The authors would like to thank Soon-Cheol Hong (M.D., Ph.D., Associate Professor, Department of Obstetrics and Gynecology, Medical College Korea University) for providing placental tissue. This work was supported in part by grants (R1211902) from the National Research Foundation of Korea (NRF), Republic of Korea.

Ethics statement: The human placenta study was conducted prospectively, with the approval of the Institutional Review Board for human research of the Korea University (AN09085-001). All experiments were performed in a Clean Germ-Free Room facility at the Korea University Medical Center. The experimental design and procedures using hPSCs were approved by the Institutional Review Board of the Korea University Medical Center (AN12277-003).
1. Preparation of Instruments, Culture Media, and Dishes
<ol>
	<li>Coat all the culture dishes with 0.1% gelatin. Autoclave phosphate-buffered saline (PBS) and forceps. Sterilize surgical scissors, microcentrifuge tubes, and gauze at 121 &#176;C under 15lb psi for more than 15 min.</li>
	<li>Prepared pre-warmed 0.25% trypsin-ethylene amine tetra-acetic acid (trypsin-EDTA) and pre-warmed filtered culture media (DMEM) containing 20% fetal bovine serum (FBS), 100 U/ml penicillin, and 100 g/ml streptomycin before commencing procedures.</li>
</ol>
2. Cell Isolation from Human Placenta
<ol>
	<li>Obtain placental tissue, after caesarean section delivery, from healthy pregnant women undergoing normal or therapeutic abortion at 7&#8211;32 weeks of gestation after obtaining written informed consent.</li>
	<li>Have the obstetric specialist surgically separate human placenta chorionic plates (HPCs) from the placenta; incubate these in 0.25% trypsin-EDTA at 37 &#176;C for 20 min, and then wash with 5 ml PBS.</li>
	<li>Isolate chorionic villi from HPCs using scissors; mince the villi and wash them three times with 1ml PBS. After mincing, place the chorionic villi into a microfuge tube using a pipette tip; wash the samples with 500 &#181;l PBS by pipetting up and down, and centrifuge the tubes for 120 x g for 3 min. Wash tissues twice with 500 &#181;l of pre-warmed culture medium.</li>
	<li>Culture cells in medium on gelatin-coated plates at 37 &#176;C, in 5% CO2, and under 95% humidity. Pre-coat all plates with 0.1% gelatin for 1 hr at 37 &#176;C. Colonies of fibroblast-like cells will form and adherent growth approximately 5&#8211;7 days after commencing culture in the same medium.</li>
	<li>Exchange the medium every 2&#8211;3 days until the third passage. During culture, removing cell debris floating in the culture medium; growing placental fibroblasts will attach to the plate. Culture the fibroblast-like cells derived from the HPC up to the 10th passage and then harvest them for hESC cultures after trypsinization and mitomycin-C (10 &#181;g/ml) treatment.</li>
	<li>Before freezing HPCs as stock samples, use reverse transcription&#8211;polymerase chain reaction (RT-PCR) to confirm that HPCs are not contaminated with pathogens that commonly infect the placenta, including mycoplasma (M. fermentans, M. hyorhinis, M. Arginine, M. orale, M. salivarium, M. hominis, M. pulmonis, M. arthritidis, M. neurolyticum, M. hyopneumoniae, and M. capricolum) and the bacterial species, Ureaplasmaurealyticum, by using a mycoplasma detection kit.
	<ol>
		<li>Follow the manufacturer&#8217;s instructions to perform RT-PCR, use all primers and mixtures provided in the kit. Use the supernatants of the cells that have been cultivated for 36 days for mycoplasma detection. Add 3 &#181;l of these samples to the PCR mixtures and perform the 1st PCR procedure for 35 cycles, each consisting of 94 &#176;C for 30 sec, 55 &#176;C for 2 min, and 72 &#176;C for 1 min.</li>
		<li>Carefully add 0.5 &#181;l of the 1st PCR product to the PCR mixture and perform the 2nd PCR procedure for 30 cycles using the same conditions as before. Analyze the amplified products by 1% agarose gel electrophoresis; apply 10 &#181;l of each of the 1st and 2nd PCR products to the gels.</li>
	</ol>
	</li>
	<li>If HPCs are found to be contaminated with pathogens, eliminate these using a combination of antibiotics (BM-Cyclin), following the manufacturer&#39;s instructions. Add new medium containing 10 &#181;g/ml of BM-Cyclin 1 for 3 days, and then treat the cells with 5 &#181;g/ml BM-Cyclin 2 for another 4 days. Repeat this cycle twice and then check for mycoplasma contamination again.</li>
</ol>
3. Harvesting Human Placenta-derived Cells Conditioned Medium (hPCCM)
<ol>
	<li>After excluding contamination, treat the attached cells (85-90% confluence; (1.5 &#215; 107 cells/flask) with mitomycin-C (10 &#181;g/ml) for 2 hr and 30 min, and washed the cells three times with 10 ml PBS. Incubate the cells with pre-warmed medium without mitomycin-C for 24 hr.</li>
	<li>One day after treatment, incubate cells in 10 ml medium (DMEM-F12 supplemented with 20% Knock-Out Serum Replacement [KOSR], 0.1 mM &#946;-mercaptoethanol, 1% NEAA, and 1% penicillin&#8211;streptomycin). After 24 hr of incubation, harvest CM in a 15-ml conical tube and filter the CM using a 0.22 &#181;m syringe filter.</li>
