Differentiation of Embryonic Stem Cells
<ol>
<li>Collect a near confluent flask of embryonic stem cells (ESC) via treatment with ESC trypsin.</li>
<li>Resuspend cells in 5 mL of Differentiation media and transfer to a non-gelatin coated T25. Incubate at 37&deg;C for 45 minutes. Retrieve supernatant and collect cells via centrifugation. Note: Mouse embryonic fibroblasts (MEFs) from the ESC cultures attach readily to the non-gelatin coated T25 and thus are depleted from the culture during this plating step. If you are not culturing your ESC on MEFs, you can skip the pre-plate. </li>
<li>Resuspend MEF-depleted ESC in Differentiation media at 333,333 cells/50 mL. This concentration results in 100 ESC/15 mL.</li>
<li>Using multi-channel pipettor, plate ESC at 100 cells/15 mL drop on 15 cm2 petri plates. With an 8-channel pipettor, you should be able to fit about 18-22 rows of drops per plate (about 5ml per plate). Note:For this protocol, 2-5 15 cm2 dishes of drops will be more than sufficient and should yield 2-5 x 106 day six EB-derived cells. </li>
<li>Gently flip plates to invert drops. Incubate at 37&deg;C 5% CO2 for 48 hours.</li>
<li>Pool drops by gently swirling plates and transfer to 15 mL conical tube. Rinse plates with 4-6 mL of PBS and add to same 15 mL conical. Note: You may pool up to five hanging drop plates. The EBs will grow as they continue to differentiate and if they are too concentrated they tend to form large clumps. </li>
<li>Allow pooled EBs to settle by gravity (about 10 minutes). Aspirate supernatant without disturbing EBs. Gently resuspend in 10 mL Differentiation media and transfer to 10 cm non-adherent petri plate.</li>
<li>Place petri plate on plate shaker at 50 rpm and incubate at 37&deg;C 5% CO2.</li>
<li>24 hours later (day four of differentiation), swirl plates to concentrate EBs in center of petri dish. Carefully exchange 50% of media (5 mL) with 5 mL fresh Differentiation Media. Return plate to incubator for two more days.</li>
</ol>
EB dissociation and infection with MSCV-HoxB4-IRES-GFP
<ol>
<li>On day six of differentiation, transfer EBs to 15 mL conical tube. Allow to settle by gravity.</li>
<li>Aspirate media and resuspend in 10 mL PBS. Allow EBs to resettle by gravity. Aspirate PBS.</li>
<li>Add 250 mL dissociation enzyme mix and 1 mL PBS. Incubate in 37&deg;C water bath for 20 minutes, occasionally swirling tube to mix enzymes and EBs.</li>
<li>Add 8 mL enzyme-free dissociation buffer.</li>
<li>Triturate mixture using 5 mL pipette until EBs are fully dissociated (about 10 times; excessive pipetting will increase death within the EB-derived cell preparation). <ol>
<li>Mixture will become cloudy with cells as EBs dissociate.</li>
<li>Placing pipette tip against bottom of conical tube during trituration will create a shear force that will greatly facilitate dissociation.</li>
</ol></li>
<li>Collect cells via centrifugation.</li>
<li>Resuspend EB-derived cells in 5 mL of 10% IMDM and count using trypan blue exclusion Note: Between day four and day six of differentiation, EBs cavitate which results in a large amount of apoptosis and cell death.Thus, at day six, upwards of 30% of EB-derived cells may stain with trypan blue. </li>
<li>Resuspend EB-derived cells at 100,000 cells/2 mL of 10% IMDM+viral supernatant such that an MOI of 5-10 is achieved.Add protamine sulfate to a final concentration of 8 mg/mL. Note: Prepare enough EB/viral supernatant mix to plate four 6-well plates (assuming 2 mL/well). </li>
<li>Plate 2 mL EB/viral supernatant mix per well of four 6 well plates pre-plated with OP9 stroma cells (see below).</li>
<li>Centrifuge plates at 2500 rpm at room temperature for 90 minutes. Transfer plates to incubator at 37&deg;C 5% CO2.</li>
<li>4-6 hours later, harvest supernatant from plates and collect any potential cells remaining in suspension via centrifugation.</li>
<li>Resuspend pellet (may be small) in 48 mL 10% IMDM+cytokines. Dispense 2 mL/well of resuspension to original four 6-well plates in which infection was performed and supernatant was collected. Note: Always prepare 10% IMDM+cytokines fresh at time of use. </li>
<li>Incubate plates at 37&deg;C 5% CO2 for seven days. Colonies should be apparent by day four post infection and large and well-formed by day seven. A robust expansion should yield 40-60 colonies/well on day seven.</li>
<li>On day seven post-infection, collect and pool all cells (including OP9 stroma) from all wells by treatment with trypsin. Note: DO NOT discard supernatant or PBS washes employed during trypsin treatment.At this point in the culture, some colonies may be only loosely adherent and there are many cells floating in suspension.Collect and pool all washes and supernatant to ensure that no potentially valuable cells are discarded. </li>
<li>Resuspend cells in 8 mL fresh 10% IMDM+cytokines. Distribute 2 mLs/flask into four T75 flasks. Add an additional 13 mLs 10% IMDM+cytokines to each flask. Incubate at 37&deg;C 5% CO2 for three days (a total of ten days post infection).</li>
</ol>
&nbsp;
Culture and plating of OP9 stroma
<ol>
<li>Maintain OP9 stroma according to standard protocols in 20% a-MEM. OP9 cells will change properties when grown to confluency. Always split at 80% confluency at no more than 1:3 split.</li>
<li>24 hours prior to infection of day six EB-derived cells with MSCV-HoxB4-IRES-GFP, plate 25,000 OP9 cells/well of four 6-well plates in 20% a-MEM.</li>
</ol>
Collection, fractionation and transplantation
<ol>
<li>Collect cells expanded on OP9 stroma for ten days via treatment with trypsin. Count cells. Note: DO NOT discard supernatant or PBS washes employed during trypsin treatment. At this point in the culture, some colonies may be only loosely adherent and there are many cells floating in suspension.Collect and pool all washes and supernatant to ensure that no potentially valuable cells are discarded. Note: A good expansion should yield between 40-50 x 106 cells/original 6-well plate infected, for a total of 160-200 x 106 cells. </li>
<li>Cells may be fractionated via magnetic bead selection or FACS according to standard techniques at this point in the protocol.</li>
<li>For transplantation, deliver cells via retro-orbital or tail vein injection to Rag-2/gc deficient recipients (weighing between 15-22 grams) subjected to a split dose of 9.25 gy of irradiation 2.5 hrs. apart. Note: It is CRITICAL that the weight of the animals fall between 15-22 grams at time of irradiation. If they are larger than 22 grams, 9.25 gy will not be a sufficient dose of irradiation to ensure the appropriate ablation and cells may not mediate rescue from lethal irradiation and/or engraft the hematopoietic compartment. If transplanting larger animals, the appropriate irradiation dose must be determined experimentally. </li>
<li>A minimum dose of 2-5 x 106 cells/animal is required to guarantee rescue from lethal irradiation. If fractionating cells, inject 2-5 x 106 cell equivalents (e.g. if population of interest represents 10% of unfractionated pool of cells, inject 2-5 x 105 cells/animal). Note: If injecting &gt;2 x 106 cells, ALWAYS inject via tail vein to avoid teratoma formation in orbit, which may result when high numbers of cells are delivered retro-orbitally. </li>
<li>Maintain Rag-2-/-/gc-/- deficient recipients in autoclaved cages. Depending on the &ldquo;cleanliness&rdquo; of the animal facility, post-transplant animals may require administration of acidified water or Trimethiprim-Sulfasoxazole (Septra) for the 5 weeks following lethal radiation. </li>
<li>Expect &gt;90% GFP+ ES-derived leukocytes in peripheral blood at 3 weeks post-transplant. Engraftment should be multi-lineage, although lymphocytes are known to silence retroviral HoxB4-IRES-GFP. </li>
</ol>

