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Find video protocols related to scientific articles indexed in Pubmed.
Hypoxia and Cellular Localization Influence the Radiosensitizing Effect of Gold Nanoparticles (AuNPs) in Breast Cancer Cells.
Radiat. Res.
PUBLISHED: 11-01-2014
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Hypoxia exists in all solid tumors and leads to clinical radioresistance and adverse prognosis. We hypothesized that hypoxia and cellular localization of gold nanoparticles (AuNPs) could be modifiers of AuNP-mediated radiosensitization. The possible mechanistic effect of AuNPs on cell cycle distribution and DNA double-strand break (DSB) repair postirradiation were also studied. Clonogenic survival data revealed that internalized and extracellular AuNPs at 0.5 mg/mL resulted in dose enhancement factors of 1.39 ± 0.07 and 1.09 ± 0.01, respectively. Radiosensitization by AuNPs was greatest in cells under oxia, followed by chronic and then acute hypoxia. The presence of AuNPs inhibited postirradiation DNA DSB repair, but did not lead to cell cycle synchronization. The relative radiosensitivity of chronic hypoxic cells is attributed to defective DSB repair (homologous recombination) due to decreased (RAD51)-associated protein expression. Our results support the need for further study of AuNPs for clinical development in cancer therapy since their efficacy is not limited in chronic hypoxic cells.
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The challenges facing block copolymer micelles for cancer therapy: in vivo barriers and clinical translation.
Adv. Drug Deliv. Rev.
PUBLISHED: 07-02-2014
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The application of block copolymer micelles (BCMs) in oncology has benefitted from advances in polymer chemistry, drug formulation and delivery as well as in vitro and in vivo biological models. While great strides have been made in each of these individual areas, there remains some disappointment overall, citing, in particular, the absence of more BCM formulations in clinical evaluation and practice. In this review, we aim to provide an overview of the challenges presented by in vivo systems to the effective design and development of BCMs. In particular, the barriers posed by systemic administration and tumor properties are examined. The impact of critical features, such as the size, stability and functionalization of BCMs is discussed, while key pre-clinical endpoints and models are critiqued. Given clinical considerations, we present this work as a means to stimulate a renewed focus on the unique chemical versatility bestowed by BCMs and a measured grasp of representative in vitro and in vivo models.
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Expression of membrane transporters and metabolic enzymes involved in estrone-3-sulphate disposition in human breast tumour tissues.
Breast Cancer Res. Treat.
PUBLISHED: 03-05-2014
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Two-thirds of newly diagnosed hormone-dependent (HR?) breast cancers are detected in post-menopausal patients where estrone-3-sulphate (E3S) is the predominant source for tumour estradiol. Understanding intra-tumoral fate of E3S would facilitate in the identification of novel molecular targets for HR? post-menopausal breast cancer patients. Hence this study investigates the clinical expression of (i) organic anion-transporting polypeptides (OATPs), (ii) multidrug resistance protein (MRP-1), breast cancer resistance proteins (BCRP), and (iii) sulphatase (STS), 17?-hydroxysteroid dehydrogenase (17?-HSD-1), involved in E3S uptake, efflux and metabolism, respectively. Fluorescent and brightfield images of stained tumour sections (n = 40) were acquired at 4× and 20× magnification, respectively. Marker densities were measured as the total area of positive signal divided by the surface area of the tumour section analysed and was reported as % area (ImageJ software). Tumour, stroma and non-tumour tissue areas were also quantified (Inform software), and the ratio of optical intensity per histologic area was reported as % area/tumour, % area/stroma and % area/non-tumour. Functional role of OATPs and STS was further investigated in HR? (MCF-7, T47-D, ZR-75) and HR-(MDA-MB-231) cells by transport studies conducted in the presence or absence of specific inhibitors. Amongst all the transporters and enzymes, OATPs and STS have significantly (p < 0.0001) higher expression in HR? tumour sections with highest target signals obtained from the tumour regions of the tissues. Specific OATP-mediated E3S uptake and STS-mediated metabolism were also observed in all HR? breast cancer cells. These observations suggest the potential of OATPs as novel molecular targets for HR? breast cancers.
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Heat-activated thermosensitive liposomal cisplatin (HTLC) results in effective growth delay of cervical carcinoma in mice.
J Control Release
PUBLISHED: 01-06-2014
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Cisplatin (CDDP) has been identified as the primary chemotherapeutic agent for the treatment of cervical cancer, but dose limiting toxicity is a key issue associated with its clinical application. A suite of liposome formulations of CDDP has been developed in efforts to reduce systemic toxicity, but their therapeutic advantage over the free drug has been modest due to insufficient drug release at the tumor site. This report describes the development of a novel heat-activated thermosensitive liposome formulation containing CDDP (HTLC) designed to release approximately 90% of the loaded drug in less than 5min under mild heating conditions (42°C). Physico-chemical characteristics of HTLC were assessed in terms of gel to liquid crystalline phase transition temperature (Tm), drug loading efficiency, particle size, and stability. The pharmacokinetic profile and biodistribution of HTLC in non-tumor-bearing mice were evaluated over a 24h period. A sophisticated spatio-temporal elucidation of HTLC release in tumor-bearing mice was achieved by way of real-time monitoring using a magnetic resonance (MR) imaging protocol, wherein a custom-built laser-based conformal heat source was applied at the tumor volume to trigger the release of HTLC co-encapsulated with the MR contrast agent gadoteridol (Gd-HP-DO3A). MR thermometry (MRT) demonstrated that a relatively uniform temperature distribution was achieved in the tumor volume using the external laser-based heating setup. In mice bearing subcutaneously-implanted ME-180 cervical tumors, the combination of HTLC and heat resulted in a 2-fold increase in tumor drug levels at 1h post-administration compared to HTLC without heating. Furthermore, the overall tumor accumulation levels for the HTLC groups (with and without heat) at 1h post-injection were significantly higher than the corresponding free CDDP group. This translated into a significant improvement in therapeutic efficacy evaluated as tumor growth delay (p<0.05) for the heated HTLC treatment group compared to the unheated HTLC, heated or unheated free CDDP, and saline groups. Overall, findings from this study demonstrate that a heat-activated, triggered release formulation of CDDP results in a significant enhancement in the therapeutic index of this drug.
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Image-based analysis of the size- and time-dependent penetration of polymeric micelles in multicellular tumor spheroids and tumor xenografts.
Int J Pharm
PUBLISHED: 01-06-2014
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While the heightened tumor accumulation of systemically administered nanomedicines relative to conventional chemotherapeutic agents has been well established, corresponding improvements in therapeutic efficacy have often been incommensurate. This observation may be attributed to the limited exposure of cancer cells to therapy due to the heterogeneous intratumoral distribution and poor interstitial penetration of nanoparticle-based drug delivery systems. In the present work, the spatio-temporal distribution of block copolymer micelles (BCMs) of different sizes was evaluated in multicellular tumor spheroids (MCTS) and tumor xenografts originating from human cervical (HeLa) and colon (HT29) cancer cells using image-based, computational techniques. Micelle penetration was found to depend on nanoparticle size, time as well as tumor and spheroid cell line. Moreover, spheroids demonstrated the capacity to predict relative trends in nanoparticle interstitial transport in tumor xenografts. Overall, techniques are presented for the assessment of nanoparticle distribution in spheroids and xenografts and used to evaluate the influence of micelle size and cell-line specific tissue properties on micelle interstitial penetration.
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Growth Factor Release from Polyelectrolyte-Coated Titanium for Implant Applications.
ACS Appl Mater Interfaces
PUBLISHED: 12-16-2013
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Polyelectrolyte multilayer coatings based on poly(methacrylic acid) and poly-l-histidine were formed on anodized titanium surfaces with adsorbed bone morphogenetic protein 2 (BMP-2) or basic fibroblast growth factor (FGFb). These coatings are proposed for use on titanium implanted devices. Coatings were capable of sustained release of growth factor over 25 days, with BMP-2 and FGFb exhibiting approximately identical release profiles. Cell culture on growth factor-eluting surfaces was more effective for preosteoblasts on BMP-2-eluting surfaces than for fibroblasts on FGFb-eluting surfaces. Cell counts at all time points on BMP-2-eluting surfaces were significantly higher than for those on anodized titanium or polyelectrolyte surfaces that did not contain BMP-2. Alkaline phosphatase levels were significantly higher after 21 days on BMP-2-eluting surfaces, indicating increased bone growth.
