Human pluripotent stem cells (hPSCs) hold great promise for regenerative medicine and biopharmaceutical applications. Currently, optimal culture and efficient expansion of large amounts of clinical-grade hPSCs are critical issues in hPSC-based therapies. Conventionally, hPSCs are propagated as colonies on both feeder and feeder-free culture systems. However, these methods have several major limitations, including low cell yields and generation of heterogeneously differentiated cells. To improve current hPSC culture methods, we have recently developed a new method, which is based on non-colony type monolayer (NCM) culture of dissociated single cells. Here, we present detailed NCM protocols based on the Rho-associated kinase (ROCK) inhibitor Y-27632. We also provide new information regarding NCM culture with different small molecules such as Y-39983 (ROCK I inhibitor), phenylbenzodioxane (ROCK II inhibitor), and thiazovivin (a novel ROCK inhibitor). We further extend our basic protocol to cultivate hPSCs on defined extracellular proteins such as the laminin isoform 521 (LN-521) without the use of ROCK inhibitors. Moreover, based on NCM, we have demonstrated efficient transfection or transduction of plasmid DNAs, lentiviral particles, and oligonucleotide-based microRNAs into hPSCs in order to genetically modify these cells for molecular analyses and drug discovery. The NCM-based methods overcome the major shortcomings of colony-type culture, and thus may be suitable for producing large amounts of homogeneous hPSCs for future clinical therapies, stem cell research, and drug discovery.
18 Related JoVE Articles!
Enrichment and Purging of Human Embryonic Stem Cells by Detection of Cell Surface Antigens Using the Monoclonal Antibodies TG30 and GCTM-2
Human embryonic stem cells (hESC) can self-renew indefinitely in vitro
, and with the appropriate cues can be induced to differentiate into potentially all somatic cell lineages. Differentiated hESC derivatives can potentially be used in transplantation therapies to treat a variety of cell-degenerative diseases. However, hESC differentiation protocols usually yield a mixture of differentiated target and off-target cell types as well as residual undifferentiated cells. For the translation of differentiated hESC-derivatives from the laboratory to the clinic, it is important to be able to discriminate between undifferentiated (pluripotent) and differentiated cells, and generate methods to separate these populations. Safe application of hESC-derived somatic cell types can only be accomplished with pluripotent stem cell-free populations, as residual hESCs could induce tumors known as teratomas following transplantation. Towards this end, here we describe a methodology to detect pluripotency associated cell surface antigens with the monoclonal antibodies TG30 (CD9) and GCTM-2 via fluorescence activated cell sorting (FACS) for the identification of pluripotent TG30Hi
hESCs using positive selection. Using negative selection with our TG30/GCTM-2 FACS methodology, we were able to detect and purge undifferentiated hESCs in populations undergoing very early-stage differentiation (TG30Neg
). In a further study, pluripotent stem cell-free samples of differentiated TG30Neg
cells selected using our TG30/GCTM-2 FACS protocol did not form teratomas once transplanted into immune-compromised mice, supporting the robustness of our protocol. On the other hand, TG30/GCTM-2 FACS-mediated consecutive passaging of enriched pluripotent TG30Hi
hESCs did not affect their ability to self-renew in vitro
or their intrinsic pluripotency. Therefore, the characteristics of our TG30/GCTM-2 FACS methodology provide a sensitive assay to obtain highly enriched populations of hPSC as inputs for differentiation assays and to rid potentially tumorigenic (or residual) hESC from derivative cell populations.
Stem Cell Biology, Issue 82, Stem cells, cell surface antigens, antibodies, FACS, purging stem cells, differentiation, pluripotency, teratoma, human embryonic stem cells (hESC)
Directed Dopaminergic Neuron Differentiation from Human Pluripotent Stem Cells
Institutions: Stanford University School of Medicine, Stanford University School of Medicine.
