Recent significant advances in stem cell research and bioengineering techniques have made great progress in utilizing biomaterials to regenerate and repair damage in simple tissues in the orthopedic and periodontal fields. However, attempts to regenerate the structures and functions of more complex three-dimensional (3D) organs such as lungs have not been very successful because the biological processes of organ regeneration have not been well explored. It is becoming clear that angiogenesis, the formation of new blood vessels, plays key roles in organ regeneration. Newly formed vasculatures not only deliver oxygen, nutrients and various cell components that are required for organ regeneration but also provide instructive signals to the regenerating local tissues. Therefore, to successfully regenerate lungs in an adult, it is necessary to recapitulate the lung-specific microenvironments in which angiogenesis drives regeneration of local lung tissues. Although conventional in vivo angiogenesis assays, such as subcutaneous implantation of extracellular matrix (ECM)-rich hydrogels (e.g., fibrin or collagen gels or Matrigel - ECM protein mixture secreted by Engelbreth-Holm-Swarm mouse sarcoma cells), are extensively utilized to explore the general mechanisms of angiogenesis, lung-specific angiogenesis has not been well characterized because methods for orthotopic implantation of biomaterials in the lung have not been well established. The goal of this protocol is to introduce a unique method to implant fibrin gel on the lung surface of living adult mouse, allowing for the successful recapitulation of host lung-derived angiogenesis inside the gel. This approach enables researchers to explore the mechanisms by which the lung-specific microenvironment controls angiogenesis and alveolar regeneration in both normal and pathological conditions. Since implanted biomaterials release and supply physical and chemical signals to adjacent lung tissues, implantation of these biomaterials on diseased lung can potentially normalize the adjacent diseased tissues, enabling researchers to develop new therapeutic approaches for various types of lung diseases.
25 Related JoVE Articles!
Interview: Glycolipid Antigen Presentation by CD1d and the Therapeutic Potential of NKT cell Activation
Institutions: La Jolla Institute for Allergy and Immunology.
Natural Killer T cells (NKT) are critical determinants of the immune response to cancer, regulation of autioimmune disease, clearance of infectious agents, and the development of artheriosclerotic plaques. In this interview, Mitch Kronenberg discusses his laboratory's efforts to understand the mechanism through which NKT cells are activated by glycolipid antigens. Central to these studies is CD1d - the antigen presenting molecule that presents glycolipids to NKT cells. The advent of CD1d tetramer technology, a technique developed by the Kronenberg lab, is critical for the sorting and identification of subsets of specific glycolipid-reactive T cells. Mitch explains how glycolipid agonists are being used as therapeutic agents to activate NKT cells in cancer patients and how CD1d tetramers can be used to assess the state of the NKT cell population in vivo following glycolipid agonist therapy. Current status of ongoing clinical trials using these agonists are discussed as well as Mitch's prediction for areas in the field of immunology that will have emerging importance in the near future.
Immunology, Issue 10, Natural Killer T cells, NKT cells, CD1 Tetramers, antigen presentation, glycolipid antigens, CD1d, Mucosal Immunity, Translational Research
Longitudinal Measurement of Extracellular Matrix Rigidity in 3D Tumor Models Using Particle-tracking Microrheology
Institutions: University of Massachusetts Boston.
The mechanical microenvironment has been shown to act as a crucial regulator of tumor growth behavior and signaling, which is itself remodeled and modified as part of a set of complex, two-way mechanosensitive interactions. While the development of biologically-relevant 3D tumor models have facilitated mechanistic studies on the impact of matrix rheology on tumor growth, the inverse problem of mapping changes in the mechanical environment induced by tumors remains challenging. Here, we describe the implementation of particle-tracking microrheology (PTM) in conjunction with 3D models of pancreatic cancer as part of a robust and viable approach for longitudinally monitoring physical changes in the tumor microenvironment, in situ
. The methodology described here integrates a system of preparing in vitro
3D models embedded in a model extracellular matrix (ECM) scaffold of Type I collagen with fluorescently labeled probes uniformly distributed for position- and time-dependent microrheology measurements throughout the specimen. In vitro
tumors are plated and probed in parallel conditions using multiwell imaging plates. Drawing on established methods, videos of tracer probe movements are transformed via the Generalized Stokes Einstein Relation (GSER) to report the complex frequency-dependent viscoelastic shear modulus, G*(ω)
. Because this approach is imaging-based, mechanical characterization is also mapped onto large transmitted-light spatial fields to simultaneously report qualitative changes in 3D tumor size and phenotype. Representative results showing contrasting mechanical response in sub-regions associated with localized invasion-induced matrix degradation as well as system calibration, validation data are presented. Undesirable outcomes from common experimental errors and troubleshooting of these issues are also presented. The 96-well 3D culture plating format implemented in this protocol is conducive to correlation of microrheology measurements with therapeutic screening assays or molecular imaging to gain new insights into impact of treatments or biochemical stimuli on the mechanical microenvironment.
Bioengineering, Issue 88, viscoelasticity, mechanobiology, extracellular matrix (ECM), matrix remodeling, 3D tumor models, tumor microenvironment, stroma, matrix metalloprotease (MMP), epithelial-mesenchymal transition (EMT)
The Bovine Lung in Biomedical Research: Visually Guided Bronchoscopy, Intrabronchial Inoculation and In Vivo Sampling Techniques
There is an ongoing search for alternative animal models in research of respiratory medicine. Depending on the goal of the research, large animals as models of pulmonary disease often resemble the situation of the human lung much better than mice do. Working with large animals also offers the opportunity to sample the same animal repeatedly over a certain course of time, which allows long-term studies without sacrificing the animals.
The aim was to establish in vivo
sampling methods for the use in a bovine model of a respiratory Chlamydia psittaci
infection. Sampling should be performed at various time points in each animal during the study, and the samples should be suitable to study the host response, as well as the pathogen under experimental conditions.
