We thank Marcos P&#233;rez Basterrechea, Lorena Rodr&#237;guez Lorenzo and Bego&#241;a Garc&#237;a M&#233;ndez (HUCA) and Paloma Cerezo, Almudena Payero and Mar&#237;a de la Poveda-Colomo (HCSC) for technical support. This work was partially supported by Medical Grants (Roche SP200221001) to A.B., an RYC fellowship (RYC-2013-12587; Ministerio de Econom&#237;a y Competitividad, Spain) and an I+D 2017 grant (SAF2017-85489-P; Ministerio de Ciencia, Innovaci&#243;n y Universidades, Spain and Fondos FEDER) to L.G., a Severo Ochoa Grant (PA-20-PF-BP19-014; Consejer&#237;a de Ciencia, Innovaci&#243;n y Universidades del Principado de Asturias, Spain) to P.M.-B. and an intramural postdoctoral grant 2018 (Fundaci&#243;n para la Investigaci&#243;n y la Innovaci&#243;n Biosanitaria de Asturias - FINBA, Oviedo, Spain) to A.A.-H. We thank Reinier van der Linden for sharing his knowledge (and time), especially his wise advice on multi-color tagged-antibody panel mix and single-color bead control preparation.

Whole blood and bone marrow samples were obtained and processed in accordance with the 1964 Declaration of Helsinki. Whole blood samples were obtained from healthy donors after giving informed consent (ISPA), within a study approved by our institutional medical ethical committee (Hospital Universitario Central de Asturias -HUCA-). Bone marrow samples were obtained from bone marrow aspirate discard material of patients managed at the Dept. of Hematology of the Hospital Cl&#237;nico San Carlos (HCSC).
<p class="jove_co...

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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+Of+Human+Megakaryocytes+By+Fluorescence-Activated+Cell+Sorting.">Purification Of Human Megakaryocytes By Fluorescence-Activated Cell Sorting.</a> Blood. 70 (6), 1735-1742 (1987).</li><li>Martinez-Botia, P., Acebes-Huerta, A., Seghatchian, J., Gutierrez, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+The+Quest+For+In+Vitro+Platelet+Production+By+Re-Tailoring+The+Concepts+Of+Megakaryocyte+Differentiation.">On The Quest For In Vitro Platelet Production By Re-Tailoring The Concepts Of Megakaryocyte Differentiation.</a> Medicina. 56 (12), (2020).</li><li>Martinez-Botia, P., Acebes-Huerta, A., Seghatchian, J., Gutierrez, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Vitro+Platelet+Production+For+Transfusion+Purposes:+Where+Are+We+Now.">In Vitro Platelet Production For Transfusion Purposes: Where Are We Now.</a> Transfusion And Apheresis Science. 59 (4), 102864 (2020).</li><li>Butov, K. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Vitro+Megakaryocyte+Culture+From+Human+Bone+Marrow+Aspirates+As+A+Research+And+Diagnostic+Tool.">In Vitro Megakaryocyte Culture From Human Bone Marrow Aspirates As A Research And Diagnostic Tool.</a> Platelets. , 1-8 (2020).</li><li>Di Buduo, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Gold+Standard+Protocol+For+Human+Megakaryocyte+Culture+Based+On+The+Analysis+Of+1,500+Umbilical+Cord+Blood+Samples.">A Gold Standard Protocol For Human Megakaryocyte Culture Based On The Analysis Of 1,500 Umbilical Cord Blood Samples.</a> Thrombosis And Haemostasis. , (2020).</li></ol>

Most of the research focusing on the study of megakaryopoiesis by flow cytometry is to date limited to the identification of MK subsets using only lineage-specific surface markers (i.e., CD42A/CD42B, CD41/CD61), while earlier MK differentiation stages have been poorly examined. In the present article we show an immunophenotyping strategy to address a comprehensive flow cytometry characterization of human megakaryopoiesis. Overall, we would like to highlight the utility of combining MK specific and non-specific s...

