This work was supported by Funda&ccedil;&atilde;o de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Conselho Nacional de Desenvolvimento Cient&iacute;fico e Tecnol&oacute;gico (CNPq) and Instituto Nacional de Ci&ecirc;ncia e Tecnologia (INCTC). We are grateful to Bruna S. Paulsen and Aline M. Fernandes for the EB images.

1. Fixation and Cryopreservation
Pluripotent stem cells were cultured onto mouse embryonic fibroblasts (MEF) inactivated with mitomycin C and maintained in DMEM/F12 supplemented with 20% knockout serum replacement (KSR) and 8ng/ mL of fibroblast growth factor (FGF-2). In order to induce EB formation H9 cells were transferred to non-adherent dishes and cultured for 7 days, maintained in DMEM/F12 supplemented with 15% KSR 8. 
Note (!): This technique can be used for EBs derived from any embryonic and induced pluripotent stem cell.
<ol>
	<li>Collect the EBs from the culture dish with a pipette.</li>
	<li>Transfer EBs to a 15 mL conical tube and wait until the material sinks to the bottom of the tube.</li>
	<li>Remove medium and fix EBs with a 4% paraformaldehyde (PFA) solution in PBS for 30 minutes in room temperature. Note (!): For in situ hybridization antigen recovery should be done in order to avoid cross link reaction with antibodies due to the use of PFA6,7.</li>
	<li> Remove PFA solution and wash with PBS for 5 min.</li>
	<li>EBs should be placed in serial dilution of PBS-buffered sucrose solutions (10, 20 and 30%, in sequence) at 25-28&deg;C, each solution must be replaced every 30 min. The material can then be stocked in the 30% sucrose solution at 4&deg;C until the embedding step with OCT.</li>
</ol>
2. Tissue Embedding, Guidance and Freezing
<ol start="6">
	<li>Carefully collect the EBs from the tube. Discharge as much sucrose solution as possible. Note (!): It is important to wet the internal wall of the tip with sucrose solution before collecting the EBs. This procedure can avoid EB to be attached to the tip.</li>
	<li>Place EBs in the mold and remove remaining sucrose solution with filter paper. Note (!): It is important not to fill the mold with EBs to avoid overlapping.</li>
	<li>Fill mold with OCT slowly, taking care not to re-suspend EBs. After that, place all EB at the center of the mold and remove bubbles with the pipette.</li>
	<li>Mildly agitate for 15 minutes.</li>
	<li>Surround the mold with crushed dry ice to freeze the sample. OCT should be completely frozen. At this point blocks can be stored at -70&deg;C, for at least one year.</li>
</ol>
3. Cryosectioning Technique
<ol start="11">
	<li>Remove the frozen block from -70&deg;C and place on cryostat previously cooled at a temperature between -18 and -21 &deg;C. Note (!): Temperatures outside this range may cause troubles like sections curling, melting or cracking.</li>
	<li>Detach the OCT block from the mold and place it into the cryostat support by adding more OCT.</li>
	<li>It is important to orient the block properly and align it parallel to the edge of the blade. Note(!): As EBs are smaller than other tissue samples, this step is extremely important to minimize loss of material.</li>
	<li>OCT blocks should be sectioned superficially until the surface plane is obtained. Thin sections (10&mu;m) of the tissue specimen must be taken and mounted onto glass slides previously coated with 200 mg/mL poly L lysine (10 &mu;L per slide) 9,10. Note(!): To avoid torned sections pay attention to any damages at the blade.</li>
	<li>All sections should be air-dried for 1 hour at room temperature and then be used or stored at -70&deg;C until use.</li>
</ol>