Bronchoscopy is a valuable diagnostic tool in human and veterinary medicine. It is a safe and minimally invasive procedure. This article describes the intrabronchial inoculation of calves as well as sampling methods for the lower respiratory tract. Videoendoscopic, intrabronchial inoculation leads to very consistent clinical and pathological findings in all inoculated animals and is, therefore, well-suited for use in models of infectious lung disease. The sampling methods described are bronchoalveolar lavage, bronchial brushing and transbronchial lung biopsy. All of these are valuable diagnostic tools in human medicine and could be adapted for experimental purposes to calves aged 6-8 weeks. The samples obtained were suitable for both pathogen detection and characterization of the severity of lung inflammation in the host.
Medicine, Issue 89, translational medicine, respiratory models, bovine lung, bronchoscopy, transbronchial lung biopsy, bronchoalveolar lavage, bronchial brushing, cytology brush
Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis
Institutions: Johns Hopkins University Bloomberg School of Public Health, Chinese University of Hong Kong, Johns Hopkins University School of Medicine.
Anastasis (Greek for “rising to life”) refers to the recovery of dying cells. Before these cells recover, they have passed through important checkpoints of apoptosis, including mitochondrial fragmentation, release of mitochondrial cytochrome c
into the cytosol, activation of caspases, chromatin condensation, DNA damage, nuclear fragmentation, plasma membrane blebbing, cell shrinkage, cell surface exposure of phosphatidylserine, and formation of apoptotic bodies. Anastasis can occur when apoptotic stimuli are removed prior to death, thereby allowing dying cells to reverse apoptosis and potentially other death mechanisms. Therefore, anastasis appears to involve physiological healing processes that could also sustain damaged cells inappropriately. The functions and mechanisms of anastasis are still unclear, hampered in part by the limited tools for detecting past events after the recovery of apparently healthy cells. Strategies to detect anastasis will enable studies of the physiological mechanisms, the hazards of undead cells in disease pathology, and potential therapeutics to modulate anastasis. Here, we describe effective strategies using live cell microscopy and a mammalian caspase biosensor for identifying and tracking anastasis in mammalian cells.
Cellular Biology, Issue 96, Anastasis, apoptosis, apoptotic bodies, caspase, cell death, cell shrinkage, cell suicide, cytochrome c, DNA damage, genetic alterations, mitochondrial outer membrane permeabilization (MOMP), programmed cell death, reversal of apoptosis
Purifying the Impure: Sequencing Metagenomes and Metatranscriptomes from Complex Animal-associated Samples
Institutions: San Diego State University, DOE Joint Genome Institute, University of Colorado, University of Colorado.
The accessibility of high-throughput sequencing has revolutionized many fields of biology. In order to better understand host-associated viral and microbial communities, a comprehensive workflow for DNA and RNA extraction was developed. The workflow concurrently generates viral and microbial metagenomes, as well as metatranscriptomes, from a single sample for next-generation sequencing. The coupling of these approaches provides an overview of both the taxonomical characteristics and the community encoded functions. The presented methods use Cystic Fibrosis (CF) sputum, a problematic sample type, because it is exceptionally viscous and contains high amount of mucins, free neutrophil DNA, and other unknown contaminants. The protocols described here target these problems and successfully recover viral and microbial DNA with minimal human DNA contamination. To complement the metagenomics studies, a metatranscriptomics protocol was optimized to recover both microbial and host mRNA that contains relatively few ribosomal RNA (rRNA) sequences. An overview of the data characteristics is presented to serve as a reference for assessing the success of the methods. Additional CF sputum samples were also collected to (i) evaluate the consistency of the microbiome profiles across seven consecutive days within a single patient, and (ii) compare the consistency of metagenomic approach to a 16S ribosomal RNA gene-based sequencing. The results showed that daily fluctuation of microbial profiles without antibiotic perturbation was minimal and the taxonomy profiles of the common CF-associated bacteria were highly similar between the 16S rDNA libraries and metagenomes generated from the hypotonic lysis (HL)-derived DNA. However, the differences between 16S rDNA taxonomical profiles generated from total DNA and HL-derived DNA suggest that hypotonic lysis and the washing steps benefit in not only removing the human-derived DNA, but also microbial-derived extracellular DNA that may misrepresent the actual microbial profiles.
Molecular Biology, Issue 94, virome, microbiome, metagenomics, metatranscriptomics, cystic fibrosis, mucosal-surface
Fluorescence-quenching of a Liposomal-encapsulated Near-infrared Fluorophore as a Tool for In Vivo Optical Imaging
Institutions: Jena University Hospital, Friedrich-Schiller-University Jena, Jena University Hospital.
Optical imaging offers a wide range of diagnostic modalities and has attracted a lot of interest as a tool for biomedical imaging. Despite the enormous number of imaging techniques currently available and the progress in instrumentation, there is still a need for highly sensitive probes that are suitable for in vivo
imaging. One typical problem of available preclinical fluorescent probes is their rapid clearance in vivo
, which reduces their imaging sensitivity. To circumvent rapid clearance, increase number of dye molecules at the target site, and thereby reduce background autofluorescence, encapsulation of the near-infrared fluorescent dye, DY-676-COOH in liposomes and verification of its potential for in vivo
imaging of inflammation was done. DY-676 is known for its ability to self-quench at high concentrations. We first determined the concentration suitable for self-quenching, and then encapsulated this quenching concentration into the aqueous interior of PEGylated liposomes. To substantiate the quenching and activation potential of the liposomes we use a harsh freezing method which leads to damage of liposomal membranes without affecting the encapsulated dye. The liposomes characterized by a high level of fluorescence quenching were termed Lip-Q. We show by experiments with different cell lines that uptake of Lip-Q is predominantly by phagocytosis which in turn enabled the characterization of its potential as a tool for in vivo
imaging of inflammation in mice models. Furthermore, we use a zymosan-induced edema model in mice to substantiate the potential of Lip-Q in optical imaging of inflammation in vivo
. Considering possible uptake due to inflammation-induced enhanced permeability and retention (EPR) effect, an always-on liposome formulation with low, non-quenched concentration of DY-676-COOH (termed Lip-dQ) and the free DY-676-COOH were compared with Lip-Q in animal trials.