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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>C57Bl/6 Rag-2/gamma-c deficient mice</td>
<td>Animal</td>
<td>Taconic Farm</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Plate shaker</td>
<td>Tool</td>
<td>VWR</td>
<td>33998-360</td>
<td>Orbital Shaker by Ikaworks</td>
</tr>
<tr>
<td>Multi-channel pipettor</td>
<td>Tool</td>
<td>VWR</td>
<td>15000-174</td>
<td>ePet by BioHit</td>
</tr>
<tr>
<td>ES trypsin</td>
<td>Reagent</td>
<td>Invitrogen</td>
<td>15090-046</td>
<td>0.25% Trypsin in PBS</td>
</tr>
<tr>
<td>Standard trypsin</td>
<td>Reagent</td>
<td>Invtrogen</td>
<td>25300-062</td>
<td>0.05% Trypsin-EDTA</td>
</tr>
<tr>
<td>PBS</td>
<td>Buffer</td>
<td>Invitrogen</td>
<td>20012-027</td>
<td>&nbsp;</td>
<tr>
<td>Enzyme-free dissociation buffer</td>
<td>Buffer</td>
<td>Invitrogen</td>
<td>13151-014</td>
<td>&nbsp;</td>
<tr>
<td>Dissociation enzyme mix</td>
<td>Buffer</td>
<td>Invitrogen</td>
<td>17104-019</td>
<td>500 mg Collagenase IV</td>
</tr>
<tr>
<td>Hyaluronidase</td>
<td>Reagent</td>
<td>Sigma</td>
<td>H2126</td>
<td>freeze in 500 uL aliquots and avoid repeated freezing and thawing.</td>
</tr>
<tr>
<td>DNAse</td>
<td>Reagent</td>
<td>Sigma</td>
<td>D4527</td>
<td>&nbsp;</td>
<tr>
<td>DMEM</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>10-017CV</td>
<td>&nbsp;</td>
<tr>
<td>Protamine sulfate</td>
<td>Reagent</td>
<td>Sigma</td>
<td>P3369</td>
<td>8 ug/mL</td>
</tr>
<tr>
<td>EB differentiation media</td>
<td>medium</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Please view recipe on attached Protocol.doc</td>
</tr>
<tr>
<td>10% IMDM</td>
<td>medium</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Please view recipe on attached Protocol.doc</td>
</tr>
<tr>
<td>10% IMDM+cytokines</td>
<td>medium</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Please view recipe on attached Protocol.doc</td>
</tr>
<tr>
<td>20% anti-MEM</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Please view recipe on attached Protocol.doc</td>
</tr>		</tbody>
		</table>
		</div>