<ol>
	<li>Thomson, J. A., Itskovitz-Eldor, J., Shapiro, S. S., Waknitz, M. A., Swiergiel, J. J., Marshall, V. S., Jones, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+stem+cell+lines+derived+from+human+blastocysts.">Embryonic stem cell lines derived from human blastocysts.</a> Science. 282, 1145-117 (1998).</li><li>Itskovitz-Eldor, J., Schuldiner, M., Karsenti, D., Eden, A., Yanuka, O., Amit, M., Soreq, H., Benvenisty, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+of+human+embryonic+stem+cells+into+embryoid+bodies+compromising+the+three+embryonic+germ+layers.">Differentiation of human embryonic stem cells into embryoid bodies compromising the three embryonic germ layers.</a> Mol Med. 6, 88-95 (2000).</li><li>Kurosawa, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+inducing+embryoid+body+formation:+in+vitro+differentiation+system+of+embryonic+stem+cells.">Methods for inducing embryoid body formation: in vitro differentiation system of embryonic stem cells.</a> J Biosci Bioeng. 103, 389-398 (2007).</li><li>Conley, B. J., Young, J. C., Trounson, A. O., Mollard, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Derivation+propagation+and+differentiation+of+human+embryonic+stem+cells.">Derivation propagation and differentiation of human embryonic stem cells.</a> Int J Biochem Cell Biol. 36, 555-567 (2004).</li><li>Moon, I. S., Cho, S. J., Jin, I., Walikonis, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+for+combined+fluorescence+in+situ+hybridization+and+immunocytochemistry.">A simple method for combined fluorescence in situ hybridization and immunocytochemistry.</a> Mol Cells. 24, 76-82 (2007).</li><li>Daneshtalab, N., Dor&#233;, J. J., Smeda, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Troubleshooting+tissue+specificity+and+antibody+selection:+Procedures+in+immunohistochemical+studies.">Troubleshooting tissue specificity and antibody selection: Procedures in immunohistochemical studies.</a> J Pharmacol Toxicol Methods. 61, 127-135 (2009).</li><li>Krenacs, L., Krenacs, T., Stelkovics, E., Raffeld, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heat-induced+antigen+retrieval+for+immunohistochemical+reactions+in+routinely+processed+paraffin+sections.">Heat-induced antigen retrieval for immunohistochemical reactions in routinely processed paraffin sections.</a> Methods Mol Biol. , 588-5103 (2010).</li><li>Nones, J., Spohr, T. C., Furtado, D. R., Sartore, R. C., Paulsen, B. S., Guimar&#227;es, M. Z., Rehen, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cannabinoids+modulate+cell+survival+in+embryoid+bodies.">Cannabinoids modulate cell survival in embryoid bodies.</a> Cell Biol Int. 12, 399-408 (2010).</li><li>Huang, W. M., Gibson, S. J., Facer, P., Gu, J., Polak, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+section+adhesion+for+immunocytochemistry+using+high+molecular+weight+polymers+of+L-lysine+as+a+slide+coating.">Improved section adhesion for immunocytochemistry using high molecular weight polymers of L-lysine as a slide coating.</a> Histochemistry. 77, 275-279 (1983).</li><li>Kuenzi, M. J., Sherwood, O. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunohistochemical+localization+of+specific+relaxin-binding+cells+in+thecervix,+mammary+glands,+and+nipples+of+pregnant+rats.">Immunohistochemical localization of specific relaxin-binding cells in thecervix, mammary glands, and nipples of pregnant rats.</a> Endocrinology. 136, 1367-1373 (1995).</li></ol>

No conflicts of interest declared.

The method described here provides an easy-to-follow protocol to obtain PFA fixed thin cryostat sections of embryoid bodies useful for immunofluorescence and in situ hybridization assays. The resulting cryosections permit the study of cellular and molecular aspects of human embryonic stem cells differentiation, while preserving their structure and organization as aggregates.