Bioengineering, Issue 95, Drug-delivery, Liposomes, Fluorochromes, Fluorescence-quenching, Optical imaging, Inflammation
Modeling Mucosal Candidiasis in Larval Zebrafish by Swimbladder Injection
Institutions: University of Maine, University of Maine.
Early defense against mucosal pathogens consists of both an epithelial barrier and innate immune cells. The immunocompetency of both, and their intercommunication, are paramount for the protection against infections. The interactions of epithelial and innate immune cells with a pathogen are best investigated in vivo
, where complex behavior unfolds over time and space. However, existing models do not allow for easy spatio-temporal imaging of the battle with pathogens at the mucosal level.
The model developed here creates a mucosal infection by direct injection of the fungal pathogen, Candida albicans
, into the swimbladder of juvenile zebrafish. The resulting infection enables high-resolution imaging of epithelial and innate immune cell behavior throughout the development of mucosal disease. The versatility of this method allows for interrogation of the host to probe the detailed sequence of immune events leading to phagocyte recruitment and to examine the roles of particular cell types and molecular pathways in protection. In addition, the behavior of the pathogen as a function of immune attack can be imaged simultaneously by using fluorescent protein-expressing C. albicans
. Increased spatial resolution of the host-pathogen interaction is also possible using the described rapid swimbladder dissection technique.
The mucosal infection model described here is straightforward and highly reproducible, making it a valuable tool for the study of mucosal candidiasis. This system may also be broadly translatable to other mucosal pathogens such as mycobacterial, bacterial or viral microbes that normally infect through epithelial surfaces.
Immunology, Issue 93, Zebrafish, mucosal candidiasis, mucosal infection, epithelial barrier, epithelial cells, innate immunity, swimbladder, Candida albicans, in vivo.
Validation of Nanobody and Antibody Based In Vivo Tumor Xenograft NIRF-imaging Experiments in Mice Using Ex Vivo Flow Cytometry and Microscopy
Institutions: University Medical Center, Hamburg, University Medical Center, Hamburg, University Medical Center, Hamburg, University Medical Center, Hamburg.
This protocol outlines the steps required to perform ex vivo
validation of in vivo
near-infrared fluorescence (NIRF) xenograft imaging experiments in mice using fluorophore labelled nanobodies and conventional antibodies.
First we describe how to generate subcutaneous tumors in mice, using antigen-negative cell lines as negative controls and antigen-positive cells as positive controls in the same mice for intraindividual comparison. We outline how to administer intravenously near-infrared fluorophore labelled (AlexaFluor680) antigen-specific nanobodies and conventional antibodies. In vivo
imaging was performed with a small-animal NIRF-Imaging system. After the in vivo
imaging experiments the mice were sacrificed. We then describe how to prepare the tumors for parallel ex vivo
analyses by flow cytometry and fluorescence microscopy to validate in vivo
The use of the near-infrared fluorophore labelled nanobodies allows for non-invasive same day imaging in vivo
. Our protocols describe the ex vivo
quantification of the specific labeling efficiency of tumor cells by flow cytometry and analysis of the distribution of the antibody constructs within the tumors by fluorescence microscopy. Using near-infrared fluorophore labelled probes allows for non-invasive, economical in vivo
imaging with the unique ability to exploit the same probe without further secondary labelling for ex vivo
validation experiments using flow cytometry and fluorescence microscopy.
Medicine, Issue 98, Nanobody, antibody, VHH, fluorescence imaging, molecular imaging, xenograft, animal model
Three-dimensional Co-culture Model for Tumor-stromal Interaction
Institutions: The University of Tokyo, The University of Tokyo, The University of Tokyo, Nihon University School of Dentistry, Ohu University School of Pharmaceutical Sciences.
Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal cells. The tumor microenvironment is comprised of a variety of cell types, such as fibroblasts, immune cells, vascular endothelial cells, pericytes and bone-marrow-derived cells, embedded in the extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs) have a pro-tumorigenic role through the secretion of soluble factors, angiogenesis and ECM remodeling. The experimental models for cancer cell survival, proliferation, migration, and invasion have mostly relied on two-dimensional monocellular and monolayer tissue cultures or Boyden chamber assays. However, these experiments do not precisely reflect the physiological or pathological conditions in a diseased organ. To gain a better understanding of tumor stromal or tumor matrix interactions, multicellular and three-dimensional cultures provide more powerful tools for investigating intercellular communication and ECM-dependent modulation of cancer cell behavior. As a platform for this type of study, we present an experimental model in which cancer cells are cultured on collagen gels embedded with primary cultures of CAFs.
Medicine, Issue 96, Three-dimensional co-culture, cancer, fibroblast, invasion, tumor stroma, collagen
Contrast Imaging in Mouse Embryos Using High-frequency Ultrasound
Institutions: University of Toronto, Sunnybrook Research Institute, Mount Sinai Hospital, Toronto.
Ultrasound contrast-enhanced imaging can convey essential quantitative information regarding tissue vascularity and perfusion and, in targeted applications, facilitate the detection and measure of vascular biomarkers at the molecular level. Within the mouse embryo, this noninvasive technique may be used to uncover basic mechanisms underlying vascular development in the early mouse circulatory system and in genetic models of cardiovascular disease. The mouse embryo also presents as an excellent model for studying the adhesion of microbubbles to angiogenic targets (including vascular endothelial growth factor receptor 2 (VEGFR2) or αv
) and for assessing the quantitative nature of molecular ultrasound. We therefore developed a method to introduce ultrasound contrast agents into the vasculature of living, isolated embryos. This allows freedom in terms of injection control and positioning, reproducibility of the imaging plane without obstruction and motion, and simplified image analysis and quantification. Late gestational stage (embryonic day (E)16.6 and E17.5) murine embryos were isolated from the uterus, gently exteriorized from the yolk sac and microbubble contrast agents were injected into veins accessible on the chorionic surface of the placental disc. Nonlinear contrast ultrasound imaging was then employed to collect a number of basic perfusion parameters (peak enhancement, wash-in rate and time to peak) and quantify targeted microbubble binding in an endoglin mouse model. We show the successful circulation of microbubbles within living embryos and the utility of this approach in characterizing embryonic vasculature and microbubble behavior.
