1. Embryo removal and placental dissection
<ol>
<li>To begin, embryos must first be isolated from pregnant dams. </li>
<li>Animals are euthanized according to approved procedures &ndash; in our case we are going to use a lethal dose of the anaesthetic isoflurane</li>
<li>First, spray the belly with ethanol and make a small incision with a pair of scissors.</li>
<li>Tear away the skin with both hands to uncover the abdomen and cut open the peritoneum. </li>
<li>With forceps, pick up the uterine horns and collect them using scissors at each distal end. Place the uterine horns in a petri dish filled with PBS and place on ice. Also, remember to wash several times with PBS before isolating the placenta. We can now isolate the placenta.</li>
<li>With two forceps, begin carefully peeling away the endometrial tissue surrounding the embryo conceptuses. One should be careful not to puncture or otherwise inflict structural damage to the embryos, as this will complicate subsequent dissection steps.</li>
<li>Place the isolated conceptuses in a new petri dish with PBS on ice and continue until all conceptuses have been freed from the endometrium.</li>
<li>Transfer one conceptus to a new petri dish with PBS placed under the microscope and with two forceps peel the decidua away from the placenta. Remove as much of the decidua as possible as decidua cells will interfere with single-cell suspension and flow cytometry. A smooth continuous peeling motion is recommended to achieve the best results.</li>
<li>Cut the yolk sac away from the placenta at the junction between the two organs and gently pull the yolk sac and vitelline vessels away from the placenta. Care should be taken not to disrupt the chorionic plate of the placenta, especially with early embryos.</li>
<li>Carefully holding the chorionic plate of the placenta with one pair of forceps and the umbilical cord with another, pull the umbilical cord and attached embryo away from the placenta. </li>
<li>Remove excess giant cell tissue at the edges of the placenta in order to minimize cell clumping during preparation of single-cell suspension.</li>
<li>Collect the placenta in a suitable container, such as a 15-ml Falcon tube, with PBS+5%FCS and on ice. Do this for all placentas dissected.</li>
<li>At this point, you can either proceed with the preparation of a single-cell suspension for flow cytometry, functional assays, such as in vitro culture or transplantation, or prepare whole placenta for tissue fixation and fixed frozen block embedding for eventual immunohistochemistry. </li>
</ol>
2. Preparation of single-cell suspension of placenta tissue
<ol>
<li>We will now show you how to generate a single cell suspension from placenta for FACS analysis.</li>
<li>To prepare a single cell suspension from placenta, mechanical and enzymatic dissociation is required. First prepare a 0.1% Collagenase solution in PBS with 10% FCS and 1% Penicillin/Streptomycin solution.</li>
<li>Add an appropriate volume of collagenase solution to the placentas, depending on how many you have. A volume that is twice the placenta volume and between 2-5ml is recommended.</li>
<li>Use a 16-G needle fitted on a 5-ml syringe to mechanically disrupt the tissue by passaging the collagenase solution and placenta through the needle 3 times. Repeat with an 18-G needle.</li>
<li>Place the sample in a 37&deg;C, 5% CO2 incubator for 45 minutes.</li>