Dopaminergic (DA) neurons in the substantia nigra pars compacta (also known as A9 DA neurons) are the specific cell type that is lost in Parkinson’s disease (PD). There is great interest in deriving A9 DA neurons from human pluripotent stem cells (hPSCs) for regenerative cell replacement therapy for PD. During neural development, A9 DA neurons originate from the floor plate (FP) precursors located at the ventral midline of the central nervous system. Here, we optimized the culture conditions for the stepwise differentiation of hPSCs to A9 DA neurons, which mimics embryonic DA neuron development. In our protocol, we first describe the efficient generation of FP precursor cells from hPSCs using a small molecule method, and then convert the FP cells to A9 DA neurons, which could be maintained in vitro
for several months. This efficient, repeatable and controllable protocol works well in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) from normal persons and PD patients, in which one could derive A9 DA neurons to perform in vitro
disease modeling and drug screening and in vivo
cell transplantation therapy for PD.
Neuroscience, Issue 91, dopaminergic neuron, substantia nigra pars compacta, midbrain, Parkinson’s disease, directed differentiation, human pluripotent stem cells, floor plate
A cGMP-applicable Expansion Method for Aggregates of Human Neural Stem and Progenitor Cells Derived From Pluripotent Stem Cells or Fetal Brain Tissue
Institutions: Cedars-Sinai Medical Center.
A cell expansion technique to amass large numbers of cells from a single specimen for research experiments and clinical trials would greatly benefit the stem cell community. Many current expansion methods are laborious and costly, and those involving complete dissociation may cause several stem and progenitor cell types to undergo differentiation or early senescence. To overcome these problems, we have developed an automated mechanical passaging method referred to as “chopping” that is simple and inexpensive. This technique avoids chemical or enzymatic dissociation into single cells and instead allows for the large-scale expansion of suspended, spheroid cultures that maintain constant cell/cell contact. The chopping method has primarily been used for fetal brain-derived neural progenitor cells or neurospheres, and has recently been published for use with neural stem cells derived from embryonic and induced pluripotent stem cells. The procedure involves seeding neurospheres onto a tissue culture Petri dish and subsequently passing a sharp, sterile blade through the cells effectively automating the tedious process of manually mechanically dissociating each sphere. Suspending cells in culture provides a favorable surface area-to-volume ratio; as over 500,000 cells can be grown within a single neurosphere of less than 0.5 mm in diameter. In one T175 flask, over 50 million cells can grow in suspension cultures compared to only 15 million in adherent cultures. Importantly, the chopping procedure has been used under current good manufacturing practice (cGMP), permitting mass quantity production of clinical-grade cell products.
Neuroscience, Issue 88, neural progenitor cell, neural precursor cell, neural stem cell, passaging, neurosphere, chopping, stem cell, neuroscience, suspension culture, good manufacturing practice, GMP
Efficient Generation Human Induced Pluripotent Stem Cells from Human Somatic Cells with Sendai-virus
Institutions: Johns Hopkins University School of Medicine.
A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs include modeling pathogenesis of human genetic diseases, autologous cell therapy after gene correction, and personalized drug screening by providing a source of patient-specific and symptom relevant cells. However, there are several hurdles to overcome, such as eliminating the remaining reprogramming factor transgene expression after human iPSCs production. More importantly, residual transgene expression in undifferentiated human iPSCs could hamper proper differentiations and misguide the interpretation of disease-relevant in vitro
phenotypes. With this reason, integration-free and/or transgene-free human iPSCs have been developed using several methods, such as adenovirus, the piggyBac system, minicircle vector, episomal vectors, direct protein delivery and synthesized mRNA. However, efficiency of reprogramming using integration-free methods is quite low in most cases.
Here, we present a method to isolate human iPSCs by using Sendai-virus (RNA virus) based reprogramming system. This reprogramming method shows consistent results and high efficiency in cost-effective manner.
Stem Cell Biology, Issue 86, Induced pluripotent stem cells, Human embryonic stem cells, Sendai-virus
The Specification of Telencephalic Glutamatergic Neurons from Human Pluripotent Stem Cells
Institutions: The University of Connecticut Health Center, The University of Connecticut Health Center, The University of Connecticut Health Center.