Developmental Biology, Issue 97, Micro-ultrasound, Molecular imaging, Mouse embryo, Microbubble, Ultrasound contrast agent, Perfusion
A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay
Institutions: Wright-Patterson Air Force Base, The Henry M. Jackson Foundation, UES, Inc..
Small molecules provide rich targets for biosensing applications due to their physiological implications as biomarkers of various aspects of human health and performance. Nucleic acid aptamers have been increasingly applied as recognition elements on biosensor platforms, but selecting aptamers toward small molecule targets requires special design considerations. This work describes modification and critical steps of a method designed to select structure-switching aptamers to small molecule targets. Binding sequences from a DNA library hybridized to complementary DNA capture probes on magnetic beads are separated from nonbinders via a target-induced change in conformation. This method is advantageous because sequences binding the support matrix (beads) will not be further amplified, and it does not require immobilization of the target molecule. However, the melting temperature of the capture probe and library is kept at or slightly above RT, such that sequences that dehybridize based on thermodynamics will also be present in the supernatant solution. This effectively limits the partitioning efficiency (ability to separate target binding sequences from nonbinders), and therefore many selection rounds will be required to remove background sequences. The reported method differs from previous structure-switching aptamer selections due to implementation of negative selection steps, simplified enrichment monitoring, and extension of the length of the capture probe following selection enrichment to provide enhanced stringency. The selected structure-switching aptamers are advantageous in a gold nanoparticle assay platform that reports the presence of a target molecule by the conformational change of the aptamer. The gold nanoparticle assay was applied because it provides a simple, rapid colorimetric readout that is beneficial in a clinical or deployed environment. Design and optimization considerations are presented for the assay as proof-of-principle work in buffer to provide a foundation for further extension of the work toward small molecule biosensing in physiological fluids.
Molecular Biology, Issue 96, Aptamer, structure-switching, SELEX, small molecule, cortisol, next generation sequencing, gold nanoparticle, assay
Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides
Institutions: University of Utah, Johns Hopkins University School of Medicine, Johns Hopkins University.
Collagen is a major structural component of the extracellular matrix that supports tissue formation and maintenance. Although collagen remodeling is an integral part of normal tissue renewal, excessive amount of remodeling activity is involved in tumors, arthritis, and many other pathological conditions. During collagen remodeling, the triple helical structure of collagen molecules is disrupted by proteases in the extracellular environment. In addition, collagens present in many histological tissue samples are partially denatured by the fixation and preservation processes. Therefore, these denatured collagen strands can serve as effective targets for biological imaging. We previously developed a caged collagen mimetic peptide (CMP) that can be photo-triggered to hybridize with denatured collagen strands by forming triple helical structure, which is unique to collagens. The overall goals of this procedure are i)
to image denatured collagen strands resulting from normal remodeling activities in vivo
, and ii)
to visualize collagens in ex vivo
tissue sections using the photo-triggered caged CMPs. To achieve effective hybridization and successful in vivo
and ex vivo
imaging, fluorescently labeled caged CMPs are either photo-activated immediately before intravenous injection, or are directly activated on tissue sections. Normal skeletal collagen remolding in nude mice and collagens in prefixed mouse cornea tissue sections are imaged in this procedure. The imaging method based on the CMP-collagen hybridization technology presented here could lead to deeper understanding of the tissue remodeling process, as well as allow development of new diagnostics for diseases associated with high collagen remodeling activity.
Bioengineering, Issue 83, collagen remodeling, triple helix, near infrared fluorescence, bioimaging, tissue staining
An Orthotopic Murine Model of Human Prostate Cancer Metastasis
Institutions: Northwestern University, Northwestern University, Northwestern University.
Our laboratory has developed a novel orthotopic implantation model of human prostate cancer (PCa). As PCa death is not due to the primary tumor, but rather the formation of distinct metastasis, the ability to effectively model this progression pre-clinically is of high value. In this model, cells are directly implanted into the ventral lobe of the prostate in Balb/c athymic mice, and allowed to progress for 4-6 weeks. At experiment termination, several distinct endpoints can be measured, such as size and molecular characterization of the primary tumor, the presence and quantification of circulating tumor cells in the blood and bone marrow, and formation of metastasis to the lung. In addition to a variety of endpoints, this model provides a picture of a cells ability to invade and escape the primary organ, enter and survive in the circulatory system, and implant and grow in a secondary site. This model has been used effectively to measure metastatic response to both changes in protein expression as well as to response to small molecule therapeutics, in a short turnaround time.
Medicine, Issue 79, Urogenital System, Male Urogenital Diseases, Surgical Procedures, Operative, Life Sciences (General), Prostate Cancer, Metastasis, Mouse Model, Drug Discovery, Molecular Biology
Targeted Expression of GFP in the Hair Follicle Using Ex Vivo Viral Transduction
Institutions: AntiCancer, Inc..
There are many cell types in the hair follicle, including hair matrix cells which form the hair shaft and stem cells which can initiate the hair shaft during early anagen, the growth phase of the hair cycle, as well as pluripotent stem cells that play a role in hair follicle growth but have the potential to differentiate to non-follicle cells such as neurons. These properties of the hair follicle are discussed. The various cell types of the hair follicle are potential targets for gene therapy. Gene delivery system for the hair follicle using viral vectors or liposomes for gene targeting to the various cell types in the hair follicle and the results obtained are also discussed.
Cellular Biology, Issue 13, Springer Protocols, hair follicles, liposomes, adenovirus, genes, stem cells
Detection of Functional Matrix Metalloproteinases by Zymography
Institutions: Baylor College of Medicine.
Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases. They degrade proteins by cleavage of peptide bonds. More than twenty MMPs have been identified and are separated into six groups based on their structure and substrate specificity (collagenases, gelatinases, membrane type [MT-MMP], stromelysins, matrilysins, and others). MMPs play a critical role in cell invasion, cartilage degradation, tissue remodeling, wound healing, and embryogenesis. They therefore participate in both normal processes and in the pathogenesis of many diseases, such as rheumatoid arthritis, cancer, or chronic obstructive pulmonary disease1-6
. Here, we will focus on MMP-2 (gelatinase A, type IV collagenase), a widely expressed MMP. We will demonstrate how to detect MMP-2 in cell culture supernatants by zymography, a commonly used, simple, and yet very sensitive technique first described in 1980 by C. Heussen and E.B. Dowdle7-10
. This technique is semi-quantitative, it can therefore be used to determine MMP levels in test samples when known concentrations of recombinant MMP are loaded on the same gel11
Solutions containing MMPs (e.g. cell culture supernatants, urine, or serum) are loaded onto a polyacrylamide gel containing sodium dodecyl sulfate (SDS; to linearize the proteins) and gelatin (substrate for MMP-2). The sample buffer is designed to increase sample viscosity (to facilitate gel loading), provide a tracking dye (bromophenol blue; to monitor sample migration), provide denaturing molecules (to linearize proteins), and control the pH of the sample. Proteins are then allowed to migrate under an electric current in a running buffer designed to provide a constant migration rate. The distance of migration is inversely correlated with the molecular weight of the protein (small proteins move faster through the gel than large proteins do and therefore migrate further down the gel). After migration, the gel is placed in a renaturing buffer to allow proteins to regain their tertiary structure, necessary for enzymatic activity. The gel is then placed in a developing buffer designed to allow the protease to digest its substrate. The developing buffer also contains p-aminophenylmercuric acetate (APMA) to activate the non-proteolytic pro-MMPs into active MMPs. The next step consists of staining the substrate (gelatin in our example). After washing the excess dye off the gel, areas of protease digestion appear as clear bands. The clearer the band, the more concentrated the protease it contains. Band staining intensity can then be determined by densitometry, using a software such as ImageJ, allowing for sample comparison.
Basic Protocols, Issue 45, Protease, enzyme, electrophoresis, gelatin, casein, fibrin
Rotating Cell Culture Systems for Human Cell Culture: Human Trophoblast Cells as a Model
Institutions: Tulane University Medical School, Tulane University Medical School, Baylor College of Medicine.
The field of human trophoblast research aids in understanding the complex environment established during placentation. Due to the nature of these studies, human in vivo
experimentation is impossible. A combination of primary cultures, explant cultures and trophoblast cell lines1
support our understanding of invasion of the uterine wall2
and remodeling of uterine spiral arteries3,4
by extravillous trophoblast cells (EVTs), which is required for successful establishment of pregnancy. Despite the wealth of knowledge gleaned from such models, it is accepted that in vitro
cell culture models using EVT-like cell lines display altered cellular properties when compared to their in vivo
. Cells cultured in the rotating cell culture system (RCCS) display morphological, phenotypic, and functional properties of EVT-like cell lines that more closely mimic differentiating in utero
EVTs, with increased expression of genes mediating invasion (e.g. matrix metalloproteinases (MMPs)) and trophoblast differentiation7,8,9
. The Saint Georges Hospital Placental cell Line-4 (SGHPL-4) (kindly donated by Dr. Guy Whitley and Dr. Judith Cartwright) is an EVT-like cell line that was used for testing in the RCCS.
The design of the RCCS culture vessel is based on the principle that organs and tissues function in a three-dimensional (3-D) environment. Due to the dynamic culture conditions in the vessel, including conditions of physiologically relevant shear, cells grown in three dimensions form aggregates based on natural cellular affinities and differentiate into organotypic tissue-like assemblies10,11,12
. The maintenance of a fluid orbit provides a low-shear, low-turbulence environment similar to conditions found in vivo.
Sedimentation of the cultured cells is countered by adjusting the rotation speed of the RCCS to ensure a constant free-fall of cells. Gas exchange occurs through a permeable hydrophobic membrane located on the back of the bioreactor. Like their parental tissue in vivo
, RCCS-grown cells are able to respond to chemical and molecular gradients in three dimensions (i.e. at their apical, basal, and lateral surfaces) because they are cultured on the surface of porous microcarrier beads. When grown as two-dimensional monolayers on impermeable surfaces like plastic, cells are deprived of this important communication at their basal surface. Consequently, the spatial constraints imposed by the environment profoundly affect how cells sense and decode signals from the surrounding microenvironment, thus implying an important role for the 3-D milieu13
We have used the RCCS to engineer biologically meaningful 3-D models of various human epithelial tissues7,14,15,16
. Indeed, many previous reports have demonstrated that cells cultured in the RCCS can assume physiologically relevant phenotypes that have not been possible with other models10,17-21
. In summary, culture in the RCCS represents an easy, reproducible, high-throughput platform that provides large numbers of differentiated cells that are amenable to a variety of experimental manipulations.
In the following protocol, using EVTs as an example, we clearly describe the steps required to three-dimensionally culture adherent cells in the RCCS.
Bioengineering, Issue 59, Extravillous trophoblasts, cytotrophoblast, invasion, matrix metalloproteinase, 3-D cell culture, RCCS, ECM, microcarriers
Enhancement of Apoptotic and Autophagic Induction by a Novel Synthetic C-1 Analogue of 7-deoxypancratistatin in Human Breast Adenocarcinoma and Neuroblastoma Cells with Tamoxifen
Institutions: University of Windsor, Brock University.