<li>After the 45 minute incubation in collagenase, passage the cell solution through a 20-G needle, and incubate for an additional 45 minutes, in 37&deg;C.</li>
<li>After the 1.5 hr total incubation in collagenase, passage the cell solution through 22-G and 25-G needles 3 times with each needle. </li>
<li>Filter the sample through a 50-&micro;m filter attached to a new 15-ml Falcon tube, wash with PBS+5%FCS and centrifuge at 4&deg;C for 5 minutes at 300 &times; g.</li>
<li>At this point, we have a single cell suspension suitable for FACS analysis or functional assays. </li>
</ol>
 3. Tissue Fixation for Frozen Sections
<ol>
<li>Immediately after isolating the placenta from each embryo, they are placed in cold 1X PBS. Usually a 96-well plate works best for young placentas (E8.5-11.5), but with older placentas, E12.5 and older, a 24-well plate may be more convenient. </li>
<li>Each placenta is transferred into a new well filled with freshly thawed 4% paraformaldahyde or PFA. For the E12.5 placentas, the tissue is moved to a new well by hand, but for the E10.5 you can remove the PBS carefully with a pipette and add the PFA. It is important that the placenta is fully immersed for 2-4 hours at 4&deg;C, depending on the age and size of the tissue.</li>
<li>Transfer the tissue into 30% sucrose, or if the tissues are very small and fragile, aspirate the PFA and add the sucrose directly. At this stage, the placentas will be floating in solution. Let the tissues stay overnight at 4&deg;C.</li>
<li>After the overnight step in 30% sucrose, the tissues should ultimately sink to the bottom of the well, indicative of proper cryopreservation. Remove half of the sucrose solution and replace the volume with OCT and place the tissue back in 4&deg;C for 1-2 hours. This facilitates OCT penetration.</li>
<li>Transfer the tissue to 100% OCT for 1 hour, after which it can be embedded. </li>
</ol>
4. Embedding the Fixed Tissue
<ol>
<li>Label plastic molds with appropriate tissue identification (show example mold).</li>
<li>Pull the tissue out of the OCT solution and cut the placenta in half by orienting the disc-shaped placenta with the umbilical cord side facing down and carefully slicing with a clean razor blade making sure to move the blade back and forth before releasing pressure to ensure an even cut. The placenta is cut in half to achieve the best prientation to later visualize the placental HSCs.</li>
<li>Place one placenta half at the bottom of the mold with the cut edge in contact with the bottom surface of the mold. Repeat with a new mold for the other half. For E10.5 placentas, both halves may be placed into the same mold using the same technique.</li>
<li>When pouring OCT into the mold, it can be difficult to keep the placentas in the proper orientation. Secure the placenta in place by holding the tissue half with forceps. Slowly pour OCT solution into the mold and avoid producing any bubbles. For E10.5 placentas, hold one tissue half by forceps and rest the other tissue half against the outside of the forceps. Slowly pour OCT solution as described for E12.5 placentas. </li>
<li>Once the mold is filled with OCT, quickly place the mold onto dry ice, the OCT will turn white flash freezing the tissue</li>
<li>Place the mold into a small plastic bag containing Drierite and immediately store in the -80&deg;C freezer.</li>
</ol>

