E. T. was supported by The Magic That Matters and AHA. C. K. was supported by grants from NICHD/NIH (R01HD086026), AHA, and MSCRF.&#160;

NOTE: In vitro generation of heart field-specific mouse cardiac progenitor cells (Figure 1).
1. Maintenance of Mouse ESCs
<ol>
	<li>Grow mESCs (mESCsTbx1-Cre; Rosa-RFP; HCN4-GFP, mESCIsl1-RFP)25 on 0.1% (w/v) gelatin coated T25 flasks in 2i medium (870 mL of glascow minimum essential medium (GMEM), 100 mL of fetal bovine serum (FBS), 10 mL of GlutaMAX, 10 mL of non-essential amino acids, 10 mL of sodium pyruvate, 3 &#956;L of beta-mercaptoethanol, 20 &#956;L of Lif (200 U/mL), 0.3 &#956;M CHIR99021 and 0.1 &#956;M PD0325901).</li>
	<li>When the cells reach 70-80% confluence, rinse the cells once with phosphate buffer solution (PBS) and then dissociate into single cells by adding 1 mL of Trypsin and incubating at 37 &#176;C for 3 min.</li>
	<li>Neutralize Trypsin by adding 4 mL of 10% FBS in Dulbecco&#8217;s Modified Eagle Medium (DMEM). Count the cells using an automated cell counter.</li>
	<li>Centrifuge ~3 x 105 cells for 3 min at 270 x g and room temperature.</li>
	<li>Aspirate the supernatant, resuspend the cells in 5 mL of 2i medium and replate on 0.1% (w/v) gelatin coated T25 flasks for maintenance.</li>
</ol>
2. Generation of Cardiac Progenitor Cells Using Cardiac Spheroids
<ol>
	<li>Centrifuge 2.5 x 106 cells from step 1.3 for 3 min at 270 x g and room temperature.</li>
	<li>Aspirate the supernatant and resuspend the cells in 25 mL of SFD medium (105 cells/mL). Depending on the scale of the experiment, mESC number can be adjusted accordingly. 
	NOTE: SFD medium contains 715 mL of Iscove&#8217;s Modified Dulbecco&#8217;s Medium (IMDM), 250 mL of Ham&#8217;s F12, 5 mL of N2-supplement, 10 mL of B27 minus Vitamin A, 5 mL of 10% (w/v) BSA (in PBS), 7.5 mL of GlutaMAX and 7.5 mL of Penicillin-Streptomycin. Add ascorbic acid (50 &#956;g/mL) and 3.9 x 10-3% (v/v) of monothioglycerol prior to using.</li>
	<li>Plate the cell suspension into one 150 mm x 25 mm sterile plate and incubate at 37 &#176;C in the 5% CO2 incubator for 48 h. Cardiac spheroids should be formed within 24 h.</li>
	<li>Collect all the formed cardiac spheroids and centrifuge for 3 min at 145 x g and room temperature to selectively isolate spheroids and avoid single cells.</li>
	<li>Aspirate the supernatant and resuspend the spheroids in 25 mL of SFD medium with 1 ng/mL of Activin A and 1.5 ng/mL of BMP4 for differentiation induction. Plate the spheroids in the same 150 mm x 25mm sterile plate and incubate them at 37 &#176;C in the 5% CO2 incubator for 40 h. 
	NOTE: Different concentrations of Activin A (0-3 ng/mL) and BMP4 (0.5-2 ng/mL) can be used for differentiation optimization depending on the mESC line.</li>
	<li>Collect all the cardiac spheroids and centrifuge for 3 min at 145 x g and room temperature.</li>
	<li>Aspirate the supernatant and resuspend the spheroids in 25 mL of SFD medium. Transfer the resuspended EBs in an ultra-low attachment 75 cm2 flask and incubate them at 37 &#176;C in the 5% CO2 incubator for 48 h.&#160;</li>
</ol>
3. Isolation of Heart Field Specific Cardiac Progenitor Cells Using Fluorescent Reporters
<ol>
	<li>Centrifuge cardiac spheroids at 145 x g and room temperature for 3min and aspirate the supernatant. Add 1 mL of Trypsin and incubate at 37 &#176;C for 3 min. Mix well by pipetting to dissociate the cells.</li>
	<li>Add 4 mL of 10% FBS in DMEM to inactivate Trypsin and mix well by pipetting. To remove the non-dissociated EBs, filter the mix using a 70 &#956;m strainer and centrifuge the filtrated cells for 3 min at 270 x g and room temperature.</li>