Breast cancer is one of the most common cancers amongst women in North America. Many current anti-cancer treatments, including ionizing radiation, induce apoptosis via DNA damage. Unfortunately, such treatments are non-selective to cancer cells and produce similar toxicity in normal cells. We have reported selective induction of apoptosis in cancer cells by the natural compound pancratistatin (PST). Recently, a novel PST analogue, a C-1 acetoxymethyl derivative of 7-deoxypancratistatin (JCTH-4), was produced by de novo synthesis and it exhibits comparable selective apoptosis inducing activity in several cancer cell lines. Recently, autophagy has been implicated in malignancies as both pro-survival and pro-death mechanisms in response to chemotherapy. Tamoxifen (TAM) has invariably demonstrated induction of pro-survival autophagy in numerous cancers. In this study, the efficacy of JCTH-4 alone and in combination with TAM to induce cell death in human breast cancer (MCF7) and neuroblastoma (SH-SY5Y) cells was evaluated. TAM alone induced autophagy, but insignificant cell death whereas JCTH-4 alone caused significant induction of apoptosis with some induction of autophagy. Interestingly, the combinatory treatment yielded a drastic increase in apoptotic and autophagic induction. We monitored time-dependent morphological changes in MCF7 cells undergoing TAM-induced autophagy, JCTH-4-induced apoptosis and autophagy, and accelerated cell death with combinatorial treatment using time-lapse microscopy. We have demonstrated these compounds to induce apoptosis/autophagy by mitochondrial targeting in these cancer cells. Importantly, these treatments did not affect the survival of noncancerous human fibroblasts. Thus, these results indicate that JCTH-4 in combination with TAM could be used as a safe and very potent anti-cancer therapy against breast cancer and neuroblastoma cells.
Cancer Biology, Issue 63, Medicine, Biochemistry, Breast adenocarcinoma, neuroblastoma, tamoxifen, combination therapy, apoptosis, autophagy
Immunohistochemical Staining of B7-H1 (PD-L1) on Paraffin-embedded Slides of Pancreatic Adenocarcinoma Tissue
Institutions: The Johns Hopkins University School of Medicine, The Johns Hopkins University School of Medicine, The Johns Hopkins University School of Medicine, Johns Hopkins University School of Medicine, The Johns Hopkins University School of Medicine, Yale School of Medicine, The Johns Hopkins University School of Medicine, The Johns Hopkins University School of Medicine.
B7-H1/PD-L1, a member of the B7 family of immune-regulatory cell-surface proteins, plays an important role in the negative regulation of cell-mediated immune responses through its interaction with its receptor, programmed death-1 (PD-1) 1,2
. Overexpression of B7-H1 by tumor cells has been noted in a number of human cancers, including melanoma, glioblastoma, and carcinomas of the lung, breast, colon, ovary, and renal cells, and has been shown to impair anti-tumor T-cell immunity3-8
Recently, B7-H1 expression by pancreatic adenocarcinoma tissues has been identified as a potential prognostic marker9,10
. Additionally, blockade of B7-H1 in a mouse model of pancreatic cancer has been shown to produce an anti-tumor response11
. These data suggest the importance of B7-H1 as a potential therapeutic target. Anti-B7-H1 blockade antibodies are therefore being tested in clinical trials for multiple human solid tumors including melanoma and cancers of lung, colon, kidney, stomach and pancreas12
In order to eventually be able to identify the patients who will benefit from B7-H1 targeting therapies, it is critical to investigate the correlation between expression and localization of B7-H1 and patient response to treatment with B7-H1 blockade antibodies. Examining the expression of B7-H1 in human pancreatic adenocarcinoma tissues through immunohistochemistry will give a better understanding of how this co-inhibitory signaling molecule contributes to the suppression of antitumor immunity in the tumor's microenvironment. The anti-B7-H1 monoclonal antibody (clone 5H1) developed by Chen and coworkers has been shown to produce reliable staining results in cryosections of multiple types of human neoplastic tissues4,8
, but staining on paraffin-embedded slides had been a challenge until recently13-18
. We have developed the B7-H1 staining protocol for paraffin-embedded slides of pancreatic adenocarcinoma tissues. The B7-H1 staining protocol described here produces consistent membranous and cytoplasmic staining of B7-H1 with little background.
Cancer Biology, Issue 71, Medicine, Immunology, Biochemistry, Molecular Biology, Cellular Biology, Chemistry, Oncology, immunohistochemistry, B7-H1 (PD-L1), pancreatic adenocarcinoma, pancreatic cancer, pancreas, tumor, T-cell immunity, cancer
Quantitative Measurement of Invadopodia-mediated Extracellular Matrix Proteolysis in Single and Multicellular Contexts
Institutions: West Virginia University .
Cellular invasion into local tissues is a process important in development and homeostasis. Malregulated invasion and subsequent cell movement is characteristic of multiple pathological processes, including inflammation, cardiovascular disease and tumor cell metastasis1
. Focalized proteolytic degradation of extracellular matrix (ECM) components in the epithelial or endothelial basement membrane is a critical step in initiating cellular invasion. In tumor cells, extensive in vitro
analysis has determined that ECM degradation is accomplished by ventral actin-rich membrane protrusive structures termed invadopodia2,3
. Invadopodia form in close apposition to the ECM, where they moderate ECM breakdown through the action of matrix metalloproteinases (MMPs). The ability of tumor cells to form invadopodia directly correlates with the ability to invade into local stroma and associated vascular components3
Visualization of invadopodia-mediated ECM degradation of cells by fluorescent microscopy using dye-labeled matrix proteins coated onto glass coverslips has emerged as the most prevalent technique for evaluating the degree of matrix proteolysis and cellular invasive potential4,5
. Here we describe a version of the standard method for generating fluorescently-labeled glass coverslips utilizing a commercially available Oregon Green-488 gelatin conjugate. This method is easily scaled to rapidly produce large numbers of coated coverslips. We show some of the common microscopic artifacts that are often encountered during this procedure and how these can be avoided. Finally, we describe standardized methods using readily available computer software to allow quantification of labeled gelatin matrix degradation mediated by individual cells and by entire cellular populations. The described procedures provide the ability to accurately and reproducibly monitor invadopodia activity, and can also serve as a platform for evaluating the efficacy of modulating protein expression or testing of anti-invasive compounds on extracellular matrix degradation in single and multicellular settings.
