The HER2+ tumor-targeted nanoparticle, HerDox, exhibits tumor-preferential accumulation and tumor-growth ablation in an animal model of HER2+ cancer. HerDox is formed by non-covalent self-assembly of a tumor targeted cell penetration protein with the chemotherapy agent, doxorubicin, via a small nucleic acid linker. A combination of electrophilic, intercalation, and oligomerization interactions facilitate self-assembly into round 10-20 nm particles. HerDox exhibits stability in blood as well as in extended storage at different temperatures. Systemic delivery of HerDox in tumor-bearing mice results in tumor-cell death with no detectable adverse effects to non-tumor tissue, including the heart and liver (which undergo marked damage by untargeted doxorubicin). HER2 elevation facilitates targeting to cells expressing the human epidermal growth factor receptor, hence tumors displaying elevated HER2 levels exhibit greater accumulation of HerDox compared to cells expressing lower levels, both in vitro and in vivo. Fluorescence intensity imaging combined with in situ confocal and spectral analysis has allowed us to verify in vivo tumor targeting and tumor cell penetration of HerDox after systemic delivery. Here we detail our methods for assessing tumor targeting via multimode imaging after systemic delivery.
21 Related JoVE Articles!
A Sensitive Method to Quantify Senescent Cancer Cells
Institutions: Université de Caen Basse-Normandie.
Human cells do not indefinitely proliferate. Upon external and/or intrinsic cues, cells might die or enter a stable cell cycle arrest called senescence. Several cellular mechanisms, such as telomere shortening and abnormal expression of mitogenic oncogenes, have been shown to cause senescence. Senescence is not restricted to normal cells; cancer cells have also been reported to senesce.
Chemotherapeutical drugs have been shown to induce senescence in cancer cells. However, it remains controversial whether senescence prevents or promotes tumorigenesis. As it might eventually be patient-specific, a rapid and sensitive method to assess senescence in cancer cell will soon be required.
To this end, the standard β-galactosidase assay, the currently used method, presents major drawbacks: it is time consuming and not sensitive. We propose here a flow cytometry-based assay to study senescence on live cells. This assay offers the advantage of being rapid, sensitive, and can be coupled to the immunolabeling of various cellular markers.
Cancer Biology, Issue 78, Medicine, Cellular Biology, Anatomy, Physiology, Genetics, Oncology, Tumor Cells, Cultured, Early Detection of Cancer, senescence, cancer, cells, flow cytometry, C12FDG, cell culture, clinical applications
In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model
Institutions: University of Texas Southwestern Medical Center , University of Texas Southwestern Medical Center , Kyoto University Graduate School of Medicine.
It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There is little knowledge about in situ, in vivo,
tumor hypoxia during intracranial development of malignant brain tumors because of lack of efficient means to monitor it in these deep-seated orthotopic tumors. Bioluminescence imaging (BLI), based on the detection of light emitted by living cells expressing a luciferase gene, has been rapidly adopted for cancer research, in particular, to evaluate tumor growth or tumor size changes in response to treatment in preclinical animal studies. Moreover, by expressing a reporter gene under the control of a promoter sequence, the specific gene expression can be monitored non-invasively by BLI. Under hypoxic stress, signaling responses are mediated mainly via the hypoxia inducible factor-1α (HIF-1α) to drive transcription of various genes. Therefore, we have used a HIF-1α reporter construct, 5HRE-ODD-luc, stably transfected into human breast cancer MDA-MB231 cells (MDA-MB231/5HRE-ODD-luc). In vitro
HIF-1α bioluminescence assay is performed by incubating the transfected cells in a hypoxic chamber (0.1% O2
) for 24 hr before BLI, while the cells in normoxia (21% O2
) serve as a control. Significantly higher photon flux observed for the cells under hypoxia suggests an increased HIF-1α binding to its promoter (HRE elements), as compared to those in normoxia. Cells are injected directly into the mouse brain to establish a breast cancer brain metastasis model. In vivo
bioluminescence imaging of tumor hypoxia dynamics is initiated 2 wks after implantation and repeated once a week. BLI reveals increasing light signals from the brain as the tumor progresses, indicating increased intracranial tumor hypoxia. Histological and immunohistochemical studies are used to confirm the in vivo
imaging results. Here, we will introduce approaches of in vitro
HIF-1α bioluminescence assay, surgical establishment of a breast cancer brain metastasis in a nude mouse and application of in vivo
bioluminescence imaging to monitor intracranial tumor hypoxia.
Medicine, Issue 56, bioluminescence imaging (BLI), tumor hypoxia dynamics, hypoxia inducible factor-1α (HIF-1α), breast cancer brain metastasis
Microfluidic Device for Recreating a Tumor Microenvironment in Vitro
Institutions: University Of Massachusetts Amherst.