	<li>To sort CPCs carrying fluorescent reporters (CPCs derived from mESCsTbx1-Cre; Rosa-RFP; HCN4-GFP), aspirate the supernatant and add 500 &#956;L of FACS sorting solution (1% (v/v) FBS, 200 mM HEPES and 10 mM of EDTA in PBS) to resuspend.</li>
	<li>To remove all cell clusters prior to sorting, filter the cells again using a 5 mL polystyrene round-bottom tube with a 40 &#956;m cell strainer. Keep the cells on ice until sorting.</li>
	<li>Sort the cells to isolate Tbx1-Cre; Rosa-RFP and HCN4-GFP positive CPCs using a fluorescent activated cell sorter (FACS). Collect the sorted cells in 1 mL of FBS. Keep the cell sample and sorted cells at 4 &#176;C.</li>
</ol>
4. Isolation of Heart Field Specific Cardiac Progenitor Cells Using Cxcr4 as a Cell Surface Protein Marker
<ol>
	<li>To isolate first vs second heart field CPCs based on the expression of the surface protein receptor Cxcr4, use the mESCIsl1-RFP line. Aspirate the supernatant from step 3.3 and resuspend the single CPCs in 300 &#956;L of 10% FBS in PBS containing 1:200 (vol/vol) PerCP-efluor 710 conjugated anti-Cxcr4 antibody.</li>
	<li>Incubate at room temperature for 5min and wash by adding 1-2 mL of cold PBS. Centrifuge the single CPCs for 3 min at 270 x g and room temperature and wash two more times followed by centrifugation.</li>
	<li>Aspirate the supernatant and add 500 &#956;L of FACS sorting solution to resuspend the single CPCs and filter as in step 3.4.</li>
	<li>Isolate Cxcr4+ and Cxcr4- cells using FACS. Collect the sorted cells in 1 mL of FBS. Keep the cell sample and sorted cells at 4 &#176;C.</li>
</ol>
5. Analysis of Isolated Heart Field Specific Cardiac Progenitor Cells
<ol>
	<li>Centrifuge sorted CPCs for 3 min at 270 x g and room temperature. Sorted cells can be used for gene and protein expression analyses or they can be recultured for analyses at later time points.&#160;</li>
	<li>To re-culture isolated CPCs, aspirate the supernatant, resuspend the cells in SFD medium and replate ~3 x 104 cells per well of a 384-well plate coated with 0.1% (w/v) gelatin.&#160; If increased cell death is noted after sorting, add 10 &#956;M of Y-27632 (ROCK inhibitor) to the sample. Two days after reculture, spontaneous beating should be noted.</li>
	<li>To analyze the ability of plated CPCs to differentiate to cardiomyocytes, collect the cells at day 12 of differentiation. Use Trypsin as described in steps 1.2-1.5 to isolate single CMs. Resuspend the cells in 4% (w/v) paraformaldehyde (PFA) and incubate for 30 min at room temperature to fix the cells.</li>
	<li>Centrifuge the cells for 3 min at 895 x g, and room temperature. Aspirate the supernatant and resuspend the cells in PBS to wash the PFA. Repeat this step once more.</li>
	<li>Aspirate the supernatant and resuspend the cells in 10% FBS in PBS. Incubate half of the cell sample with mouse anti-Troponin T antibody (1:500) and use the rest of the sample as a negative control. Incubate for 30 min at room temperature.</li>
	<li>Wash the cells twice as described in step 5.4 using PBS. Aspirate the supernatant and resuspend both cell samples in 10% FBS in PBS with 1:500 donkey anti-mouse IgG (H+L) secondary antibody, Alexa Fluor 647 conjugate. Incubate for 30 min at room temperature.</li>
	<li>Wash twice with PBS as in step 5.6. Aspirate the supernatant and resuspend the cells in 200 &#956;L of PBS. Use a flow cytometer to analyze the cells.</li>
</ol>

