-regulation of tumor necrosis factor (TNF)-α by oral RNA interference therapy. Control (scrambled sequence) or TNF-α specific small interfering RNA (siRNA) was encapsulated in type B gelatin nanoparticles and further entrapped in poly(epsilon-caprolactone) (PCL) microspheres to form a nanoparticles-in-microsphere oral system (NiMOS). Upon confirmation of the dextran sulfate sodium (DSS)-induced acute colitis model, mice were divided into several treatment groups receiving no treatment, blank NiMOS, NiMOS with scramble siRNA, or NiMOS with TNF-α silencing siRNA by oral administration. Successful gene silencing led to decreased colonic levels of TNF-α, suppressed expression of other pro-inflammatory cytokines (e.g., interleukin (IL)-1β, interferon (IFN)-γ) and chemokines (MCP-1), an increase in body weight, and reduced tissue myeloperoxidase activity. Results of this study established the clinical potential of a NiMOS-based oral TNF-α gene silencing system for the treatment of inflammatory bowel disease as demonstrated in an acute colitis model.

Nanomedicine for Cancer Therapy

Pharmaceutical Research. Feb, 2011  |  Pubmed ID: 20845066

Multi-modal Strategies for Overcoming Tumor Drug Resistance: Hypoxia, the Warburg Effect, Stem Cells, and Multifunctional Nanotechnology

Journal of Controlled Release : Official Journal of the Controlled Release Society. Oct, 2011  |  Pubmed ID: 21497176

Inefficiencies in systemic drug delivery and tumor residence as well as micro-environmental selection pressures contribute to the development of multidrug resistance (MDR) in cancer. Characteristics of MDR include abnormal vasculature, regions of hypoxia, up-regulation of ABC-transporters, aerobic glycolysis, and an elevated apoptotic threshold. Nano-sized delivery vehicles are ideal for treating MDR cancer as they can improve the therapeutic index of drugs and they can be engineered to achieve multifunctional parameters. The multifunctional ability of nanocarriers makes them more adept at treating heterogeneous tumor mass than traditional chemotherapy. Nanocarriers also have preferential tumor accumulation via the EPR effect; this accumulation can be further enhanced by actively targeting the biological profile of MDR cells. Perhaps the most significant benefit of using nanocarrier drug delivery to treat MDR cancer is that nanocarrier delivery diverts the effects of ABC-transporter mediated drug efflux; which is the primary mechanism of MDR. This review discusses the capabilities, applications, and examples of multifunctional nanocarriers for the treatment of MDR. This review emphasizes multifunctional nanocarriers that enhance drug delivery efficiency, the application of RNAi, modulation of the tumor apoptotic threshold, and physical approaches to overcome MDR.

Mucoadhesive Nanosystems for Vaginal Microbicide Development: Friend or Foe?

Wiley Interdisciplinary Reviews. Nanomedicine and Nanobiotechnology. Jul-Aug, 2011  |  Pubmed ID: 21506290

Topical microbicides are a promising strategy in the prevention of vaginal and rectal HIV transmission as well as other sexually transmitted pathogens. The perspective of developing nanotechnology-based systems for topical microbicides seems to be useful because important features such as enhanced drug release, targeting, and epithelial penetration can be achieved. However, the interaction of nanoparticles with the mucus fluids that cover the cervicovaginal mucosal epithelium, which can work either as a docking point or as a barrier for diffusion, has been frequently neglected. In this review, we discuss the principles of nanosystems' adhesion to the mucosal tissue and how this relates to the development of optimized microbicide formulations.