We have developed a microfluidic device that mimics the delivery and systemic clearance of drugs to heterogeneous three-dimensional tumor tissues in vitro. Nutrients delivered by vasculature fail to reach all parts of tumors, giving rise to heterogeneous microenvironments consisting of viable, quiescent and necrotic cell types. Many cancer drugs fail to effectively penetrate and treat all types of cells because of this heterogeneity. Monolayers of cancer cells do not mimic this heterogeneity, making it difficult to test cancer drugs with a suitable in vitro model. Our microfluidic devices were fabricated out of PDMS using soft lithography. Multicellular tumor spheroids, formed by the hanging drop method, were inserted and constrained into rectangular chambers on the device and maintained with continuous medium perfusion on one side. The rectangular shape of chambers on the device created linear gradients within tissue. Fluorescent stains were used to quantify the variability in apoptosis within tissue. Tumors on the device were treated with the fluorescent chemotherapeutic drug doxorubicin, time-lapse microscopy was used to monitor its diffusion into tissue, and the effective diffusion coefficient was estimated. The hanging drop method allowed quick formation of uniform spheroids from several cancer cell lines. The device enabled growth of spheroids for up to 3 days. Cells in proximity of flowing medium were minimally apoptotic and those far from the channel were more apoptotic, thereby accurately mimicking regions in tumors adjacent to blood vessels. The estimated value of the doxorubicin diffusion coefficient agreed with a previously reported value in human breast cancer. Because the penetration and retention of drugs in solid tumors affects their efficacy, we believe that this device is an important tool in understanding the behavior of drugs, and developing new cancer therapeutics.
Bioengineering, Issue 57, Microfluidic Device, Tumor Microenvironment, Hanging Drop Spheroids, Apoptosis, Drug Penetration
Rat Model of Blood-brain Barrier Disruption to Allow Targeted Neurovascular Therapeutics
Institutions: Vanderbilt University School of Medicine.
Endothelial cells with tight junctions along with the basement membrane and astrocyte end feet surround cerebral blood vessels to form the blood-brain barrier1
. The barrier selectively excludes molecules from crossing between the blood and the brain based upon their size and charge. This function can impede the delivery of therapeutics for neurological disorders. A number of chemotherapeutic drugs, for example, will not effectively cross the blood-brain barrier to reach tumor cells2
. Thus, improving the delivery of drugs across the blood-brain barrier is an area of interest.
The most prevalent methods for enhancing the delivery of drugs to the brain are direct cerebral infusion and blood-brain barrier disruption3
. Direct intracerebral infusion guarantees that therapies reach the brain; however, this method has a limited ability to disperse the drug4
. Blood-brain barrier disruption (BBBD) allows drugs to flow directly from the circulatory system
into the brain and thus more effectively reach dispersed tumor cells. Three methods of barrier disruption include osmotic barrier disruption, pharmacological barrier disruption, and focused ultrasound with microbubbles. Osmotic disruption, pioneered by Neuwelt, uses a hypertonic solution of 25% mannitol that dehydrates the cells of the blood-brain barrier causing them to shrink and disrupt their tight junctions. Barrier disruption can also be accomplished pharmacologically with vasoactive compounds such as histamine5
. This method, however, is selective primarily for the brain-tumor barrier7
. Additionally, RMP-7, an analog of the peptide bradykinin, was found to be inferior when compared head-to-head with osmotic BBBD with 25% mannitol8
. Another method, focused ultrasound (FUS) in conjunction with microbubble ultrasound contrast agents, has also been shown to reversibly open the blood-brain barrier9
. In comparison to FUS, though, 25% mannitol has a longer history of safety in human patients that makes it a proven tool for translational research10-12
In order to accomplish BBBD, mannitol must be delivered at a high rate directly into the brain's arterial circulation. In humans, an endovascular catheter is guided to the brain where rapid, direct flow can be accomplished. This protocol models human BBBD as closely as possible. Following a cut-down to the bifurcation of the common carotid artery, a catheter is inserted retrograde into the ECA and used to deliver mannitol directly into the internal carotid artery (ICA) circulation. Propofol and N2
O anesthesia are used for their ability to maximize the effectiveness of barrier disruption13
. If executed properly, this procedure has the ability to safely, effectively, and reversibly open the blood-brain barrier and improve the delivery of drugs that do not ordinarily reach the brain 8,13,14
Medicine, Issue 69, Neuroscience, Immunology, Cancer Biology, Blood-brain barrier disruption, neurovascular, endovascular, intra-arterial, neurosurgery, oncology, neuro-oncology, animal model, rat
Cytotoxic Efficacy of Photodynamic Therapy in Osteosarcoma Cells In Vitro
Institutions: Balgrist University Hospital, Zurich, Switzerland.