derivation of hematopoietic stem cells from murine embryonic stem cells

A stem cell is defined as a cell with the capacity to both self-renew and generate multiple differentiated progeny.  Embryonic stem cells (ESC) are derived from the blastocyst of the early embryo and are pluripotent in differentiative ability.  Their vast differentiative potential has made them the focus of much research centered on deducing how to coax them to generate clinically useful cell types.  The successful derivation of hematopoietic stem cells (HSC) from mouse ESC has recently been accomplished and can be visualized in this video protocol.  HSC, arguably the most clinically exploited cell population, are used to treat a myriad of hematopoietic malignancies and disorders.  However, many patients that might benefit from HSC therapy lack access to suitable donors.  ESC could provide an alternative source of HSC for these patients.  The following protocol establishes a baseline from which ESC-HSC can be studied and inform efforts to isolate HSC from human ESC.  In this protocol, ESC are differentiated as embryoid bodies (EBs) for 6 days in commercially available serum pre-screened for optimal hematopoietic differentiation.  EBs are then dissociated and infected with retroviral HoxB4.  Infected EB-derived cells are plated on OP9 stroma, a bone marrow stromal cell line derived from the calvaria of  M-CSF-/- mice, and co-cultured in the presence of hematopoiesis promoting cytokines for ten days.  During this co-culture, the infected cells expand greatly, resulting in the generation a heterogeneous pool of 100s of millions of cells.  These cells can then be used to rescue and reconstitute lethally irradiated mice.