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The authors have nothing for disclosures.

In our protocol, we describe a methodology to generate cardiac spheroids and isolated heart field-specific CPCs. Those can be used to study mechanisms of CPC specification and their properties, as well as for cardiac chamber-specific disease modelling. One previously published work used a mESC line with two fluorescent reporters (Mef2c/Nkx2.5) to study cardiogenesis in vitro, however, both those markers are expressed at embryonic day 9.5-10 when cardiomyocytes are already formed26. To our knowledg...

The use of pluripotent stem cells (PSCs) has revolutionized the field of cardiac regeneration and personalized medicine with patient-specific myocytes for disease modeling and drug therapies1,2,3,4. More recently, in vitro protocols for the generation of atrial vs ventricular as well as pacemaker-like PSC-derived cardiomyocytes have been developed5,6. However, whether cardiogenesis can be recreated in vitro to study cardiac development and subsequently generate ventricular chamber-specific cardiac cells is still unclear.
During early embryonic development, mesodermal cells under the influence of secreted morphogens such as BMP4, Wnts and Activin A form the primitive streak7. Cardiac mesodermal cells marked by the expression of Mesp1, migrate anteriorly and latterly to form the cardiac crescent and then the primitive heart tube7,8. This migratory group of cells includes two very distinct populations of cardiac progenitor cells (CPCs), namely the first and the second heart field (FHF and SHF)9,10. Cells from the SHF are highly proliferative and migratory and are primarily responsible for the elongation and looping of the heart tube. Additionally, SHF cells differentiate to cardiomyocytes, fibroblasts, smooth muscle and endothelial cells as they enter the heart tube to form the right ventricle, right ventricular outflow tract and large part of both atria7,10. In contrast, FHF cells are less proliferative and migratory and differentiate mainly to cardiomyocytes as they give rise to the left ventricle and a smaller part of the atria11. Moreover, SHF progenitors are marked by the expression of Tbx1, FGF8, FGF10 and Six2 while FHF cells express Hcn4 and Tbx511,12,13,14,15.
PSCs can differentiate to all three germ layers and subsequently to any cell type in the body4,16. Therefore, they offer tremendous potential for understanding heart development and for modelling specific developmental defects resulting in congenital heart disease, the most frequent cause of birth defects17. A large subgroup of congenital heart disease includes chamber-specific cardiac abnormalities18,19. However, it still unclear whether these originate from anomalous heart field development. In addition, given the inability of cardiomyocytes to proliferate after birth, there have been extensive efforts to create cardiac tissue for heart regeneration1,7,20. Considering the physiological and morphological differences between cardiac chambers, generation of chamber-specific cardiac tissue using PSCs is of significant importance. While recent advances in developmental cardiology have led to robust generation of cardiac cells from PSCs, it is still unclear if the two heart fields can be induced in PSC systems.
To recapitulate cardiogenesis in vitro and study the specification and properties of CPCs, we previously used a system based on differentiating PSC-derived cardiac spheroids21,22,23,24. Recently, we generated mouse embryonic stem cells (mESCs) with GFP and RFP reporters under the control of the FHF gene Hcn4 and the SHF gene Tbx1, respectively (mESCsTbx1-Cre; Rosa-RFP; HCN4-GFP) 25. In vitro differentiated mESCs formed cardiac spheroids in which GFP+ and RFP+ cells appeared from two distinct areas of mesodermal cells and patterned in a complementary manner. The resulting GFP+ and RFP+ cells exhibited FHF and SHF characteristics, respectively, determined by RNA-sequencing and clonal analyses. Importantly, using mESCs carrying the Isl1-RFP reporter (mESCIsl1-RFP), we discovered that SHF cells were faithfully marked by the cell-surface protein CXCR4, and this can enable isolation of heart field-specific cells without transgenes. The present protocol will describe the generation and isolation of heart field-specific CPCs from mESCs, which may serve as a valuable tool for studying chamber-specific heart disease.