In recent years, there has been the difficulty in finding more effective therapies against cancer with less systemic side effects. Therefore Photodynamic Therapy is a novel approach for a more tumor selective treatment.
Photodynamic Therapy (PDT) that makes use of a nontoxic photosensitizer (PS), which, upon activation with light of a specific wavelength in the presence of oxygen, generates oxygen radicals that elicit a cytotoxic response1
. Despite its approval almost twenty years ago by the FDA, PDT is nowadays only used to treat a limited number of cancer types (skin, bladder) and nononcological diseases (psoriasis, actinic keratosis)2
The major advantage of the use of PDT is the ability to perform a local treatment, which prevents systemic side effects. Moreover, it allows the treatment of tumors at delicate sites (e.g.
around nerves or blood vessels). Here, an intraoperative application of PDT is considered in osteosarcoma (OS), a tumor of the bone, to target primary tumor satellites left behind in tumor surrounding tissue after surgical tumor resection. The treatment aims at decreasing the number of recurrences and at reducing the risk for (postoperative) metastasis.
In the present study, we present in vitro
PDT procedures to establish the optimal PDT settings for effective treatment of widely used OS cell lines that are used to reproduce the human disease in well established intratibial OS mouse models. The uptake of the PS mTHPC was examined with a spectrophotometer and phototoxicity was provoked with laser light excitation of mTHPC at 652 nm to induce cell death assessed with a WST-1 assay and by the counting of surviving cells. The established techniques enable us to define the optimal PDT settings for future studies in animal models. They are an easy and quick tool for the evaluation of the efficacy of PDT in vitro
before an application in vivo
Medicine, Issue 85, Photodynamic Therapy (PDT), 5,10,15,20-tetrakis(meta-hydroxyphenyl)chlorin (mTHPC), phototoxicity, dark-toxicity, osteosarcoma (OS), photosensitizer
Establishing Intracranial Brain Tumor Xenografts With Subsequent Analysis of Tumor Growth and Response to Therapy using Bioluminescence Imaging
Institutions: University of California, San Francisco - UCSF.
Transplantation models using human brain tumor cells have served an essential function in neuro-oncology research for many years. In the past, the most commonly used procedure for human tumor xenograft establishment consisted of the collection of cells from culture flasks, followed by the subcutaneous injection of the collected cells in immunocompromised mice. Whereas this approach still sees frequent use in many laboratories, there has been a significant shift in emphasis over the past decade towards orthotopic xenograft establishment, which, in the instance of brain tumors, requires tumor cell injection into appropriate neuroanatomical structures. Because intracranial xenograft establishment eliminates the ability to monitor tumor growth through direct measurement, such as by use of calipers, the shift in emphasis towards orthotopic brain tumor xenograft models has necessitated the utilization of non-invasive imaging for assessing tumor burden in host animals. Of the currently available imaging methods, bioluminescence monitoring is generally considered to offer the best combination of sensitivity, expediency, and cost. Here, we will demonstrate procedures for orthotopic brain tumor establishment, and for monitoring tumor growth and response to treatment when testing experimental therapies.
Neuroscience, Issue 41, brain tumors, implantation, xenograft, athymic mice, bioluminescence imaging, therapeutic testing
Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors
Institutions: Eindhoven University of Technology & NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Center for Nanotechnology Innovation, NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Center for Nanotechnology Innovation.
The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro
, in living cells and in vivo
. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo
in mouse brain.
Chemistry, Issue 79, Investigative Techniques, Chemistry and Materials (General), dendrimer, fluorescence, sensors, pH, delivery, confocal
Therapeutic Gene Delivery and Transfection in Human Pancreatic Cancer Cells using Epidermal Growth Factor Receptor-targeted Gelatin Nanoparticles
Institutions: Northeastern University.
More than 32,000 patients are diagnosed with pancreatic cancer in the United States per year and the disease is associated with very high mortality 1
. Urgent need exists to develop novel clinically-translatable therapeutic strategies that can improve on the dismal survival statistics of pancreatic cancer patients. Although gene therapy in cancer has shown a tremendous promise, the major challenge is in the development of safe and effective delivery system, which can lead to sustained transgene expression.