Cellular Biology, Issue 66, Cancer Biology, Anatomy, Molecular Biology, Biochemistry, invadopodia, extracellular matrix, gelatin, confocal microscopy, quantification, oregon green
Improved Visualization of Lung Metastases at Single Cell Resolution in Mice by Combined In-situ Perfusion of Lung Tissue and X-Gal Staining of lacZ-Tagged Tumor Cells
Institutions: Balgrist University Hospital, Zurich.
Metastasis is the main cause of death in the majority of cancer types and consequently a main focus in cancer research. However, the detection of micrometastases by radiologic imaging and the success in their therapeutic eradication remain limited.
While animal models have proven to be invaluable tools for cancer research1
, the monitoring/visualization of micrometastases remains a challenge and inaccurate evaluation of metastatic spread in preclinical studies potentially leads to disappointing results in clinical trials2
. Consequently, there is great interest in refining the methods to finally allow reproducible and reliable detection of metastases down to the single cell level in normal tissue. The main focus therefore is on techniques, which allow the detection of tumor cells in vivo
, like micro-computer tomography (micro-CT), positron emission tomography (PET), bioluminescence or fluorescence imaging3,4
. We are currently optimizing these techniques for in vivo
monitoring of primary tumor growth and metastasis in different osteosarcoma models. Some of these techniques can also be used for ex vivo
analysis of metastasis beside classical methods like qPCR5
or different types of histological staining. As a benchmark, we have established in the present study the stable transfection or transduction of tumor cells with the lacZ
gene encoding the bacterial enzyme β-galactosidase that metabolizes the chromogenic substrate 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) to an insoluble indigo blue dye7
and allows highly sensitive and selective histochemical blue staining of tumor cells in mouse tissue ex vivo
down to the single cell level as shown here. This is a low-cost and not equipment-intensive tool, which allows precise validation of metastasis8
in studies assessing new anticancer therapies9-11
. A limiting factor of X-gal staining is the low contrast to e.g.
blood-related red staining of well vascularized tissues. In lung tissue this problem can be solved by in-situ
lung perfusion, a technique that was recently established by Borsig et al.12
who perfused the lungs of mice under anesthesia to clear them from blood and to fix and embed them in-situ
under inflation through the trachea. This method prevents also the collapse of the lung and thereby maintains the morphology of functional lung alveoli, which improves the quality of the tissue for histological analysis. In the present study, we describe a new protocol, which takes advantage of a combination of X-gal staining of lacZ-
expressing tumor cells and in-situ
perfusion and fixation of lung tissue. This refined protocol allows high-sensitivity detection of single metastatic cells in the lung and enabled us in a recent study to detect "dormant" lung micrometastases in a mouse model13
, which was originally described to be non-metastatic14
Cancer Biology, Issue 66, Medicine, Molecular Biology, Cellular Biology, lung metastasis, lacZ-tagging, 5-Bromo-4-chloro-3-indolyl-beta-D-galactoside (X-Gal) staining, in-situ lung perfusion, metastases, imaging
Cerenkov Luminescence Imaging (CLI) for Cancer Therapy Monitoring
Institutions: Stanford University .
In molecular imaging, positron emission tomography (PET) and optical imaging (OI) are two of the most important and thus most widely used modalities1-3
. PET is characterized by its excellent sensitivity and quantification ability while OI is notable for non-radiation, relative low cost, short scanning time, high throughput, and wide availability to basic researchers. However, both modalities have their shortcomings as well. PET suffers from poor spatial resolution and high cost, while OI is mostly limited to preclinical applications because of its limited tissue penetration along with prominent scattering optical signals through the thickness of living tissues.
Recently a bridge between PET and OI has emerged with the discovery of Cerenkov Luminescence Imaging (CLI)4-6
. CLI is a new imaging modality that harnesses Cerenkov Radiation (CR) to image radionuclides with OI instruments. Russian Nobel laureate Alekseyevich Cerenkov and his colleagues originally discovered CR in 1934. It is a form of electromagnetic radiation emitted when a charged particle travels at a superluminal speed in a dielectric medium7,8
. The charged particle, whether positron or electron, perturbs the electromagnetic field of the medium by displacing the electrons in its atoms. After passing of the disruption photons are emitted as the displaced electrons return to the ground state. For instance, one 18
F decay was estimated to produce an average of 3 photons in water5
Since its emergence, CLI has been investigated for its use in a variety of preclinical applications including in vivo
tumor imaging, reporter gene imaging, radiotracer development, multimodality imaging, among others4,5,9,10,11
. The most important reason why CLI has enjoyed much success so far is that this new technology takes advantage of the low cost and wide availability of OI to image radionuclides, which used to be imaged only by more expensive and less available nuclear imaging modalities such as PET.
Here, we present the method of using CLI to monitor cancer drug therapy. Our group has recently investigated this new application and validated its feasibility by a proof-of-concept study12
. We demonstrated that CLI and PET exhibited excellent correlations across different tumor xenografts and imaging probes. This is consistent with the overarching principle of CR that CLI essentially visualizes the same radionuclides as PET. We selected Bevacizumab (Avastin; Genentech/Roche) as our therapeutic agent because it is a well-known angiogenesis inhibitor13,14
. Maturation of this technology in the near future can be envisioned to have a significant impact on preclinical drug development, screening, as well as therapy monitoring of patients receiving treatments.
Cancer Biology, Issue 69, Medicine, Molecular Biology, Cerenkov Luminescence Imaging, CLI, cancer therapy monitoring, optical imaging, PET, radionuclides, Avastin, imaging
In vivo Measurement of the Mouse Pulmonary Endothelial Surface Layer
Institutions: University of Colorado School of Medicine.