Here, a stepwise procedure for efficiently generating telencephalic glutamatergic neurons from human pluripotent stem cells (PSCs) has been described. The differentiation process is initiated by breaking the human PSCs into clumps which round up to form aggregates when the cells are placed in a suspension culture. The aggregates are then grown in hESC medium from days 1-4 to allow for spontaneous differentiation. During this time, the cells have the capacity to become any of the three germ layers. From days 5-8, the cells are placed in a neural induction medium to push them into the neural lineage. Around day 8, the cells are allowed to attach onto 6 well plates and differentiate during which time the neuroepithelial cells form. These neuroepithelial cells can be isolated at day 17. The cells can then be kept as neurospheres until they are ready to be plated onto coverslips. Using a basic medium without any caudalizing factors, neuroepithelial cells are specified into telencephalic precursors, which can then be further differentiated into dorsal telencephalic progenitors and glutamatergic neurons efficiently. Overall, our system provides a tool to generate human glutamatergic neurons for researchers to study the development of these neurons and the diseases which affect them.
Stem Cell Biology, Issue 74, Neuroscience, Neurobiology, Developmental Biology, Cellular Biology, Molecular Biology, Stem Cells, Embryonic Stem Cells, ESCs, Pluripotent Stem Cells, Induced Pluripotent Stem Cells, iPSC, neural differentiation, forebrain, glutamatergic neuron, neural patterning, development, neurons
In vivo Reprogramming of Adult Somatic Cells to Pluripotency by Overexpression of Yamanaka Factors
Institutions: University College London, University of Manchester.
Induced pluripotent stem (iPS) cells that result from the reprogramming of somatic cells to a pluripotent state by forced expression of defined factors are offering new opportunities for regenerative medicine. Such clinical applications of iPS cells have been limited so far, mainly due to the poor efficiency of the existing reprogramming methodologies and the risk of the generated iPS cells to form tumors upon implantation.
We hypothesized that the reprogramming of somatic cells towards pluripotency could be achieved in vivo
by gene transfer of reprogramming factors. In order to efficiently reprogram cells in vivo
, high levels of the Yamanaka (OKSM) transcription factors need to be expressed at the target tissue. This can be achieved by using different viral or nonviral gene vectors depending on the target tissue. In this particular study, hydrodynamic tail-vein (HTV) injection of plasmid DNA was used to deliver the OKSM factors to mouse hepatocytes. This provided proof-of-evidence of in vivo
reprogramming of adult, somatic cells towards a pluripotent state with high efficiency and fast kinetics. Furthermore no tumor or teratoma formation was observed in situ.
It can be concluded that reprogramming somatic cells in vivo
may offer a potential approach to induce enhanced pluripotency rapidly, efficiently, and safely compared to in vitro
performed protocols and can be applied to different tissue types in the future.
Stem Cell Biology, Issue 82, Pluripotent Stem Cells, Induced Pluripotent Stem Cells (iPSCs), Transcription Factors, General, Gene Therapy, Gene Expression, iPS, OKSM, regenerative medicine
Transfecting and Nucleofecting Human Induced Pluripotent Stem Cells
Institutions: University of California Riverside.
Genetic modification is continuing to be an essential tool in studying stem cell biology and in setting forth potential clinical applications of human embryonic stem cells (HESCs)1
. While improvements in several gene delivery methods have been described2-9
, transfection remains a capricious process for HESCs, and has not yet been reported in human induced pluripotent stem cells (iPSCs). In this video, we demonstrate how our lab routinely transfects and nucleofects human iPSCs using plasmid with an enhanced green fluorescence protein (eGFP) reporter. Human iPSCs are adapted and maintained as feeder-free cultures to eliminate the possibility of feeder cell transfection and to allow efficient selection of stable transgenic iPSC clones following transfection. For nucleofection, human iPSCs are pre-treated with ROCK inhibitor11
, trypsinized into small clumps of cells, nucleofected and replated on feeders in feeder cell-conditioned medium to enhance cell recovery. Transgene-expressing human iPSCs can be obtained after 6 hours. Antibiotic selection is applied after 24 hours and stable transgenic lines appear within 1 week. Our protocol is robust and reproducible for human iPSC lines without altering pluripotency of these cells.