	<li>Add another 10 ml of new medium and incubation. Collect all supernatants from the cultures every day for 1 week and freeze the harvested medium at &#8211;80 &#176;C. Avoid repeated freeze-thaw cycles.</li>
</ol>
4.&#160;Culture of Human Embryonic Stem Cells (hESCs) and Induction of Pluripotent Stem Cells (iPSCs)
<ol>
	<li>Obtain Human embryonic stem cell lines, H1 and H9 cells (listed in the NIH hESC registry under the name WA01 and WA09, respectively) and induced-pluripotent stem cell iPSC-1: iPS(foreskin)-1 and iPSC-2 (IISH1i-BM) from the WiCell Research Institute (Madison, WI, USA). Cells should be thawed and cultured following the manufacturer&#8217;s instructions.</li>
	<li>For the control group, culture cells on Basement Membrane Matrix-coated dishes in widely used feeder-free and serum-free defined culture medium at 37 &#176;C and in 5% CO2. Initially, seed 80-100 clumps of hPSCs in 35-mm dishes. Grow cells in these dishes until 70-80% confluence and routinely passage cells for sub-culturing once every 5&#8211;6 days, using mechanical or enzymatic methods (Dispase). Wash cells twice with medium and plate them at a ratio of 1:4. Replace the medium with fresh medium every day.</li>
	<li>For the experimental groups, culture cells in hPCCM on dishes pre-coated with 0.1% gelatin and perform routine passaging once every 5 days, either mechanically or enzymatically. Plate cells at ratios in the range of 1:6&#8211;1:10. hPSCs attach to the gelatin within 2 days after transfer. Replace the medium with fresh medium daily.</li>
</ol>
5. Characterization of Human Pluripotent Stem Cells
NOTE: Characterize hPSCs using several methods, such as alkaline phosphatase staining, immunocytochemistry, Quantitative real-time PCR (qRT-PCR), and western blotting.
<ol>
	<li>Immunofluorescence staining
	<ol>
		<li>For immunofluorescence staining, culture hPSCs and fix the cells in 8-well slide chambers with 4% (w/v) paraformaldehyde for 10 min; then, permeabilized the cells with 0.1% (v/v) Triton-X100 for 15 min, and block the cells for 1 hr with 3% (v/v) normal horse serum in PBS containing 0.1% (v/v) Tween-20. Wash PBS twice for 5 min between every step.</li>
		<li>Incubate cells with the primary antibody (OCT-4, SSEA4, TRA-1-81, TRA-1-60, dilution of 1:1,000) O/N at 4 &#176;C and with the secondary antibody.</li>
		<li>Before mounting, incubate cells with 4&#8242;,6-diamidino-2-phenylindole (DAPI) for 5 min in the dark. Wash cells stringently three times for 5 min each and dry cells completely, in the dark. Preserve cells in fluorescence mounting medium and observe them under a fluorescence microscope.</li>
	</ol>
	</li>
	<li>qRT-PCR
	<ol>
		<li>Isolate total RNA from cells using an RNeasy mini kit according to manufacturer&#39;s specifications and quantify the extracted RNA using a Nano Drop Spectrophotometer.</li>
		<li>Synthesize cDNA by adding 2 &#181;g of the total RNA to a 20-&#181;l reaction mixture containing oligo(dT) primers and Superscript II reverse transcriptase; follow the manufacturer&#8217;s instructions in this procedure.</li>
		<li>Amplify the synthesized cDNA with a Bio-Rad iCycler iQ system, using iQ SYBR Green qPCR Master Mix and the primer sequences described in Supplemental Table S1. Normalize the cycle threshold values of the genes of interest to those of glyceraldehyde-3-phosphate dehydrogenase (GAPDH).</li>
	</ol>
	</li>
	<li>Alkaline phosphatase (AP) staining
	<ol>
		<li>Detect AP activity using the ES Cell Characterization Kit, according to the manufacturer&#8217;s protocol.</li>
		<li>On day 5, aspirate the media and fix the hPSCs with 4% paraformaldehyde in PBS for 12 min. Do not overfix; fixing cells for longer than 2 min will result in the inactivation of alkaline phosphatase. Aspirate the fixative and rinse with 1x Rinse Buffer. Do not allow wells to dry between steps.</li>
		<li>Add enough staining solution to cover each well (1 ml per well of a 35 mm dish). Incubate plates in the dark at RT&#160;for 15 min.</li>
		<li>After incubation, wash dishes with 1x Rinse Buffer. Cover cells with 1x PBS to prevent drying and examine and image the stained cells using an Olympus microscope.</li>
	</ol>
	</li>
	<li>Western Blot
	<ol>
		<li>Perform western blot analysis as previously described in9. Briefly, determine protein concentrations in cell lysates. Resolve equal amounts of protein on a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel and transfer the proteins onto a polyvinylidene fluoride (PVDF) membrane.</li>
		<li>Block the blot and probe it O/N with different primary antibodies at 4 &#176;C; subsequently incubate the blot with HRP-conjugated secondary antibodies for 1 hr. Wash the membrane three times for 10 min each time between incubations. Detect signals using an ECL reagent.</li>
	</ol>
	</li>
	<li>Short Tandem Repeat (STR) Analysis
	<ol>
		<li>hPSCs were harvested from the control and experimental groups at the same passage. Genomic DNA was extracted using a DNA Micro kit, according to the manufacturer&#8217;s instructions.</li>