The endothelial glycocalyx is a layer of proteoglycans and associated glycosaminoglycans lining the vascular lumen. In vivo
, the glycocalyx is highly hydrated, forming a substantial endothelial surface layer (ESL) that contributes to the maintenance of endothelial function. As the endothelial glycocalyx is often aberrant in vitro
and is lost during standard tissue fixation techniques, study of the ESL requires use of intravital microscopy. To best approximate the complex physiology of the alveolar microvasculature, pulmonary intravital imaging is ideally performed on a freely-moving lung. These preparations, however, typically suffer from extensive motion artifact. We demonstrate how closed-chest intravital microscopy of a freely-moving mouse lung can be used to measure glycocalyx integrity via ESL exclusion of fluorescently-labeled high molecular weight dextrans from the endothelial surface. This non-recovery surgical technique, which requires simultaneous brightfield and fluorescent imaging of the mouse lung, allows for longitudinal observation of the subpleural microvasculature without evidence of inducing confounding lung injury.
Medicine, Issue 72, Cellular Biology, Anatomy, Physiology, Biomedical Engineering, Biophysics, Surgery, Endothelium, Vascular, Inflammation, Pulmonary Circulation, Intravital Microscopy, endothelial surface layer, endothelial, glycocalyx, pulmonary microvasculature, catheter, tracheostomy, venous, catheterization, lung injury, mouse, animal model
MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent
Institutions: Case Western Reserve University , Case Western Reserve University , Case Western Reserve University .
Tumor extracellular matrix has abundance of cancer related proteins that can be used as biomarkers for cancer molecular imaging. In this work, we demonstrated effective MR cancer molecular imaging with a small molecular peptide targeted Gd-DOTA monoamide complex as a targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma. We performed the experiment of evaluating the effectiveness of the agent for non-invasive detection of prostate tumor with MRI in a mouse orthotopic PC-3 prostate cancer model. The targeted contrast agent was effective to produce significant tumor contrast enhancement at a low dose of 0.03 mmol Gd/kg. The peptide targeted MRI contrast agent is promising for MR molecular imaging of prostate tumor.
Cancer Biology, Issue 79, Medicine, Molecular Biology, Cellular Biology, Biomedical Engineering, Anatomy, Physiology, Biochemistry, Oncology, Biomedical and Dental Materials, Pharmaceutical Preparations, Diagnosis, MRI, magnetic resonance imaging, molecular imaging, conjugation, CLT1, prostate cancer, cancer, prostate, imaging, clinical techniques, clinical applications
Microarray-based Identification of Individual HERV Loci Expression: Application to Biomarker Discovery in Prostate Cancer
Institutions: Joint Unit Hospices de Lyon-bioMérieux, BioMérieux, Hospices Civils de Lyon, Lyon 1 University, BioMérieux, Hospices Civils de Lyon, Hospices Civils de Lyon.
The prostate-specific antigen (PSA) is the main diagnostic biomarker for prostate cancer in clinical use, but it lacks specificity and sensitivity, particularly in low dosage values1
. ‘How to use PSA' remains a current issue, either for diagnosis as a gray zone corresponding to a concentration in serum of 2.5-10 ng/ml which does not allow a clear differentiation to be made between cancer and noncancer2
or for patient follow-up as analysis of post-operative PSA kinetic parameters can pose considerable challenges for their practical application3,4
. Alternatively, noncoding RNAs (ncRNAs) are emerging as key molecules in human cancer, with the potential to serve as novel markers of disease, e.g.
PCA3 in prostate cancer5,6
and to reveal uncharacterized aspects of tumor biology. Moreover, data from the ENCODE project published in 2012 showed that different RNA types cover about 62% of the genome. It also appears that the amount of transcriptional regulatory motifs is at least 4.5x higher than the one corresponding to protein-coding exons. Thus, long terminal repeats (LTRs) of human endogenous retroviruses (HERVs) constitute a wide range of putative/candidate transcriptional regulatory sequences, as it is their primary function in infectious retroviruses. HERVs, which are spread throughout the human genome, originate from ancestral and independent infections within the germ line, followed by copy-paste propagation processes and leading to multicopy families occupying 8% of the human genome (note that exons span 2% of our genome). Some HERV loci still express proteins that have been associated with several pathologies including cancer7-10
. We have designed a high-density microarray, in Affymetrix format, aiming to optimally characterize individual HERV loci expression, in order to better understand whether they can be active, if they drive ncRNA transcription or modulate coding gene expression. This tool has been applied in the prostate cancer field (Figure 1
Medicine, Issue 81, Cancer Biology, Genetics, Molecular Biology, Prostate, Retroviridae, Biomarkers, Pharmacological, Tumor Markers, Biological, Prostatectomy, Microarray Analysis, Gene Expression, Diagnosis, Human Endogenous Retroviruses, HERV, microarray, Transcriptome, prostate cancer, Affymetrix
Hybrid µCT-FMT imaging and image analysis
Institutions: RWTH Aachen University, RWTH Aachen University, Utrecht University.
Fluorescence-mediated tomography (FMT) enables longitudinal and quantitative determination of the fluorescence distribution in vivo
and can be used to assess the biodistribution of novel probes and to assess disease progression using established molecular probes or reporter genes. The combination with an anatomical modality, e.g.
, micro computed tomography (µCT), is beneficial for image analysis and for fluorescence reconstruction. We describe a protocol for multimodal µCT-FMT imaging including the image processing steps necessary to extract quantitative measurements. After preparing the mice and performing the imaging, the multimodal data sets are registered. Subsequently, an improved fluorescence reconstruction is performed, which takes into account the shape of the mouse. For quantitative analysis, organ segmentations are generated based on the anatomical data using our interactive segmentation tool. Finally, the biodistribution curves are generated using a batch-processing feature. We show the applicability of the method by assessing the biodistribution of a well-known probe that binds to bones and joints.
Bioengineering, Issue 100, Fluorescence-mediated Tomography, Computed Tomography, Image Segmentation, Multimodal Imaging, Image Analysis, Hybrid Imaging, Biodistribution, Diffuse Optical Tomography