Medicine, Issue 56, Developmental Biology, Transfection, iPS cells, IPSCs, ES cells, HESCs, Nucleofection
Teratoma Generation in the Testis Capsule
Institutions: Scripps Research Institute, Scripps Research Institute , University of California.
Pluripotent stem cells (PSCs) have the unique characteristic that they can differentiate into cells from all three germ layers. This makes them a potentially valuable tool for the treatment of many different diseases. With the advent of induced pluripotent stem cells (iPSCs) and continuing research with human embryonic stem cells (hESCs) there is a need for assays that can demonstrate that a particular cell line is pluripotent. Germline transmission has been the gold standard for demonstrating the pluripotence of mouse embryonic stem cell (mESC) lines1,2,3
. Using this assay, researchers can show that a mESC line can make all cell types in the embryo including germ cells4
. With the generation of human ESC lines5,6
, the appropriate assay to prove pluripotence of these cells was unclear since human ESCs cannot be tested for germline transmission. As a surrogate, the teratoma assay is currently used to demonstrate the pluripotency of human pluripotent stem cells (hPSCs)7,8,9
. Though this assay has recently come under scrutiny and new technologies are being actively explored, the teratoma assay is the current gold standard7
. In this assay, the cells in question are injected into an immune compromised mouse. If the cells are pluripotent, a teratoma will eventually develop and sections of the tumor will show tissues from all 3 germ layers10
. In the teratoma assay, hPSCs can be injected into different areas of the mouse. The most common injection sites include the testis capsule, the kidney capsule, the liver; or into the leg either subcutaneously or intramuscularly11
. Here we describe a robust protocol for the generation of teratomas from hPSCs using the testis capsule as the site for tumor growth.
Medicine, Issue 57, stem cells, pluripotent stem cells, hPSCs, teratoma assay, animal model, mouse testis capsule
Recombineering Homologous Recombination Constructs in Drosophila
Institutions: University of Texas Southwestern Medical Center at Dallas, University of Texas Southwestern Medical Center at Dallas, University of Texas Southwestern Medical Center at Dallas.
The continued development of techniques for fast, large-scale manipulation of endogenous gene loci will broaden the use of Drosophila melanogaster
as a genetic model organism for human-disease related research. Recent years have seen technical advancements like homologous recombination and recombineering. However, generating unequivocal null mutations or tagging endogenous proteins remains a substantial effort for most genes. Here, we describe and demonstrate techniques for using recombineering-based cloning methods to generate vectors that can be used to target and manipulate endogenous loci in vivo.
Specifically, we have established a combination of three technologies: (1) BAC transgenesis/recombineering, (2) ends-out homologous recombination and (3) Gateway technology to provide a robust, efficient and flexible method for manipulating endogenous genomic loci. In this protocol, we provide step-by-step details about how to (1) design individual vectors, (2) how to clone large fragments of genomic DNA into the homologous recombination vector using gap repair, and (3) how to replace or tag genes of interest within these vectors using a second round of recombineering. Finally, we will also provide a protocol for how to mobilize these cassettes in vivo
to generate a knockout, or a tagged gene via knock-in. These methods can easily be adopted for multiple targets in parallel and provide a means for manipulating the Drosophila
genome in a timely and efficient manner.
Genetics, Issue 77, Bioengineering, Molecular Biology, Biomedical Engineering, Physiology, Drosophila melanogaster, genetics (animal and plant), Recombineering, Drosophila, Homologous Recombination, Knock-out, recombination, genetic engineering, gene targeting, gene, genes, DNA, PCR, Primers, sequencing, animal model
Genetic Manipulation in Δku80 Strains for Functional Genomic Analysis of Toxoplasma gondii
Institutions: The Geisel School of Medicine at Dartmouth.
Targeted genetic manipulation using homologous recombination is the method of choice for functional genomic analysis to obtain a detailed view of gene function and phenotype(s). The development of mutant strains with targeted gene deletions, targeted mutations, complemented gene function, and/or tagged genes provides powerful strategies to address gene function, particularly if these genetic manipulations can be efficiently targeted to the gene locus of interest using integration mediated by double cross over homologous recombination.