Gelatin is one of the most versatile natural biopolymer, widely used in food and pharmaceutical products. Previous studies from our laboratory have shown that type B gelatin could physical encapsulate DNA, which preserved the supercoiled structure of the plasmid and improved transfection efficiency upon intracellular delivery. By thiolation of gelatin, the sulfhydryl groups could be introduced into the polymer and would form disulfide bond within nanoparticles, which stabilizes the whole complex and once disulfide bond is broken due to the presence of glutathione in cytosol, payload would be released 2-5
. Poly(ethylene glycol) (PEG)-modified GENS, when administered into the systemic circulation, provides long-circulation times and preferentially targets to the tumor mass due to the hyper-permeability of the neovasculature by the enhanced permeability and retention
. Studies have shown over-expression of the epidermal growth factor receptor (EGFR) on Panc-1 human pancreatic adenocarcinoma cells 7
. In order to actively target pancreatic cancer cell line, EGFR specific peptide was conjugated on the particle surface through a PEG spacer.8
Most anti-tumor gene therapies are focused on administration of the tumor suppressor genes, such as wild-type p53 (wt-p53), to restore the pro-apoptotic function in the cells 9
. The p53 mechanism functions as a critical signaling pathway in cell growth, which regulates apoptosis, cell cycle arrest, metabolism and other processes 10
. In pancreatic cancer, most cells have mutations in p53 protein, causing the loss of apoptotic activity. With the introduction of wt-p53, the apoptosis could be repaired and further triggers cell death in cancer cells 11
Based on the above rationale, we have designed EGFR targeting peptide-modified thiolated gelatin nanoparticles for wt-p53 gene delivery and evaluated delivery efficiency and transfection in Panc-1 cells.
Bioengineering, Issue 59, Gelatin Nanoparticle, Gene Therapy, Targeted Delivery, Pancreatic Cancer, Epidermal Growth Factor Receptor, EGFR
Pre-clinical Evaluation of Tyrosine Kinase Inhibitors for Treatment of Acute Leukemia
Institutions: University of Colorado Anschutz Medical Campus, University Hospital of Essen.
Receptor tyrosine kinases have been implicated in the development and progression of many cancers, including both leukemia and solid tumors, and are attractive druggable therapeutic targets. Here we describe an efficient four-step strategy for pre-clinical evaluation of tyrosine kinase inhibitors (TKIs) in the treatment of acute leukemia. Initially, western blot analysis is used to confirm target inhibition in cultured leukemia cells. Functional activity is then evaluated using clonogenic assays in methylcellulose or soft agar cultures. Experimental compounds that demonstrate activity in cell culture assays are evaluated in vivo
using NOD-SCID-gamma (NSG) mice transplanted orthotopically with human leukemia cell lines. Initial in vivo
pharmacodynamic studies evaluate target inhibition in leukemic blasts isolated from the bone marrow. This approach is used to determine the dose and schedule of administration required for effective target inhibition. Subsequent studies evaluate the efficacy of the TKIs in vivo
using luciferase expressing leukemia cells, thereby allowing for non-invasive bioluminescent monitoring of leukemia burden and assessment of therapeutic response using an in vivo
bioluminescence imaging system. This strategy has been effective for evaluation of TKIs in vitro
and in vivo
and can be applied for identification of molecularly-targeted agents with therapeutic potential or for direct comparison and prioritization of multiple compounds.
Medicine, Issue 79, Leukemia, Receptor Protein-Tyrosine Kinases, Molecular Targeted Therapy, Therapeutics, novel small molecule inhibitor, receptor tyrosine kinase, leukemia
Tumor Treating Field Therapy in Combination with Bevacizumab for the Treatment of Recurrent Glioblastoma
Institutions: Southern Illinois University School of Medicine.
A novel device that employs TTF therapy has recently been developed and is currently in use for the treatment of recurrent glioblastoma (rGBM). It was FDA approved in April 2011 for the treatment of patients 22 years or older with rGBM. The device delivers alternating electric fields and is programmed to ensure maximal tumor cell kill1
Glioblastoma is the most common type of glioma and has an estimated incidence of approximately 10,000 new cases per year in the United States alone2
. This tumor is particularly resistant to treatment and is uniformly fatal especially in the recurrent setting3-5
. Prior to the approval of the TTF System, the only FDA approved treatment for rGBM was bevacizumab6
. Bevacizumab is a humanized monoclonal antibody targeted against the vascular endothelial growth factor (VEGF) protein that drives tumor angiogenesis7
. By blocking the VEGF pathway, bevacizumab can result in a significant radiographic response (pseudoresponse), improve progression free survival and reduce corticosteroid requirements in rGBM patients8,9
. Bevacizumab however failed to prolong overall survival in a recent phase III trial26
. A pivotal phase III trial (EF-11) demonstrated comparable overall survival between physicians’ choice chemotherapy and TTF Therapy but better quality of life were observed in the TTF arm10
There is currently an unmet need to develop novel approaches designed to prolong overall survival and/or improve quality of life in this unfortunate patient population. One appealing approach would be to combine the two currently approved treatment modalities namely bevacizumab and TTF Therapy. These two treatments are currently approved as monotherapy11,12
, but their combination has never been evaluated in a clinical trial. We have developed an approach for combining those two treatment modalities and treated 2 rGBM patients. Here we describe a detailed methodology outlining this novel treatment protocol and present representative data from one of the treated patients.
