This work was funded by a New Faculty Award II from the California Institute of Regenerative Medicine (RN2-00921-1), and an NIH-funded National Research Award (F32-HL104924)

1. Preparation of Mouse Embryonic Feeders
<ol>
 <li>The MEFs used in the co-culture of hESCs should be previously treated by irradiation or Mitomycin-C to inhibit the cells from undergoing division.</li>
 <li>Two hours prior to MEF seeding, coat each 60 mm plasma treated culture dish with 2 ml of 0.05% Gelatin.</li>
 <li>Thaw a vial of treated MEFs and plate at ~20,000 cells/cm2.</li>
 <li>Allow the cells to adhere overnight.</li>
</ol>
2. Co-seeding hESCS onto MEFs
<ol>
 <li>New co...

<ol>
	<li>Bongso, A., Fong, C. Y., Ng, S. C., Ratnam, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+culture+of+inner+cell+mass+cells+from+human+blastocysts.">Isolation and culture of inner cell mass cells from human blastocysts.</a> Hum. Reprod. 9, 2110-2117 (1994).</li><li>Reubinoff, B. E., Pera, M. F., Fong, C. Y., Trounson, A., Bongso, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+stem+cell+lines+from+human+blastocysts:+somatic+differentiation+in+vitro.">Embryonic stem cell lines from human blastocysts: somatic differentiation in vitro.</a> Nat. Biotechnol. 18, 399-404 (2000).</li><li>Thomson, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+stem+cell+lines+derived+from+human+blastocysts.">Embryonic stem cell lines derived from human blastocysts.</a> Science. 282, 1145-1147 (1998).</li><li>Thomas, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated,+scalable+culture+of+human+embryonic+stem+cells+in+feeder-free+conditions.">Automated, scalable culture of human embryonic stem cells in feeder-free conditions.</a> Biotechnol Bioeng. 102, 1636-1644 (2009).</li><li>Kolhar, P., Kotamraju, V. R., Hikita, S. T., Clegg, D. O., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+surfaces+for+human+embryonic+stem+cell+culture.">Synthetic surfaces for human embryonic stem cell culture.</a> J. Biotechnol. 146, 143-146 (2010).</li><li>Hovatta, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+culture+system+using+human+foreskin+fibroblasts+as+feeder+cells+allows+production+of+human+embryonic+stem+cells.">A culture system using human foreskin fibroblasts as feeder cells allows production of human embryonic stem cells.</a> Hum. Reprod. 18, 1404-1409 (2003).</li><li>McKay, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+feeder+cell+line+for+derivation+and+culture+of+hESc/hiPSc.">Human feeder cell line for derivation and culture of hESc/hiPSc.</a> Stem Cell Res. 7, 154-162 (2011).</li><li>Xu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feeder-free+growth+of+undifferentiated+human+embryonic+stem+cells.">Feeder-free growth of undifferentiated human embryonic stem cells.</a> Nat. Biotechnol. 19, 971-974 (2001).</li><li>Stein, G. S., Shi, M. J., Stencel, K., Borowski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Thawing, Seeding, and Changing Medium of Human Embryonic Stem Cells. , (2010).</li><li>Schwartz, P. H., Brick, D. J., Nethercott, H. E., Stover, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traditional+human+embryonic+stem+cell+culture.">Traditional human embryonic stem cell culture.</a> Methods Mol. Biol. 767, 107-123 .</li></ol>

No conflicts of interest declared.

The method presented in this manuscript offers a rapid and less costly alternative to eliminating fibroblast feeder cells from human embryonic cell cultures. The successful removal of fibroblasts is dependent on the existence of a tightly confluent monolayer of these cells that develops in longer stem cell cultures. After 7-10 days, the growing hESC colonies will push the feeder fibroblasts in an outward direction, generating an increasingly dense fibroblast monolayer between colonies. The strong cell-to-cell attachments...

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments (optional)</td>
		</tr>
		<tr>
			<td>DDR2</td>
			<td>Santa Cruz</td>
			<td>7555</td>
			<td>Fibroblast Marker</td>
		</tr>
		<tr>
			<td>Dapi</td>
			<td>Calbiochem</td>
			<td>268298</td>
			<td>Cell Nucleus Marker</td>
		</tr>
		<tr>
			<td>SSEA-4</td>
			<td>Millipore</td>
			<td>MAB4304</td>
			<td>Human ESC Marker</td>
		</tr>
		<tr>
			<td>Oct 3/4</td>
			<td>Santa Cruz</td>
			<td>9081</td>
			<td>Human ESC Marker</td>
		</tr>
		<tr>
			<td>Flk-1</td>
			<td>BD Pharma</td>
			<td>555307</td>
			<td>Early Differentiation Marker</td>
		</tr>
		<tr>
			<td>Tra-1-81</td>
			<td>Acris</td>
			<td>AM20377AF4-S</td>
			<td>Human ESC Marker</td>
		</tr>
	</tbody>
</table>
Table 1. Table of specific reagents used for immunostaining the hESC.

rapid fibroblast removal from high density human embryonic stem cell cultures

Mouse embryonic fibroblasts (MEFs) were used to establish human embryonic stem cells (hESCs) cultures after blastocyst isolation1. This feeder system maintains hESCs from undergoing spontaneous differentiation during cell expansion. However, this co-culture method is labor intensive, requires highly trained personnel, and yields low hESC purity4. Many laboratories have attempted to minimize the number of feeder cells in hESC cultures (i.e. incorporating matrix-coated dishes or other feeder cell types5-8). These modified culture systems have shown some promise, but have not supplanted the standard method for culturing hESCs with mitomycin C-treated mouse embyronic fibroblasts in order to retard unwanted spontaneous differentiation of the hESC cultures. Therefore, the feeder cells used in hESC expansion should be removed during differentiation experiments. Although several techniques are available for purifying the hESC colonies (FACS, MACS, or use of drug resistant vectors) from feeders, these techniques are labor intensive, costly and/or destructive to the hESC. The aim of this project was to invent a method of purification that enables the harvesting of a purer population of hESCs. We have observed that in a confluent hESC culture, the MEF population can be removed using a simple and rapid aspiration of the MEF sheet. This removal is dependent on several factors, including lateral cell-to-cell binding of MEFs that have a lower binding affinity to the styrene culture dish, and the ability of the stem cell colonies to push the fibroblasts outward during the generation of their own "niche". The hESC were then examined for SSEA-4, Oct3/4 and Tra 1-81 expression up to 10 days after MEF removal to ensure maintenance of pluripotency. Moreover, hESC colonies were able to continue growing from into larger formations after MEF removal, providing an additional level of hESC expansion.

Watch this Scientific Journal Video about Rapid Fibroblast Removal from High Density Human Embryonic Stem Cell Cultures at JoVE.com

Rapid Fibroblast Removal from High Density Human Embryonic Stem Cell Cultures

Despite ongoing efforts to transition cultures to feeder-free conditions, the derivation and culture of human embryonic stem cells (hESC) remain largely dependent on co-cultures with mouse embryonic feeders (MEFs). Here, we show a novel methodology for rapidly removing feeders from hESC cultures prior to experimentation.

Mouse embryonic fibroblasts (MEFs) were used to establish human embryonic stem cells (hESCs) cultures after blastocyst isolation1. This feeder system ...

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11.7K Views.  University of California, Merced. Despite ongoing efforts to transition cultures to feeder-free conditions, the derivation and culture of human embryonic stem cells (hESC) remain largely dependent on co-cultures with mouse embryonic feeders (MEFs). Here, we show a novel methodology for rapidly removing feeders from hESC cultures prior to experimentation.