Due to very high rates of nonhomologous recombination, functional genomic analysis of Toxoplasma gondii
has been previously limited by the absence of efficient methods for targeting gene deletions and gene replacements to specific genetic loci. Recently, we abolished the major pathway of nonhomologous recombination in type I and type II strains of T. gondii
by deleting the gene encoding the KU80 protein1,2
. The Δku80
strains behave normally during tachyzoite (acute) and bradyzoite (chronic) stages in vitro
and in vivo
and exhibit essentially a 100% frequency of homologous recombination. The Δku80
strains make functional genomic studies feasible on the single gene as well as on the genome scale1-4
Here, we report methods for using type I and type II Δku80Δhxgprt
strains to advance gene targeting approaches in T. gondii
. We outline efficient methods for generating gene deletions, gene replacements, and tagged genes by targeted insertion or deletion of the hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT
) selectable marker. The described gene targeting protocol can be used in a variety of ways in Δku80
strains to advance functional analysis of the parasite genome and to develop single strains that carry multiple targeted genetic manipulations. The application of this genetic method and subsequent phenotypic assays will reveal fundamental and unique aspects of the biology of T. gondii
and related significant human pathogens that cause malaria (Plasmodium
sp.) and cryptosporidiosis (Cryptosporidium
Infectious Diseases, Issue 77, Genetics, Microbiology, Infection, Medicine, Immunology, Molecular Biology, Cellular Biology, Biomedical Engineering, Bioengineering, Genomics, Parasitology, Pathology, Apicomplexa, Coccidia, Toxoplasma, Genetic Techniques, Gene Targeting, Eukaryota, Toxoplasma gondii, genetic manipulation, gene targeting, gene deletion, gene replacement, gene tagging, homologous recombination, DNA, sequencing
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
High Efficiency Differentiation of Human Pluripotent Stem Cells to Cardiomyocytes and Characterization by Flow Cytometry
Institutions: Medical College of Wisconsin, Stanford University School of Medicine, Medical College of Wisconsin, Hong Kong University, Johns Hopkins University School of Medicine, Medical College of Wisconsin.
There is an urgent need to develop approaches for repairing the damaged heart, discovering new therapeutic drugs that do not have toxic effects on the heart, and improving strategies to accurately model heart disease. The potential of exploiting human induced pluripotent stem cell (hiPSC) technology to generate cardiac muscle “in a dish” for these applications continues to generate high enthusiasm. In recent years, the ability to efficiently generate cardiomyogenic cells from human pluripotent stem cells (hPSCs) has greatly improved, offering us new opportunities to model very early stages of human cardiac development not otherwise accessible. In contrast to many previous methods, the cardiomyocyte differentiation protocol described here does not require cell aggregation or the addition of Activin A or BMP4 and robustly generates cultures of cells that are highly positive for cardiac troponin I and T (TNNI3, TNNT2), iroquois-class homeodomain protein IRX-4 (IRX4), myosin regulatory light chain 2, ventricular/cardiac muscle isoform (MLC2v) and myosin regulatory light chain 2, atrial isoform (MLC2a) by day 10 across all human embryonic stem cell (hESC) and hiPSC lines tested to date. Cells can be passaged and maintained for more than 90 days in culture. The strategy is technically simple to implement and cost-effective. Characterization of cardiomyocytes derived from pluripotent cells often includes the analysis of reference markers, both at the mRNA and protein level. For protein analysis, flow cytometry is a powerful analytical tool for assessing quality of cells in culture and determining subpopulation homogeneity. However, technical variation in sample preparation can significantly affect quality of flow cytometry data. Thus, standardization of staining protocols should facilitate comparisons among various differentiation strategies. Accordingly, optimized staining protocols for the analysis of IRX4, MLC2v, MLC2a, TNNI3, and TNNT2 by flow cytometry are described.