Megakaryocytes (MKs) develop from hematopoietic stem cells (HSCs) following a complex process called megakaryopoiesis, which is orchestrated mainly by the hormone thrombopoietin (TPO). The classical view of megakaryopoiesis describes the cellular journey from HSCs through a succession of hierarchical stages of committed progenitors and precursor cells, leading ultimately to a mature MK. During maturation, MKs experience multiple rounds of endomitosis, develop an intricate intracellular demarcation membrane system (DMS), which provides enough membrane surface for platelet production, and efficiently produce and pack the plethora of factors that are contained in the different granules inherited by mature platelets1,2,3. As a result, mature MKs are large cells (40-60 &#181;m) characterized by a highly polyploid nucleus (reaching even &#62;64N). Recent studies suggest alternative routes by which HSCs differentiate into MKs bypassing traditional lineage commitment checkpoints in response to certain physio-pathological conditions4,5,6,7,8,9,10,11. These findings highlight that hematopoietic differentiation towards the mature MK is a continuum and adaptive process that responds to biological needs.
With the increasing knowledge on the cell biology and the molecular aspects characterizing megakaryopoiesis12, most of the research dedicated to the study of the process by flow cytometry are limited to the identification of mature MKs using lineage-specific surface markers (i.e., CD42A/B, CD41/CD61), while earlier MK differentiation stages remain unexplored. We previously documented a strategy to stage megakaryopoiesis in mouse bone marrow and bone marrow-derived MK cultures13,14, which we have adapted and applied to humans15. In the present article we show an immunophenotyping strategy that allows the characterization of megakaryopoiesis, from HSCs to mature MKs, in human primary sources (bone marrow -BM- and peripheral blood -PB-) or in vitro cultures using a panel integrating MK specific and non-specific surface markers (CD61, CD42B, CD49B, CD31, KIT and CD71, amongst others). Despite its large size and fragility, MKs can be immunophenotyped using the above-mentioned cell surface markers and enriched by fluorescence-activated cell sorting under specific conditions of pressure and nozzle diameter to minimize cell rupture and/or damage. This technique facilitates multi-Omics approaches, with the aim to better understand the complexity of megakaryopoiesis and platelet production in human health and disease. Noteworthy, it will pose as a useful tool to aid diagnosis and prognosis in a clinical context of growing demand.
In this manuscript we document a strategy to stage human megakaryopoiesis with a panel integrating MK-specific and non-specific surface markers from primary sources or generated in vitro. Additionally, we provide a protocol to sort, with a fluorescence-activated cell sorter, the preferred fractions and mature MKs (Figure 1). This step is not popular, as it is technically difficult due to the large size and fragility of MKs. However, it has been employed both in mouse and human bone marrow samples previously, and due to technological advancement, with a better result each time16,17,18. Human primary sources where MKs or MK precursors can be studied include bone marrow, cord blood and peripheral blood, amongst other. The proper sample processing to isolate the relevant cell fraction for analysis on each sample is of importance. Standard procedures are incorporated, with some considerations to take into account when aiming at the study of megakaryopoiesis.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>130 micron Nozzle</td>
			<td>BD</td>
			<td>643943</td>
			<td>required for MK sorting</td>
		</tr>
		<tr>
			<td>5810R Centrifuge</td>
			<td>Eppendorf</td>
			<td></td>
			<td>Cell isolation and washes</td>
		</tr>
		<tr>
			<td>A-4-62 Swing Bucket Rotor</td>
			<td>Eppendorf</td>
			<td></td>
			<td>Cell isolation and washes</td>
		</tr>
		<tr>
			<td>Aerospray Pro Hematology Slide Stainer / Cytocentrifuge</td>
			<td>ELITech Group</td>
			<td></td>
			<td>Automatized cytology devise, where slides are stained with Mat-Gr&#252;nwald Giemsa</td>
		</tr>
		<tr>
			<td>CO2 Incubator Galaxy 170 S</td>
			<td>Eppendorf</td>
			<td></td>
			<td>Cell Incubation</td>
		</tr>
		<tr>
			<td>Cytospin 4 Cytocentrifuge</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td>To prepare cytospins</td>