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>D (+) Sucrose</td>
<td>Reagent</td>
<td>Vetec</td>
<td>228</td>
<td>&nbsp;</td>
<tr>
<td>Paraformaldehyde</td>
<td>Reagent</td>
<td>Rieden-de Ha&euml;n</td>
<td>16005</td>
<td>&nbsp;</td>
<tr>
<td>PBS solution</td>
<td>Reagent</td>
<td>LGC Biotecnology</td>
<td>13-30259.05</td>
<td>&nbsp;</td>
<tr>
<td>Poly-L-lysine hydrobromide</td>
<td>Reagent</td>
<td>Sigma</td>
<td>P2636</td>
<td>200mg/mL in water</td>
</tr>
<tr>
<td>Tissue-Tek O.C.T. Compound</td>
<td>Reagent</td>
<td>Sakura</td>
<td>P2636</td>
<td>&nbsp;</td>
<tr>
<td>Sucrose Solution</td>
<td>Reagent</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>10% Sucrose Solution in PBS w/v</td>
</tr>
<tr>
<td>Sucrose Solution</td>
<td>Reagent</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>20% Sucrose Solution in PBS w/v</td>
</tr>
<tr>
<td>Sucrose Solution</td>
<td>Reagent</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>30% Sucrose Solution in PBS w/v</td>
</tr>
<tr>
<td>Conic Tube</td>
<td>Tool</td>
<td>TPP</td>
<td>91015</td>
<td>15mL conic tube</td>
</tr>
<tr>
<td>Plate shaker</td>
<td>Tool</td>
<td>Biomixer</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Cryostat</td>
<td>Tool</td>
<td>Leica</td>
<td>CM 1850</td>
<td>&nbsp;</td>
<tr>
<td>Mold for OCT platform</td>
<td>Tool</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Plastic mold plataform</td>
</tr>		</tbody>
		</table>
		</div>

analysis of pluripotent stem cells by using cryosections of embryoid bodies

Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocyst-stage early mammalian embryos 1. A crucial stage in the differentiation of ES cells is the formation of embryoid bodies (EBs) aggregates 2, 3. EB formation is based on spontaneous aggregation when ES cells are cultured in non adherent plates. Three-dimensional EB recapitulates many aspects of early mammalian embryogenesis and differentiate into the three germ layers: ectoderm, mesoderm and endoderm 4.
Immunofluorescence and in situ hybridization are widely used techniques for the detection of target proteins and mRNA present in cells of a tissue section 5, 6, 7. Here we present a simple technique to generate high quality cryosections of embryoid bodies. This approach relies on the spatial orientation of EB embedding in OCT followed by the cryosection technique. The resulting sections can be subjected to a wide variety of analytical procedures in order to characterize populations of cells containing certain proteins, RNA or DNA. In this sense, the preparation of EB cryosections (10&mu;m) are essential tools for histology staining analysis (e.g. Hematoxilin and Eosin, DAPI), immunofluorescence (e.g. Oct4, nestin) or in situ hybridization. This technique can also help to understand aspects of embryogenesis with regards to the maintenance of the tri-dimensional spherical structure of EBs.

Watch this Scientific Journal Video about Analysis of Pluripotent Stem Cells by using Cryosections of Embryoid Bodies at JoVE.com

Analysis of Pluripotent Stem Cells by using Cryosections of Embryoid Bodies

Pluripotent stem cells growing in suspension differentiate into embryoid bodies (EBs). Here we demonstrate how to obtain high quality EB cryosections useful for studying cellular and molecular aspects of embryogenesis, while preserving their organization as aggregates.

Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocyst-stage early mammalian embryos 1. A crucial stage in the ...

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13.8K visualizações.  Universidade Federal do Rio de Janeiro (UFRJ), Brazil. Células-tronco pluripotentes de crescimento em suspensão se diferenciar em corpos embrióides (EBs). Aqui demonstramos como obter criosecções de alta qualidade EB útil para estudar os aspectos celulares e moleculares da embriogênese, preservando a sua organização como agregados.

Vídeo: Analysis of Pluripotent Stem Cells by using Cryosections of Embryoid Bodies

Shrinky-Dink Hanging Drops: A Simple Way to Form and Culture Embryoid Bodies

Embryoid bodies (EB) are aggregates of embryonic stem cells. The most common way of creating these aggregates is the hanging drop method, a laborious approach of pipetting an arbitrary number of cells into well plates. The interactions between the stem cells forced into close proximity of one another promotes the generation of the EBs. Because the media in each of the wells has to be manually exchanged every day, this approach is manually intensive.
Moreover, because environmental parameters including cell-cell, cell-soluble factor interactions, pH, and oxygen availability can be functions of EB size, cell populations obtained from traditional hanging drops can vary dramatically even when cultured under identical conditions. Recent studies have indeed shown that the initial number of cells forming the aggregate can have significant effects on stem cell differentiation. We have developed a simple, rapid, and scalable culture method to load pre-defined numbers of cells into microfabricated wells and maintain them for embryoid body development. Finally, these cells are easily accessible for further analysis and experimentation. This method is amenable to any lab and requires no dedicated equipment. We demonstrate this method by creating embryoid bodies using a red fluorescent mouse cell line (129S6B6-F1).