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Sono-Assembly of Highly Biocompatible Polysaccharide Capsules for Hydrophobic Drug Delivery.
Adv Healthc Mater
PUBLISHED: 10-30-2013
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Cells like sugar. General synthesis and potential of intracellular hydrophobic drug delivery of single-component polysaccharide capsules are pursued. The capsules can be generally assembled through hydrogen bonding networks but show striking shell robustness. The evidenced cell internalization, stimuli-responsiveness to local pH changes and high biocompatibilities of the capsules specifically favor their potential intracellular drug delivery.
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Active Targeting of Block Copolymer Micelles with Trastuzumab Fab Fragments and Nuclear Localization Signal Leads to Increased Tumor Uptake and Nuclear Localization in HER2-Overexpressing Xenografts.
Mol. Pharm.
PUBLISHED: 10-22-2013
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Block copolymer micelles (BCMs) have been employed as effective drug delivery systems to solid tumors by virtue of their capacity to transport large therapeutic payloads and passively target tumor sites. Active targeting of nanoparticles (NPs) has been exploited as a means to increase the therapeutic efficacy of NP-based drugs by promoting their delivery to cellular sites of action. Effective whole tumor accumulation and cellular uptake constitute key objectives in the success of preclinical drug formulations, although they have seldom been investigated concurrently in vivo. The current study aims to elucidate the in vivo fate of 31-nm-sized block copolymer micelles (BCMs) targeted to the nucleus of HER2-overexpressing breast cancer cells. Pharmacokinetics, biodistribution, tumor uptake, and intratumoral distribution of BCMs were investigated in mice bearing subcutaneous BT-474 and MDA-MB-231 xenografts expressing high and low levels of HER2, respectively. Radiolabeling with (111)indium enabled quantitative assessment of BCM distribution at the whole body, tissue, and cellular levels. Surface-grafted trastuzumab Fab fragments (TmAb-Fab) facilitated binding and internalization of BCMs by HER2-positive breast cancer cells, while synthetic 13-mer nuclear localization signal (NLS) peptides conjugated to the TmAb-Fab conferred nuclear translocation capability. Active targeting of BCMs led to a 5-fold increase in tumor uptake in HER2-overexpressing BT-474 tumors, alongside a correspondingly greater level of cellular uptake and nuclear localization, relative to the nontargeted formulations. This study distinctively highlights the quantitative evaluation of active targeting on tumor, cellular and subcellular uptake of BCMs and presents a promising platform for the effective delivery of chemo- and/or radiotherapy in vivo.
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Continuous Intraperitoneal Carboplatin Delivery for the Treatment of Late-Stage Ovarian Cancer.
Mol. Pharm.
PUBLISHED: 08-21-2013
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The rate of failure of chemotherapy treatment in ovarian cancer remains high, resulting in a low 5-year survival rate of 20-40% in patients that present with advanced-stage disease. Treatment-free periods between cycles of chemotherapy may contribute to accelerated tumor cell proliferation and decreased treatment response. The elimination of treatment-free breaks has been deemed beneficial in the context of cell-cycle-specific agents. The potential benefit of this approach for non-cell-cycle-specific agents has not yet been elucidated. The present study is the first to address this issue by investigating the impact of continuous versus intermittent intraperitoneal administration of carboplatin over a 14 day period to SCID mice bearing SKOV-3 ovarian cancer xenografts. Immunostaining of tumor sections was employed to quantify tumor proliferation, angiogenesis, and apoptosis using Ki-67, CD-31, caspase-3 (CASP3), and terminal deoxytransferase-mediated dUTP nick-end labeling (TUNEL). Continuous ip administration of carboplatin resulted in greater tumor growth inhibition than intermittent therapy (p < 0.05). Significantly greater tumor cell apoptosis and less cell proliferation and angiogenesis were measured in tumors of mice treated with continuous carboplatin as compared to both intermittent and control groups. These results indicate that continuous local administration may be a promising approach to improve the effectiveness of platinum-based chemotherapy regimens.
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Multi-arm PEG/Silica Hydrogel for Sustained Ocular Drug Delivery.
J Pharm Sci
PUBLISHED: 06-02-2013
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In the present study, a series of sustained drug delivery multiarm poly(ethylene glycol) (PEG)/silica hydrogels were prepared and characterized. The hydrogels were formed by hydrolysis and condensation of poly(4-arm PEG silicate) using the sol-gel method. The relationships between water content in the PEG/silica hydrogel and stability as well as rheological properties were evaluated. Scanning electron microscopy analysis of the PEG/silica hydrogels revealed water content-dependent changes in microstructure. An increase in water content resulted in larger pores within the hydrogel, longer gelation time and higher viscosity. The PEG/silica hydrogels were loaded with dexamethasone (DMS) or dexamethasone sodium phosphate (DMSP), drugs that are hydrophobic and hydrophilic in nature, respectively. Evaluation of in vitro release revealed a zero-order release profile for DMS over the first 6 days, suggesting that degradation of the silica hydrogel matrix was the primary mechanism of drug release. It was also found that the drug-release profile could be tailored by varying the water content used during hydrogel preparation. In contrast, more than 90% of DMSP was released within 1 h, suggesting that DMSP release was only controlled by diffusion. Overall, results from this study indicate that PEG/silica hydrogels may be promising drug-eluting depot materials for the sustained delivery of hydrophobic, ophthalmic drugs. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:216-226, 2014.
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Tumor perfusion imaging predicts the intra-tumoral accumulation of liposomes.
J Control Release
PUBLISHED: 05-22-2013
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Liposomes have proven to be a viable drug delivery strategy resulting in significant increases in tumor accumulation of drugs via exploitation of the enhanced permeability and retention (EPR) effect. However, significant variability has been observed in their bulk tumor accumulation and intra-tumoral distribution. The heterogeneous accumulation of liposomes in solid tumors is largely believed to result from the chaotic morphology and physiology of tumor blood vessels. Thus, tumor perfusion imaging may provide a novel method to predict the accumulation and resulting therapeutic effect of liposome formulations. In this study, dynamic contrast enhanced computed tomography (DCE-CT) was employed to quantitatively estimate the intra-tumoral distribution of perfusion and anatomical CT was used to map the spatio-temporal accumulation of a CT-liposome contrast agent. A statistically significant positive correlation was found between quantitative and semi-quantitative measures of tumor perfusion (i.e. K(trans), vp, and AUC(iox)) and liposome accumulation (AUC(lipo) and C(peak)) in two mouse xenograft models of human cervical cancer. Specifically, it was found that regions with higher K(trans),vp, and AUC(iox) had greater liposome accumulation. These findings demonstrate that DCE-CT measurements of tumor perfusion may be an important technique for selecting patients that are likely to respond to liposome and potentially other nanoparticle-based therapies.
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The impact of sustained and intermittent docetaxel chemotherapy regimens on cognition and neural morphology in healthy mice.
Psychopharmacology (Berl.)
PUBLISHED: 03-20-2013
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A subset of cancer survivors demonstrates impairments in cognition long after chemotherapy completion. At present, it is unclear whether these changes are due to direct neurotoxic effects of chemotherapy.
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Comparison of computed tomography- and optical image-based assessment of liposome distribution.
Mol Imaging
PUBLISHED: 03-16-2013
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The use of multimodal imaging as a tool to assess the in vivo pharmacokinetics and biodistribution of nanocarriers is important in understanding the nature of their in vivo transport. The current study reports the development of a nano-sized liposomal computed tomographic (CT)/optical imaging probe carrying iohexol and Cy5.5 and its use in micro-CT and optical imaging to quantitatively assess the whole-body (macroscopic), intratumoral, and microscopic distribution over a period of 8 days. These multimodal liposomes have a vascular half-life of 30.3 ± 8.9 hours in mice bearing subcutaneous H520 non-small cell lung cancer tumors, with the maximum liposome accumulation in tumor achieved 48 hours postinjection. The in vivo liposome distribution and stability were quantitatively assessed using both micro-CT and fluorescence molecular tomography. The combination of CT and optical imaging enables visualization of the liposomes at the whole-body, tumor, and cellular scales with high sensitivity. Such noninvasive tracking of therapeutic vehicles at the macro- and microscale is important for informed and rational development of novel nanocarrier systems.