<ol>
	<li>Gekas, C., Dieterlen-Lievre, F., Orkin, S. H., Mikkola, H. K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+placenta+is+a+niche+for+hematopoietic+stem+cells.">The placenta is a niche for hematopoietic stem cells.</a> Dev Cell. 8, 365-375 (2005).</li><li>Rhodes, K. E., Gekas, C., Wang, Y., Lux, C. T., Francis, C. S., Chan, D. N., Conway, S., Orkin, S. H., Yoder, M. C., Mikkola, H. K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Emergence+of+Hematopoietic+Stem+Cells+Is+Initiated+in+the+Placental+Vasculature+in+the+Absence+of+Circulation.">The Emergence of Hematopoietic Stem Cells Is Initiated in the Placental Vasculature in the Absence of Circulation.</a> Cell Stem Cell. 2, 252-263 (2008).</li></ol>

The experimental procedures described in this protocol will allow for isolation and visualization of placental tissue and hematopoietic stem and progenitor cells. For a comprehensive summary on expected cellular yield and number of HSCs in placenta and other fetal hematopoietic organs throughout fetal development we refer to Gekas, et al. 2005. For localization of developing HSCs and other hematopoietic cells in the placenta we refer to Rhodes, et al. 2008.

Materials List: 
100mM Glucose 
10mM NaN3 
15-ml conical tubes (BD) 
16-G, 18-G, 20-G, 22-G and 25-G needles (BD) 
30% Sucrose Solution 
35mm Petri Dishes (BD) 
4% Paraformaldehyde 
50- m cell filters (Celltrics) 
5-ml syringes (BD) 
Alkaline Phosphatase Substrate Kit I (Vector Red, Vector) 
Alkaline Phosphatase Substrate Kit III (Vector Blue, Vector) 
Antibiotic (Penicillin/Streptomycin, P/S) solution 
Collagenase type I (Sigma) 
Cryomold Disposable Vinyl Specimen Molds (10mm x 10mm x 5 mm, Tissue-Tek) 
Cytokeratin Primary Antibody (DakoCytomation) 
Dissection forceps, stainless steel or titanium, number 5 or 55 
Drierite 
Fetal Bovine Serum (FBS) 
Fisherbrand Plastic Microscope Slide Mailer (Fisher) 
Glucose Oxidase 1000u/ml 
Levamisole (Vector) 
Mounting media, Aqueous-based Mounting Medium (VectamountTM AQ) 
Normal Horse Serum (Vector) 
Optimal Cutting Temperature (O.C.T., Tissue-Tek) 
Peroxidase Substrate Kit DAB (Vector) 
Phosphate Buffered Saline (PBS) with Calcium/Magnesium (w Ca2+/Mg2+) 
Phosphate Buffered Saline (PBS) without Calcium/Magnesium (w/o Ca2+/Mg2+) 
Plastic Slide Box (holds 100 slides) 
Plastic Tubing (Nalgene 180 PVC Non-toxic Autoclavable) 
Polypropylene Round-Bottom Test Tube, 5 ml (12x75 mm, BD Falcon) 
Proteinase K 20mg/ml Solution (Amresco) 
Research Products International Corp Super Pap Pen HT* Slide Markers (2,5 mm, Fisher) 
Tissue-culture treated U-shaped (round-bottom) 96-well or 24-well plates (BD Falcon) 
Tween20, SigmaUltra (Sigma) 
Tyramide Amplification Kit (Invitrogen) 
Vectastain ABC Alkaline Phosphatase Standard Kit (Vector) 
Vectastain ABC Standard Elite Kit (Vector)

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.

Watch this Scientific Journal Video about Isolation and Analysis of Hematopoietic Stem Cells from the Placenta at JoVE.com

Isolation and Analysis of Hematopoietic Stem Cells from the Placenta

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. ...

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A Hierarchical Stem-Cell System: Blood Cell Formation

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Video: Isolation and Analysis of Hematopoietic Stem Cells from the Placenta

Isolation and Transplantation of Hematopoietic Stem Cells (HSCs)

Isolation and Transplantation of Hematopoietic Stem Cells HSCs

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.

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 ...

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 of Retinal Stem Cells from the Mouse Eye

The adult mouse retinal stem cell (RSC) is a rare quiescent cell found within the ciliary epithelium (CE) of the mammalian eye1,2,3. The CE is made up of non-pigmented inner and pigmented outer cell layers, and the clonal RSC colonies that arise from a single pigmented cell from the CE are made up of both pigmented and non-pigmented cells which can be differentiated to form all the cell types of the neural retina and the RPE. There is some controversy about whether all the cells within the spheres all contain at least some pigment4; however the cells are still capable of forming the different cell types found within the neural retina1-3. In some species, such as amphibians and fish, their eyes are capable of regeneration after injury5, however; the mammalian eye shows no such regenerative properties. We seek to identify the stem cell in vivo and to understand the mechanisms that keep the mammalian retinal stem cells quiescent6-8, even after injury as well as using them as a potential source of cells to help repair physical or genetic models of eye injury through transplantation9-12. Here we describe how to isolate the ciliary epithelial cells from the mouse eye and grow them in culture in order to form the clonal retinal stem cell spheres. Since there are no known markers of the stem cell in vivo, these spheres are the only known way to prospectively identify the stem cell population within the ciliary epithelium of the eye.

In this video, we will demonstrate how to isolate retinal stem cells from the ciliary epithelium of the mouse eye and grow them in culture to form clonal retinal spheres. The spheres that are isolated possess the cardinal properties of stem cells: self-renewal and multipotentiality.