Watch this Scientific Journal Video about Derivation of Hematopoietic Stem Cells from Murine Embryonic Stem Cells at JoVE.com

Derivation of Hematopoietic Stem Cells from Murine Embryonic Stem Cells

This protocol details the derivation of transplantable hematopoietic stem cells from mouse embryonic stem cells (ESC) and their subsequent injection into lethally irradiated recipient mice. Briefly, ESC are differentiated as embryoid bodies, which are then infected with retroviral HoxB4 and co-cultured with OP9 stromal cells and hematopoietic cytokines.

A stem cell is defined as a cell with the capacity to both self-renew and generate multiple differentiated progeny.  Embryonic stem cells (ESC) are ...

derivation-hematopoietic-stem-cells-from-murine-embryonic-stem

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JoVE Journal

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13.2K Views.  Harvard Medical School. This protocol details the derivation of transplantable hematopoietic stem cells from mouse embryonic stem cells (ESC) and their subsequent injection into lethally irradiated recipient mice. Briefly, ESC are differentiated as embryoid bodies, which are then infected with retroviral HoxB4 and co-cultured with OP9 stromal cells and hematopoietic cytokines.

Video: Derivation of Hematopoietic Stem Cells from Murine Embryonic Stem Cells

Propagation of Human Embryonic Stem (ES) Cells

Propagation of Human Embryonic Stem ES Cells

Rozprzestrzenianie się człowieka zarodkowych komórek macierzystych (ES) Cells

Isolation and Transplantation of Hematopoietic Stem Cells (HSCs)

Isolation and Transplantation of Hematopoietic Stem Cells HSCs

Derivation of Human Embryonic Stem Cells by Immunosurgery

The ability of human embryonic stem cells to self-renew and differentiate into all cell types of 
the body suggests that they hold great promise for both medical applications and as a research 
tool for addressing fundamental questions in development and disease. Here, we provide a 
concise, step-by-step protocol for the derivation of human embryonic stem cells from embryos 
by immunosurgical isolation of the inner cell mass. 


The ability of human embryonic stem cells to self-renew and differentiate into all cell types of 
the body suggests that they hold great promise for both medical applications and as a research 
tool for addressing fundamental questions in development and disease. Here, we provide a 
concise, step-by-step protocol for the derivation of human embryonic stem cells from embryos 
by immunosurgical isolation of the inner cell mass.

The ability of human embryonic stem cells to self-renew and differentiate into all cell types of 
the body suggests that they hold great promise for both ...

Isolation and Analysis of Hematopoietic Stem Cells from the Placenta

Hematopoietic stem cells (HSCs) have the ability to self-renew and generate all cell types of the blood lineages throughout the lifetime of an individual. All HSCs emerge during embryonic development, after which their pool size is maintained by self-renewing cell divisions. Identifying the anatomical origin of HSCs and the critical developmental events regulating the process of HSC development has been complicated as many anatomical sites participate during fetal hematopoiesis. Recently, we identified the placenta as a major hematopoietic organ where HSCs are generated and expanded in unique microenvironmental niches (Gekas, et al 2005, Rhodes, et al 2008). Consequently, the placenta is an important source of HSCs during their emergence and initial expansion.
In this article, we show dissection techniques for the isolation of murine placenta from E10.5 and E12.5 embryos, corresponding to the developmental stages of initiation of HSCs and the peak in the size of the HSC pool in the placenta, respectively. In addition, we present an optimized protocol for enzymatic and mechanical dissociation of placental tissue into single-cell suspension for use in flow cytometry or functional assays. We have found that use of collagenase for single-cell suspension of placenta gives sufficient yields of HSCs. An important factor affecting HSC yield from the placenta is the degree of mechanical dissociation prior to, and duration of, enzymatic treatment.
We also provide a protocol for the preparation of fixed-frozen placental tissue sections for the visualization of developing HSCs by immunohistochemistry in their precise cellular niches. As hematopoietic specific antigens are not preserved during preparation of paraffin embedded sections, we routinely use fixed frozen sections for localizing placental HSCs and progenitors.