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Thermosensitive depot-forming injectable phosphatidylcholine blends tailored for localized drug delivery.
J Pharm Sci
PUBLISHED: 03-06-2013
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A thermosensitive depot-forming system was developed for sustained and localized delivery of the anticancer drug, paclitaxel. The formulation is injectable as a melt slightly above the body temperature and forms a solid depot upon cooling to 37°C. The thermosensitive system was prepared by blending various combinations of phosphatidylcholines at specific weight ratios solubilized in laurinaldehyde. Of the blends investigated, distearoyl-phosphatidylcholine (DSPC) and egg-phosphatidylcholine (ePC) were found to be most miscible. A liquid-to-gel phase transition temperature (TC ) of 39°C was observed for the 70:30 (w/w) DSPC-ePC blend and a TC of 38.4°C with the addition of paclitaxel. Blends containing higher concentrations of ePC had a greater degree of swelling and weight loss. Furthermore, microscopy revealed an increase in porosity and erosion as the amount of ePC was increased in blends incubated in biologically relevant media. DSPC-ePC blends provided sustained release of paclitaxel over a 30-day period and the rate of drug release increased as the amount of ePC increased. Overall, the relationships established between the composition and properties of the blend may be employed to tailor the thermosensitive injectable formulation for localized chemotherapy of solid tumors.
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A mathematical model of the enhanced permeability and retention effect for liposome transport in solid tumors.
PLoS ONE
PUBLISHED: 01-01-2013
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The discovery of the enhanced permeability and retention (EPR) effect has resulted in the development of nanomedicines, including liposome-based formulations of drugs, as cancer therapies. The use of liposomes has resulted in substantial increases in accumulation of drugs in solid tumors; yet, significant improvements in therapeutic efficacy have yet to be achieved. Imaging of the tumor accumulation of liposomes has revealed that this poor or variable performance is in part due to heterogeneous inter-subject and intra-tumoral liposome accumulation, which occurs as a result of an abnormal transport microenvironment. A mathematical model that relates liposome accumulation to the underlying transport properties in solid tumors could provide insight into inter and intra-tumoral variations in the EPR effect. In this paper, we present a theoretical framework to describe liposome transport in solid tumors. The mathematical model is based on biophysical transport equations that describe pressure driven fluid flow across blood vessels and through the tumor interstitium. The model was validated by direct comparison with computed tomography measurements of tumor accumulation of liposomes in three preclinical tumor models. The mathematical model was fit to liposome accumulation curves producing predictions of transport parameters that reflect the tumor microenvironment. Notably, all fits had a high coefficient of determination and predictions of interstitial fluid pressure agreed with previously published independent measurements made in the same tumor type. Furthermore, it was demonstrated that the model attributed inter-subject heterogeneity in liposome accumulation to variations in peak interstitial fluid pressure. These findings highlight the relationship between transvascular and interstitial flow dynamics and variations in the EPR effect. In conclusion, we have presented a theoretical framework that predicts inter-subject and intra-tumoral variations in the EPR effect based on fundamental properties of the tumor microenvironment and forms the basis for transport modeling of liposome drug delivery.
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A novel minimally invasive technique to create a rabbit VX2 lung tumor model for nano-sized image contrast and interventional studies.
PLoS ONE
PUBLISHED: 01-01-2013
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The rabbit VX2 lung cancer model is a large animal model useful for preclinical lung cancer imaging and interventional studies. However, previously reported models had issues in terms of invasiveness of tumor inoculation, control of tumor aggressiveness and incidence of complications.
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Estrone-3-sulphate, a potential novel ligand for targeting breast cancers.
PLoS ONE
PUBLISHED: 01-01-2013
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The current study investigates the potential of estrone-3-sulphate (E3S) as a ligand for targeting Organic Anion Transporting Polypeptides (OATP), a family of membrane associated uptake transporters, for detection and diagnosis of hormone dependent breast cancers. E3S, an OATP substrate, is a predominant source of tumour estradiol in post-menopausal patients. To assess the potential of E3S as a ligand, distribution of exogenous E3S was determined at the whole body, tumour and cellular levels in murine models of hormone-dependent (MCF-7) and independent (MDA-MB-231) breast cancers. The highest levels of tumour uptake were observed at 6 h post injection (p.i) with significant difference (p?=?0.04) between the level in MCF-7 (13.9±3.1%ID/g) and MDA-MB-231 (10.4±1.1%ID/g) (%ID/g: percentage of the total injected dose per gram tissue). The highest tumour-to-blood ratios (MCF-7?7.4±1.2; MDA-MB-231?9.1±2.1) were observed at 48 p.i., and highest tumour-to-muscle ratios (MCF-7?10.7±1.5; MDA-MB-231?3.8±0.7) were observed at 6 h p.i. Analogous to total tumour uptake, ex vivo tumour cell uptake at 2 h p.i. was 6 fold higher in MCF-7 in comparison to MDA-MB-231 tumour cells. Blocking studies, conducted by pre-administration of 100-fold excess E3S, resulted in significantly lower (MCF-7: p?=?0.01; MDA-MB-231: p?=?0.02) tumour uptake in both xenograft models, suggesting the involvement of an active carrier-mediated process. The expression of OATP1A2 was detected in tumour sections from both xenografts, with significantly higher expression (p?=?0.002) in the MCF-7 xenografts. Overall, the higher tumour uptake and tumour-to-muscle ratio, alongside the higher expression of OATP1A2, in the MCF-7 xenograft model suggests the potential of E3S to serve as a novel ligand for targeting hormone dependent breast cancers.
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Multicellular tumor spheroids for evaluation of cytotoxicity and tumor growth inhibitory effects of nanomedicines in vitro: a comparison of docetaxel-loaded block copolymer micelles and Taxotere®.
PLoS ONE
PUBLISHED: 01-01-2013
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While 3-D tissue models have received increasing attention over the past several decades in the development of traditional anti-cancer therapies, their potential application for the evaluation of advanced drug delivery systems such as nanomedicines has been largely overlooked. In particular, new insight into drug resistance associated with the 3-D tumor microenvironment has called into question the validity of 2-D models for prediction of in vivo anti-tumor activity. In this work, a series of complementary assays was established for evaluating the in vitro efficacy of docetaxel (DTX) -loaded block copolymer micelles (BCM+DTX) and Taxotere® in 3-D multicellular tumor spheroid (MCTS) cultures. Spheroids were found to be significantly more resistant to treatment than monolayer cultures in a cell line dependent manner. Limitations in treatment efficacy were attributed to mechanisms of resistance associated with properties of the spheroid microenvironment. DTX-loaded micelles demonstrated greater therapeutic effect in both monolayer and spheroid cultures in comparison to Taxotere®. Overall, this work demonstrates the use of spheroids as a viable platform for the evaluation of nanomedicines in conditions which more closely reflect the in vivo tumor microenvironment relative to traditional monolayer cultures. By adaptation of traditional cell-based assays, spheroids have the potential to serve as intermediaries between traditional in vitro and in vivo models for high-throughput assessment of therapeutic candidates.
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An injectable depot system for sustained intraperitoneal chemotherapy of ovarian cancer results in favorable drug distribution at the whole body, peritoneal and intratumoral levels.