The adult mouse retinal stem cell (RSC) is a rare quiescent cell found within the ciliary epithelium (CE) of the mammalian eye1,2,3. The CE is made up of ...

Lentiviral-mediated Knockdown During Ex Vivo Erythropoiesis of Human Hematopoietic Stem Cells

Erythropoiesis is a commonly used model system to study cell differentiation. During erythropoiesis, pluripotent adult human hematopoietic stem cells (HSCs) differentiate into oligopotent progenitors, committed precursors and mature red blood cells 1. This process is regulated for a large part at the level of gene expression, whereby specific transcription factors activate lineage-specific genes while concomitantly repressing genes that are specific to other cell types 2. Studies on transcription factors regulating erythropoiesis are often performed using human and murine cell lines that represent, to some extent, erythroid cells at given stages of differentiation 3-5. However transformed cell lines can only partially mimic erythroid cells and most importantly they do not allow one to comprehensibly study the dynamic changes that occur as cells progress through many stages towards their final erythroid fate. Therefore, a current challenge remains the development of a protocol to obtain relatively homogenous populations of primary HSCs and erythroid cells at various stages of differentiation in quantities that are sufficient to perform genomics and proteomics experiments.
Here we describe an ex vivo cell culture protocol to induce erythroid differentiation from human hematopoietic stem/progenitor cells that have been isolated from either cord blood, bone marrow, or adult peripheral blood mobilized with G-CSF (leukapheresis). This culture system, initially developed by the Douay laboratory 6, uses cytokines and co-culture on mesenchymal cells to mimic the bone marrow microenvironment. Using this ex vivo differentiation protocol, we observe a strong amplification of erythroid progenitors, an induction of differentiation exclusively towards the erythroid lineage and a complete maturation to the stage of enucleated red blood cells. Thus, this system provides an opportunity to study the molecular mechanism of transcriptional regulation as hematopoietic stem cells progress along the erythroid lineage. 
Studying erythropoiesis at the transcriptional level also requires the ability to over-express or knockdown specific factors in primary erythroid cells. For this purpose, we use a lentivirus-mediated gene delivery system that allows for the efficient infection of both dividing and non-dividing cells 7. Here we show that we are able to efficiently knockdown the transcription factor TAL1 in primary human erythroid cells. In addition, GFP expression demonstrates an efficiency of lentiviral infection close to 90%. Thus, our protocol provides a highly useful system for characterization of the regulatory network of transcription factors that control erythropoiesis.

Lentiviral-mediated Knockdown During Ex Vivo Erythropoiesis of Human Hematopoietic Stem Cells

An ex vivo protocol to generate mature human red blood cells from hematopoietic stem/progenitors is described. Additionally we describe an efficient lentiviral-delivery method to knockdown the transcription factor TAL1 in primary erythroid cells. The efficiency of lentivirus mediated gene delivery is demonstrated using GFP expressing viruses.

Erythropoiesis is a commonly used model system to study cell differentiation. During erythropoiesis, pluripotent adult human hematopoietic stem cells ...

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 ...

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 ...

Isolation and Culture of Dental Epithelial Stem Cells from the Adult Mouse Incisor

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest1-4, and the mouse incisor provides a model for these processes. This remarkable organ grows continuously throughout the animal&#39;s life and generates all the necessary cell types from active pools of adult stem cells housed in the labial (toward the lip) and lingual (toward the tongue) cervical loop (CL) regions. Only the dental stem cells from the labial CL give rise to ameloblasts that generate enamel, the outer covering of teeth, on the labial surface. This asymmetric enamel formation allows abrasion at the incisor tip, and progenitors and stem cells in the proximal incisor ensure that the dental tissues are constantly replenished. The ability to isolate and grow these progenitor or stem cells in vitro allows their expansion and opens doors to numerous experiments not achievable in vivo, such as high throughput testing of potential stem cell regulatory factors. Here, we describe and demonstrate a reliable and consistent method to culture cells from the labial CL of the mouse incisor.