		</tr>
		<tr>
			<td>FACSAria IIu sorter</td>
			<td>BD</td>
			<td></td>
			<td>Lasers 488-nm and 633-nm</td>
		</tr>
		<tr>
			<td>FACSCanto II flow cytometer</td>
			<td>BD</td>
			<td></td>
			<td>Lasers 488-nm , 633-nm and 405-nm</td>
		</tr>
		<tr>
			<td>Olympus Microscope BX 41</td>
			<td>Olympus</td>
			<td></td>
			<td>Microphotographs</td>
		</tr>
		<tr>
			<td>Olympus Microscope BX 61</td>
			<td>Olympus</td>
			<td></td>
			<td>Microphotographs</td>
		</tr>
		<tr>
			<td>Zoe Fluorescent Cell Imager</td>
			<td>BioRad</td>
			<td></td>
			<td>Microphotographs</td>
		</tr>
		<tr>
			<td>To obtain PBMCs</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lipids Cholesterol Rich from adult bovine serum</td>
			<td>Sigma-Aldrich</td>
			<td>L4646</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Lymphoprep</td>
			<td>Stem Cell Technologies</td>
			<td>#07801</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Sigma-Aldrich</td>
			<td>P4333</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Recombinant human Erythropoietin (EPO)</td>
			<td>&#160;R&#38;D Systems</td>
			<td>287-TC-500</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Recombinant human stem cell factor (SCF)</td>
			<td>Thermo Fisher Scientific, Gibco&#8482;</td>
			<td>PHC2115</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Recombinant human thrombopoietin (TPO)</td>
			<td>Thermo Fisher Scientific, Gibco&#8482;</td>
			<td>PHC9514</td>
			<td>or TPO receptor agonists</td>
		</tr>
		<tr>
			<td>StemSpan SFEM</td>
			<td>Stem Cell Technologies</td>
			<td>#09650</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow Cytometry Analyses</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Merck</td>
			<td>A7906-100G</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>BD CompBead Anti-Mouse Ig, &#954;/Negative Control Compensation Particles Set</td>
			<td>BD</td>
			<td>552843</td>
			<td>Antibodies for human cells are generally from mouse.</td>
		</tr>
		<tr>
			<td>BD Cytofix/Cytoperm</td>
			<td>BD</td>
			<td>554714</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>BD FACS Accudrop Beads</td>
			<td>BD</td>
			<td>345249</td>
			<td></td>
		</tr>
		<tr>
			<td>CD31 AF-647</td>
			<td>BD</td>
			<td>561654</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD31 FITC</td>
			<td>Immunostep</td>
			<td>31F-100T</td>
			<td></td>
		</tr>
		<tr>
			<td>CD34 FITC</td>
			<td>BD</td>
			<td>555821</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD41 PE</td>
			<td>BD</td>
			<td>555467</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD41 PerCP-Cy5.5</td>
			<td>BD</td>
			<td>333148</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD42A APC</td>
			<td>Immunostep</td>
			<td>42AA-100T</td>
			<td>We observed unspecific binding... that needs to be assessed</td>
		</tr>
		<tr>
			<td>CD42A PE</td>
			<td>BD</td>
			<td>558819</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD42B PerCP</td>
			<td>Biolegend</td>
			<td>303910</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD49B PE</td>
			<td>BD</td>
			<td>555669</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD61 FITC</td>
			<td>BD</td>
			<td>555753</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>CD71 APC-Cy7</td>
			<td>Biolegend</td>
			<td>334109</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td>Thermo Fisher Scientific</td>
			<td>H3570</td>
			<td></td>
		</tr>
		<tr>
			<td>Human BD Fc Block</td>
			<td>BD</td>
			<td>564219</td>
			<td>Fc blocking - control</td>
		</tr>
		<tr>
			<td>KIT PE-Cy7</td>
			<td>Biolegend</td>
			<td>313212</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>Lineage Cocktail 2 FITC</td>
			<td>BD</td>
			<td>643397</td>
			<td>Mouse anti-human</td>
		</tr>
		<tr>
			<td>RNAse</td>
			<td>Merck</td>
			<td>R6513</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Triton X-500</td>
			<td>Merck</td>
			<td>93443-500ML</td>
			<td>or similar</td>
		</tr>
		<tr>
			<td>Cell strainers for sorting</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CellTrics Filters 100 micrometers</td>
			<td>Sysmex</td>
			<td>04-004-2328</td>
			<td>Cell strainers</td>
		</tr>
		<tr>
			<td colspan="4">Note: we do not specify general reagents/chemicals (PBS, EDTA, etc) or disposables (tubes, etc), or reagents specified in previous published and standard protocols&#160; - unless otherwise specified.</td>
		</tr>
	</tbody>
</table>