J Control Release
PUBLISHED: 09-29-2011
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The current study characterizes the impact of docetaxel (DTX) distribution on efficacy following sustained intraperitoneal (IP) chemotherapy in murine models of ovarian cancer. A polymer-lipid biodegradable depot (PoLigel) was used to deliver DTX in a sustained manner over 21-days following IP administration. Distribution and efficacy studies were carried out in SCID mice bearing SKOV3 IP solid tumors or C57BL/6 mice with ID8 IP ascites fluid. In addition, a subcutaneous (SC) SKOV3 model was used to determine whether systemic drug levels that result from IP administration of the PoLigel influence antitumor efficacy. Immunostained IP and SC SKOV3 tumor sections were used to study cell death, intratumoral drug distribution and tumor penetration. Sustained concentrations of DTX were observed in plasma, tissue, tumor and ascites over the entire study period. Drug accumulation was several fold greater in tumors and ascites when compared to plasma levels. Sustained chemotherapy resulted in significant reduction in tumor burden and ascites volume. IP tumors showed greater cell death compared to the SC tumors as seen by higher TUNEL and caspase-3 expression. At the intratumoral level, DTX distributed more towards the core of IP tumors compared to the SC tumors. Tumor penetration of drug from nearest blood vessel was 1.5 fold greater in the IP tumors than the SC tumors. Overall, favorable drug distribution at the whole-body, peritoneal and intratumoral levels in combination with local and systemic sustained drug exposure contribute to the high efficacy observed. These results encourage the clinical use of IP sustained chemotherapy for ovarian cancer.
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RapidChek SELECT Salmonella enteritidis test system for the detection of Salmonella enteritidis in poultry house drag swabs, shell egg pools, and chicken carcass rinsates.
J AOAC Int
PUBLISHED: 09-17-2011
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The RapidChek SELECT Salmonella Enteritidis Test System was validated for the detection of Salmonella Enteritidis (SE) in poultry house drag swabs, shell egg pools, and chicken carcass rinsates. The method utilizes RapidChek SELECT Salmonella (AOAC PTM License No. 080601) proprietary primary and secondary enrichment media. Following enrichment, an immunochromatographic test strip is inserted into the tube containing the secondary enrichment broth, developed for 10 min, and interpreted. Salmonella Enteritidis-inoculated samples (1-5 CFU SE/analytical unit) were tested by the test method as well as the appropriate cultural reference method U.S. Food and Drug Administration-Bacteriological Analytical Manual (drag swabs and egg pools) or U.S. Department of Agriculture-Food Safety and Inspection Service (chicken carcass rinsates). A total of 80 samples were tested by both methods in the study. Fifty-two samples were positive by the RapidChek SELECT Salmonella Enteritidis method and 38 were found positive by the respective reference method. The sensitivity of the method was 100% and the specificity was 100%. The accuracy of the test method was 137%, indicating that the method was more sensitive than the reference method. The RapidChek SELECT Salmonella Enteritidis method was tested with 82 Salmonella Group D1 strains including 63 Salmonella Enteritidis strains as well as 32 non-Salmonella Group D1 strains representing 10 bacteria genera. The test method detected all 82 Group D1 strains (100% sensitivity). None of the non-Salmonella Group D1 or other genera of bacteria were detected, indicating a specificity of 100%. The method was shown to be highly robust and stable under control and accelerated stability conditions.
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Polymer brush controlled bioinspired calcium phosphate mineralization and bone cell growth.
Biomacromolecules
PUBLISHED: 09-06-2011
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Polymer brushes on thiol-modified gold surfaces were synthesized by using terminal thiol groups for the surface-initiated free radical polymerization of methacrylic acid and dimethylaminoethyl methacrylate, respectively. Atomic force microscopy shows that the resulting poly(methacrylic acid) (PMAA) and poly(dimethylaminoethyl methacrylate) (PDMAEMA) brushes are homogeneous. Contact angle measurements show that the brushes are pH-responsive and can reversibly be protonated and deprotonated. Mineralization of the brushes with calcium phosphate at different pH yields homogeneously mineralized surfaces, and preosteoblastic cells proliferate on both the nonmineralized and mineralized surfaces. The number of living cells on the mineralized hybrid surfaces is ca. 3 times (PDMAEMA) and 10 times (PMAA) higher than on the corresponding nonmineralized brushes.
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Hydrogels Containing Core Cross-Linked Block Co-Polymer Micelles.
J Biomater Sci Polym Ed
PUBLISHED: 05-31-2011
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Poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels loaded with core cross-linked PEG-b-PCL micelles with different morphologies (spherical and rod-like) were prepared and evaluated for use as drug-eluting soft contact lenses. The relationship between the composition of micelle-loaded pHEMA hydrogels and properties such as transparency and swelling were determined. The incorporation of core cross-linked micelles into pHEMA hydrogels led to the formation of different internal nanostructures which were dependent on the amount and morphology of the micelles added. 7-Hydroxy-9H-(1,3-dichloro-9,9-dimethylacridin-2-one) (DDAO), a hydrophobic fluorescent dye, was loaded into the micelles prior to their incorporation within the hydrogel matrix. The in vitro release of DDAO demonstrated the potential of the micelles/pHEMA hydrogels to provide controlled drug delivery for at least 14 days. This study demonstrates the feasibility of both chemical and physical incorporation of block co-polymer micelles within pHEMA hydrogels as a means to achieve sustained release of drugs for potential application in ophthalmic therapies.
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Chemotherapy dosing schedule influences drug resistance development in ovarian cancer.
Mol. Cancer Ther.
PUBLISHED: 05-06-2011
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Drug resistance leads to chemotherapy failure and is responsible for the death of a great majority of patients with metastatic, late-stage ovarian cancer. The present study addressed whether changes in the chemotherapy dosing schedule affect the development, further worsening, or circumvention of drug resistance in chemosensitive and chemoresistant ovarian cancer. Severe combined immunodeficient mice bearing HeyA8 and HeyA8-MDR xenografts were treated with docetaxel intermittently (1×/wk or 3×/wk) or continuously for 21 days. Tumor mRNA expression of genes implicated in docetaxel resistance was measured by quantitative real-time-PCR. Analyzed genes included those encoding for the drug efflux transporters mdr1 and mrp7 and for molecules that interfere with or overcome the effects of docetaxel, including ?-tubulinIII, actinin4, stathmin1, bcl2, rpn2, thoredoxin, and akt2. In both models, continuous docetaxel resulted in greater antitumor efficacy than 1×/wk or 3×/wk dosing and did not induce upregulation of any analyzed genes. Once weekly dosing caused upregulation of various drug resistance-related genes, especially in chemoresistant xenografts. More frequent, 3×/wk dosing diminished this effect, although levels of various genes were higher than for continuous chemotherapy. Drug efflux transporter expression was further examined by Western blotting, confirming that intermittent, but not continuous, docetaxel induced significant upregulation. Overall, our results show that the presence and length of treatment-free intervals contribute to the development of drug resistance. Elimination of these intervals by continuous dosing resulted in superior antitumor efficacy and prevented drug resistance induction in chemosensitive and chemoresistant disease. These results encourage the clinical implementation of continuous chemotherapy to overcome and/or prevent drug resistance in newly diagnosed and recurrent, refractory ovarian cancer.
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Influence of formulation variables on the biodistribution of multifunctional block copolymer micelles.