We have identified the placenta as a major hematopoietic organ during development. We found that hematopoietic stem cells (HSCs) are both generated and expanded in the placenta in unique microenvironmental niches. Here, we describe experimental techniques required for isolation and visualization of HSCs in the mouse placenta.

Hematopoietic stem cells (HSCs) have the ability to self-renew and generate all cell types of the blood lineages throughout the lifetime of an individual. ...

Chromatin Immunoprecipitation from Human Embryonic Stem Cells

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are characterized by two fundamental properties: self-renewal and multipotency that allows a stem cell to differentiate into virtually any cell type 1. The progression stem cell to differentiated cell is characterized by loss of multipotency, structural and morphological changes and the hierarchic activity of transcription factors and signaling molecules, whose activities establish and maintain cell-type specific gene expression patterns. At the molecular level, cell differentiation involves dynamic changes of the structure and composition of chromatin and the detection of those dynamic changes can provide valuable insights into the functional features of stem cells and the cell differentiation process 2,3. Chromatin is a highly compacted DNA-protein complex that forms when cells package chromosomal DNA with proteins, mainly histones 4. Stemcellness and cell differentiation has been correlated with the presence of specific arrays of regulatory proteins such as epigenetic factors, histone variants, and transcription factors 2,3,5.
 Chromatin immunoprecipitation (ChIP) provides a valuable method to monitor the presence of RNA, proteins, and protein modifications in chromatin 6,7. The comparison of chromatin from different cell types can elucidate dynamic changes in protein-chromatin associations that occur during cell differentiation.
Chromatin immunoprecipitation involves the purification of in vivo cross-linked chromatin. The isolated chromatin is reduced to smaller fragments by enzymatic digestion or mechanical force. Chromatin fragments are precipitated using specific antibodies to target proteins or protein and DNA modifications. The precipitated DNA or RNA is purified and used as a template for PCR or DNA microarray based assays. Prerequisites for a successful ChIP are high quality antibodies to the desired antigen and the availability of chromatin from control cells that do not express the target molecule. ChIP can correlate the presence of proteins, protein and RNA modifications, and RNA with specific target DNA, and depending on the choice of outread tool, detects the association of target molecules at specific target genes or in the context of an entire genome. The comparison of the distribution of proteins in the chromatin of differentiating cells can elucidate the dynamic changes of chromatin composition that coincide with the progression of cells along a cell lineage.

The differentiation of ESC coincides with cell-type specific changes in the structure and composition of chromatin. The detection of those changes provides valuable insights into the mechanisms that define stemcellness and cell differentiation. Chromatin immunoprecipitation (ChIP) represents a valuable method to dissect the molecular mechanisms underlying stem cell differentiation.

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are ...

Isolation of Early Hematopoietic Stem Cells from Murine Yolk Sac and AGM

In the mouse embryo, early hematopoiesis occurs simultaneously in multiple organs, which includes the yolk sac and aorta-gonad-mesonephros region. These regions are crucial in establishing the blood system in the embryos and leads to the eventual movement of stem cells into the fetal liver and then development of adult stem cells in the bonemarrow. Early hematopoietic stem cells can be isolated from these organs through microdissection of the embryo followed by flow cytometric sorting to obtain a more pure population. It remains unclear how these stem cell populations contribute to the fetal and adult stem cell pool.   Also, our lab investigates how early stem cells functionally differ from fetal and adult hematopoietic stem cells. Furthermore, our lab sorts different populations of hematopoietic stem cells and test their functional role in the context of a variety of genetic models. In this video, we demonstrate the micro-dissection procedure we commonly use and also show the results of a typical FACS plotfter isolating these rare populations, it is possible to perform a variety of functional assays including: colony assays and bone marrow transplants. 