We show a simple and rapid method to load pre-defined numbers of cells into microfabricated wells and maintain them for embryoid body development.

Embryoid bodies (EB) are aggregates of embryonic stem cells. The most common way of creating these aggregates is the hanging drop method, a laborious ...

Generation of Induced Pluripotent Stem Cells by Reprogramming Human Fibroblasts with the Stemgent Human TF Lentivirus Set

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing the pluripotent state in mouse fibroblasts.1 The same group also reported the successful reprogramming of human somatic cells into induced pluripotent stem (iPS) cells using human versions of the same transcription factors delivered by retroviral vectors.2 Additionally, James Thomson et al. reported that the lentivirus-mediated co-expression of another set of factors (Oct4, Sox2, Nanog and Lin28) was capable of reprogramming human somatic cells into iPS cells.3
iPS cells are similar to ES cells in morphology, proliferation and the ability to differentiate into all tissue types of the body. Human iPS cells have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction. The generation of patient-specific iPS cells circumvents an important roadblock to personalized regenerative medicine therapies by eliminating the potential for immune rejection of non-autologous transplanted cells.
Here we demonstrate the protocol for reprogramming human fibroblast cells using the Stemgent Human TF Lentivirus Set. We also show that cells reprogrammed with this set begin to show iPS morphology four days post-transduction. Using the Stemolecule Y27632, we selected for iPS cells and observed correct morphology after three sequential rounds of colony picking and passaging. We also demonstrate that after reprogramming cells displayed the pluripotency marker AP, surface markers TRA-1-81, TRA-1-60, SSEA-4, and SSEA-3, and nuclear markers Oct4, Sox2 and Nanog.

We demonstrate the protocol for the generation of induced pluripotent stem cells from human somatic cells using lentivirus-mediated delivery of the human factors Oct4, Sox2, Nanog, and Lin28. Pluripotency was confirmed by morphology and the presence of embryonic stem (ES) cell-specific markers.

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing ...

Immunocytochemical Analysis of Human Pluripotent Stem Cells using a Self-Made Cytospin Apparatus

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.

Suspension immunocytochemical staining of human pluripotent stem cells (hPSCs) for cell-surface markers (SSEA-3/SSEA-4) was achieved based on use of a self-made cytospin apparatus to create a monolayer of cells for observation and quantification.

Human pluripotent stem cells (hPSCs) that include human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) are exciting cell ...

Transfecting and Nucleofecting Human Induced Pluripotent Stem Cells

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.

Despite recent advancements in genetic modification, transfection of human embryonic stem cells (HESCs) remains a capricious process. To our knowledge, systematic and efficient methods to transfect human induced pluripotent stem cells (iPSCs) have not been reported. Here, we describe robust protocols to efficiently transfect and nucleofect human iPSCs.

Genetic modification is continuing to be an essential tool in studying stem cell biology and in setting forth potential clinical applications of human ...

Reprogramming Human Somatic Cells into Induced Pluripotent Stem Cells (iPSCs) Using Retroviral Vector with GFP

Human embryonic stem cells (hESCs) are pluripotent and an invaluable cellular sources for in vitro disease modeling and regenerative medicine1. It has been previously shown that human somatic cells can be reprogrammed to pluripotency by ectopic expression of four transcription factors (Oct4, Sox2, Klf4 and Myc) and become induced pluripotent stem cells (iPSCs)2-4 . Like hESCs, human iPSCs are pluripotent and a potential source for autologous cells. Here we describe the protocol to reprogram human fibroblast cells with the four reprogramming factors cloned into GFP-containing retroviral backbone4. Using the following protocol, we generate human iPSCs in 3-4 weeks under human ESC culture condition. Human iPSC colonies closely resemble hESCs in morphology and display the loss of GFP fluorescence as a result of retroviral transgene silencing. iPSC colonies isolated mechanically under a fluorescence microscope behave in a similar fashion as hESCs. In these cells, we detect the expression of multiple pluripotency genes and surface markers.