Medicine, Issue 92, Tumor Treating Fields, TTF System, TTF Therapy, Recurrent Glioblastoma, Bevacizumab, Brain Tumor
Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors
Institutions: University College London.
Inhibitory neurons act in the central nervous system to regulate the dynamics and spatio-temporal co-ordination of neuronal networks. GABA (γ-aminobutyric acid) is the predominant inhibitory neurotransmitter in the brain. It is released from the presynaptic terminals of inhibitory neurons within highly specialized intercellular junctions known as synapses, where it binds to GABAA
Rs) present at the plasma membrane of the synapse-receiving, postsynaptic neurons. Activation of these GABA-gated ion channels leads to influx of chloride resulting in postsynaptic potential changes that decrease the probability that these neurons will generate action potentials.
During development, diverse types of inhibitory neurons with distinct morphological, electrophysiological and neurochemical characteristics have the ability to recognize their target neurons and form synapses which incorporate specific GABAA
Rs subtypes. This principle of selective innervation of neuronal targets raises the question as to how the appropriate synaptic partners identify each other.
To elucidate the underlying molecular mechanisms, a novel in vitro
co-culture model system was established, in which medium spiny GABAergic neurons, a highly homogenous population of neurons isolated from the embryonic striatum, were cultured with stably transfected HEK293 cell lines that express different GABAA
R subtypes. Synapses form rapidly, efficiently and selectively in this system, and are easily accessible for quantification. Our results indicate that various GABAA
R subtypes differ in their ability to promote synapse formation, suggesting that this reduced in vitro
model system can be used to reproduce, at least in part, the in vivo
conditions required for the recognition of the appropriate synaptic partners and formation of specific synapses. Here the protocols for culturing the medium spiny neurons and generating HEK293 cells lines expressing GABAA
Rs are first described, followed by detailed instructions on how to combine these two cell types in co-culture and analyze the formation of synaptic contacts.
Neuroscience, Issue 93, Developmental neuroscience, synaptogenesis, synaptic inhibition, co-culture, stable cell lines, GABAergic, medium spiny neurons, HEK 293 cell line
Live Imaging of Drug Responses in the Tumor Microenvironment in Mouse Models of Breast Cancer
Institutions: Watson School of Biological Sciences, Cold Spring Harbor Laboratory, University of Oslo and Oslo University Hospital.
The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional co-culture systems are frequently used to explicate tumor-stroma interactions, including their role in drug responses. However, many of the interactions that occur in vivo
in the intact microenvironment cannot be completely replicated in these in vitro
settings. Thus, direct visualization of these processes in real-time has become an important tool in understanding tumor responses to therapies and identifying the interactions between cancer cells and the stroma that can influence these responses. Here we provide a method for using spinning disk confocal microscopy of live, anesthetized mice to directly observe drug distribution, cancer cell responses and changes in tumor-stroma interactions following administration of systemic therapy in breast cancer models. We describe procedures for labeling different tumor components, treatment of animals for observing therapeutic responses, and the surgical procedure for exposing tumor tissues for imaging up to 40 hours. The results obtained from this protocol are time-lapse movies, in which such processes as drug infiltration, cancer cell death and stromal cell migration can be evaluated using image analysis software.
Cancer Biology, Issue 73, Medicine, Molecular Biology, Cellular Biology, Biomedical Engineering, Genetics, Oncology, Pharmacology, Surgery, Tumor Microenvironment, Intravital imaging, chemotherapy, Breast cancer, time-lapse, mouse models, cancer cell death, stromal cell migration, cancer, imaging, transgenic, animal model
Setting-up an In Vitro Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport
Institutions: VECT-HORUS SAS, CNRS, NICN UMR 7259.