		<li>Amplify the genomic DNA for 16 different genetic loci using the AmpF/STR PCR Amplification Kit, according to the manufacturer&#8217;s specifications and capillary electrophoresis was performed using a Genetic Analyzer.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Xu, C., 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=Feeder-free+growth+of+undifferentiated+human+embryonic+stem+cells.">Feeder-free growth of undifferentiated human embryonic stem cells.</a> Nat Biotechnol. 19 (10), 971-974 (2001).</li><li>Amit, M. C., Shakiri, V., Margulets, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Itskovitz-Eldor+Feeder+layer+and+serum-free+culture+of+human+embryonic+stem+cells.">Itskovitz-Eldor Feeder layer and serum-free culture of human embryonic stem cells.</a> Biol Reprod. 70 (3), 837-845 (2004).</li><li>Nagaoka, M., Si-Tayeb, K., Akaike, T., Duncan, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culture+of+human+pluripotent+stem+cells+using+completely+defined+conditions+on+a+recombinant+E-cadherin+substratum.">Culture of human pluripotent stem cells using completely defined conditions on a recombinant E-cadherin substratum.</a> BMC Dev Biol. 10, 60 (2010).</li><li>Jin, S., Yao, H., Weber, J. L., Melkoumian, Z. K., Ye, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+synthetic,+xeno-free+peptide+surface+for+expansion+and+directed+differentiation+of+human+induced+pluripotent+stem+cells.">A synthetic, xeno-free peptide surface for expansion and directed differentiation of human induced pluripotent stem cells.</a> PLoS One. 7 (11), e50880 (2012).</li><li>Xu, R. H., 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=Basic+FGF+and+suppression+of+BMP+signaling+sustain+undifferentiated+proliferation+of+human+ES+cells.">Basic FGF and suppression of BMP signaling sustain undifferentiated proliferation of human ES cells.</a> Nat Methods. 2 (3), 185-190 (2005).</li><li>Xu, C., 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=Basic+fibroblast+growth+factor+supports+undifferentiated+human+embryonic+stem+cell+growth+without+conditioned+medium.">Basic fibroblast growth factor supports undifferentiated human embryonic stem cell growth without conditioned medium.</a> Stem Cells. 23 (3), 315-323 (2005).</li><li>Levenstein, M. E., 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=Basic+fibroblast+growth+factor+support+of+human+embryonic+stem+cell+self-renewal.">Basic fibroblast growth factor support of human embryonic stem cell self-renewal.</a> Stem Cells. 24 (3), 568-574 (2006).</li><li>Park, Y., 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=Human+feeder+cells+can+support+the+undifferentiated+growth+of+human+and+mouse+embryonic+stem+cells+using+their+own+basic+fibroblast+growth+factors.">Human feeder cells can support the undifferentiated growth of human and mouse embryonic stem cells using their own basic fibroblast growth factors.</a> Stem Cells Dev. 20 (11), 1901-1910 (2011).</li><li>Park, Y., 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=The+efficacy+of+human+placenta+as+a+source+of+the+universal+feeder+in+human+and+mouse+pluripotent+stem+cell+culture.">The efficacy of human placenta as a source of the universal feeder in human and mouse pluripotent stem cell culture.</a> Cell Reprogram. 12 (3), 315-328 (2010).</li><li>Park, Y., 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=Undifferentiated+propagation+of+the+human+embryonic+stem+cell+lines,+H1+and+HSF6,+on+human+placenta-derived+feeder+cells+without+basic+fibroblast+growth+factor+supplementation.">Undifferentiated propagation of the human embryonic stem cell lines, H1 and HSF6, on human placenta-derived feeder cells without basic fibroblast growth factor supplementation.</a> Stem Cells Dev. 19 (11), 1713-1722 (2010).</li><li>Seok, K., 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=Human+placenta-derived+feeders+support+prolonged+undifferentiated+propagation+of+a+human+embryonic+stem+cell+line,+SNUhES3:+comparison+with+human+bone+marrow-derived+feeders.">Human placenta-derived feeders support prolonged undifferentiated propagation of a human embryonic stem cell line, SNUhES3: comparison with human bone marrow-derived feeders.</a> Stem Cells Dev. 16 (3), 421-428 (2007).</li><li>Levenstein, M. E., 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=Basic+fibroblast+growth+factor+support+of+human+embryonic+stem+cell+self-renewal.">Basic fibroblast growth factor support of human embryonic stem cell self-renewal.</a> Stem Cells. 24 (3), 568-574 (2006).</li><li>Xu, R. H., Peck, R. M., Li, D. S., Feng, X., Ludwig, T., Thomson, J. 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=Basic+FGF+and+suppression+of+BMP+signaling+sustain+undifferentiated+proliferation+of+human+ES+cells.">Basic FGF and suppression of BMP signaling sustain undifferentiated proliferation of human ES cells.</a> Nat Methods. 2 (3), 185-190 (2005).</li><li>Mahmood, A., Harkness, L., Schrøder, H. D., Abdallah, B. M., Kassem, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+differentiation+of+stem+cells+mesenchymal+progenitors+by+inhibition+of+TGF-beta/activin/nodal+using+SB-431542.">Enhanced differentiation of stem cells mesenchymal progenitors by inhibition of TGF-beta/activin/nodal using SB-431542.</a> J Bone Miner Res. 25 (6), 1216-1233 (2010).</li></ol>