<table border="0" cellpadding="0" cellspacing="0" style="width:1251px;" width="1250">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:420px;">&#946;-mercaptoethanol</td>
			<td style="width:245px;">Sigma</td>
			<td style="width:344px;">M6250</td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">0.1% (w/v) Gelatin</td>
			<td>EMD Millipore</td>
			<td>ES-006-B</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">100mM Sodium Pyruvate</td>
			<td>Gibco</td>
			<td align="right">11360</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">100X Pen/Strep</td>
			<td>Gibco</td>
			<td>15070-063</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">1X PBS w/o Calcium and Magnesium</td>
			<td>Thermo Fisher Scientific</td>
			<td>21-040-CV</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">20% Paraformaldehyde</td>
			<td>Thermo Fisher Scientific</td>
			<td>50-980-493</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:420px;">5 ml Polystyrene round-bottom tube with a 40&#956;m cell strainer</td>
			<td>BD Falcon</td>
			<td align="right">35223</td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Activin A</td>
			<td>R &#38; D Systems</td>
			<td>338-AC-010</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Ascorbic Acid</td>
			<td>Sigma</td>
			<td>A-4544</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">B27 minus vitamin A (50x)</td>
			<td>Thermo Fisher Scientific</td>
			<td align="right">12587010</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">BMP4</td>
			<td>R &#38; D Systems</td>
			<td>314-BP</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Bovine Serum Albumin</td>
			<td>Sigma</td>
			<td>A2153</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:420px;">Cell sorter</td>
			<td style="width:245px;">Sony</td>
			<td style="width:344px;">SH800</td>
			<td style="width:241px;">Sony or any other fluorescence-activated cell sorter</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:420px;">Cell strainer 70&#956;m</td>
			<td>Thermo Fisher Scientific</td>
			<td>08-771-2</td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Centrifuge Sorvall Legend XT</td>
			<td>Thermo Fisher Scientific</td>
			<td align="right">75004508</td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">CHIR99021</td>
			<td>Selleck chemicals</td>
			<td>S2924</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:420px;">CO2 Incubator</td>
			<td>Thermo Fisher Scientific</td>
			<td align="right">51030285</td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Corning Ultra Low Attachment T75 flask</td>
			<td>Corning</td>
			<td>07-200-875</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Countless II FL automated cell counter</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Donkey anti-mouse IgG secondary antibody, Alexa Fluor 647 conjugate</td>
			<td>Thermo Fisher Scientific</td>
			<td>A-31571, Lot #1757130</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Dulbecco&#39;s Modified Eagle&#39;s Medium high glucose (DMEM)</td>
			<td>Gibco</td>
			<td>11965-092</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA</td>
			<td>Sigma</td>
			<td>E6758</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ESGRO (LIF)</td>
			<td>Millipore</td>
			<td>ESG1106</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EVOS FL microscope</td>
			<td>Thermo Fisher Scientific</td>
			<td>AMF4300</td>
			<td style="width:241px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal Bovine Serum</td>
			<td>Invitrogen</td>
			<td>SH30071.03</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glasgow&#8217;s MEM (GMEM)</td>
			<td>Gibco</td>
			<td align="right">11710035</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GlutaMAX (100 x)</td>
			<td>Gibco</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ham&#8217;s F12</td>
			<td>Gibco</td>
			<td>10-080-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HEPES</td>
			<td>Sigma</td>
			<td>H3375</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">IMDM</td>
			<td>Gibco</td>
			<td align="right">12440053</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Monothioglycero (MTG)</td>
			<td>Sigma</td>
			<td>M-6145</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse anti-Troponin T antibody</td>
			<td>Thermo Fisher Scientific</td>
			<td>MS-295-P1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">N2-SUPPLEMENT</td>
			<td>Gibco</td>
			<td>17502-048</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Non-essential amino acid solution (NEAA</td>
			<td>Invitrogen</td>
			<td>11140-050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PD0325901</td>
			<td>Selleckchem</td>
			<td>S1036</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PerCP-efluor 710 conjugated anti-Cxcr4 antibody</td>
			<td>Thermo Fisher Scientific</td>
			<td>46-9991-82</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Suspension culture dish 150 mm x 25mm</td>
			<td>Corning</td>
			<td align="right">430597</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">T25 flasks</td>
			<td>Corning</td>
			<td align="right">353109</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TrypLE (Trypsin)</td>
			<td>Gibco</td>
			<td align="right">12604</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Y-27632 (ROCK inhibitor)</td>
			<td>Stem cell technologies</td>
			<td align="right">72304</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vitro generation of heart field-specific cardiac progenitor cells

Pluripotent stem cells offer great potential for understanding heart development and disease and for regenerative medicine. While recent advances in developmental cardiology have led to generating cardiac cells from pluripotent stem cells, it is unclear if the two cardiac fields - the first and second heart fields (FHF and SHF) &#8212; are induced in pluripotent stem cells systems. To address this, we generated a protocol for in vitro specification and isolation of heart field-specific cardiac progenitor cells. We used embryonic stem cells lines carrying Hcn4-GFP and Tbx1-Cre; Rosa-RFP reporters of the FHF and the SHF, respectively, and live cell immunostaining of the cell membrane protein Cxcr4, a SHF marker. With this approach, we generated progenitor cells which recapitulate the functional properties and transcriptome of their in vivo counterparts. Our protocol can be utilized to study early specification and segregation of the two heart fields and to generate chamber-specific cardiac cells for heart disease modelling. Since this is an in vitro organoid system, it may not provide precise anatomical information. However, this system overcomes the poor accessibility of gastrulation-stage embryos and can be upscaled for high-throughput screens.

After approximately 132 h of differentiation, Tbx1-RFP and Hcn4-GFP CPCs can be detected using a fluorescent microscope (Figure 2). Generally, GFP and RFP cells appear approximately around the same time. The two populations of CPCs continue to expand in close proximity and commonly in a complementary pattern. Adjusting the concentrations of Activin A and BMP4 will alter the percentages of FHF vs SHF CPCs (Figure 3). CPC specification in vitro was primarily deter...

Watch this Scientific Journal Video about In Vitro Generation of Heart Field-specific Cardiac Progenitor Cells at JoVE.com

In Vitro Generation of Heart Field-specific Cardiac Progenitor Cells

The purpose of this method is to generate heart field-specific cardiac progenitor cells in vitro in order to study the progenitor cell specification and functional properties, and to generate chamber specific cardiac cells for heart disease modelling.