Mucoadhesive Nanomedicines: Characterization and Modulation of Mucoadhesion at the Nanoscale

Expert Opinion on Drug Delivery. Aug, 2011  |  Pubmed ID: 21599564

INTRODUCTION: The benefits of mucoadhesive systems are related to the increased in situ residence and intimate contact of the delivery vehicle with the mucosa. The recent emergence of nanomedicine and the properties of nanoparticulate systems have created new challenges in understanding the nature and mechanisms of nanoscale mucoadhesion and in the development of methodologies for measuring its mucoadhesive potential. Even when usually regarded as an advantageous property, mucoadhesion can be an inconvenience for nanosystems, and strategies have been developed for minimizing interactions with the mucosal tissues/fluids. AREAS COVERED: This article summarizes the basic concepts of mucoadhesion at the nanoscale, different techniques used for measuring the mucoadhesive potential of nanosystems and strategies for increasing/decreasing mucoadhesive interactions. EXPERT OPINION: The mucoadhesion behavior of materials in bulk and at the nanoscale can significantly differ. Advances in the methodology used for studying the mucoadhesion phenomenon have contributed to its better understanding and, more importantly, the development of strategies to increase/decrease mucoadhesion. However, development of new methodologies for studying mucoadhesion at the nanoscale and the refinement of existing methodologies are still required. Also, a substantial amount of information is still lacking, particularly related to formulation issues, on how to translate lessons learnt at the bench top to the bed side.

Non-condensing Polymeric Nanoparticles for Targeted Gene and SiRNA Delivery

International Journal of Pharmaceutics. May, 2011  |  Pubmed ID: 21621597

Gene therapy has shown a tremendous potential to benefit patients in a variety of disease conditions. However, finding a safe and effective systemic delivery system is the major obstacle in this area. Although viral vectors showed promise for high transfection rate, the immunogenicity associated with these systems has hindered further development. As an alternative to viral gene delivery, this review focuses on application of novel safe and effective non-condensing polymeric systems that have shown high transgene expression when administered systemically or by the oral route. Type B gelatin-based engineered nanocarriers were evaluated for passive and active tumor-targeted delivery and transfection using both reporter and therapeutic plasmid DNA. Additionally, we have shown that nanoparticles-in-microsphere oral system (NiMOS) can efficiently deliver reporter and therapeutic gene constructs in the gastrointestinal tract. Additionally, there has been a significant recent interest in the use small interfering RNA (siRNA) as a therapeutic system for gene silencing. Both gelatin nanoparticles and NiMOS have shown activity in systemic and oral delivery of siRNA, respectively.

Anti-angiogenic Effects of Betulinic Acid Administered in Nanoemulsion Formulation Using Chorioallantoic Membrane Assay

Journal of Biomedical Nanotechnology. Apr, 2011  |  Pubmed ID: 21702370

Betulinic acid (3beta, hydroxy-lup-20(29)-en-28-oic acid, BA), a pentacyclic triterpenoid, is derived from a widely distributed natural anticancer compound betulin. It has selective anticancer activity against several tumor cells, and recently it was shown that it also possess anti-angiogenic effects. The objective of this study was to formulate betulinic acid, a poorly aqueous-soluble compound, in flax-seed oil containing nanoemulsion formulation for enhanced delivery efficiency and to effectively inhibit the tumor angiogenic process. The nanoemulsion was prepared using high pressure homogenization method with a Microfludizer processor. The betulinic acid nanoemulsion was studied for the effect on the angiogenic process by performing the in vivo chick embryo chorioallantoic membrane (CAM) assay. The sample volume of 1 microl and 5 microl of the blank and BA nanoemulsions were applied directly on the CAM. The preliminary results from macroscopic, morphological and immunohistochemical evaluations have shown that morphological change was produced in the CAM mesenchyme with a negative impact on the normal growth of the capillaries. Betulinic acid does possess anti-angiogenic activity in a dose dependent manner, and the nanoemulsion formulation maintained this effect.