immunophenotyping and cell sorting of human mks from human primary sources or differentiated in vitro from hematopoietic progenitors

Megakaryocyte (MK) differentiation encompasses a number of endomitotic cycles that result in a highly polyploid (reaching even&#160;&#62;64N) and extremely large cell (40-60 &#181;m). As opposed to the fast-increasing knowledge in megakaryopoiesis at the cell biology and molecular level, the characterization of megakaryopoiesis by flow cytometry is limited to the identification of mature MKs using lineage-specific surface markers, while earlier MK differentiation stages remain unexplored. Here, we present an immunophenotyping strategy that allows the identification of successive MK differentiation stages, with increasing ploidy status, in human primary sources or in vitro cultures with a panel integrating MK specific and non-specific surface markers. Despite its size and fragility, MKs can be immunophenotyped using the above-mentioned panel and enriched by fluorescence-activated cell sorting under specific conditions of pressure and nozzle diameter. This approach facilitates multi-Omics studies, with the aim to better understand the complexity of megakaryopoiesis and platelet production in humans. A better characterization of megakaryopoiesis may pose fundamental in the diagnosis or prognosis of lineage-related pathologies and malignancy.

Bone Marrow and Ploidy 
In Figure 4, we show a representative immunophenotyping analysis of megakaryopoiesis in BM samples (aspiration) from patients. When plotting the cellular fraction against CD71 and CD31, we have gated six main populations: CD31- CD71- (red), CD31- CD71+ (blue), CD31+ CD71- (orange), CD31+ CD71mid (light green), CD31+ CD71+...

Watch this Scientific Journal Video about Immunophenotyping and Cell Sorting of Human MKs from Human Primary Sources or Differentiated In Vitro from Hematopoietic Progenitors at JoVE.com

Immunophenotyping and Cell Sorting of Human MKs from Human Primary Sources or Differentiated In Vitro from Hematopoietic Progenitors

Here, we present an immunophenotyping strategy for the characterization of megakaryocyte differentiation, and show how that strategy allows the sorting of megakaryocytes at different stages with a fluorescence-activated cell sorter. The methodology can be applied to human primary tissues, but also to megakaryocytes generated in culture in vitro.

Immunophenotyping and Cell Sorting of Human MKs from Human Primary Sources or Differentiated In Vitro from Hematopoietic Progenitors

Megakaryocyte (MK) differentiation encompasses a number of endomitotic cycles that result in a highly polyploid (reaching even&#160;&#62;64N) and ...

Hello.I am Andrea Acebes Huerta.Postdoctoral Researcher at the Platelet Research Lab part of the Health Research Institute of the Principality of Asturias, ISPA.Which is located in Oviedo, Spain.Hello.I am Laura Guti

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Research

JoVE Journal

Biology

Human ES cells: Starting Culture from Frozen Cells

Here we demonstrate how our lab begins a HuES human embryonic stem cell line culture from a frozen stock.  First, a one to two day old ten cm plate of  approximately one (to two) million irradiated mouse embryonic fibroblast feeder cells is rinsed with HuES media to remove residual serum and cell debris, and then HuES media added and left to equilibrate in the cell culture incubator.  A frozen vial of cells from long term liquid nitrogen storage or a -80C freezer is sourced and quickly submerged in a 37C water bath for quick thawing.  Cells in freezing media are then removed from the vial and placed in a large volume of HuES media.  The large volume of HuES media facilitates removal of excess serum and DMSO, which can cause HuES human embryonic stem cells to differentiate.  Cells are gently spun out of suspension, and then re-suspended in a small volume of fresh HuES media that is then used to seed the MEF plate.  It is considered important to seed the MEF plate by gently adding the HuES cells in a drop wise fashion to evenly disperse them throughout the plate.  The newly established HuES culture plate is returned to the incubator for 48 hrs before media is replaced, then is fed every 24 hours thereafter.