Pluripotent stem cells offer great potential for understanding heart development and disease and for regenerative medicine. While recent advances in ...

in-vitro-generation-of-heart-field-specific-cardiac-progenitor-cells

Research

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Developmental Biology

6.2K Views.  Johns Hopkins School of Medicine. The purpose of this method is to generate heart field-specific cardiac progenitor cells in vitro in order to study the progenitor cell specification and functional properties, and to generate chamber specific cardiac cells for heart disease modelling.

Video: In Vitro Generation of Heart Field-specific Cardiac Progenitor Cells

Derivation of Cardiac Progenitor Cells from Embryonic Stem Cells

Cardiac progenitor cells (CPCs) have the capacity to differentiate into cardiomyocytes, smooth muscle cells (SMC), and endothelial cells and hold great promise in cell therapy against heart disease. Among various methods to isolate CPCs, differentiation of embryonic stem cell (ESC) into CPCs attracts great attention in the field since ESCs can provide unlimited cell source. As a result, numerous strategies have been developed to derive CPCs from ESCs. In this protocol, differentiation and purification of embryonic CPCs from both mouse and human ESCs is described. Due to the difficulty of using cell surface markers to isolate embryonic CPCs, ESCs are engineered with fluorescent reporters activated by CPC-specific cre recombinase expression. Thus, CPCs can be enriched by fluorescence-activated cell sorting (FACS). This protocol illustrates procedures to form embryoid bodies (EBs) from ESCs for CPC specification and enrichment. The isolated CPCs can be subsequently cultured for cardiac lineage differentiation and other biological assays. This protocol is optimized for robust and efficient derivation of CPCs from both mouse and human ESCs.

In this protocol, derivation of cardiac progenitor cells from both mouse and human embryonic stem cells will be illustrated. A major strategy in this protocol is to enrich cardiac progenitor cells with flow cytometry using fluorescent reporters engineered into the embryonic stem cell lines.

Cardiac progenitor cells (CPCs) have the capacity to differentiate into cardiomyocytes, smooth muscle cells (SMC), and endothelial cells and hold great ...

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Treatment of the &#8220;sick sinus syndrome&#8221; is based on artificial pacemakers. These bear hazards such as battery failure and infections. Moreover, they lack hormone responsiveness and the overall procedure is cost-intensive. &#8220;Biological pacemakers&#8221; generated from PSCs may become an alternative, yet the typical content of pacemaker cells in Embryoid Bodies (EBs) is extremely low. The described protocol combines &#8220;forward programming&#8221; of murine PSCs via the sinus node inducer TBX3 with Myh6-promoter based antibiotic selection. This yields cardiomyocyte aggregates consistent of &#62;80% physiologically functional pacemaker cells. These &#8220;induced-sinoatrial-bodies&#8221; (&#8220;iSABs&#8221;) are spontaneously contracting at yet unreached frequencies (400-500 bpm) corresponding to nodal cells isolated from mouse hearts and are able to pace murine myocardium ex vivo. Using the described protocol highly pure sinus nodal single cells can be generated which e.g. can be used for in vitro drug testing. Furthermore, the iSABs generated according to this protocol may become a crucial step towards heart tissue engineering.

This protocol describes how to produce functional sinus nodal tissue from murine pluripotent stem cells (PSC). T-Box3 (TBX3) overexpression plus cardiac Myosin-heavy-chain (Myh6) promoter antibiotic selection leads to highly pure pacemaker cell aggregates. These &#8220;Induced-sinoatrial-bodies&#8221; (&#8220;iSABs&#8221;) contain over 80% pacemaker cells, show highly increased beating rates and are able to pace myocardium ex vivo.

Treatment of the &#8220;sick sinus syndrome&#8221; is based on artificial pacemakers. These bear hazards such as battery failure and infections. Moreover, ...

Initiating Differentiation in Immortalized Multipotent Otic Progenitor Cells

Use of human induced pluripotent stem cells (iPSC) or embryonic stem cells (ESC) for cell replacement therapies holds great promise. Several limitations including low yields and heterogeneous populations of differentiated cells hinder the progress of stem cell therapies. A fate restricted immortalized multipotent otic progenitor (iMOP) cell line was generated to facilitate efficient differentiation of large numbers of functional hair cells and spiral ganglion neurons (SGN) for inner ear cell replacement therapies. Starting from dissociated cultures of single iMOP cells, protocols that promote cell cycle exit and differentiation by basic fibroblast growth factor (bFGF) withdrawal were described. A significant decrease in proliferating cells after bFGF withdrawal was confirmed using an EdU cell proliferation assay. Concomitant with a decrease in proliferation, successful differentiation resulted in expression of molecular markers and morphological changes. Immunostaining of Cdkn1b (p27KIP) and Cdh1 (E-cadherin) in iMOP-derived otospheres was used as an indicator for differentiation into inner ear sensory epithelia while immunostaining of Cdkn1b and Tubb3 (neuronal &#946;-tubulin) was used to identify iMOP-derived neurons. Use of iMOP cells provides an important tool for understanding cell fate decisions made by inner ear neurosensory progenitors and will help develop protocols for generating large numbers of iPSC or ESC-derived hair cells and SGNs. These methods will accelerate efforts for generating otic cells for replacement therapies.