The authors indicate no conflicts of interest.

This model was developed to successfully propagate hPSCs, while maintaining their characteristics, in humanized feeder-free culture conditions without the addition of exogenous recombinant growth factors such as bFGF or insulin, enabling the manipulation of hPSCs in a humanized microenvironment. Exogenous bFGF supplementation is common and the application of substrata such as Matrigel or laminin is essential for feeder-free culturing of hPSCs14.
This protocol is simple and easy to i...

The goal of this protocol is the propagation of human pluripotent stem cells (hPSCs) including human embryonic stem cells (hESCs) and human induced pluripotent stem cells (iPSCs) in fully humanized ex vivo feeder-free conditions without requiring additional exogenous supplementation and synthetic substrates. To date, the development of ex vivo hPSC culture models, that enable the introduction of culture products to the clinic, has been a major concern in stem cell research. Specifically, two critical problems need to be addressed. First, a humanized ex vivo culture system for the propagation of hPSCs that obviates the risk of contamination by animal cell products is needed. Second, a feeder-free culture model is needed to facilitate easy and economic mass production of hPSCs. For therapeutic applications of hPSCs, it is necessary to identify the factors that regulate their self-renewal and differentiation.
Since Xu et al. initially reported the feasibility of using conditioned media (CM) derived from mouse embryonic fibroblasts (MEF) to grow hESCs on Matrigel1, many studies have examined optimal ex vivo propagation methods for hPSCs2-4. However, an ideal humanized ex vivo feeder-free hPSC propagation system has not been developed because current methods require additional exogenous substrates including bFGF and insulin, well-known hPSC-sustaining factors, in culture media5-7. Moreover, synthetic substrata such as Matrigel or laminin are used in all feeder-free cultures.
The rationale behind the development and use of this protocol is based on our previous studies showing that human placenta chorion cells excellently support the propagation of hPSCs without bFGF supplementation8-11. This protocol has a number of advantages including its simplicity with respect to handling and its cost-effectiveness, and it is a near-perfect humanized culture that enables hPSC propagation without exogenous synthetic substrates. The application of human placenta-derived CM (hPCCM) for hPSCs involves 3 steps. First, chorion cells are isolated from the human placenta and cultured. Second, hPCCM is produced from cultured cells. Third, hPSCs are cultured using hPCCM and their characteristics are confirmed. 
This protocol will facilitate clinical applications of hPSCs and studies of the mechanisms of hPSC proliferation and attachment. In this paper, the protocol for the successful propagation of hPSCs in hPCCM on a gelatin-coated dish is presented.

<table><tbody><tr><td>Mitomycin-C</td><td>Sigma-Aldrich Corporation</td><td>M4287</td><td>10 &amp;mu;g/ml</td></tr><tr><td>Mycoplasma detection kit</td><td>TaKaRa Bio Inc.</td><td>#6601</td><td></td></tr><tr><td>Matrigel</td><td>BD Biosciences</td><td>#354277</td><td></td></tr><tr><td>mTeSR1</td><td>STEMCELL Technologies Inc.</td><td>#05850</td><td></td></tr><tr><td>Dispase</td><td>Worthington Biochemical Corporation</td><td>LS02100</td><td>1 mg/ml</td></tr><tr><td>Gelatin</td><td>Sigma-Aldrich Corporation</td><td>G2500</td><td>0.10%</td></tr><tr><td>BM-Cyclin</td><td>Roche</td><td>799 050</td><td>10 &amp;mu;g/ml</td></tr><tr><td>RNeasy mini kit&amp;nbsp;</td><td>Qiagen</td><td>74104</td><td></td></tr><tr><td>Nano Drop Spectrophotometer</td><td>Thermo Fisher Scientific Inc</td><td></td><td></td></tr><tr><td>iQ SYBR Green qPCR Master Mix&amp;nbsp;</td><td>Bio-Rad Laboratories</td><td>#170-8882AP</td><td></td></tr><tr><td>ES Cell Characterization kit</td><td>Chemicon International, Inc.,</td><td>SCR001</td><td></td></tr><tr><td>Power cDNA Synthesis Kit&amp;nbsp;</td><td>iNtRON Biotechnology</td><td>25011</td><td></td></tr><tr><td>QIAamp&amp;reg; DNA Micro kit</td><td>Qiagen</td><td>56304</td><td></td></tr><tr><td>AmpF/STR&amp;reg; Identifiler&amp;reg; PCR Amplification kit</td><td>Applied Biosystems Inc.</td><td>4322288</td><td></td></tr><tr><td>Applied Biosystems&amp;reg; 3130xl Genetic Analyzer&amp;nbsp;</td><td>Applied Biosystems Inc.</td><td></td><td></td></tr></tbody></table>

a novel culture model for human pluripotent stem cell propagation on gelatin in placenta-conditioned media

The propagation of human pluripotent stem cells (hPSCs) in conditioned medium derived from human cells in feeder-free culture conditions has been of interest. Nevertheless, an ideal humanized ex vivo feeder-free propagation method for hPSCs has not been developed; currently, additional exogenous substrates including basic fibroblast growth factor (bFGF), a master hPSC-sustaining factor, is added to all of culture media and synthetic substrata such as Matrigel or laminin are used in all feeder-free cultures. Recently, our group developed a simple and efficient protocol for the propagation of hPSCs using only conditioned media derived from the human placenta on a gelatin-coated dish without additional exogenous supplementation or synthetic substrata specific to hPSCs. This protocol has not been reported previously and might enable researchers to propagate hPSCs efficiently in humanized culture conditions. Additionally, this model obviates hPSC contamination risks by animal products such as viruses or unknown proteins. Furthermore, this system facilitates easy mass production of hPSCs using the gelatin coating, which is simple to handle, dramatically decreases the overall costs of ex vivo hPSC maintenance.