Combinatorial-designed Multifunctional Polymeric Nanosystems for Tumor-targeted Therapeutic Delivery

Accounts of Chemical Research. Oct, 2011  |  Pubmed ID: 21761902

By definition, multifunctional nanosystems include several features within a single construct so that these devices can target tumors or other disease tissue, facilitate in vivo imaging, and deliver a therapeutic agent. Investigations of these nanosystems are rapidly progressing and provide new opportunities in the management of cancer. Tumor-targeted nanosystems are currently designed based primarily on the intrinsic physico-chemical properties of off-the-shelf polymers. Following fabrication, the surfaces of these nanoscale structures are functionalized for passive or active targeted delivery to the tumors. In this Account, we describe a novel approach for the construction of multifunctional polymeric nanosystems based on combinatorial design principles. Combinatorial approaches offer several advantages over conventional methods because they allow for the integration of multiple components with varied properties into a nanosystem via self-assembly or chemical conjugation. High-throughput synthesis and screening is required in polymer design because polymer composition directly affects properties including drug loading, retention in circulation, and targeting of the nanosystems. The first approach relies on the self-assembly of macromolecular building blocks with specific functionalities in aqueous media to yield a large variety of nanoparticle systems. These self-assembled nanosystems with diverse functionalities can then be rapidly screened in a high-throughput fashion for selection of ideal formulations, or hits, which are further evaluated for safety and efficacy. In another approach, a library of a large number of polymeric materials is synthesized using different monomers. Each of the formed polymers is screened for the selection of the best candidates for nanoparticle fabrication. The combinatorial design principles allow for the selection of those nanosystems with the most favorable properties based on the type of payload, route of administration, and the desired target for imaging and delivery.

Therapeutic Efficacy and Safety of Paclitaxel/lonidamine Loaded EGFR-targeted Nanoparticles for the Treatment of Multi-drug Resistant Cancer

PloS One. 2011  |  Pubmed ID: 21931642

The treatment of multi-drug resistant (MDR) cancer is a clinical challenge. Many MDR cells over-express epidermal growth factor receptor (EGFR). We exploit this expression through the development of EGFR-targeted, polymer blend nanocarriers for the treatment of MDR cancer using paclitaxel (a common chemotherapeutic agent) and lonidamine (an experimental drug; mitochondrial hexokinase 2 inhibitor). An orthotopic model of MDR human breast cancer was developed in nude mice and used to evaluate the safety and efficacy of nanoparticle treatment. The efficacy parameters included tumor volume measurements from day 0 through 28 days post-treatment, terminal tumor weight measurements, tumor density and morphology assessment through hematoxylin and eosin staining of excised tumors, and immunohistochemistry of tumor sections for MDR protein markers (P-glycoprotein, Hypoxia Inducible Factor, EGFR, Hexokinase 2, and Stem Cell Factor). Toxicity was assessed by tracking changes in animal body weight from day 0 through 28 days post-treatment, by measuring plasma levels of the liver enzymes ALT (Alanine Aminotransferase) and LDH (lactate dehydrogenase), and by white blood cell and platelet counts. In these studies, this nanocarrier system demonstrated superior efficacy relative to combination (paclitaxel/lonidamine) drug solution and single agent treatments in nanoparticle and solution form. The combination nanoparticles were the only treatment group that decreased tumor volume, sustaining this decrease until the 28 day time point. In addition, treatment with the EGFR-targeted lonidamine/paclitaxel nanoparticles decreased tumor density and altered the MDR phenotype of the tumor xenografts. These EGFR-targeted combination nanoparticles were considerably less toxic than solution treatments. Due to the flexible design and simple conjugation chemistry, this nanocarrier system could be used as a platform for the development of other MDR cancer therapies; the use of this system for EGFR-targeted, combination paclitaxel/lonidamine therapy is an advance in personalized medicine.

'Click' Synthesis of Dextran Macrostructures for Combinatorial-designed Self-assembled Nanoparticles Encapsulating Diverse Anticancer Therapeutics