The current protocols to maintain immortalized multipotent otic progenitor (iMOP) cells and otic differentiation are described. Culture conditions and molecular markers that indicate differentiation into sensory epithelia and spiral ganglion neurons (SGN) are highlighted.

Use of human induced pluripotent stem cells (iPSC) or embryonic stem cells (ESC) for cell replacement therapies holds great promise. Several limitations ...

In Vitro Colony Assays for Characterizing Tri-potent Progenitor Cells Isolated from the Adult Murine Pancreas

Stem and progenitor cells from the adult pancreas could be a potential source of therapeutic beta-like cells for treating patients with type 1 diabetes. However, it is still unknown whether stem and progenitor cells exist in the adult pancreas. Research strategies using cre-lox lineage-tracing in adult mice have yielded results that either support or refute the idea that beta cells can be generated from the ducts, the presumed location where adult pancreatic progenitors may reside. These in vivo cre-lox lineage-tracing methods, however, cannot answer the questions of self-renewal and multi-lineage differentiation-two criteria necessary to define a stem cell. To begin addressing this technical gap, we devised 3-dimensional colony assays for pancreatic progenitors. Soon after our initial publication, other laboratories independently developed a similar, but not identical, method called the organoid assay. Compared to the organoid assay, our method employs methylcellulose, which forms viscous solutions that allow the inclusion of extracellular matrix proteins at low concentrations. The methylcellulose-containing assays permit easier detection and analyses of progenitor cells at the single-cell level, which are critical when progenitors constitute a small sub-population, as is the case for many adult organ stem cells. Together, results from several laboratories demonstrate in vitro self-renewal and multi-lineage differentiation of pancreatic progenitor-like cells from mice. The current protocols describe two methylcellulose-based colony assays to characterize mouse pancreatic progenitors; one contains a commercial preparation of murine extracellular matrix proteins and the other an artificial extracellular matrix protein known as a laminin hydrogel. The techniques shown here are 1) dissociation of the pancreas and sorting of CD133+Sox9/EGFP+ ductal cells from adult mice, 2) single cell manipulation of the sorted cells, 3) single colony analyses using microfluidic qRT-PCR and whole-mount immunostaining, and 4) dissociation of primary colonies into single-cell suspensions and re-plating into secondary colony assays to assess self-renewal or differentiation.

In Vitro Colony Assays for Characterizing Tri-potent Progenitor Cells Isolated from the Adult Murine Pancreas

In vitro colony assays to detect self-renewal and differentiation of progenitor cells isolated from adult murine pancreas are devised. In these assays, pancreatic progenitors give rise to cell colonies in 3-dimensional space in methylcellulose-containing semi-solid medium. Protocols for handling single cells and characterization of individual colonies are described.

Stem and progenitor cells from the adult pancreas could be a potential source of therapeutic beta-like cells for treating patients with type 1 diabetes. ...

Hypoxic Preconditioning of Marrow-derived Progenitor Cells As a Source for the Generation of Mature Schwann Cells

This manuscript describes a means to enrich for neural progenitors from the marrow stromal cell (MSC) population and thereafter to direct them to the mature Schwann cell fate. We subjected rat and human MSCs to transient hypoxic conditions (1% oxygen for 16 h) followed by expansion as neurospheres upon low-attachment substratum with epidermal growth factor (EGF)/basic fibroblast growth factor (bFGF) supplementation. Neurospheres were seeded onto poly-D-lysine/laminin-coated tissue culture plastic and cultured in a gliogenic cocktail containing &#946;-Heregulin, bFGF, and platelet-derived growth factor (PDGF) to generate Schwann cell-like cells (SCLCs). SCLCs were directed to fate commitment via coculture for 2 weeks with purified dorsal root ganglia (DRG) neurons obtained from E14-15 pregnant Sprague Dawley rats. Mature Schwann cells demonstrate persistence in S100&#946;/p75 expression and can form myelin segments. Cells generated in this manner have potential applications in autologous cell transplantation following spinal cord injury, as well as in disease modeling.

Marrow stromal cells (MSCs) with neural potential exist within the bone marrow. Our protocol enriches this population of cells via hypoxic preconditioning and thereafter directs them to become mature Schwann cells.