One advantage of this hPSC propagation method is that it uses components secreted from human cells. A most ciritical step in the protocol is the isolation and culture of human placenta-derived cells. This requires and accurate dissection from a precise part of HPC plate villi. Figure 1 shows the procedure for human placenta-derived cell isolation. This process is simple and convenient for the isolation of cells, and can easily be performed within 1 hr. As described in Figure 2, tissues a...

Watch this Scientific Journal Video about A Novel Culture Model for Human Pluripotent Stem Cell Propagation on Gelatin in Placenta-conditioned Media at JoVE.com

A Novel Culture Model for Human Pluripotent Stem Cell Propagation on Gelatin in Placenta-conditioned Media

This protocol provides a simple and efficient way to propagate human pluripotent stem cells (hPSCs) using only conditioned media derived from the human placenta in a gelatin-coated dish without additional exogenous supplementation or hPSC-specific synthetic substrata.

The propagation of human pluripotent stem cells (hPSCs) in conditioned medium derived from human cells in feeder-free culture conditions has been of ...

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Developmental Biology

7.8K Views.  Graduate School of Medicine, Korea University. This protocol provides a simple and efficient way to propagate human pluripotent stem cells (hPSCs) using only conditioned media derived from the human placenta in a gelatin-coated dish without additional exogenous supplementation or hPSC-specific synthetic substrata.

Video: A Novel Culture Model for Human Pluripotent Stem Cell Propagation on Gelatin in Placenta-conditioned Media

Scalable 96-well Plate Based iPSC Culture and Production Using a Robotic Liquid Handling System

Continued advancement in pluripotent stem cell culture is closing the gap between bench and bedside for using these cells in regenerative medicine, drug discovery and safety testing. In order to produce stem cell derived biopharmaceutics and cells for tissue engineering and transplantation, a cost-effective cell-manufacturing technology is essential. Maintenance of pluripotency and stable performance of cells in downstream applications (e.g., cell differentiation) over time is paramount to large scale cell production. Yet that can be difficult to achieve especially if cells are cultured manually where the operator can introduce significant variability as well as be prohibitively expensive to scale-up. To enable high-throughput, large-scale stem cell production and remove operator influence novel stem cell culture protocols using a bench-top multi-channel liquid handling robot were developed that require minimal technician involvement or experience. With these protocols human induced pluripotent stem cells (iPSCs) were cultured in feeder-free conditions directly from a frozen stock and maintained in 96-well plates. Depending on cell line and desired scale-up rate, the operator can easily determine when to passage based on a series of images showing the optimal colony densities for splitting. Then the necessary reagents are prepared to perform a colony split to new plates without a centrifugation step. After 20 passages (~3 months), two iPSC lines maintained stable karyotypes, expressed stem cell markers, and differentiated into cardiomyocytes with high efficiency. The system can perform subsequent high-throughput screening of new differentiation protocols or genetic manipulation designed for 96-well plates. This technology will reduce the labor and technical burden to produce large numbers of identical stem cells for a myriad of applications.

The protocols described allow laboratories to perform scalable, adherent stem cell culture in high throughput with minimal labor, experience and equipment investment cost using a programmable liquid handling robot and 96-well plates. iPSCs passaged more than 20 times on this system maintained pluripotency, normal karyotypes and differentiated into cardiomyocytes.

Continued advancement in pluripotent stem cell culture is closing the gap between bench and bedside for using these cells in regenerative medicine, drug ...

Rotating Cell Culture Systems for Human Cell Culture: Human Trophoblast Cells as a Model

The field of human trophoblast research aids in understanding the complex environment established during placentation. Due to the nature of these studies, human in vivo experimentation is impossible. A combination of primary cultures, explant cultures and trophoblast cell lines1 support our understanding of invasion of the uterine wall2 and remodeling of uterine spiral arteries3,4 by extravillous trophoblast cells (EVTs), which is required for successful establishment of pregnancy. Despite the wealth of knowledge gleaned from such models, it is accepted that in vitro cell culture models using EVT-like cell lines display altered cellular properties when compared to their in vivo counterparts5,6. Cells cultured in the rotating cell culture system (RCCS) display morphological, phenotypic, and functional properties of EVT-like cell lines that more closely mimic differentiating in utero EVTs, with increased expression of genes mediating invasion (e.g. matrix metalloproteinases (MMPs)) and trophoblast differentiation7,8,9. The Saint Georges Hospital Placental cell Line-4 (SGHPL-4) (kindly donated by Dr. Guy Whitley and Dr. Judith Cartwright) is an EVT-like cell line that was used for testing in the RCCS.
The design of the RCCS culture vessel is based on the principle that organs and tissues function in a three-dimensional (3-D) environment. Due to the dynamic culture conditions in the vessel, including conditions of physiologically relevant shear, cells grown in three dimensions form aggregates based on natural cellular affinities and differentiate into organotypic tissue-like assemblies10,11,12 . The maintenance of a fluid orbit provides a low-shear, low-turbulence environment similar to conditions found in vivo. Sedimentation of the cultured cells is countered by adjusting the rotation speed of the RCCS to ensure a constant free-fall of cells. Gas exchange occurs through a permeable hydrophobic membrane located on the back of the bioreactor. Like their parental tissue in vivo, RCCS-grown cells are able to respond to chemical and molecular gradients in three dimensions (i.e. at their apical, basal, and lateral surfaces) because they are cultured on the surface of porous microcarrier beads. When grown as two-dimensional monolayers on impermeable surfaces like plastic, cells are deprived of this important communication at their basal surface. Consequently, the spatial constraints imposed by the environment profoundly affect how cells sense and decode signals from the surrounding microenvironment, thus implying an important role for the 3-D milieu13.
We have used the RCCS to engineer biologically meaningful 3-D models of various human epithelial tissues7,14,15,16. Indeed, many previous reports have demonstrated that cells cultured in the RCCS can assume physiologically relevant phenotypes that have not been possible with other models10,17-21. In summary, culture in the RCCS represents an easy, reproducible, high-throughput platform that provides large numbers of differentiated cells that are amenable to a variety of experimental manipulations. 
In the following protocol, using EVTs as an example, we clearly describe the steps required to three-dimensionally culture adherent cells in the RCCS.