Cellular Biology, Issue 91, human induced pluripotent stem cell, flow cytometry, directed differentiation, cardiomyocyte, IRX4, TNNI3, TNNT2, MCL2v, MLC2a
Zinc-finger Nuclease Enhanced Gene Targeting in Human Embryonic Stem Cells
Institutions: Monash University.
One major limitation with current human embryonic stem cell (ESC) differentiation protocols is the generation of heterogeneous cell populations. These cultures contain the cells of interest, but are also contaminated with undifferentiated ESCs, non-neural derivatives and other neuronal subtypes. This limits their use in in vitro
and in vivo
applications, such as in vitro
modeling for drug discovery or cell replacement therapy. To help overcome this, reporter cell lines, which offer a means to visualize, track and isolate cells of interest, can be engineered. However, to achieve this in human embryonic stem cells via conventional homologous recombination is extremely inefficient. This protocol describes targeting of the Pituitary homeobox 3
) locus in human embryonic stem cells using custom designed zinc-finger nucleases, which introduce site-specific double-strand DNA breaks, together with a PITX3
-specific DNA donor vector. Following the generation of the PITX3
reporter cell line, it can then be differentiated using published protocols for use in studies such as in vitro
Parkinson’s disease modeling or cell replacement therapy.
Molecular Biology, Issue 90, Electroporation, human embryonic stem cell, genome editing, reporter cell line, midbrain dopaminergic neurons
Feeder-free Derivation of Neural Crest Progenitor Cells from Human Pluripotent Stem Cells
Institutions: Sloan-Kettering Institute for Cancer Research, The Rockefeller University.
Human pluripotent stem cells (hPSCs) have great potential for studying human embryonic development, for modeling human diseases in the dish and as a source of transplantable cells for regenerative applications after disease or accidents. Neural crest (NC) cells are the precursors for a large variety of adult somatic cells, such as cells from the peripheral nervous system and glia, melanocytes and mesenchymal cells. They are a valuable source of cells to study aspects of human embryonic development, including cell fate specification and migration. Further differentiation of NC progenitor cells into terminally differentiated cell types offers the possibility to model human diseases in vitro
, investigate disease mechanisms and generate cells for regenerative medicine. This article presents the adaptation of a currently available in vitro
differentiation protocol for the derivation of NC cells from hPSCs. This new protocol requires 18 days of differentiation, is feeder-free, easily scalable and highly reproducible among human embryonic stem cell (hESC) lines as well as human induced pluripotent stem cell (hiPSC) lines. Both old and new protocols yield NC cells of equal identity.
Neuroscience, Issue 87, Embryonic Stem Cells (ESCs), Pluripotent Stem Cells, Induced Pluripotent Stem Cells (iPSCs), Neural Crest, Peripheral Nervous System (PNS), pluripotent stem cells, neural crest cells, in vitro differentiation, disease modeling, differentiation protocol, human embryonic stem cells, human pluripotent stem cells
Rapid and Efficient Generation of Neurons from Human Pluripotent Stem Cells in a Multititre Plate Format
Institutions: Max Planck Institute for Molecular Biomedicine, University of Münster.
Existing protocols for the generation of neurons from human pluripotent stem cells (hPSCs) are often tedious in that they are multistep procedures involving the isolation and expansion of neural precursor cells, prior to terminal differentiation. In comparison to these time-consuming approaches, we have recently found that combined inhibition of three signaling pathways, TGFβ/SMAD2, BMP/SMAD1, and FGF/ERK, promotes rapid induction of neuroectoderm from hPSCs, followed by immediate differentiation into functional neurons. Here, we have adapted our procedure to a novel multititre plate format, to further enhance its reproducibility and to make it compatible with mid-throughput applications. It comprises four days of neuroectoderm formation in floating spheres (embryoid bodies), followed by a further four days of differentiation into neurons under adherent conditions. Most cells obtained with this protocol appear to be bipolar sensory neurons. Moreover, the procedure is highly efficient, does not require particular expert skills, and is based on a simple chemically defined medium with cost-efficient small molecules. Due to these features, the procedure may serve as a useful platform for further functional investigation as well as for cell-based screening approaches requiring human sensory neurons or neurons of any type.