The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and characterize a highly reproducible rat syngeneic in vitro
model of the BBB using co-cultures of primary rat brain endothelial cells (RBEC) and astrocytes to study receptors involved in transcytosis across the endothelial cell monolayer. Astrocytes were isolated by mechanical dissection following trypsin digestion and were frozen for later co-culture. RBEC were isolated from 5-week-old rat cortices. The brains were cleaned of meninges and white matter, and mechanically dissociated following enzymatic digestion. Thereafter, the tissue homogenate was centrifuged in bovine serum albumin to separate vessel fragments from nervous tissue. The vessel fragments underwent a second enzymatic digestion to free endothelial cells from their extracellular matrix. The remaining contaminating cells such as pericytes were further eliminated by plating the microvessel fragments in puromycin-containing medium. They were then passaged onto filters for co-culture with astrocytes grown on the bottom of the wells. RBEC expressed high levels of tight junction (TJ) proteins such as occludin, claudin-5 and ZO-1 with a typical localization at the cell borders. The transendothelial electrical resistance (TEER) of brain endothelial monolayers, indicating the tightness of TJs reached 300 ohm·cm2
on average. The endothelial permeability coefficients (Pe) for lucifer yellow (LY) was highly reproducible with an average of 0.26 ± 0.11 x 10-3
cm/min. Brain endothelial cells organized in monolayers expressed the efflux transporter P-glycoprotein (P-gp), showed a polarized transport of rhodamine 123, a ligand for P-gp, and showed specific transport of transferrin-Cy3 and DiILDL across the endothelial cell monolayer. In conclusion, we provide a protocol for setting up an in vitro
BBB model that is highly reproducible due to the quality assurance methods, and that is suitable for research on BBB transporters and receptors.
Medicine, Issue 88, rat brain endothelial cells (RBEC), mouse, spinal cord, tight junction (TJ), receptor-mediated transport (RMT), low density lipoprotein (LDL), LDLR, transferrin, TfR, P-glycoprotein (P-gp), transendothelial electrical resistance (TEER),
Polymalic Acid-based Nano Biopolymers for Targeting of Multiple Tumor Markers: An Opportunity for Personalized Medicine?
Institutions: Cedars-Sinai Medical Center.
Tumors with similar grade and morphology often respond differently to the same treatment because of variations in molecular profiling. To account for this diversity, personalized medicine is developed for silencing malignancy associated genes. Nano drugs fit these needs by targeting tumor and delivering antisense oligonucleotides for silencing of genes. As drugs for the treatment are often administered repeatedly, absence of toxicity and negligible immune response are desirable. In the example presented here, a nano medicine is synthesized from the biodegradable, non-toxic and non-immunogenic platform polymalic acid by controlled chemical ligation of antisense oligonucleotides and tumor targeting molecules. The synthesis and treatment is exemplified for human Her2-positive breast cancer using an experimental mouse model. The case can be translated towards synthesis and treatment of other tumors.
Chemistry, Issue 88, Cancer treatment, personalized medicine, polymalic acid, nanodrug, biopolymer, targeting, host compatibility, biodegradability
Single Plane Illumination Module and Micro-capillary Approach for a Wide-field Microscope
Institutions: Aalen University.
A module for light sheet or single plane illumination microscopy (SPIM) is described which is easily adapted to an inverted wide-field microscope and optimized for 3-dimensional cell cultures, e.g.,
multi-cellular tumor spheroids (MCTS). The SPIM excitation module shapes and deflects the light such that the sample is illuminated by a light sheet perpendicular to the detection path of the microscope. The system is characterized by use of a rectangular capillary for holding (and in an advanced version also by a micro-capillary approach for rotating) the samples, by synchronous adjustment of the illuminating light sheet and the objective lens used for fluorescence detection as well as by adaptation of a microfluidic system for application of fluorescent dyes, pharmaceutical agents or drugs in small quantities. A protocol for working with this system is given, and some technical details are reported. Representative results include (1) measurements of the uptake of a cytostatic drug (doxorubicin) and its partial conversion to a degradation product, (2) redox measurements by use of a genetically encoded glutathione sensor upon addition of an oxidizing agent, and (3) initiation and labeling of cell necrosis upon inhibition of the mitochondrial respiratory chain. Differences and advantages of the present SPIM module in comparison with existing systems are discussed.
Physics, Issue 90,
Fluorescence, light sheet, single plane illumination microscopy (SPIM), 3D cell cultures, rectangular capillary, microfluidics, multi-cellular tumor spheroids (MCTS), wide-field microscopy
Systemic and Local Drug Delivery for Treating Diseases of the Central Nervous System in Rodent Models
Institutions: University of California, San Francisco - UCSF.
Thorough preclinical testing of central nervous system (CNS) therapeutics includes a consideration of routes of administration and agent biodistribution in assessing therapeutic efficacy. Between the two major classifications of administration, local vs. systemic, systemic delivery approaches are often preferred due to ease of administration. However, systemic delivery may result in suboptimal drug concentration being achieved in the CNS, and lead to erroneous conclusions regarding agent efficacy. Local drug delivery methods are more invasive, but may be necessary to achieve therapeutic CNS drug levels. Here, we demonstrate proper technique for three routes of systemic drug delivery: intravenous injection, intraperitoneal injection, and oral gavage. In addition, we show a method for local delivery to the brain: convection-enhanced delivery (CED). The use of fluorescently-labeled compounds is included for in vivo
imaging and verification of proper drug administration. The methods are presented using murine models, but can easily be adapted for use in rats.