The continuously growing mouse incisor provides a model for studying renewal of dental tissues from dental epithelial stem cells (DESCs). A robust system for consistently and reliably obtaining these cells from the incisor and expanding them in vitro is reported here.

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest1-4, and the mouse ...

Retroviral Infection of Murine Embryonic Stem Cell Derived Embryoid Body Cells for Analysis of Hematopoietic Differentiation

Embryonic stem cells (ESCs) are an outstanding model for elucidating the molecular mechanisms of cellular differentiation. They are especially useful for investigating the development of early hematopoietic progenitor cells (HPCs). Gene expression in ESCs can be manipulated by several techniques that allow the role for individual molecules in development to be determined. One difficulty is that expression of specific genes often has different phenotypic effects dependent on their temporal expression. This problem can be circumvented by the generation of ESCs that inducibly express a gene of interest using technology such as the doxycycline-inducible transgene system. However, generation of these inducible cell lines is costly and time consuming. Described here is a method for disaggregating ESC-derived embryoid bodies (EBs) into single cell suspensions, retrovirally infecting the cell suspensions, and then reforming the EBs by hanging drop. Downstream differentiation is then evaluated by flow cytometry. Using this protocol, it was demonstrated that exogenous expression of a microRNA gene at the beginning of ESC differentiation blocks HPC generation. However, when expressed in EB derived cells after nascent mesoderm is produced, the microRNA gene enhances hematopoietic differentiation. This method is useful for investigating the role of genes after specific germ layer tissue is derived.

Manipulating temporal gene expression in differentiating embryonic stem cells (ESCs) can be achieved using inducible gene systems. However, generation of these cell lines is costly and time consuming. This protocol achieves rapid expression of a transgene in differentiating ES-derived cells and subsequent analysis of downstream hematopoietic differentiation.

Embryonic stem cells (ESCs) are an outstanding model for elucidating the molecular mechanisms of cellular differentiation. They are especially useful for ...

Identification of Key Factors Regulating Self-renewal and Differentiation in EML Hematopoietic Precursor Cells by RNA-sequencing Analysis

Hematopoietic stem cells (HSCs) are used clinically for transplantation treatment to rebuild a patient&#39;s hematopoietic system in many diseases such as leukemia and lymphoma. Elucidating the mechanisms controlling HSCs self-renewal and differentiation is important for application of HSCs for research and clinical uses. However, it is not possible to obtain large quantity of HSCs due to their inability to proliferate in vitro. To overcome this hurdle, we used a mouse bone marrow derived cell line, the EML (Erythroid, Myeloid, and Lymphocytic) cell line, as a model system for this study.
RNA-sequencing (RNA-Seq) has been increasingly used to replace microarray for gene expression studies. We report here a detailed method of using RNA-Seq technology to investigate the potential key factors in regulation of EML cell self-renewal and differentiation. The protocol provided in this paper is divided into three parts. The first part explains how to culture EML cells and separate Lin-CD34+ and Lin-CD34- cells. The second part of the protocol offers detailed procedures for total RNA preparation and the subsequent library construction for high-throughput sequencing. The last part describes the method for RNA-Seq data analysis and explains how to use the data to identify differentially expressed transcription factors between Lin-CD34+ and Lin-CD34- cells. The most significantly differentially expressed transcription factors were identified to be the potential key regulators controlling EML cell self-renewal and differentiation. In the discussion section of this paper, we highlight the key steps for successful performance of this experiment.
In summary, this paper offers a method of using RNA-Seq technology to identify potential regulators of self-renewal and differentiation in EML cells. The key factors identified are subjected to downstream functional analysis in vitro and in vivo.

RNA-sequencing and bioinformatics analyses were used to identify significantly and differentially expressed transcription factors in Lin-CD34+ and Lin-CD34- subpopulations of mouse EMLcells. These transcription factors might play important roles in determining the switch between self-renewing Lin-CD34+ and partially differentiated Lin-CD34- cells.

Hematopoietic stem cells (HSCs) are used clinically for transplantation treatment to rebuild a patient&#39;s hematopoietic system in many diseases such as ...