J Control Release
PUBLISHED: 05-03-2011
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The physico-chemical characteristics and composition of block copolymer micelles (BCMs) may influence the pharmacokinetics and consequently, the desired delivery characteristics. In this study the influence of formulation variables such as size, density of targeting ligand [i.e. epidermal growth factor (hEGF)] and the bifunctional chelator (BFC) used for labelling the BCMs with (111)In, on the pharmacokinetics and biodistribution in mice were evaluated. BCMs were prepared from Me-PEG(x)-b-PCL(y) (x=2.5 k, y=1.2 k for 15 nm BCMs and x=5 k, y=5 k for 60 nm BCMs) with (targeted, 1 or 5 mol% hEGF) or without (non-targeted) hEGF-PEG(x)-b-PCL(y). To investigate the effect of the BFC on the pharmacokinetics, the BCMs were labelled with (111)In using p-SCN-Bn-DOTA (Bn-DOTA-PEG(x)-b-PCL(y)), H(2)N-DOTA (DOTA-PEG(x)-b-PCL(y)), DTPA anhydride (DTPA-PEG(x)-b-PCL(y)) or p-SCN-Bn-DTPA (Bn-DTPA-PEG(x)-b-PCL(y)). The resulting 15 nm or 60 nm non-targeted or targeted (1 or 5 mol% hEGF) were injected via a tail vein to mice bearing MDA-MB-468 human breast cancer xenograft that overexpress EGFR, followed by pharmacokinetics and biodistribution studies. Pharmacokinetic parameters were determined by fitting the blood concentration vs time data using a two compartment model with i.v. bolus input. Pharmacokinetic parameters were found to depend on BCM size, the BFC used as well as the density of hEGF on the surface of the BCMs. BCMs labelled with p-SCN-Bn-DTPA ((111)In-Bn-BCMs) showed improved pharmacokinetics (i.e. extended circulation lifetime) and tumor uptake compared to those labelled with DOTA-PEG(x)-b-PCL(y), p-SCN-Bn-DOTA or DTPA dianhydride. Formulations with a high density of hEGF (5 mol% hEGF) had short circulation half-lives. BCMs labelled with (111)In via p-SCN-Bn-DTPA showed highest accumulation in the liver and spleen and slower whole body elimination. Smaller sized BCMs were rapidly cleared from the circulation. Increasing the density of hEGF on the surface did not improve tumor uptake due to faster clearance from the circulation. To achieve improved pharmacokinetics and in turn effective exploitation of the EPR effect, p-SCN-Bn-DTPA emerged as the optimal BFC for radiolabelling BCMs while a lower density of hEGF gave more favourable organ distribution.
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Docetaxel distribution following intraperitoneal administration in mice.
J Pharm Pharm Sci
PUBLISHED: 04-20-2011
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Intraperitoneal (IP) chemotherapy with high molecular weight lipophilic antineoplastic agents such as the taxanes has shown promise in clinical trial evaluation for treatment of localized peritoneal cancers. We have previously developed an IP injectable hydrogel formulation (PoLigel) for sustained peritoneal delivery of docetaxel (DTX), and observed significant efficacy in murine models of ovarian cancer when compared to Taxotere®, the FDA approved formulation of DTX. In order to understand the relationship between drug distribution and efficacy, the current study compares the tissue distribution and pharmacokinetics of DTX administered IP in the PoLigel or Taxotere® formulations.
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Computational approaches to the rational design of nanoemulsions, polymeric micelles, and dendrimers for drug delivery.
Nanomedicine
PUBLISHED: 02-10-2011
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Nanoparticles are promising drug delivery systems whose selection and optimization can be gainfully conducted by theoretical methods. This review is targeted to experimentalists who are interested in enhancing their time and cost efficiency through the incorporation of theoretical approaches. This review thus begins with a brief overview of theoretical approaches available to the development of contemporary drug delivery systems. Approaches include solubility parameters, Flory-Huggins theory, analytical predictions of partition coefficients, and molecular simulations. These methods are then compared as they relate to the optimization of drug-material pairs using important performance-related parameters including the size of the delivery particles, their surface properties, and the compatibility of the materials with the drug to be sequestered. Next, this review explores contemporary efforts to optimize a selection of existing nanoparticle platforms, including nanoemulsions, linear and star-shaped block co-polymer micelles, and dendrimers. The review concludes with an outlook on the challenges remaining in the successful application of these theoretical methods to the development of new drug formulations.
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APN/CD13-targeting as a strategy to alter the tumor accumulation of liposomes.
J Control Release
PUBLISHED: 01-08-2011
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Targeting angiogenic vasculature has been validated as a viable approach for cancer imaging and therapy. The tumor vasculature-specific ligand asparagine-glycine-arginine (NGR) peptide targets the isoform of aminopeptidase N (APN, also referred to as CD13) that is expressed on the endothelial cells in angiogenic vessels such as the neovasculature in tumors. APN/CD13 has become widely recognized as a rational target for therapeutic development and several NGR-conjugated agents are now in pre-clinical and clinical development. In the current study, a CT image-based approach is used to evaluate the in vivo performance of several NGR conjugated liposome formulations that vary in terms of NGR density and PEG spacer arm length. Indeed, for the first time it is demonstrated that CT imaging can be used for quantitative and longitudinal assessment of the pharmacokinetics and biodistribution of an actively targeted liposome formulation containing an iodinated agent. In comparison to conventional methods, the CT image guided drug delivery approach enables visualization of the intratumoral distribution of liposomes and quantification of the fraction of tumor occupied by the vesicles over time. This study is the first to use CT for molecular imaging.
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Combination drug delivery strategy for the treatment of multidrug resistant ovarian cancer.
Mol. Pharm.
PUBLISHED: 12-17-2010
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The onset of multidrug resistance (MDR) in ovarian cancer is one of the main causes of treatment failure and low survival rates. Inadequate drug exposure and treatment-free periods due to intermittent chemotherapy select for cancer cells overexpressing drug efflux transporters, resulting in resistant disease. The present study examines the sustained administration of the chemotherapeutic agent docetaxel (DTX) alone and in combination with cepharanthine (CEP), a potent drug efflux transporter inhibitor. DTX and CEP were delivered via the intraperitoneal route in a sustained manner using an injectable polymer-lipid formulation. In vitro, the combination strategy resulted in significantly (p < 0.05) more apoptosis, greater intracellular accumulation of DTX, and lower DTX efflux in ovarian cancer cells showing the MDR phenotype. In vivo, sustained treatment with DTX and CEP showed significantly greater (p < 0.05) tumor inhibition (91 ± 4%) in a murine model of multidrug resistant ovarian cancer compared to sustained DTX treatment (76 ± 6%) and was more than twice as efficacious as intermittent DTX treatment. Overall findings from these studies highlight the impact of sustained delivery of monotherapy and combination therapy in the management of refractory ovarian cancer displaying the MDR phenotype.
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Liposome contrast agent for CT-based detection and localization of neoplastic and inflammatory lesions in rabbits: validation with FDG-PET and histology.
Contrast Media Mol Imaging
PUBLISHED: 06-30-2010
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This study was aimed at assessing the performance of a liposome-based computed tomography (CT) contrast agent to detect tumor and inflammatory lesions in a rabbit model relative to (18)F-fluorodeoxyglucose- positron emission tomography (FDG-PET).
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Continuous docetaxel chemotherapy improves therapeutic efficacy in murine models of ovarian cancer.
Mol. Cancer Ther.
PUBLISHED: 06-08-2010
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Ovarian cancer is known as the silent killer for being asymptomatic until late stages. Current first-line treatment consists of debulking surgery followed by i.v. chemotherapeutics administered intermittently, which leads to insufficient drug concentrations at tumor sites, accelerated tumor proliferation rates, and drug resistance, resulting in an overall median survival of only 2 to 4 years. For these reasons, more effective treatment strategies must be developed. We have investigated a localized, continuous chemotherapy approach in tumor models of human and murine ovarian cancers using the antineoplastic agent docetaxel. We show here that continuous docetaxel therapy is considerably more efficacious than intermittent therapy, resulting in a greater decrease in tumor burden and ascites fluid accumulation. Immunohistochemical analyses show that continuous chemotherapy abrogates tumor cell proliferation and angiogenesis to the tumor microenvironment, leading to greater tumor cell death than intermittent docetaxel therapy. Overall, our results show greater therapeutic advantages of continuous over intermittent chemotherapy in the treatment of ovarian cancer.
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Gold nanoparticles as radiation sensitizers in cancer therapy.
Radiat. Res.
PUBLISHED: 06-04-2010
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Among other nanoparticle systems, gold nanoparticles have been explored as radiosensitizers. While most of the research in this area has focused on either gold nanoparticles with diameters of less than 2 nm or particles with micrometer dimensions, it has been shown that nanoparticles 50 nm in diameter have the highest cellular uptake. We present the results of in vitro studies that focus on the radiosensitization properties of nanoparticles in the size range from 14-74 nm. Radiosensitization was dependent on the number of gold nanoparticles internalized within the cells. Gold nanoparticles 50-nm in diameter showed the highest radiosensitization enhancement factor (REF) (1.43 at 220 kVp) compared to gold nanoparticles of 14 and 74 nm (1.20 and 1.26, respectively). Using 50-nm gold nanoparticles, the REF for lower- (105 kVp) and higher- (6 MVp) energy photons was 1.66 and 1.17, respectively. DNA double-strand breaks were quantified using radiation-induced foci of gamma-H2AX and 53BP1, and a modest increase in the number of foci per nucleus was observed in irradiated cell populations with internalized gold nanoparticles. The outcome of this research will enable the optimization of gold nanoparticle-based sensitizers for use in therapy.