Here we demonstrate how our lab begins a HuES human embryonic stem cell line culture from a frozen stock.

Here we demonstrate how our lab begins a HuES human embryonic stem cell line culture from a frozen stock.  First, a one to two day old ten cm plate of  ...

The Preparation of Primary Hematopoietic Cell Cultures From Murine Bone Marrow for Electroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell  electroporation system and Gene Pulser  electroporation buffer were specifically developed to transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells.This video demonstrates how to establish primary hematopoietic cell cultures from murine bone marrow, and then prepare them for electroporation in the MXcell system. We begin by isolating femur and tibia. Bone marrow from both femur and tibia are then harvested and cultures are established. Cultured bone marrow cells are then transfected and analyzed.

This procedure describes how to establish primary hematopoietic cell cultures from murine bone marrow and is followed by transfection using the Gene Pulser MXCell electroporation system.

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Primary Human Bronchial Epithelial Cells Grown from Explants

Human bronchial epithelial cells are needed for cell models of disease and to investigate the effect of excipients and pharmacologic agents on the function and structure of human epithelial cells. Here we describe in detail the method of growing bronchial epithelial cells from bronchial airway tissue that is harvested by the surgeon at the times of lung surgery (e.g. lung cancer or lung volume reduction surgery). With ethics approval and informed consent, the surgeon takes what is needed for pathology and provides us with a bronchial portion that is remote from the diseased areas. The tissue is then used as a source of explants that can be used for growing primary bronchial epithelial cells in culture. Bronchial segments about 0.5-1cm long and &le;1cm in diameter are rinsed with cold EBSS and excess parenchymal tissue is removed. Segments are cut open and minced into 2-3mm3 pieces of tissue. The pieces are used as a source of primary cells. After coating 100mm culture plates for 1-2 hr with a combination of collagen (30 &mu;g/ml), fibronectin (10 &mu;g/ml), and BSA (10 &mu;g/ml), the plates are scratched in 4-5 areas and tissue pieces are placed in the scratched areas, then culture medium (DMEM/Ham F-12 with additives) suitable for epithelial cell growth is added and plates are placed in an incubator at 37&deg;C in 5% CO2 humidified air. The culture medium is changed every 3-4 days. The epithelial cells grow from the pieces forming about 1.5 cm diameter rings in 3-4 weeks. Explants can be re-used up to 6 times by moving them into new pre-coated plates. Cells are lifted using trypsin/EDTA, pooled, counted, and re-plated in T75 Cell Bind flasks to increase their numbers. T75 flasks seeded with 2-3 million cells grow to 80% confluence in 4 weeks. Expanded primary human epithelial cells can be cultured and allowed to differentiate on air-liquid interface. Methods described here provide an abundant source of human bronchial epithelial cells from freshly isolated tissues and allow for studying these cells as models of disease and for pharmacology and toxicology screening.

Here we describe a detailed method for growing primary human bronchial epithelial cells from explants of human bronchial airway tissue including differentiated growth on an air-liquid interface. This method provides an abundant source of primary cells for investigating the role of the airway epithelium in human lung health and disease.

Human bronchial epithelial cells are needed for cell models of disease and to investigate the effect of excipients and pharmacologic agents on 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 ...