Traditional, two dimensional cell culture techniques often result in altered characteristics with respect to differentiation markers, cytokines and growth factors. Three-dimensional cell culture in the rotating cell culture system (RCCS) reestablishes expression of many of these factors as shown here with an extravillous trophoblast cell line.

The field of human trophoblast research aids in  understanding the complex environment established during placentation. Due to the  nature of these ...

Bioengineering

Efficient Derivation of Human Neuronal Progenitors and Neurons from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

There is a large unfulfilled need for a clinically-suitable human neuronal cell source for repair or regeneration of the damaged central nervous system (CNS) structure and circuitry in today's healthcare industry. Cell-based therapies hold great promise to restore the lost nerve tissue and function for CNS disorders. However, cell therapies based on CNS-derived neural stem cells have encountered supply restriction and difficulty to use in the clinical setting due to their limited expansion ability in culture and failing plasticity after extensive passaging1-3. Despite some beneficial outcomes, the CNS-derived human neural stem cells (hNSCs) appear to exert their therapeutic effects primarily by their non-neuronal progenies through producing trophic and neuroprotective molecules to rescue the endogenous cells1-3. Alternatively, pluripotent human embryonic stem cells (hESCs) proffer cures for a wide range of neurological disorders by supplying the diversity of human neuronal cell types in the developing CNS for regeneration1,4-7. 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 tumorigenicity7-10. 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 problematic11-13. 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 molecules14 (please see a schematic in Fig. 1). Retinoic acid (RA) does not induce neuronal differentiation of undifferentiated hESCs maintained on feeders1, 14. And unlike mouse ESCs, treating hESC-differentiated embryoid bodies (EBs) only slightly increases the low yield of neurons1, 14, 15. However, after screening a variety of small molecules and growth factors, we found that such defined conditions rendered retinoic acid (RA) sufficient to induce the specification of neuroectoderm direct from pluripotent hESCs that further progressed to neuroblasts that generated human neuronal progenitors and neurons in the developing CNS with high efficiency (Fig. 2). We defined conditions for induction of neuroblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human neuronal cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of neuroblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human neuronal progenitors and neuronal cell types in the developing CNS for neural repair.

There is a large unfulfilled need for a clinically-suitable human neuronal cell source for repair or regeneration of the damaged central nervous system ...

Neuroscience

Human Placental and Decidual Organ Cultures to Study Infections at the Maternal-fetal Interface

The placenta shows a large degree of interspecies anatomic variability. To best understand biology and pathophysiology of the human placenta, it is imperative to design experiments using human cells and tissues. An advantage of organ culture is maintenance of three-dimensional (3D) structural organization and extracellular matrix. The goal of the method described here is successful establishment of ex vivo human gestational tissue organ cultures and their healthy culture maintenance for 72-96 hr. The protocol details the immediate processing of research-consented, placental and decidual specimens fresh from the operating suite. These are abundant specimens that would otherwise be discarded. Detailed instructions on the sterile collection of these samples, including morphologic details on how to select appropriate tissues to establish 3D organ cultures, is provided. Placental villous and decidual tissues are microdissected into 2-3 mm3 pieces and placed separately on matrix-lined transwell filters and cultured for several days. Villous and decidual organ cultures are well suited for the study of human host-pathogen interaction. As compared to other model organisms, these human cultures are particularly advantageous to examine mechanism of infection for pathogens that demonstrate variable patterns of host specificity. As an example, we demonstrate infection of placental and decidual organ cultures with the clinically relevant, facultative intracellular bacterial pathogen Listeria monocytogenes.

A simple method to establish primary human placental (villous) and decidual organ cultures is described. Villous and decidual organ cultures are invaluable tools for studying pathogenesis at the human maternal-fetal interface. Infection with the facultative intracellular bacterium Listeria monocytogenes is demonstrated.

The placenta shows a large degree of interspecies anatomic variability. To best understand biology and pathophysiology of the human placenta, it is ...

Immunology and Infection

Human Pluripotent Stem Cell Culture on Polyvinyl Alcohol-Co-Itaconic Acid Hydrogels with Varying Stiffness Under Xeno-Free Conditions

The effect of physical cues, such as the stiffness of biomaterials on the proliferation and differentiation of stem cells, has been investigated by several researchers. However, most of these investigators have used polyacrylamide hydrogels for stem cell culture in their studies. Therefore, their results are controversial because those results might originate from the specific characteristics of the polyacrylamide and not from the physical cue (stiffness) of the biomaterials. Here, we describe a protocol for preparing hydrogels, which are not based on polyacrylamide, where various stem, cells including human embryonic stem (ES) cells and human induced pluripotent stem (iPS) cells, can be cultured. Hydrogels with varying stiffness were prepared from bioinert polyvinyl alcohol-co-itaconic acid (P-IA), with stiffness controlled by crosslinking degree by changing crosslinking time. The P-IA hydrogels grafted with and without oligopeptides derived from extracellular matrix were investigated as a future platform for stem cell culture and differentiation. The culture and passage of amniotic fluid stem cells, adipose-derived stem cells, human ES cells, and human iPS cells is described in detail here. The oligopeptide P-IA hydrogels showed superior performances, which were induced by their stiffness properties. This protocol reports the synthesis of the biomaterial, their surface manipulation, along with controlling the stiffness properties and finally, their impact on stem cell fate using xeno-free culture conditions. Based on recent studies, such modified substrates can act as future platforms to support and direct the fate of various stem cells line to different linkages; and further, regenerate and restore the functions of the lost organ or tissue.