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Utility of transdermal fentanyl for prevention of iatrogenic opioid abstinence syndrome in children.
J Opioid Manag
PUBLISHED: 05-21-2010
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Iatrogenic opioid abstinence syndrome (IOAS) can occur in critically ill infants/ children following abrupt discontinuation of opioids. There are no standard guidelines for the prevention of IOAS. Transdermal fentanyl (TF) has been infrequently used at our institution for the prevention of IOAS.
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The effects of particle size and molecular targeting on the intratumoral and subcellular distribution of polymeric nanoparticles.
Mol. Pharm.
PUBLISHED: 05-19-2010
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The current study describes the impact of particle size and/or molecular targeting (epidermal growth factor, EGF) on the in vivo transport of block copolymer micelles (BCMs) in athymic mice bearing human breast cancer xenografts that express differential levels of EGF receptors (EGFR). BCMs with diameters of 25 nm (BCM-25) and 60 nm (BCM-60) were labeled with indium-111 ((111)In) or a fluorescent probe to provide a quantitative and qualitative means of evaluating their whole body, intratumoral, and subcellular distributions. BCM-25 was found to clear rapidly from the plasma compared to BCM-60, leading to an almost 2-fold decrease in their total tumor accumulation. However, the tumoral clearance of BCM-25 was delayed through EGF functionalization, enabling the targeted BCM-25 (T-BCM-25) to achieve a comparable level of total tumor deposition as the nontargeted BCM-60 (NT-BCM-60). Confocal fluorescence microscopy combined with MATLAB analyses revealed that NT-BCM-25 diffuses further away from the blood vessels (D(mean) = 42 +/- 9 microm) following extravasation, compared to NT-BCM-60 which mainly remains in the perivascular regions (D(mean) = 23 +/- 4 microm). The introduction of molecular targeting imposes the "binding site barrier" effect, which retards the tumor penetration of T-BCM-25 (D(mean) = 29 +/- 7 microm, p < 0.05). The intrinsic nuclear translocation property of EGF/EGFR leads to a significant increase in the nuclear uptake of T-BCM-25 in vitro and in vivo via active transport. Overall, these results highlight the need to consider multiple design parameters in the development of nanosystems for delivery of anticancer agents.
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Polymeric drug delivery systems for localized cancer chemotherapy.
Drug Deliv
PUBLISHED: 05-01-2010
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Cancer has become one of the most difficult health challenges of our time, accounting for millions of deaths yearly. Systemic chemotherapy is the most common therapeutic approach; however, considerable limitations exist including toxicities to healthy tissues and low achievable drug concentrations at tumor sites. More than 85% of human cancers are solid tumors, which can greatly benefit from localized delivery. This approach allows for high drug concentrations at the target site, lower systemic toxicity, and extended drug exposure which may be beneficial for cell cycle-specific drugs. Polymers have been widely considered in the development of localized delivery systems. This review focuses on both natural and synthetic biodegradable polymers that have been explored for localized chemotherapy, exploring their advantages, disadvantages, and clinical potential while citing examples of their use in pre-clinical development.
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Poly(ethylene glycol)-b-poly(epsilon-caprolactone) micelles containing chemically conjugated and physically entrapped docetaxel: synthesis, characterization, and the influence of the drug on micelle morphology.
Biomacromolecules
PUBLISHED: 04-08-2010
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Docetaxel (DTX), a chemotherapeutic agent, was coupled to the hydrophobic block of poly(ethylene glycol)-b-poly(epsilon-caprolactone) (PEG-b-PCL) copolymers synthesized by metal free ring-opening polymerization. Synthesis of the copolymers and the copolymer-drug conjugate (PEG-b-PCL-DTX) were confirmed by (1)H NMR and GPC analyses. The PEG-b-PCL-DTX conjugates had a approximately 1:3 drug/copolymer ratio (w/w) and a low critical micelle concentration in aqueous solution (14 mg/L). Encapsulation of DTX in PEG-b-PCL-DTX micelles resulted in an 1840-fold increase in the aqueous solubility of the drug. Release of physically encapsulated DTX from PEG-b-PCL-DTX micelles was slower than drug release from PEG-b-PCL micelles due to the improved compatibility between DTX and the micelle core. Core-conjugated DTX was released over the course of one week indicating that PEG-b-PCL-DTX micelles have the capacity for sustained drug release in the absence of physically encapsulated drug. Importantly, conjugation of DTX to the core-forming block had a profound effect on the morphology of the copolymer aggregates.
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In vivo distribution of polymeric nanoparticles at the whole-body, tumor, and cellular levels.
Pharm. Res.
PUBLISHED: 01-11-2010
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Block copolymer micelles (BCMs) were functionalized with indium-111 and/or epidermal growth factor (EGF), which enabled investigation of the in vivo transport of passively and actively targeted BCMs. The integration of conventional and image-based techniques afforded novel quantitative means to achieve an in-depth insight into the fate of polymeric nanoparticles in vivo.
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Noninvasive monitoring of the fate of 111In-labeled block copolymer micelles by high resolution and high sensitivity microSPECT/CT imaging.
Mol. Pharm.
PUBLISHED: 09-01-2009
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The validation of high sensitivity and high resolution microSPECT/CT imaging for tracking the in vivo pathway and fate of an 111Indium-labeled (111In) amphiphilic diblock copolymer micelle formulation is presented. Heterobifunctional poly(ethylene glycol) was used to initiate cationic ring opening polymerization of epsilon-caprolactone, which was then conjugated to 2-(4-isothiocyanatobenzyl)-diethylenetriaminepentaacetic acid (p-SCN-Bn-DTPA) for chelation with 111In. The micelles were characterized in terms of their physicochemical properties including size, size distribution, zeta-potential, and radiochemical purity. Elimination kinetics and tissue deposition were evaluated in healthy mice following administration of 111In-micelles, 111In-DTPA-b-PCL unimers (i.e., administered under the critical micelle concentration) or 111In-Bn-DTPA. Healthy and MDA-MB-231 tumor-bearing mice were imaged using microSPECT/CT following iv administration of 111In-micelles or 111In-Bn-DTPA. Overall, incorporation of 111In onto the surface of thermodynamically stable micelles results in long plasma residence times for the radionuclide and preferential localization within the spleen (22 +/- 5% i.d/g), liver (13 +/- 3% i.d./g), and tumor (9 +/- 2% i.d./g). MicroSPECT/CT imaging provided noninvasive longitudinal visualization of circulation dynamics and tissue deposition. A strong correlation between image-based region of interest (ROI) analysis and biodistribution data was found, implying that nuclear imaging can be used as a noninvasive tool to accurately quantify tissue distribution. As well, the image-based assessment provided unique insight into the intratumoral distribution of the micelles in vivo.
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Enhancement of docetaxel solubility via conjugation of formulation-compatible moieties.
Org. Biomol. Chem.
PUBLISHED: 07-02-2009
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Computer-based theoretical calculations were employed to direct the design of docetaxel conjugates with enhanced solubility in the internal phase of a nano-emulsion formulation. The theoretically-identified optimal docetaxel conjugates were synthesized by direct attachment of lauroyl moieties through an ester linkage to docetaxel. In comparison to docetaxel, the conjugates exhibited significantly improved solubility in oil, as predicted by our theoretical calculations. This contributed to high drug entrapment efficiencies (up to 97%) and a high drug loading capacity (5.7% w/w) for the docetaxel conjugates. The mono-substitution of an acyl group at C-2 of docetaxel resulted in a conjugate with 37- to 46-fold lower cytotoxicity than that of the parent drug in two human cancer cell lines. Importantly, the activity exerted by the mono-substituted docetaxel on the cancer cells was due in part to the cytotoxicity of the parent drug that was released via hydrolysis of the ester bond between the lauroyl moiety and the drug under biologically relevant conditions. In contrast, di- and tri-substitution of acyl groups at C-2, C-7 and/or C-10 of docetaxel resulted in non-hydrolysable conjugates that were found to be inactive. Overall, our results show that computer-based theoretical calculation is a promising strategy for guiding the enhancement of material-drug compatibility in formulation development. Also, these studies confirm that chemical modification of docetaxel for enhancement of material-drug compatibility should be limited to mono-substitution at C-2 and result in a prodrug that is hydrolysable at a moderate rate under biologically relevant conditions.