Na&iuml;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

Over the last decade, several adult stem cell populations have been identified in human skin 1-4. The isolation of multipotent adult dermal precursors was first reported by Miller F. D laboratory 5, 6. These early studies described a multipotent precursor cell population from adult mammalian dermis 5. These cells--termed SKPs, for skin-derived precursors-- were isolated and expanded from rodent and human skin and differentiated into both neural and mesodermal progeny, including cell types never found in skin, such as neurons 5. Immunocytochemical studies on cultured SKPs revealed that cells expressed vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors, in addition to fibronectin and multipotent stem cell markers 6. Until now, the adult stem cells population SKPs have been isolated from freshly collected mammalian skin biopsies.
Recently, we have established and reported that a population of skin derived precursor cells could remain present in primary fibroblast cultures established from skin biopsies 7. The assumption that a few somatic stem cells might reside in primary fibroblast cultures at early population doublings was based upon the following observations: (1) SKPs and primary fibroblast cultures are derived from the dermis, and therefore a small number of SKP cells could remain present in primary dermal fibroblast cultures and (2) primary fibroblast cultures grown from frozen aliquots that have been subjected to unfavorable temperature during storage or transfer contained a small number of cells that remained viable 7. These rare cells were able to expand and could be passaged several times. This observation suggested that a small number of cells with high proliferation potency and resistance to stress were present in human fibroblast cultures 7.
We took advantage of these findings to establish a protocol for rapid isolation of adult stem cells from primary fibroblast cultures that are readily available from tissue banks around the world (Figure 1). This method has important significance as it allows the isolation of precursor cells when skin samples are not accessible while fibroblast cultures may be available from tissue banks, thus, opening new opportunities to dissect the molecular mechanisms underlying rare genetic diseases as well as modeling diseases in a dish.

Na&amp;#239;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

We report a method to isolate na&#239;ve multipotent skin-derived precursor (SKP) cells from primary human fibroblast cultures. We show that these SKPs derived from fibroblast cultures share similar stem cell properties to the ones derived directly from human skin biopsies. These cells express the neural crest marker, nestin, in addition to the multipotent markers such as OCT4 and Nanog.

Over the last decade, several adult stem cell  populations have been identified in human skin 1-4.  The isolation of multipotent adult dermal precursors ...

Isolation of Primary Myofibroblasts from Mouse and Human Colon Tissue

The myofibroblast is a stromal cell of the gastrointestinal (GI) tract that has been gaining considerable attention for its critical role in many GI functions. While several myofibroblast cell lines are commercially available to study these cells in vitro, research results from a cell line exposed to experimental cell culture conditions have inherent limitations due to the overly reductionist nature of the work. Use of primary myofibroblasts offers a great advantage in terms of confirming experimental findings identified in a cell line. Isolation of primary myofibroblasts from an animal model allows for the study of myofibroblasts under conditions that more closely mimic the disease state being studied. Isolation of primary myofibroblasts from human colon tissue provides arguably the most relevant experimental data, since the cells come directly from patients with the underlying disease. We describe a well-established technique that can be utilized to isolate primary myofibroblasts from both mouse and human colon tissue. These isolated cells have been characterized to be alpha-smooth muscle actin and vimentin-positive, and desmin-negative, consistent with subepithelial intestinal myofibroblasts. Primary myofibroblast cells can be grown in cell culture and used for experimental purposes over a limited number of passages.

The myofibroblast is an influential stromal cell of the gastrointestinal tract that regulates important physiologic processes in both normal and disease states. We describe a technique that allows for the isolation of primary myofibroblasts from both mouse and human colon tissue, which can be utilized for in vitro experimentation.

The myofibroblast is  a stromal cell of the gastrointestinal (GI) tract that has been gaining  considerable attention for its critical role in many GI ...

Efficient Generation Human Induced Pluripotent Stem Cells from Human Somatic Cells with Sendai-virus

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs include modeling pathogenesis of human genetic diseases, autologous cell therapy after gene correction, and personalized drug screening by providing a source of patient-specific and symptom relevant cells. However, there are several hurdles to overcome, such as eliminating the remaining reprogramming factor transgene expression after human iPSCs production. More importantly, residual transgene expression in undifferentiated human iPSCs could hamper proper differentiations and misguide the interpretation of disease-relevant in vitro phenotypes. With this reason, integration-free and/or transgene-free human iPSCs have been developed using several methods, such as adenovirus, the piggyBac system, minicircle vector, episomal vectors, direct protein delivery and synthesized mRNA. However, efficiency of reprogramming using integration-free methods is quite low in most cases.
Here, we present a method to isolate human iPSCs by using Sendai-virus (RNA virus) based reprogramming system. This reprogramming method shows consistent results and high efficiency in cost-effective manner.