A protocol is presented to prepare polyvinyl alcohol-co-itaconic acid hydrogels with varying stiffness, which were grafted with and without oligopeptides, to investigate the effect of the stiffness of biomaterials on the differentiation and proliferation of stem cells. The stiffness of the hydrogels was controlled by the crosslinking time.

The effect of physical cues, such as the stiffness of biomaterials on the proliferation and differentiation of stem cells, has been investigated by ...

Induced Pluripotent Stem Cell Differentiation Using an Automated Culture System

An Automated Culture System for Maintaining and Differentiating Human-Induced Pluripotent Stem Cells

Human induced pluripotent stem cells (hiPSCs) with infinite self-proliferating ability have been expected to have applications in numerous fields, including the elucidation of rare disease pathologies, the development of new medicines, and regenerative medicine aiming to restore damaged organs. Despite this, the social implementation of hiPSCs is still limited. This is partly because of the difficulty of reproducing differentiation in culture, even with advanced knowledge and sophisticated technical skills, due to the high sensitivity of iPSCs to minute environmental changes. The application of an automated culture system can solve this issue. Experiments with high reproducibility independent of a researcher's skill can be expected according to a shared procedure across various institutes. Although several automated culture systems that can maintain iPSC cultures and induce differentiation have been developed previously, these systems are heavy, large, and costly because they make use of humanized, multi-articulated robotic arms. To improve on the above issues, we developed a new system using a simple x-y-z axis slide rail system, allowing it to be more compact, lighter, and cheaper. Furthermore, the user can easily modify parameters in the new system to develop new handling tasks. Once a task is established, all the user needs to do is prepare the iPSC, supply the reagents and consumables needed for the desired task in advance, select the task number, and specify the time. We confirmed that the system could maintain iPSCs in an undifferentiated state through several passages without feeder cells and differentiate into various cell types, including cardiomyocytes, hepatocytes, neural progenitors, and keratinocytes. The system will enable highly reproducible experiments across institutions without the need for skilled researchers and will facilitate the social implementation of hiPSCs in a wider range of research fields by diminishing the obstacles for new entries.

Author Spotlight: Automating iPSC Culture for Enhanced Reproducibility 

Here, we present a protocol for an automated cell culture system. This automated culture system reduces labor and benefits the users, including researchers unfamiliar with handling induced pluripotent stem (iPS) cells, from the maintenance of iPS cells to differentiation into various types of cells.

Human induced pluripotent stem cells (hiPSCs) with infinite self-proliferating ability have been expected to have applications in numerous fields, ...

Matrix Comparison for Efficient Human Intestinal Organoid Generation from iPSCs

Comparative Study of Basement-Membrane Matrices for Human Stem Cell Maintenance and Intestinal Organoid Generation

Extracellular matrix (ECM) plays a critical role in cell behavior and development. Organoids generated from human induced pluripotent stem cells (hiPSCs) are in the spotlight of many research areas. However, the lack of physiological cues in classical cell culture materials hinders efficient iPSC differentiation. Incorporating commercially available ECM into stem cell culture provides physical and chemical cues beneficial for cell maintenance. Animal-derived commercially available basement membrane products are composed of ECM proteins and growth factors that support cell maintenance. Since the ECM holds tissue-specific properties that can modulate cell fate, xeno-free matrices are used to stream up translation to clinical studies. While commercially available matrices are widely used in hiPSC and organoid work, the equivalency of these matrices has not been evaluated yet. Here, a comparative study of hiPSC maintenance and human intestinal organoids (hIO) generation in four different matrices: Matrigel (Matrix 1-AB), Geltrex (Matrix 2-AB), Cultrex (Matrix 3-AB), and VitroGel (Matrix 4-XF) was conducted. Although the colonies lacked a perfectly round shape, there was minimal spontaneous differentiation, with over 85% of the cells expressing the stem cell marker SSEA-4. Matrix 4-XF led to the formation of 3D round clumps. Also, increasing the concentration of supplement and growth factors in the media used to make the Matrix 4-XF hydrogel solution improved hiPSC expression of SSEA-4 by 1.3-fold. Differentiation of Matrix 2-AB -maintained hiPSC led to fewer spheroid releases during the mid-/hindgut stage compared to the other animal-derived basement membranes. Compared to others, the xeno-free organoid matrix (Matrix 4-O3) leads to larger and more mature hIO, suggesting that the physical properties of xeno-free hydrogels can be harnessed to optimize organoid generation. Altogether, the results suggest that variations in the composition of different matrices affect stages of IO differentiation. This study raises awareness about the differences in commercially available matrices and provides a guide for matrix optimization during iPSC and IO work.