Bioorganic & Medicinal Chemistry. Nov, 2011  |  Pubmed ID: 21978947

With the non-specific toxicity of anticancer drugs to healthy tissues upon systemic administration, formulations capable of enhanced selectivity in delivery to the tumor mass and cells are highly desirable. Based on the diversity of the drug payloads, we have investigated a combinatorial-designed strategy where the nano-sized formulations are tailored based on the physicochemical properties of the drug and the delivery needs. Individually functionalized C(2) to C(12) lipid-, thiol-, and poly(ethylene glycol) (PEG)-modified dextran derivatives were synthesized via 'click' chemistry from O-pentynyl dextran and relevant azides. These functionalized dextrans in combination with anticancer drugs form nanoparticles by self-assembling in aqueous medium having PEG surface functionalization and intermolecular disulfide bonds. Using anticancer drugs with logP values ranging from -0.5 to 3.0, the optimized nanoparticles formulations were evaluated for preliminary cellular delivery and cytotoxic effects in SKOV3 human ovarian adenocarcinoma cells. The results show that with the appropriate selection of lipid-modified dextran, one can effectively tailor the self-assembled nano-formulation for intended therapeutic payload.

Therapeutic Strategies for Endothelial Dysfunction

Expert Opinion on Biological Therapy. Dec, 2011  |  Pubmed ID: 21992579

INTRODUCTION: A functionally compromised vascular endothelium is associated with tissue-damaging responses including inflammation, immune stimulation, oxidative stress and platelet activation/aggregation and can lead to severe end-organ damage, as implicated in the pathology of several cardiac, cerebral and renal disorders. Multiple noninvasive techniques are available for assessing endothelial dysfunction in clinical settings. Diverse interventions have been identified as having therapeutic potential for treating endothelial dysfunction and preventing its pathophysiological sequellae. AREAS COVERED: Evaluation techniques and interventional treatment approaches for endothelial dysfunction, with particular reference to prevalent cardiovascular and metabolic disorders such as coronary artery disease and diabetes. Limitations of the current treatments and avenues for improved endothelium-targeted therapies. EXPERT OPINION: Beneficial pleiotropic effects of various agents (cardiovascular medicines, antioxidants, nutritional supplements) on vascular endothelial function in humans notwithstanding, a growing body of preclinical data suggests that protein-, cell- and gene-based approaches hold promise for selective therapeutic targeting of the dysfunctional vascular endothelium. Additional efficacy data in appropriate animal models of vascular injury and cardiometabolic disease, further refinement of delivery modalities and continued investigation of the mechanisms underlying endothelial repair and regeneration should help identify the most promising therapeutic approaches for improving endothelial function that merit evaluation in human trials.

Photodynamic Effects of Methylene Blue-loaded Polymeric Nanoparticles on Dental Plaque Bacteria

Lasers in Surgery and Medicine. Sep, 2011  |  Pubmed ID: 22057487

Photodynamic therapy (PDT) is increasingly being explored for treatment of oral infections. Here, we investigate the effect of PDT on human dental plaque bacteria in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles with a positive or negative charge and red light at 665 nm.

Polymeric Nanoparticles Affect the Intracellular Delivery, Antiretroviral Activity and Cytotoxicity of the Microbicide Drug Candidate Dapivirine

Pharmaceutical Research. Nov, 2011  |  Pubmed ID: 22072053

PURPOSE: To assess the intracellular delivery, antiretroviral activity and cytotoxicity of poly(ε-caprolactone) (PCL) nanoparticles containing the antiretroviral drug dapivirine. METHODS: Dapivirine-loaded nanoparticles with different surface properties were produced using three surface modifiers: poloxamer 338 NF (PEO), sodium lauryl sulfate (SLS) and cetyl trimethylammonium bromide (CTAB). The ability of nanoparticles to promote intracellular drug delivery was assessed in different cell types relevant for vaginal HIV transmission/microbicide development. Also, antiretroviral activity of nanoparticles was determined in different cell models, as well as their cytotoxicity. RESULTS: Dapivirine-loaded nanoparticles were readily taken up by different cells, with particular kinetics depending on the cell type and nanoparticles, resulting in enhanced intracellular drug delivery in phagocytic cells. Different nanoparticles showed similar or improved antiviral activity compared to free drug. There was a correlation between increased antiviral activity and increased intracellular drug delivery, particularly when cell models were submitted to a single initial short-course treatment. PEO-PCL and SLS-PCL nanoparticles consistently showed higher selectivity index values than free drug, contrasting with high cytotoxicity of CTAB-PCL. CONCLUSIONS: These results provide evidence on the potential of PCL nanoparticles to affect in vitro toxicity and activity of dapivirine, depending on surface engineering. Thus, this formulation approach may be a promising strategy for the development of next generation microbicides.