This video shows how to micro-dissect the yolk sac and aorta-gonad-mesonephros region from embryos and use flow cytometry to sort hematopoietic stem cells.

In the mouse embryo, early hematopoiesis occurs simultaneously in multiple organs, which includes the yolk sac and aorta-gonad-mesonephros region. These ...

Isolation and Derivation of Mouse Embryonic Germinal Cells

The ability of embryonic germinal cells (EG) to differentiate into primordial germinal cells (PGCs) and later into gametes during early developmental stages is a perfect model to address our hypothesis about cancer and infertility. This protocol shows how to isolate primordial germinal cells from developing gonads in 10.5-11.5 days post coitum (dpc) mouse embryos.  Developing gonadal ridges from mouse embryos (C57BL6J) were dissociated by mechanical disruption with collagenase, then plated in a mouse embryo fibroblast feeder layer (MEF-CF1) that was previously mitotically inactivated with mitomycin C in the presence of knockout media and supplemented with Leukemia Inhibitor Factor (LIF), basic Fibroblast Growth Factor (bFGF), and Stem Cell Factor (SCF).  Using these optimized methods for PCG identification, isolation, and establishment of culture conditions permits long term cultures of EG cells for more than 40 days.  The embryonic germinal cell lines showed embryonic phenotype and expression of common used markers of the pluripotent state.  Isolation and derivation of germinal cells in culture provide a tool to understand their development in vitro and offer the opportunity to monitor cumulative damage at genetic and epigenetic levels after exposure to oxidative stress.

The ability of embryonic germinal cells to differentiate into primordial germinal cells during early development stages is a perfect model to address our hypothesis about cancer and infertility. This protocol shows how to isolate primordial germinal cells from developing gonads in 10.5-11.5 days post coitum mouse embryos.

The ability of embryonic germinal cells (EG) to differentiate into primordial germinal cells (PGCs) and later into gametes during early developmental ...

Derivation of Mouse Trophoblast Stem Cells from Blastocysts

Specification of the trophectoderm is one of the earliest differentiation events of mammalian development. The trophoblast lineage derived from the trophectoderm mediates implantation and generates the fetal part of the placenta. As a result, the development of this lineage is essential for embryo survival. Derivation of trophoblast stem (TS) cells from mouse blastocysts was first described by Tanaka et al. 1998. The ability of TS cells to preserve the trophoblast specific property and their expression of stage- and cell type-specific markers after proper stimulation provides a valuable model system to investigate trophoblast lineage development whereby recapitulating early placentation events. Furthermore, trophoblast cells are one of the few somatic cell types undergoing natural genome amplification. Although the molecular pathways underlying trophoblast polyploidization have begun to unravel, the physiological role and advantage of trophoblast genome amplification remains largely elusive. The development of diploid stem cells into polyploid trophoblast cells in culture makes this ex vivo system an excellent tool for elucidating the regulatory mechanism of genome replication and instability in health and disease. Here we describe a protocol based on previous reports with modification published in Chiu et al. 2008.

In this video, we demonstrate the isolation of mouse blastocysts and the derivation of trophoblast stem cells from blastocysts. We also describe conditions for maintenance of the stem cell property as well as induction of differentiation in culture.

Specification of the trophectoderm is one of the earliest differentiation events of mammalian development. The trophoblast lineage derived from the ...