This manuscript describes a means to enrich for neural progenitors from the marrow stromal cell (MSC) population and thereafter to direct them to the ...

Quantitative Whole-mount Immunofluorescence Analysis of Cardiac Progenitor Populations in Mouse Embryos

The use of ever-advancing imaging techniques has contributed broadly to our increased understanding of embryonic development. Pre-implantation development and organogenesis are two areas of research that have benefitted greatly from these advances, due to the high quality of data that can be obtained directly from imaging pre-implantation embryos or ex vivo organs. While pre-implantation embryos have yielded data with especially high spatial resolution, later stages have been less amenable to three-dimensional reconstruction. Obtaining high-quality 3D or volumetric data for known embryonic structures in combination with fate mapping or genetic lineage tracing will allow for a more comprehensive analysis of the morphogenetic events taking place during embryogenesis.
This protocol describes a whole-mount immunofluorescence approach that allows for the labeling, visualization, and quantification of progenitor cell populations within the developing cardiac crescent, a key structure formed during heart development. The approach is designed in such a way that both cell- and tissue-level information can be obtained. Using confocal microscopy and image processing, this protocol allows for three-dimensional spatial reconstruction of the cardiac crescent, thereby providing the ability to analyze the localization and organization of specific progenitor populations during this critical phase of heart development. Importantly, the use of reference antibodies allows for successive masking of the cardiac crescent and subsequent quantitative measurements of areas within the crescent. This protocol will not only enable a detailed examination of early heart development, but with adaptations should be applicable to most organ systems in the gastrula to early somite stage mouse embryo.

Here, we describe a protocol for whole mount immunofluorescence and image-based quantitative volumetric analysis of early stage mouse embryos. We present this technique as a powerful approach to qualitatively and quantitatively assess cardiac structures during development, and propose that it may be widely adaptable to other organ systems.

The use of ever-advancing imaging techniques has contributed broadly to our increased understanding of embryonic development. Pre-implantation development ...

Development of an In Vitro Assay to Quantitate Hematopoietic Stem and Progenitor Cells (HSPCs) in Developing Zebrafish Embryos

Hematopoiesis is an essential cellular process in which hematopoietic stem and progenitor cells (HSPCs) differentiate into the multitude of different cell lineages that comprise mature blood. Isolation and identification of these HSPCs is difficult because they are defined ex post facto; they can only be defined after their differentiation into specific cell lineages. Over the past few decades, the zebrafish (Danio rerio) has become a model organism to study hematopoiesis. Zebrafish embryos develop ex utero, and by 48 h post-fertilization (hpf) have generated definitive HSPCs. Assays to assess HSPC differentiation and proliferation capabilities have been developed, utilizing transplantation and subsequent reconstitution of the hematopoietic system in addition to visualizing specialized transgenic lines with confocal microscopy. However, these assays are cost prohibitive, technically difficult, and time consuming for many laboratories. Development of an in vitro model to assess HSPCs would be cost effective, quicker, and present fewer difficulties compared to previously described methods, allowing laboratories to quickly assess mutagenesis and drug screens that affect HSPC biology. This novel in vitro assay to assess HSPCs is performed by plating dissociated whole zebrafish embryos and adding exogenous factors that promote only HSPC differentiation and proliferation. Embryos are dissociated into single cells and plated with HSPC-supportive colony stimulating factors that cause them to generate colony forming units (CFUs) that arise from a single progenitor cell. These assays should allow more careful examination of the molecular pathways responsible for HSPC proliferation, differentiation, and regulation, which will allow researchers to understand the underpinnings of vertebrate hematopoiesis and its dysregulation during disease.

Development of an In Vitro Assay to Quantitate Hematopoietic Stem and Progenitor Cells HSPCs in Developing Zebrafish Embryos

Here, we present a simple method to quantitate hematopoietic stem and progenitor cells (HSPCs) in embryonic zebrafish. HSPCs from dissociated zebrafish are plated in methylcellulose with supportive factors, differentiating into mature blood. This allows the detection of blood defects and allows drug screening to be easily conducted.

Hematopoiesis is an essential cellular process in which hematopoietic stem and progenitor cells (HSPCs) differentiate into the multitude of different cell ...