Nanoparticles: a Promising Modality in the Treatment of Sarcomas

Pharmaceutical Research. Feb, 2011  |  Pubmed ID: 20505985

Improvements in surgical technique, chemotherapy, and radiotherapy have enhanced the prognosis of sarcoma patients, but have since reached a plateau in recent years. Novel approaches have been sought but with limited results. Nanomedicine offers solutions in diverse areas of sarcoma therapy including diagnosis and treatment. Several varieties of nanoparticles, including multifunctional nanoparticles, are available that localize the biodistribution of conventional chemotherapeutics to the tumor site. Also, nanoparticles loaded with chemotherapeutic drugs have the ability to overcome drug resistance which is a major obstacle impeding the progress of the treatment. Multifunctional nanoparticles, which have the potential to further augment the bioavailability of drugs, are being actively investigated. In this review, we will discuss the application of nanoparticles for improving the treatment of sarcoma patients.

Fluorescence-guided Optical Coherence Tomography Imaging for Colon Cancer Screening: a Preliminary Mouse Study

Biomedical Optics Express. Jan, 2012  |  Pubmed ID: 22254178

A new concept for cancer screening has been preliminarily investigated. A cancer targeting agent loaded with a near-infrared (NIR) dye was topically applied on the tissue to highlight cancer-suspect locations and guide optical coherence tomography (OCT) imaging, which was used to further investigate tissue morphology at the micron scale. A pilot study on ApcMin mice has been performed to preliminarily test this new cancer screening approach. As a cancer-targeting agent, poly(epsilon-caprolactone) microparticles (PCLMPs), labeled with a NIR dye and functionalized with an RGD (argenine-glycine-aspartic acid) peptide, were used. This agent recognizes the α(ν)β(3) integrin receptor (ABIR), which is over-expressed by epithelial cancer cells. The contrast agent was administered topically in vivo in mouse colon. After incubation, the animals were sacrificed and fluorescence-guided high resolution optical coherence tomography (OCT) imaging was used to visualize colon morphology. The preliminary results show preferential staining of the abnormal tissue, as indicated by both microscopy and laser-induced fluorescence imaging, and OCT's capability to differentiate between normal mucosal areas, early dysplasia, and adenocarcinoma. Although very preliminary, the results of this study suggest that fluorescence-guided OCT imaging might be a suitable approach for cancer screening. If successful, this approach could be used by clinicians to more reliably diagnose early stage cancers in vivo.

Multi-Compartmental Nanoparticles-in-Emulsion Formulation for Macrophage-Specific Anti-Inflammatory Gene Delivery

Pharmaceutical Research. Jan, 2012  |  Pubmed ID: 22281760

PURPOSE: To develop a safe and effective non-viral vector for gene delivery and transfection in macrophages for potential anti-inflammatory therapy. METHODS: Solid nanoparticles-in-emulsion (NiE) multi-compartmental delivery system was designed using plasmid DNA-encapsulated type B gelatin nanoparticles suspended in the inner aqueous phase of safflower oil-containing water-in-oil-in-water (W/O/W) multiple emulsion. Control and NiE formulations were evaluated for DNA delivery and transfection efficiency in J774A.1 adherent murine macrophages. RESULTS: Using green fluorescent protein (GFP) and murine interleukin-10 (mIL-10) expressing plasmid DNA constructs, the NiE formulation was found superior in enhancing intracellular delivery and gene transfection efficiency in cells. Anti-inflammatory effects of transfected mIL-10 were examined by suppression of tumor necrosis factor-alpha (TNFα) and interleukin 1-beta (IL-1β) production in lipopolysaccharide (LPS)-stimulated cells. CONCLUSIONS: Overall, the results were very encouraging towards development of a macrophage-specific NiE-based multi-compartmental gene delivery strategy that can potentially affect a number of acute and chronic inflammatory diseases.