Reprogramming Human Somatic Cells into Induced Pluripotent Stem Cells iPSCs Using Retroviral Vector with GFP

A method to generate human induced pluripotent stem cells (iPSCs) via retrovirus-mediated ectopic expression of OCT4, SOX2, KLF4 and MYC is described. A practical way to identify human iPSC colonies based on GFP expression is also discussed.

Human embryonic stem cells (hESCs) are pluripotent and an invaluable cellular sources for in vitro disease modeling and regenerative medicine1. It has ...

Generation of Mice Derived from Induced Pluripotent Stem Cells

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also produce a source of patient-matched cells for regenerative therapies. iPSCs may be generated using multiple protocols and derived from multiple cell sources. Once generated, iPSCs are tested using a variety of assays including immunostaining for pluripotency markers, generation of three germ layers in embryoid bodies and teratomas, comparisons of gene expression with embryonic stem cells (ESCs) and production of chimeric mice with or without germline contribution2. Importantly, iPSC lines that pass these tests still vary in their capacity to produce different differentiated cell types2. This has made it difficult to establish which iPSC derivation protocols, donor cell sources or selection methods are most useful for different applications.
The most stringent test of whether a stem cell line has sufficient developmental potential to generate all tissues required for survival of an organism (termed full pluripotency) is tetraploid embryo complementation (TEC)3-5. Technically, TEC involves electrofusion of two-cell embryos to generate tetraploid (4n) one-cell embryos that can be cultured in vitro to the blastocyst stage6. Diploid (2n) pluripotent stem cells (e.g. ESCs or iPSCs) are then injected into the blastocoel cavity of the tetraploid blastocyst and transferred to a recipient female for gestation (see Figure 1). The tetraploid component of the complemented embryo contributes almost exclusively to the extraembryonic tissues (placenta, yolk sac), whereas the diploid cells constitute the embryo proper, resulting in a fetus derived entirely from the injected stem cell line.
Recently, we reported the derivation of iPSC lines that reproducibly generate adult mice via TEC1. These iPSC lines give rise to viable pups with efficiencies of 5-13%, which is comparable to ESCs3,4,7 and higher than that reported for most other iPSC lines8-12. These reports show that direct reprogramming can produce fully pluripotent iPSCs that match ESCs in their developmental potential and efficiency of generating pups in TEC tests. At present, it is not clear what distinguishes between fully pluripotent iPSCs and less potent lines13-15. Nor is it clear which reprogramming methods will produce these lines with the highest efficiency. Here we describe one method that produces fully pluripotent iPSCs and "all- iPSC" mice, which may be helpful for investigators wishing to compare the pluripotency of iPSC lines or establish the equivalence of different reprogramming methods.

Generating induced pluripotent stem cell (iPSC) lines produces lines of differing developmental potential even when they pass standard tests for pluripotency. Here we describe a protocol to produce mice derived entirely from iPSCs, which defines the iPSC lines as possessing full pluripotency1.

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also ...

Generation of Human Induced Pluripotent Stem Cells from Peripheral Blood Using the STEMCCA Lentiviral Vector

Through the ectopic expression of four transcription factors, Oct4, Klf4, Sox2 and cMyc, human somatic cells can be converted to a pluripotent state, generating so-called induced pluripotent stem cells (iPSCs)1-4. Patient-specific iPSCs lack the ethical concerns that surround embryonic stem cells (ESCs) and would bypass possible immune rejection. Thus, iPSCs have attracted considerable attention for disease modeling studies, the screening of pharmacological compounds, and regenerative therapies5.
We have shown the generation of transgene-free human iPSCs from patients with different lung diseases using a single excisable polycistronic lentiviral Stem Cell Cassette (STEMCCA) encoding the Yamanaka factors6. These iPSC lines were generated from skin fibroblasts, the most common cell type used for reprogramming. Normally, obtaining fibroblasts requires a skin punch biopsy followed by expansion of the cells in culture for a few passages. Importantly, a number of groups have reported the reprogramming of human peripheral blood cells into iPSCs7-9. In one study, a Tet inducible version of the STEMCCA vector was employed9, which required the blood cells to be simultaneously infected with a constitutively active lentivirus encoding the reverse tetracycline transactivator. In contrast to fibroblasts, peripheral blood cells can be collected via minimally invasive procedures, greatly reducing the discomfort and distress of the patient. A simple and effective protocol for reprogramming blood cells using a constitutive single excisable vector may accelerate the application of iPSC technology by making it accessible to a broader research community. Furthermore, reprogramming of peripheral blood cells allows for the generation of iPSCs from individuals in which skin biopsies should be avoided (i.e. aberrant scarring) or due to pre-existing disease conditions preventing access to punch biopsies.
Here we demonstrate a protocol for the generation of human iPSCs from peripheral blood mononuclear cells (PBMCs) using a single floxed-excisable lentiviral vector constitutively expressing the 4 factors. Freshly collected or thawed PBMCs are expanded for 9 days as described10,11 in medium containing ascorbic acid, SCF, IGF-1, IL-3 and EPO before being transduced with the STEMCCA lentivirus. Cells are then plated onto MEFs and ESC-like colonies can be visualized two weeks after infection. Finally, selected clones are expanded and tested for the expression of the pluripotency markers SSEA-4, Tra-1-60 and Tra-1-81. This protocol is simple, robust and highly consistent, providing a reliable methodology for the generation of human iPSCs from readily accessible 4 ml of blood.