Neuroscience, Issue 42, mouse, in vivo optical imaging, preclinical, central nervous system, fluorescent imaging, convection-enhanced delivery, oral gavage, intravenous injection, intraperitoneal injection
Modeling Astrocytoma Pathogenesis In Vitro and In Vivo Using Cortical Astrocytes or Neural Stem Cells from Conditional, Genetically Engineered Mice
Institutions: University of North Carolina School of Medicine, University of North Carolina School of Medicine, University of North Carolina School of Medicine, University of North Carolina School of Medicine, University of North Carolina School of Medicine, Emory University School of Medicine, University of North Carolina School of Medicine.
Current astrocytoma models are limited in their ability to define the roles of oncogenic mutations in specific brain cell types during disease pathogenesis and their utility for preclinical drug development. In order to design a better model system for these applications, phenotypically wild-type cortical astrocytes and neural stem cells (NSC) from conditional, genetically engineered mice (GEM) that harbor various combinations of floxed oncogenic alleles were harvested and grown in culture. Genetic recombination was induced in vitro
using adenoviral Cre-mediated recombination, resulting in expression of mutated oncogenes and deletion of tumor suppressor genes. The phenotypic consequences of these mutations were defined by measuring proliferation, transformation, and drug response in vitro
. Orthotopic allograft models, whereby transformed cells are stereotactically injected into the brains of immune-competent, syngeneic littermates, were developed to define the role of oncogenic mutations and cell type on tumorigenesis in vivo
. Unlike most established human glioblastoma cell line xenografts, injection of transformed GEM-derived cortical astrocytes into the brains of immune-competent littermates produced astrocytomas, including the most aggressive subtype, glioblastoma, that recapitulated the histopathological hallmarks of human astrocytomas, including diffuse invasion of normal brain parenchyma. Bioluminescence imaging of orthotopic allografts from transformed astrocytes engineered to express luciferase was utilized to monitor in vivo
tumor growth over time. Thus, astrocytoma models using astrocytes and NSC harvested from GEM with conditional oncogenic alleles provide an integrated system to study the genetics and cell biology of astrocytoma pathogenesis in vitro
and in vivo
and may be useful in preclinical drug development for these devastating diseases.
Neuroscience, Issue 90, astrocytoma, cortical astrocytes, genetically engineered mice, glioblastoma, neural stem cells, orthotopic allograft
Inducing Plasticity of Astrocytic Receptors by Manipulation of Neuronal Firing Rates
Institutions: University of California Riverside, University of California Riverside, University of California Riverside.
Close to two decades of research has established that astrocytes in situ
and in vivo
express numerous G protein-coupled receptors (GPCRs) that can be stimulated by neuronally-released transmitter. However, the ability of astrocytic receptors to exhibit plasticity in response to changes in neuronal activity has received little attention. Here we describe a model system that can be used to globally scale up or down astrocytic group I metabotropic glutamate receptors (mGluRs) in acute brain slices. Included are methods on how to prepare parasagittal hippocampal slices, construct chambers suitable for long-term slice incubation, bidirectionally manipulate neuronal action potential frequency, load astrocytes and astrocyte processes with fluorescent Ca2+
indicator, and measure changes in astrocytic Gq GPCR activity by recording spontaneous and evoked astrocyte Ca2+
events using confocal microscopy. In essence, a “calcium roadmap” is provided for how to measure plasticity of astrocytic Gq GPCRs. Applications of the technique for study of astrocytes are discussed. Having an understanding of how astrocytic receptor signaling is affected by changes in neuronal activity has important implications for both normal synaptic function as well as processes underlying neurological disorders and neurodegenerative disease.
Neuroscience, Issue 85, astrocyte, plasticity, mGluRs, neuronal Firing, electrophysiology, Gq GPCRs, Bolus-loading, calcium, microdomains, acute slices, Hippocampus, mouse
Long-term Silencing of Intersectin-1s in Mouse Lungs by Repeated Delivery of a Specific siRNA via Cationic Liposomes. Evaluation of Knockdown Effects by Electron Microscopy
Institutions: Rush University, Rush University.