Generation of First Heart Field-like Cardiac Progenitors and Ventricular-like Cardiomyocytes from Human Pluripotent Stem Cells

The generation of large amounts of functional human pluripotent stem cells-derived cardiac progenitors and cardiomyocytes of defined heart field origin is a pre-requisite for cell-based cardiac therapies and disease modeling. We have recently shown that Id genes are both necessary and sufficient to specify first heart field progenitors during vertebrate development. This differentiation protocol leverages these findings and uses Id1 overexpression in combination with Activin A as potent specifying cues to produce first heart field-like (FHF-L) progenitors. Importantly, resulting progenitors efficiently differentiate (~70&#8211;90%) into ventricular-like cardiomyocytes. Here we describe a detailed method to 1) generate Id1-overexpressing hPSCs and 2) differentiate scalable quantities of cryopreservable FHF-L progenitors and ventricular-like cardiomyocytes.

Here we describe a scalable method, using a simple combination of Activin A and lentivirus-mediated Id1-overexpression, to generate first heart field-like cardiac progenitors and ventricular-like cardiomyocytes from human pluripotent stem cells.

The generation of large amounts of functional human pluripotent stem cells-derived cardiac progenitors and cardiomyocytes of defined heart field origin is ...

Induction of Endothelial Differentiation in Cardiac Progenitor Cells Under Low Serum Conditions

Cardiac progenitor cells (CPCs) may have therapeutic potential for cardiac regeneration after injury. In the adult mammalian heart, intrinsic CPCs are extremely scarce, but expanded CPCs could be useful for cell therapy. A prerequisite for their use is their ability to differentiate in a controlled manner into the various cardiac lineages using defined and efficient protocols. In addition, upon in vitro expansion, CPCs isolated from patients or preclinical disease models may offer fruitful research tools for the investigation of disease mechanisms.
Current studies use different markers to identify CPCs. However, not all of them are expressed in humans, which limits the translational impact of some preclinical studies. Differentiation protocols that are applicable irrespective of the isolation technique and marker expression will allow for the standardized expansion and priming of CPCs for cell therapy purpose. Here we describe that the priming of CPCs under a low fetal bovine serum (FBS) concentration and low cell density conditions facilitates the endothelial differentiation of CPCs. Using two different subpopulations of mouse and rat CPCs, we show that laminin is a more suitable substrate than fibronectin for this purpose under the following protocol: after culturing for 2 - 3 days in medium including supplements that maintain multipotency and with 3.5% FBS, CPCs are seeded on laminin at &#60;60% confluence and cultured in supplement-free medium with low concentrations of FBS (0.1%) for 20 - 24 hours before differentiation in endothelial differentiation medium. Because CPCs are a heterogeneous population, serum concentrations and incubation times may need to be adjusted depending on the properties of the respective CPC subpopulation. Considering this, the technique can be applied to other types of CPCs as well and provides a useful method to investigate the potential and mechanisms of differentiation and how they are affected by disease when using CPCs isolated from respective disease models.

This protocol describes an endothelial differentiation technique for cardiac progenitor cells. It particularly focuses on how serum concentration and cell-seeding density affect the endothelial differentiation potential.

Cardiac progenitor cells (CPCs) may have therapeutic potential for cardiac regeneration after injury. In the adult mammalian heart, intrinsic CPCs are ...

In Vitro Generation of Somite Derivatives from Human Induced Pluripotent Stem Cells

In response to signals such as WNTs, bone morphogenetic proteins (BMPs), and sonic hedgehog (SHH) secreted from surrounding tissues, somites (SMs) give rise to multiple cell types, including the myotome (MYO), sclerotome (SCL), dermatome (D), and syndetome (SYN), which in turn develop into skeletal muscle, axial skeleton, dorsal dermis, and axial tendon/ligament, respectively. Therefore, the generation of SMs and their derivatives from human induced pluripotent stem cells (iPSCs) is critical to obtain pluripotent stem cells (PSCs) for application in regenerative medicine and for disease research in the field of orthopedic surgery. Although the induction protocols for MYO and SCL from PSCs have been previously reported by several researchers, no study has yet demonstrated the induction of SYN and D from iPSCs. Therefore, efficient induction of fully competent SMs remains a major challenge. Here, we recapitulate human SM patterning with human iPSCs in vitro by mimicking the signaling environment during chick/mouse SM development, and report on methods of systematic induction of SM derivatives (MYO, SCL, D, and SYN) from human iPSCs under chemically defined conditions through the presomitic mesoderm (PSM) and SM states. Knowledge regarding chick/mouse&#160;SM development was successfully applied to the induction of SMs with human iPSCs. This method could be a novel tool for studying human somitogenesis and patterning without the use of embryos and for cell-based therapy and disease modeling.

We present here a protocol for the differentiation of human induced pluripotent stem cells into each somite derivative (myotome, sclerotome, dermatome, and syndetome) in chemically defined conditions, which has applications in future disease modeling and cell-based therapies in orthopedic surgery.

In response to signals such as WNTs, bone morphogenetic proteins (BMPs), and sonic hedgehog (SHH) secreted from surrounding tissues, somites (SMs) give ...