Here we show a simple and effective protocol for the generation of human iPSCs from 3-4 ml of peripheral blood using a single lentiviral reprogramming vector. Reprogramming of readily available blood cells promises to accelerate the utilization of iPSC technology by making it accessible to a broader research community.

Through the ectopic expression of four transcription factors, Oct4, Klf4, Sox2 and cMyc, human somatic cells can be converted to a pluripotent state, ...

Induction and Analysis of Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is essential for proper morphogenesis during development. Misregulation of this process has been implicated as a key event in fibrosis and the progression of carcinomas to a metastatic state. Understanding the processes that underlie EMT is imperative for the early diagnosis and clinical control of these disease states. Reliable induction of EMT in vitro is a useful tool for drug discovery as well as to identify common gene expression signatures for diagnostic purposes. Here we demonstrate a straightforward method for the induction of EMT in a variety of cell types. Methods for the analysis of cells pre- and post-EMT induction by immunocytochemistry are also included. Additionally, we demonstrate the effectiveness of this method through antibody-based array analysis and migration/invasion assays.

A straightforward method is described for the induction of epithelial to mesenchymal transition (EMT) in a variety of cell types. Methods for the analysis of cells in EMT states by immunocytochemistry are included.

Epithelial  to mesenchymal transition (EMT) is essential for proper morphogenesis during  development. Misregulation of this  process has been implicated ...

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) maintain the turnover of all mature blood cell lineages. The coordination of the complex signals leading to specific HSC fates relies upon the interaction between HSCs and the intricate bone marrow microenvironment, which is still poorly understood[1-2].
We describe how by combining a newly developed specimen holder for stable animal positioning with multi-step confocal and two-photon in vivo imaging techniques, it is possible to obtain high-resolution 3D stacks containing HSPCs and their surrounding niches and to monitor them over time through multi-point time-lapse imaging. High definition imaging allows detecting ex vivo labeled hematopoietic stem and progenitor cells (HSPCs) residing within the bone marrow. Moreover, multi-point time-lapse 3D imaging, obtained with faster acquisition settings, provides accurate information about HSPC movement and the reciprocal interactions between HSPCs and stroma cells.
Tracking of HSPCs in relation to GFP positive osteoblastic cells is shown as an exemplary application of this method. This technique can be utilized to track any appropriately labeled hematopoietic or stromal cell of interest within the mouse calvarium bone marrow space.

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

The nature of the interactions between hematopoietic stem and progenitor cells (HSPCs) and bone marrow niches is poorly understood. Custom hardware modifications and a multi-step acquisition protocol allow the use of two-photon and confocal microscopy to image ex vivo labeled HSPCs homed within bone marrow areas, tracking interactions and movement.

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) ...

High Efficiency Differentiation of Human Pluripotent Stem Cells to Cardiomyocytes and Characterization by Flow Cytometry

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 &#8220;in a dish&#8221; 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.

The article describes the detailed methodology to efficiently differentiate human pluripotent stem cells into cardiomyocytes by selectively modulating the Wnt pathway, followed by flow cytometry analysis of reference markers to assess homogeneity and identity of the population.

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 ...