Author Spotlight: Advancing Organoid Generation for Drug Development Using iPSCs

Organoids have become valuable tools for disease modeling. The extracellular matrix (ECM)&#160;guides cell fate during organoid generation, and using a system that resembles the native tissue can improve model accuracy. This study compares the generation of induced pluripotent stem cells-derived human intestinal organoids in animal-derived ECM and xeno-free hydrogels.

Extracellular matrix (ECM) plays a critical role in cell behavior and development. Organoids generated from human induced pluripotent stem cells (hiPSCs) ...

Alternative Cultures for Human Pluripotent Stem Cell Production, Maintenance, and Genetic Analysis

Human pluripotent stem cells (hPSCs) hold great promise for regenerative medicine and biopharmaceutical applications. Currently, optimal culture and efficient expansion of large amounts of clinical-grade hPSCs are critical issues in hPSC-based therapies. Conventionally, hPSCs are propagated as colonies on both feeder and feeder-free culture systems. However, these methods have several major limitations, including low cell yields and generation of heterogeneously differentiated cells. To improve current hPSC culture methods, we have recently developed a new method, which is based on non-colony type monolayer (NCM) culture of dissociated single cells. Here, we present detailed NCM protocols based on the Rho-associated kinase (ROCK) inhibitor Y-27632. We also provide new information regarding NCM culture with different small molecules such as Y-39983 (ROCK I inhibitor), phenylbenzodioxane (ROCK II inhibitor), and thiazovivin (a novel ROCK inhibitor). We further extend our basic protocol to cultivate hPSCs on defined extracellular proteins such as the laminin isoform 521 (LN-521) without the use of ROCK inhibitors. Moreover, based on NCM, we have demonstrated efficient transfection or transduction of plasmid DNAs, lentiviral particles, and oligonucleotide-based microRNAs into hPSCs in order to genetically modify these cells for molecular analyses and drug discovery. The NCM-based methods overcome the major shortcomings of colony-type culture, and thus may be suitable for producing large amounts of homogeneous hPSCs for future clinical therapies, stem cell research, and drug discovery.

Here, we present human pluripotent stem cell (hPSC) culture protocols, based on non-colony type monolayer (NCM) growth of dissociated single cells. This new method, utilizing Rho-associated kinase inhibitors or the laminin isoform 521 (LN-521), is suitable for producing large amounts of homogeneous hPSCs, genetic manipulation, and drug discovery.

Human pluripotent stem cells (hPSCs) hold great promise for regenerative medicine and biopharmaceutical applications. Currently, optimal culture and ...

Biology

Measuring the Confluence of iPSCs Using an Automated Imaging System

This study focuses on understanding how growing iPSCs on different ECM coating substrates can affect cell confluence. A protocol to assess iPSC confluence in real time has been established without the need to count cells in single cell suspension to avoid any growth perturbation. A high-content image analysis system was used to assess iPCS confluence on 4 different ECMs over time in an automated manner. Different analysis settings were used to assess cell confluence of adherent iPSCs and only a slight difference (at 24 and 48 hours with laminin) has been observed whether a 60, 80 or 100% mask was applied. We also show that laminin lead to the best confluence compared to Matrigel, vitronectin and fibronectin.

The goal of the protocol is to compare different extracellular matrix (ECM) coating conditions to assess how differential coating affects the growth rate of induced pluripotent stem cells (iPSCs). In particular, we aim to set up conditions to obtain optimal growth of iPSC cultures.

This study focuses on understanding how growing iPSCs on different ECM coating substrates can affect cell confluence. A protocol to assess iPSC confluence ...

Single Cell Collection of Trophoblast Cells in Peri-implantation Stage Human Embryos

Human implantation, the apposition and adhesion to the uterine surface epithelia and subsequent invasion of the blastocyst into the maternal decidua, is a critical yet enigmatic biological event that has been historically difficult to study due to technical and ethical limitations. Implantation is initiated by the development of the trophectoderm to early trophoblast and subsequent differentiation into distinct trophoblast sublineages. Aberrant early trophoblast differentiation may lead to implantation failure, placental pathologies, fetal abnormalities, and miscarriage. Recently, methods have been developed to allow human embryos to grow until day 13 post-fertilization in vitro in the absence of maternal tissues, a time-period that encompasses the implantation period in humans. This has given researchers the opportunity to investigate human implantation and recapitulate the dynamics of trophoblast differentiation during this critical period without confounding maternal influences and avoiding inherent obstacles to study early embryo differentiation events in vivo. To characterize different trophoblast sublineages during implantation, we have adopted existing two-dimensional (2D) extended culture methods and developed a procedure to enzymatically digest and isolate different types of trophoblast cells for downstream assays. Embryos cultured in 2D conditions have a relatively flattened morphology and may be suboptimal in modeling in vivo three-dimensional (3D) embryonic architectures. However, trophoblast differentiation seems to be less affected as demonstrated by anticipated morphology and gene expression changes over the course of extended culture. Different trophoblast sublineages, including cytotrophoblast, syncytiotrophoblast and migratory trophoblast can be separated by size, location, and temporal emergence, and used for further characterization or experimentation. Investigation of these early trophoblast cells may be instrumental in understanding human implantation, treating common placental pathologies, and mitigating the incidence of pregnancy loss.

Here, we describe a method for warming vitrified human blastocysts, culturing them through the implantation period in vitro, digesting them into single cells and collecting early trophoblast cells for further investigation.

Human implantation, the apposition and adhesion to the uterine surface epithelia and subsequent invasion of the blastocyst into the maternal decidua, is a ...

A Novel Culture Model for Human Pluripotent Stem Cell Propagation on Gelatin in Placenta-conditioned Media

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