Stem Cell Biology, Issue 73, Neuroscience, Biomedical Engineering, Medicine, Bioengineering, Physiology, Genetics, Molecular Biomedicine, human pluripotent stem cells, hPSC, neuronal differentiation, neuroectoderm, embryoid bodies, chemically defined conditions, stem cells, neurons, signalling pathways, mid-throughput, PCR, multititre, cell culture
Derivation and Characterization of a Transgene-free Human Induced Pluripotent Stem Cell Line and Conversion into Defined Clinical-grade Conditions
Institutions: University of California, Los Angeles (UCLA), University of California, Los Angeles (UCLA).
Human induced pluripotent stem cells (hiPSCs) can be generated with lentiviral-based reprogramming methodologies. However, traces of potentially oncogenic genes remaining in actively transcribed regions of the genome, limit their potential for use in human therapeutic applications1
. Additionally, non-human antigens derived from stem cell reprogramming or differentiation into therapeutically relevant derivatives preclude these hiPSCs from being used in a human clinical context2
. In this video, we present a procedure for reprogramming and analyzing factor-free hiPSCs free of exogenous transgenes. These hiPSCs then can be analyzed for gene expression abnormalities in the specific intron containing the lentivirus. This analysis may be conducted using sensitive quantitative polymerase chain reaction (PCR), which has an advantage over less sensitive techniques previously used to detect gene expression differences3
. Full conversion into clinical-grade good manufacturing practice (GMP) conditions, allows human clinical relevance. Our protocol offers another methodology—provided that current safe-harbor criteria will expand and include factor-free characterized hiPSC-based derivatives for human therapeutic applications—for deriving GMP-grade hiPSCs, which should eliminate any immunogenicity risk due to non-human antigens. This protocol is broadly applicable to lentiviral reprogrammed cells of any type and provides a reproducible method for converting reprogrammed cells into GMP-grade conditions.
Stem Cell Biology, Issue 93, Human induced pluripotent stem cells, STEMCCA, factor-free, GMP, xeno-free, quantitative PCR
Immunocytochemical Analysis of Human Pluripotent Stem Cells using a Self-Made Cytospin Apparatus
Institutions: Virginia Commonwealth University.
Human pluripotent stem cells (hPSCs) that include human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) are exciting cell sources due to their limitless self-renewal capabilities and their potential to differentiate into multiple cell types. The pluripotent state of hPSCs is typically assessed by techniques such as qPCR, immunocytochemistry, and by other in vitro
and in vivo
differentiation strategies into multiple cell types. Among these, immunocytochemical techniques have been developed for routine characterization of the undifferentiated state of hPSCs based on analysis of candidate intracellular and cell-surface biomarkers. Given the fact that hPSCs grow as colonies, problems arise in quantifying the expression of these markers at the individual cell level on a routine basis. Flow cytometry analyses serve to address this issue but require cell numbers and use of reagents that are not normally conducive for routine quality control assessment of hPSC cultures. Thus, the development of practical and reproducible means of creating monolayer cell samples with preserved integrity for marker evaluation has many advantages in stem cell research. This greatly benefits immunocytochemical analysis because individual cells from the monolayer can be easily observed and quantified for the expression of specific markers. Towards this goal, a self-made cytospin apparatus was constructed and optimized for use with immunocytochemical staining. Two cell-surface markers (SSEA3/SSEA4) expression were analyzed in a variant BG01 stem cell line for the purpose of this protocol.
Cellular Biology, Issue 38, stem cells, immunostaining, cytospin, cell surface marker
Christopher Hughes: An in vitro model for the Study of Angiogenesis (Interview)
Institutions: University of California, Irvine (UCI).
Christopher C.W. Hughes describes the utility of his culture system for studying angiogenesis in vitro. He explains the importance of fibroblasts that secrete a critical, yet unidentified, soluble factor that allow endothelial cells to form vessels in culture that branch, form proper lumens, and undergo anastamosis.
Cellular Biology, Issue 3, angiogenesis, fibrin, endothelial, HUVEC, umbilical, Translational Research