Here, we present our established method to reprogram human somatic cells into transgene-free human iPSCs with Sendai virus, which shows consistent outcome and enhanced efficiency.

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs ...

In Vitro Pancreas Organogenesis from Dispersed Mouse Embryonic Progenitors

The pancreas is an essential organ that regulates glucose homeostasis and secretes digestive enzymes. Research on pancreas embryogenesis has led to the development of protocols to produce pancreatic cells from stem cells 1. The whole embryonic organ can be cultured at multiple stages of development 2-4. These culture methods have been useful to test drugs and to image developmental processes. However the expansion of the organ is very limited and morphogenesis is not faithfully recapitulated since the organ flattens. 
We propose three-dimensional (3D) culture conditions that enable the efficient expansion of dissociated mouse embryonic pancreatic progenitors. By manipulating the composition of the culture medium it is possible to generate either hollow spheres, mainly composed of pancreatic progenitors expanding in their initial state, or, complex organoids which progress to more mature expanding progenitors and differentiate into endocrine, acinar and ductal cells and which spontaneously self-organize to resemble the embryonic pancreas. 
We show here that the in vitro process recapitulates many aspects of natural pancreas development. This culture system is suitable to investigate how cells cooperate to form an organ by reducing its initial complexity to few progenitors. It is a model that reproduces the 3D architecture of the pancreas and that is therefore useful to study morphogenesis, including polarization of epithelial structures and branching. It is also appropriate to assess the response to mechanical cues of the niche such as stiffness and the effects on cell&#180;s tensegrity.

In Vitro Pancreas Organogenesis from Dispersed Mouse Embryonic Progenitors

The three-dimensional culture method described in this protocol recapitulates pancreas development from dispersed embryonic mouse pancreas progenitors, including their substantial expansion, differentiation and morphogenesis into a branched organ. This method is amenable to imaging, functional interference and manipulation of the niche.

The pancreas is an essential organ that regulates glucose homeostasis and secretes digestive enzymes. Research on pancreas embryogenesis has led to the ...

Isolation of Human Primary Valve Cells for In vitro Disease Modeling

Calcific aortic valve disease (CAVD) is present in nearly a third of the elderly population. Thickening, stiffening, and calcification of the aortic valve causes aortic stenosis and contributes to heart failure and stroke. Disease pathogenesis is multifactorial, and stresses such as inflammation, extracellular matrix remodeling, turbulent flow, and mechanical stress and strain contribute to the osteogenic differentiation of valve endothelial and valve interstitial cells. However, the precise initiating factors that drive the osteogenic transition of a healthy cell into a calcifying cell are not fully defined. Further, the only current therapy for CAVD-induced aortic stenosis is aortic valve replacement, whereby the native valve is removed (surgical aortic valve replacement, SAVR) or a fully collapsible replacement valve is inserted via a catheter (transcatheter aortic valve replacement, TAVR). These surgical procedures come at a high cost and with serious risks; thus, identifying novel therapeutic targets for drug discovery is imperative. To that end, the present study develops a workflow where surgically removed tissues from patients and donor cadaver tissues are used to create patient-specific primary lines of valvular cells for in vitro disease modeling. This protocol introduces the utilization of a cold storage solution, commonly utilized in organ transplant, to reduce the damage caused by the often-lengthy procurement time between tissue excision and laboratory processing with the benefit of greatly stabilizing cells of the excised tissue. The results of the present study demonstrate that isolated valve cells retain their proliferative capacity and endothelial and interstitial phenotypes in culture upwards of several days after valve removal from the donor. Using these materials allows for the collection of control and CAVD cells, from which both control and disease cell lines are established.

This protocol describes the collection of human aortic valves extracted during surgical aortic valve replacement procedures or from cadaveric tissue, and the subsequent isolation, expansion, and characterization of patient specific primary valve endothelial and interstitial cells. Included are important details regarding the processes needed to ensure cell viability and phenotype specificity.

Calcific aortic valve disease (CAVD) is present in nearly a third of the elderly population. Thickening, stiffening, and calcification of the aortic valve ...