Efficient Derivation of Human Cardiac Precursors and Cardiomyocytes from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based transplantation or by cardiac tissue engineering1-3. Cardiomyocytes become terminally-differentiated soon after birth and lose their ability to proliferate. There is no evidence that stem/progenitor cells derived from other sources, such as the bone marrow or the cord blood, are able to give rise to the contractile heart muscle cells following transplantation into the heart1-3. The need to regenerate or repair the damaged heart muscle has not been met by adult stem cell therapy, either endogenous or via cell delivery1-3. The genetically stable human embryonic stem cells (hESCs) have unlimited expansion ability and unrestricted plasticity, proffering a pluripotent reservoir for in vitro derivation of large supplies of human somatic cells that are restricted to the lineage in need of repair and regeneration4,5. Due to the prevalence of cardiovascular disease worldwide and acute shortage of donor organs, there is intense interest in developing hESC-based therapies as an alternative approach. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity6-8 (see a schematic in Fig. 1A). In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic9-11. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules12 (see a schematic in Fig. 1B). After screening a variety of small molecules and growth factors, we found that such defined conditions rendered nicotinamide (NAM) sufficient to induce the specification of cardiomesoderm direct from pluripotent hESCs that further progressed to cardioblasts that generated human beating cardiomyocytes with high efficiency (Fig. 2). We defined conditions for induction of cardioblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human cardiac cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of cardioblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human cardiac progenitors and functional cardiomyocytes for cardiovascular repair.

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based ...

Phenotypic Analysis and Isolation of Murine Hematopoietic Stem Cells and Lineage-committed Progenitors

The bone marrow is the principal site where HSCs and more mature blood cells lineage progenitors reside and differentiate in an adult organism. HSCs constitute a minute cell population of pluripotent cells capable of generating all blood cell lineages for a life-time1. The molecular dissection of HSCs homeostasis in the bone marrow has important implications in hematopoiesis, oncology and regenerative medicine. We describe the labeling protocol with fluorescent antibodies and the electronic gating procedure in flow cytometry to score hematopoietic progenitor subsets and HSCs distribution in individual mice (Fig. 1). In addition, we describe a method to extensively enrich hematopoietic progenitors as well as long-term (LT) and short term (ST) reconstituting HSCs from pooled bone marrow cell suspensions by magnetic enrichment of cells expressing c-Kit. The resulting cell preparation can be used to sort selected subsets for in vitro and in vivo functional studies (Fig. 2).
Both trabecular osteoblasts2,3 and sinusoidal endothelium4 constitute functional niches supporting HSCs in the bone marrow. Several mechanisms in the osteoblastic niche, including a subset of N-cadherin+ osteoblasts3 and interaction of the receptor tyrosine kinase Tie2 expressed in HSCs with its ligand angiopoietin-15 concur in determining HSCs quiescence. "Hibernation" in the bone marrow is crucial to protect HSCs from replication and eventual exhaustion upon excessive cycling activity6. Exogenous stimuli acting on cells of the innate immune system such as Toll-like receptor ligands7 and interferon-&alpha;6 can also induce proliferation and differentiation of HSCs into lineage committed progenitors. Recently, a population of dormant mouse HSCs within the lin- c-Kit+ Sca-1+ CD150+ CD48- CD34- population has been described8. Sorting of cells based on CD34 expression from the hematopoietic progenitors-enriched cell suspension as described here allows the isolation of both quiescent self-renewing LT-HSCs and ST-HSCs9. A similar procedure based on depletion of lineage positive cells and sorting of LT-HSC with CD48 and Flk2 antibodies has been previously described10. In the present report we provide a protocol for the phenotypic characterization and ex vivo cell cycle analysis of hematopoietic progenitors, which can be useful for monitoring hematopoiesis in different physiological and pathological conditions. Moreover, we describe a FACS sorting procedure for HSCs, which can be used to define factors and mechanisms regulating their self-renewal, expansion and differentiation in cell biology and signal transduction assays as well as for transplantation.

A method to analyse the distribution of bone marrow hematopoietic progenitors in flow cytometry as well as to efficiently isolate highly purified hematopoietic stem cells (HSCs) is described. The isolation procedure is essentially based on magnetic enrichment of c-Kit+ cells and cell sorting to purify HSCs for cellular and molecular studies.

The bone marrow is the principal site where HSCs and more mature blood cells lineage progenitors reside and differentiate in an adult organism. HSCs ...