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Intracellular uptake, transport, and processing of nanostructures in cancer cells.
Nanomedicine
PUBLISHED: 05-30-2009
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Nanotechnology has been used to provide advanced biomedical research tools in diagnostic imaging and therapy, which requires targeting of nanoparticles (NPs) to individual cells and subcellular compartments. However, a complete understanding of the intracellular uptake, transport, and subcellular distribution of nanostructured materials remains limited. Hence, gold NPs were explored as a model system to study the intracellular behavior of NPs in real time. Our results show that the cellular uptake of gold NPs is dependent on their size and surface properties. The NPs were transported in vesicles of 300-500 nm diameter within the cytoplasm. The average velocity and diffusion coefficient of the vesicles containing NPs were 10.2 (+/-1.8) microm/hr and 3.33 (+/-0.52) microm 2/hr, respectively. Analysis of the time-dependent intracellular spatial distribution of the NPs demonstrated that they reside in lysosomes (final degrading organelles) within 40 minutes of incubation. These findings can be used to tailor nanoscale devices for effective cell targeting and delivery.
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Chitosan-phospholipid blend for sustained and localized delivery of docetaxel to the peritoneal cavity.
Int J Pharm
PUBLISHED: 04-27-2009
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Localized and sustained delivery of chemotherapeutics presents a "magic bullet" effect by providing high drug concentrations at the target site, extended drug exposure and reduced systemic toxicity. In the present study, an injectable chitosan-phospholipid (PoLi(gel)) blend is put forth as a strategy to achieve sustained and localized delivery of docetaxel (DTX) following intraperitoneal (IP) administration. The stability of the blend was confirmed in vitro, by turbidity measurements and attributed to specific molecular interactions and the organization of the materials within the blend, as evidenced by FTIR analysis and confocal laser scanning microscopy, respectively. The chitosan and phospholipid were found to colocalize in regions surrounding a mean object area of 11.2mum(2) with colocalization coefficients of 43% and 46% for the chitosan and phospholipid, respectively. The PoLi(gel) blend afforded sustained drug release as seen both in vitro (2.4+/-0.7% DTX per day) and in vivo (4.4+/-0.7% DTX per day). Constant concentrations of DTX were observed over a 2-week period in plasma and relevant peritoneal tissues, with no signs of toxicity or inflammation, following IP administration of the blend in healthy CD-1 mice. At DTX doses of 28.8 and 19.2mg/kg, the blend showed significant tumor inhibition of 87.3+/-9.3% and 74.1+/-25.9%, respectively, in a murine xenograft model of human ovarian adenocarcinoma. This localized delivery system has shown excellent potential for sustained IP treatment of cancers, such as ovarian, that reside in the peritoneal cavity.
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Quantitative CT imaging of the spatial and temporal distribution of liposomes in a rabbit tumor model.
Mol. Pharm.
PUBLISHED: 03-21-2009
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Successful employment of noninvasive imaging techniques to quantitatively assess the in vivo pharmacokinetics and biodistribution of nanoparticle drug delivery systems will facilitate the rational design of novel targeted drug carriers. This study reports on the bulk organ/tissue (liver, kidneys, spleen, tumor and blood) and intratumoral distribution of liposomes containing iohexol and gadoteridol over a 14-day period in VX2 sarcoma-bearing New Zealand White rabbits using computed tomography (CT). The vascular half-life of the liposomes was found to be 63.6 +/- 5.8 h and the maximum tumor-to-muscle iodine concentration ratio of 11.9 +/- 6.0 was measured 7 days postinjection with 1.13 +/- 0.29% ID of liposomes accumulating at the tumor site. The liposomes achieved their highest intratumoral distribution volume ratio at 48 h postadministration, occupying 72 +/- 5% of the total tumor volume. This investigation demonstrated the feasibility of using CT to perform quantitative, volumetric and longitudinal assessment of the pharmacokinetics and biodistribution of iodinated liposomes with sensitivities in the range of microg/cm3 while maintaining the ability to identify boundaries of anatomical structures at submillimeter resolution and with imaging time of less than one minute per scan. If successfully approved for clinical adoption, the use of CT imaging to monitor nanoparticulate drug delivery will provide an opportunity for online adjustment of therapeutic regimens and implementation of personalized medicine.
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Block copolymer micelles for delivery of cancer therapy: transport at the whole body, tissue and cellular levels.
J Control Release
PUBLISHED: 02-18-2009
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The use of block copolymer micelles (BCMs) for the targeted delivery of chemotherapeutics has proven to be a promising approach for improving the therapeutic efficacy of pharmaceutical cancer therapy. Acceleration of the translation of BCM-based drug formulations from the fundamental stages of pre-clinical development to clinical use requires a greater understanding of the transport mechanisms that influence the fate of these nano-carrier systems at the whole body, tissue, and cellular levels. New information emerging regarding the intratumoral distribution, and tumor penetration of BCMs and other nanosystems in vivo, by non-invasive image-based assessment, has the potential to revolutionize our understanding and current approach to drug delivery in this field. This review aims to highlight these and other important advancements as well as to bring attention to the many critical questions that remain to be addressed regarding the fate of BCM-based drug formulations in vivo.
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RapidChek SELECT Salmonella. Performance Tested Method 080601.
J AOAC Int
PUBLISHED: 02-09-2009
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RapidChek SELECT Salmonella was previously validated in the Performance Tested Methods program for the detection of Salmonella spp. in raw ground chicken, chicken carcass rinse, sliced cooked turkey, and liquid eggs. The present matrix extension study conducted under the AOAC Research Institute Emergency Response Validation program compared the RapidChek SELECT Salmonella method to the U.S. Food and Drug Administrations Bacteriological Analytical Manual (FDA-BAM) method for the detection of Salmonella Typhimurium in peanut butter. Overall, 27 samples were found positive by the RapidChek SELECT Salmonella method and 27 were found to be positive by the reference method. All RapidChek SELECT Salmonella presumptive positives were confirmed positive by the cultural reference method; additionally, all presumptive negative results were confirmed negative by the cultural reference method. Accordingly 0% false-negative rate and 0% false-positive rate were found. No significant difference between the RapidCheck SELECT Salmonella and FDA-BAM reference method was found; calculated Chi-square was 0. Results indicate that a low level of Salmonella in peanut butter can be successfully recovered and detected in the minimum 24 h enrichment protocol.
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Cellular uptake and transport of gold nanoparticles incorporated in a liposomal carrier.
Nanomedicine
PUBLISHED: 02-06-2009
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Recent interest in using gold nanoparticles (Au NPs) for therapy in radiation medicine has motivated development of a liposome-based system to enhance their delivery to cells. In this study, liposomes were demonstrated to perform like a "Trojan Horse" to deliver small (1.4 nm) Au NPs into tumor cells by overcoming the energetically unfavorable endocytosis process for small NPs. The results reveal that the liposomal approach provides a thousand-fold enhancement in the cellular uptake of the small Au NPs. Real-time intracellular tracking of the Au NP-liposomes revealed an average speed of 12.48 +/- 3.12 microm/hr for their intracellular transport. Analysis of the time-dependent intracellular spatial distribution of the Au NP-liposomes demonstrated that they reside in lysosomes (final degrading organelles) within 40 minutes of incubation. Knowledge gained in these studies opens the door to pursuing liposomes as a viable strategy for delivery of Au NPs in radiation therapy applications.
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Biocompatibility of injectable chitosan-phospholipid implant systems.