Previous studies showed that knockdown of ITSN-1s (KDITSN
), an endocytic protein involved in regulating lung vascular permeability and endothelial cells (ECs) survival, induced apoptotic cell death, a major obstacle in developing a cell culture system with prolonged ITSN-1s inhibition1
. Using cationic liposomes as carriers, we explored the silencing of ITSN-1s gene in mouse lungs by systemic administration of siRNA targeting ITSN-1 gene (siRNAITSN
). Cationic liposomes offer several advantages for siRNA delivery: safe with repeated dosing, nonimmunogenic, nontoxic, and easy to produce2
. Liposomes performance and biological activity depend on their size, charge, lipid composition, stability, dose and route of administration3
Here, efficient and specific KDITSN
in mouse lungs has been obtained using a cholesterol and dimethyl dioctadecyl ammonium bromide combination. Intravenous delivery of siRNAITSN
/cationic liposome complexes transiently knocked down ITSN-1s protein and mRNA in mouse lungs at day 3, which recovered after additional 3 days. Taking advantage of the cationic liposomes as a repeatable safe carrier, the study extended for 24 days. Thus, retro-orbital treatment with freshly generated complexes was administered every 3rd day, inducing sustained KDITSN
throughout the study4
. Mouse tissues collected at several time points post-siRNAITSN
were subjected to electron microscopy (EM) analyses to evaluate the effects of chronic KDITSN
, in lung endothelium. High-resolution EM imaging allowed us to evaluate the morphological changes caused by KDITSN in the lung vascular bed (i.e.
disruption of the endothelial barrier, decreased number of caveolae and upregulation of alternative transport pathways), characteristics non-detectable by light microscopy. Overall these findings established an important role of ITSN-1s in the ECs function and lung homeostasis, while illustrating the effectiveness of siRNA-liposomes delivery in vivo
Bioengineering, Issue 76, Biomedical Engineering, Biochemistry, Genetics, Molecular Biology, Cellular Biology, Anatomy, Physiology, Medicine, Immunology, Pharmacology, animal models, Cardiovascular Diseases, intersectin-1s, siRNA, liposomes, retro-orbital injection, acute and chronic ITSN-1s knockdown, transgenic mice, liposome, endothelial cells, tissue, lung, perfusion, electron microscopy, animal model
A Simple Guide Screw Method for Intracranial Xenograft Studies in Mice
Institutions: Monash Institute of Medical Research , University of Texas .
The grafting of human tumor cells into the brain of immunosuppressed mice is an established method for the study of brain cancers including glioblastoma (glioma) and medulloblastoma. The widely used stereotactic approach only allows for the injection of a single animal at a time, is labor intensive and requires highly specialized equipment. The guide screw method, initially developed by Lal et al.
was developed to eliminate cumbersome stereotactic procedures. We now describe a modified guide screw approach that is rapid and exceptionally safe; both of which are critical ethical considerations. Notably, our procedure now incorporates an infusion pump that allows up to 10 animals to be simultaneously injected with tumor cells.
To demonstrate the utility of this procedure, we established human U87MG glioma cells as intracranial xenografts in mice, which were then treated with AMG102; a fully human antibody directed to HGF/scatter factor currently undergoing clinical evaluation2-5
. Systemic injection of AMG102 significantly prolonged the survival of all mice with intracranial U87MG xenografts and resulted in a number of complete cures.
This study demonstrates that the guide screw method is an inexpensive, highly reproducible approach for establishing intracranial xenografts. Furthermore, it provides a relevant physiological model for validating novel therapeutic strategies for the treatment of brain cancers.
Medicine, Issue 55, Neuroscience, Intracranial, Guide Screw, Xenografts, Glioma, Mouse
In vivo Bioluminescent Imaging of Mammary Tumors Using IVIS Spectrum
Institutions: Caliper Life Sciences.
4T1 mouse mammary tumor cells can be implanted sub-cutaneously in nu/nu mice to form palpable tumors in 15 to 20 days. This xenograft tumor model system is valuable for the pre-clinical in vivo
evaluation of putative antitumor compounds.
The 4T1 cell line has been engineered to constitutively express the firefly luciferase gene (luc2). When mice carrying 4T1-luc2 tumors are injected with Luciferin the tumors emit a visual light signal that can be monitored using a sensitive optical imaging system like the IVIS Spectrum. The photon flux from the tumor is proportional to the number of light emitting cells and the signal can be measured to monitor tumor growth and development. IVIS is calibrated to enable absolute quantitation of the bioluminescent signal and longitudinal studies can be performed over many months and over several orders of signal magnitude without compromising the quantitative result.
Tumor growth can be monitored for several days by bioluminescence before the tumor size becomes palpable or measurable by traditional physical means. This rapid monitoring can provide insight into early events in tumor development or lead to shorter experimental procedures.
Tumor cell death and necrosis due to hypoxia or drug treatment is indicated early by a reduction in the bioluminescent signal. This cell death might not be accompanied by a reduction in tumor size as measured by physical means. The ability to see early events in tumor necrosis has significant impact on the selection and development of therapeutic agents.
Quantitative imaging of tumor growth using IVIS provides precise quantitation and accelerates the experimental process to generate results.
Cellular Biology, Issue 26, tumor, mammary, mouse, bioluminescence, in vivo, imaging, IVIS, luciferase, luciferin