Biomaterials
PUBLISHED: 01-21-2009
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Injectable biomaterials are desirable therapeutic platforms due to minimal invasiveness and improved patient compliance, and are applicable in such areas as compound delivery and tissue engineering. The present work examined the biocompatibility of injectable blends composed of chitosan, phospholipid and lauric aldehyde (PoLi(gel)-LA) or lauric chloride (PoLi(gel)-LCl). In vitro cytotoxicity was evaluated in L929 and HeLa cell lines. Both blends resulted in acceptable biocompatibility, although greater cell viability was seen with PoLi(gel)-LA. In vivo biocompatibility was investigated in healthy CD-1 mice. Subcutaneous injection of the PoLi(gel)-LA blend caused no local or systemic toxicities over a four-week period while the PoLi(gel)-LCl caused immediate local toxicity. Mice injected intraperitoneally with PoLi(gel)-LA did not show physical or behavioural alterations, and body weight changes did not differ from control animals. Furthermore, histological examination of spleen and liver showed unaltered morphology. Interleukin-6 levels in mice injected with PoLi(gel)-LA did not differ from levels of control animals (6.91+/-3.61 pg/mL versus 6.92+/-5.02 pg/mL, respectively). Biodegradation occurred progressively, with 7.4+/-5.02% of the original injected mass remaining after four weeks. Results obtained herein establish the biocompatibility of PoLi(gel)-LA and indicate its potential for use in various localized therapeutic applications.
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Hydrogel containing silica shell cross-linked micelles for ocular drug delivery.
J Pharm Sci
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Poly(2-hydroxyethyl methacrylate-methacrylic acid-ethylene glycol dimethacrylate) hydrogels loaded with silica shell cross-linked methoxy(polyethylene glycol)-block-polycaprolactone (MePEG-b-PCL) micelles with rod-like morphology were prepared as a potential soft contact lens material for the sustained release of ocular drugs. The silica shell cross-linked methoxy micelles (SSCMs) comprising a polycaprolactone core surrounded by a silica shell were synthesized and their size, morphology, stability, and drug release kinetics were evaluated. The relationships between the composition of the SSCM-loaded poly(2-hydroxyethyl methacrylate) (pHEMA)-based hydrogels and their transparency, surface wettability, and equilibrium water content were determined. Scanning electron microscopy (SEM) images of SSCM-hydrogel systems showed the presence of intact SSCMs within the hydrogel matrix. Dexamethasone acetate (DMSA), a hydrophobic ophthalmic drug, was loaded into the SSCMs prior to their incorporation into the hydrogels. In vitro release of DMSA from the SSCM-hydrogels, with varying drug loading levels, was observed for up to 30 days. Overall, the incorporation of rod-like SSCMs within pHEMA-based hydrogels provided sustained release over prolonged periods while maintaining optical transparency. This delivery system may be suitable for use as a therapeutic soft contact lens material.
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SDIX RapidChek Listeria F.A.S.T. environmental test system for the detection of Listeria species on environmental surfaces.
J AOAC Int
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The SDIX RapidChek Listeria F.A.S.T. test system was validated against the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) cultural reference method for the detection of Listeria species on stainless steel, plastic, rubber, and painted concrete. The SDIX method uses a proprietary RapidChek Listeria enrichment media for a one-step, 24-40 h enrichment at 30 degrees C, and detects Listeria on an immunochromatographic lateral flow device in 10 min. Different Listeria species were used to spike each of the environmental surfaces. Environmental surfaces were spiked at levels ranging from 50 to 400 CFU/surface (1 in.2 swabs for painted concrete, 4 in.(2) for sponge). A total of 120 spiked samples were tested by the SDIX method at 24 and 40 h and the cultural reference method. Total confirmed positives were 49, 54, and 48 for the SDIX 24 h method, the SDIX 40 h method, and the USDA-FSIS cultural reference method, respectively. Nonspiked samples from all environmental surfaces were reported as negative for Listeria spp. by all methods. The overall Chi square was 0.017 (P = 0.104) and 0.611 (P= 0.566) after a 24 and 40 h enrichment, respectively, indicating that the test method was equivalent in performance to the reference method at both enrichment times. The SDIX method was evaluated for the detection of 50 Listeria and 35 non-Listeria bacterial strains. All 50 Listeria strains were detected by the method (100% sensitivity). Five out of 35 non-Listeria species gave light test signals when grown in nonselective broth culture and tested undiluted. However, when grown in the RapidChek Listeria F.A.S.T. proprietary media, only one bacterial strain (Staphylococcus aureus) was detected, giving a very low test signal (97% specificity). The method was shown to be robust toward several alterations in testing and storage conditions.
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Neoplastic cell response to tiopronin-coated gold nanoparticles.
Nanomedicine
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The present study characterized the in vitro biological response of a comprehensive set of cancer cell lines to gold nanoparticles (2.7 nm) coated with tiopronin (AuNPs-TP). Our findings suggest that upon entering cells, the AuNPs-TP are sequestered in vacuoles such as endosomes and lysosomes, and mostly localize in perinuclear areas. Peak cell accumulation was achieved at 8 hours after incubation. L929 and H520 cells showed more than 75% surviving fraction when treated with 0.5 mg/mL of AuNPs-TP for 24 hours, whereas the surviving fractions were 60% in MCF-7 and 20% in HeLa cells. Reactive oxygen species (ROS) production by the AuNPs-TP was dependent on cell line and exposure time. Antioxidants inhibited ROS generation to various extents, with glutathione and tiopronin being most effective. Overall, exposure time, concentration of the AuNPs-TP, and cell line influenced neoplastic cell response. Furthermore, the mechanism of cytotoxicity of the AuNPs-TP was found to be ROS generation.
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Differential role of organic anion-transporting polypeptides in estrone-3-sulphate uptake by breast epithelial cells and breast cancer cells.
J. Pharmacol. Exp. Ther.
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The purpose of this study was to investigate the differential expression and function of organic anion-transporting polypeptides (OATPs) in breast epithelial and breast cancer cells. Estrone-3-sulfate (E3S), a substrate for 7 of 11 OATPs, is a predominant source of tumor estrogen in postmenopausal, hormone-dependent patients with breast cancer. Overexpression of certain OATPs (e.g., OATP1A2) reported in breast tumor tissues compared with surrounding normal tissues could contribute toward two to three times higher tumoral E3S concentration. Little is known about expression and function of other OATP family members among breast epithelial and breast cancer cells. We therefore compared gene and protein expression of seven OATPs (OATP1A2, OATP1B1, OATP1B3, OATP1C1, OATP2B1, OATP3A1, and OATP4A1) in immortalized breast epithelial cells (MCF10A), hormone-dependent breast cancer cells (MCF7), and hormone-independent breast cancer cells (MDA/LCC6-435, MDA-MB-231, and MDA-MB-468) by quantitative polymerase chain reaction and immunoblotting, respectively. Expression of solute carrier superfamily encoding for OATPs (SLCO) 1A2, 1B1, 1B3, 2B1, and 3A1 is exclusive, similar, or significantly higher in cancer cells compared with MCF10A cells. Protein expression of OATPs is found to be either exclusive or higher in cancer cells compared with MCF10A cells. Specificity of OATP-mediated E3S uptake is observed only in cancer cells, with the highest total uptake in MCF7 cells. Transport kinetics of E3S uptake demonstrates transport efficiency that is 10 times greater in the MCF7 cells than in the hormone-independent cells. These data suggest that OATPs could be a novel therapeutic target for hormone-dependent breast cancers, particularly in postmenopausal patients, where the major source of tumor estrogen is E3S.
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Recent advances in drug delivery strategies for treatment of ovarian cancer.
Expert Opin Drug Deliv
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Ovarian cancer is associated with the highest mortality rate of all gynecological malignancies, due in part to inadequate treatment strategies and the asymptomatic nature of the disease. Current standard of care includes surgery and systemic chemotherapy. However, this approach can result in toxicities and eventual disease relapse, due to the emergence of multidrug resistance. Drug delivery systems (DDS) have shown promise in overcoming many of the limitations facing conventional treatment regimens.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.