Name: Standardizing Limbal Niche Cell (LNC) Isolation and Characterization to Support Widespread LNC Research (Video) | JoVE
Uploaded: 2023-10-27T14:10:00
Description: Watch this Scientific Journal Video about Standardizing Limbal Niche Cell LNC Isolation and Characterization to Support Widespread LNC Research at JoVE.com

Thanks to Wei Wang, Lingjuan Xu, and Rong Liu for the guidance on this work, Yongyao Tan, Bihui Jin, Chunxiu You, and Li Guigang for providing some of the material, Guanyu Su for writing the manuscript, Xiao Zhou, Yihong Xiong, and Huatao Xie for correcting the manuscript, and Guigang Li for his full guidance. This study was supported by the National Natural Science Foundation of China (No. 82070936, 81470606, 81570819), Hubei Province health and family planning scientific research project (No. WJ2017M073), Top Ten Translational Medical Research Projects from Tongji Hospital (No.2016ZHYX20), Training Project of Young medical Pioneers in Wuhan City (No.2015whzqnyxggrc10), Global Talents Recruitment Program (G2022154028L), National Health Commission of Hubei Province project In 2022(WJ2021ZH0005), and Subject Construction Foundation of Finance Department of Hubei In 2022(42000022815T000000102)

Limbus tissue from donors aged between 50 and 60 years was obtained from the Red Cross Eye Bank, Tongji Hospital (Wuhan, China). The protocol was approved by the Tongji Ethics Committee and was conducted in accordance with the Declaration of Helsinki.
1. Isolation
<ol>
	<li>Obtain limbus tissue from intermediate-term corneal storage medium and operate under aseptic conditions on an ultra-clean workbench.</li>
	<li>Scrape and remove the iris and endothelium around the cornea ...

A Protocol to Isolate, Culture, and Identify Human Limbal Niche Cells

<ol>
	<li>Le, Q., Xu, J., Deng, S. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+diagnosis+of+limbal+stem+cell+deficiency.">The diagnosis of limbal stem cell deficiency.</a> Ocular Surface. 16 (1), 58-69 (2018).</li><li>Polisetty, N., Fatima, A., Madhira, S. L., Sangwan, V. S., Vemuganti, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+cells+from+limbal+stroma+of+human+eye.">Mesenchymal cells from limbal stroma of human eye.</a> Molecular Vision. 14, 431-442 (2008).</li><li>Xie, H. T., Chen, S. Y., Li, G. G., Tseng, S. C. <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+expansion+of+human+limbal+stromal+niche+cells.">Isolation and expansion of human limbal stromal niche cells.</a> Investigative Ophthalmology &amp; Visual Science. 53 (1), 279-286 (2012).</li><li>Li, G. G., Zhu, Y. T., Xie, H. T., Chen, S. Y., Tseng, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+derived+from+human+limbal+niche+cells.">Mesenchymal stem cells derived from human limbal niche cells.</a> Investigative Ophthalmology &amp; Visual Science. 53 (9), 5686-5697 (2012).</li><li>Li, G. G., Chen, S. Y., Xie, H. T., Zhu, Y. T., Tseng, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angiogenesis+potential+of+human+limbal+stromal+niche+cells.">Angiogenesis potential of human limbal stromal niche cells.</a> Investigative Ophthalmology &amp; Visual Science. 53 (7), 3357-3367 (2012).</li><li>Hu, W., Zhang, Y., Tighe, S., Zhu, Y. T., Li, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+isolation+method+of+human+lacrimal+canaliculus+epithelial+stem+cells+by+maintaining+close+association+with+their+niche+cells.">A new isolation method of human lacrimal canaliculus epithelial stem cells by maintaining close association with their niche cells.</a> International Journal of Medical Sciences. 15 (12), 1260-1267 (2018).</li><li>Kumar, A., Xu, Y., Yang, E., Du, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stemness+and+regenerative+potential+of+corneal+stromal+stem+cells+and+their+secretome+after+long-term+storage:+Implications+for+ocular+regeneration.">Stemness and regenerative potential of corneal stromal stem cells and their secretome after long-term storage: Implications for ocular regeneration.</a> Investigative Ophthalmology &amp; Visual Science. 59 (8), 3728-3738 (2018).</li><li>Xiao, Y. T., Qu, J. Y., Xie, H. T., Zhang, M. C., Zhao, X. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparison+of+methods+for+isolation+of+limbal+niche+cells:+Maintenance+of+limbal+epithelial+stem/progenitor+cells.">A comparison of methods for isolation of limbal niche cells: Maintenance of limbal epithelial stem/progenitor cells.</a> Investigative Ophthalmology &amp; Visual Science. 61 (14), 16 (2020).</li><li>Zhu, 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=Limbal+niche+cells+and+three-dimensional+matrigel-induced+dedifferentiation+of+mature+corneal+epithelial+cells.">Limbal niche cells and three-dimensional matrigel-induced dedifferentiation of mature corneal epithelial cells.</a> Investigative Ophthalmology &amp; Visual Science. 63 (5), 1 (2022).</li><li>Basu, S., 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+limbal+biopsy-derived+stromal+stem+cells+prevent+corneal+scarring.">Human limbal biopsy-derived stromal stem cells prevent corneal scarring.</a> Science Translational Medicine. 6 (266), 266ra172 (2014).</li><li>Acar, U., 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=Effect+of+allogeneic+limbal+mesenchymal+stem+cell+therapy+in+corneal+healing:+role+of+administration+route.">Effect of allogeneic limbal mesenchymal stem cell therapy in corneal healing: role of administration route.</a> Ophthalmic Research. 53 (2), 82-89 (2015).</li><li>Katikireddy, K. R., Dana, R., Jurkunas, U. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+potential+of+limbal+fibroblasts+and+bone+marrow+mesenchymal+stem+cells+to+corneal+epithelial+cells.">Differentiation potential of limbal fibroblasts and bone marrow mesenchymal stem cells to corneal epithelial cells.</a> Stem Cells. 32 (3), 717-729 (2014).</li><li>Polisetti, N., Sharaf, L., Reinhard, T., Schlunck, G. <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+ex+vivo+expansion+of+limbal+mesenchymal+stromal+cells.">Isolation and ex vivo expansion of limbal mesenchymal stromal cells.</a> Bio-Protocols. 12 (14), e4471 (2022).</li><li>Xie, H. T., Chen, S. Y., Li, G. G., Tseng, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Limbal+epithelial+stem/progenitor+cells+attract+stromal+niche+cells+by+SDF-1/CXCR4+signaling+to+prevent+differentiation.">Limbal epithelial stem/progenitor cells attract stromal niche cells by SDF-1/CXCR4 signaling to prevent differentiation.</a> Stem Cells. 29 (11), 1874-1885 (2011).</li><li>Li, G., 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+limbal+niche+cells+are+a+powerful+regenerative+source+for+the+prevention+of+limbal+stem+cell+deficiency+in+a+rabbit+model.">Human limbal niche cells are a powerful regenerative source for the prevention of limbal stem cell deficiency in a rabbit model.</a> Scientific Reports. 8, 6566 (2018).</li><li>Kumar, A., Yun, H., Funderburgh, M. L., Du, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regenerative+therapy+for+the+cornea.">Regenerative therapy for the cornea.</a> Progress In Retinal and Eye Research. 87, 101011 (2022).</li><li>Pineda, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> World Corneal Blindness. Foundations of Corneal Disease. , 299-305 (2020).</li><li>Zieske, J. D., Guimar&#227;es, S. R., Hutcheon, 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=Kinetics+of+keratocyte+proliferation+in+response+to+epithelial+debridement.">Kinetics of keratocyte proliferation in response to epithelial debridement.</a> Experimental Eye Research. 72 (1), 33-39 (2001).</li><li>Resnikoff, S., 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=Global+data+on+visual+impairment+in+the+year+2002.">Global data on visual impairment in the year 2002.</a> Bulletin of the World Health Organization. 82 (11), 844-851 (2004).</li><li>Tan, 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=Limbal+bio-engineered+tissue+employing+3D+nanofiber-aerogel+scaffold+to+facilitate+LSCs+growth+and+migration.">Limbal bio-engineered tissue employing 3D nanofiber-aerogel scaffold to facilitate LSCs growth and migration.</a> Macromolecular Bioscience. 22 (5), e2100441 (2022).</li><li>Aghamirsalim, M., 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=3D+printed+hydrogels+for+ocular+wound+healing.">3D printed hydrogels for ocular wound healing.</a> Biomedicines. 10 (7), 1562 (2022).</li><li>Sasamoto, Y., Ksander, B. R., Frank, M. H., Frank, N. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Repairing+the+corneal+epithelium+using+limbal+stem+cells+or+alternative+cell-based+therapies.">Repairing the corneal epithelium using limbal stem cells or alternative cell-based therapies.</a> Expert Opinion on Biological Therapy. 18 (5), 505-513 (2018).</li><li>Rohaina, C. M., 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=Reconstruction+of+limbal+stem+cell+deficient+corneal+surface+with+induced+human+bone+marrow+mesenchymal+stem+cells+on+amniotic+membrane.">Reconstruction of limbal stem cell deficient corneal surface with induced human bone marrow mesenchymal stem cells on amniotic membrane.</a> Translational Research. 163 (3), 200-210 (2014).</li><li>O'Callaghan, A. R., Dziasko, M. A., Sheth-Shah, R., Lewis, M. P., Daniels, J. T. J. A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oral+mucosa+tissue+equivalents+for+the+treatment+of+limbal+stem+cell+deficiency.">Oral mucosa tissue equivalents for the treatment of limbal stem cell deficiency.</a> Advanced Biosystems. 4 (7), e1900265 (2020).</li><li>Yu, D., Chen, M., Sun, X., Ge, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+of+mouse+induced+pluripotent+stem+cells+into+corneal+epithelial-like+cells.">Differentiation of mouse induced pluripotent stem cells into corneal epithelial-like cells.</a> Cell Biology International. 37 (1), 87-94 (2013).</li><li>Zeppieri, M., 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=Adipose-derived+stem+cells+for+corneal+wound+healing+after+laser-induced+corneal+lesions+in+mice.">Adipose-derived stem cells for corneal wound healing after laser-induced corneal lesions in mice.</a> Journal of Clinical Medicine. 6 (12), 115 (2017).</li><li>Kumar, A., Kumar, V., Rattan, V., Jha, V., Bhattacharyya, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Secretome+cues+modulate+the+neurogenic+potential+of+bone+marrow+and+dental+stem+cells.">Secretome cues modulate the neurogenic potential of bone marrow and dental stem cells.</a> Molecular Neurobiology. 54 (6), 4672-4682 (2017).</li><li>Hayashi, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordinated+generation+of+multiple+ocular-like+cell+lineages+and+fabrication+of+functional+corneal+epithelial+cell+sheets+from+human+iPS+cells.">Coordinated generation of multiple ocular-like cell lineages and fabrication of functional corneal epithelial cell sheets from human iPS cells.</a> Nature Protocols. 12 (4), 683-696 (2017).</li><li>Guo, P., 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=Limbal+niche+cells+are+a+potent+resource+of+adult+mesenchymal+progenitors.">Limbal niche cells are a potent resource of adult mesenchymal progenitors.</a> Journal of Cellular and Molecular Medicine. 22 (7), 3315-3322 (2018).</li><li>Wang, W., 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=Differential+gene+expression+between+limbal+niche+progenitors+and+bone+marrow+derived+mesenchymal+stem+cells.">Differential gene expression between limbal niche progenitors and bone marrow derived mesenchymal stem cells.</a> International Journal of Medical Sciences. 17 (4), 549-557 (2020).</li><li>Gonz&#225;lez, S., Deng, S. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Presence+of+native+limbal+stromal+cells+increases+the+expansion+efficiency+of+limbal+stem/progenitor+cells+in+culture.">Presence of native limbal stromal cells increases the expansion efficiency of limbal stem/progenitor cells in culture.</a> Experimental Eye Research. 116, 169-176 (2013).</li><li>Funderburgh, M. L., Du, Y., Mann, M. M., SundarRaj, N., Funderburgh, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PAX6+expression+identifies+progenitor+cells+for+corneal+keratocytes.">PAX6 expression identifies progenitor cells for corneal keratocytes.</a> FASEB Journal. 19 (10), 1371-1373 (2005).</li><li>Funderburgh, J. L., Funderburgh, M. L., Du, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cells+in+the+limbal+stroma.">Stem cells in the limbal stroma.</a> Ocular Surface. 14 (2), 113-120 (2016).</li><li>Chen, S. Y., Hayashida, Y., Chen, M. Y., Xie, H. T., Tseng, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+isolation+method+of+human+limbal+progenitor+cells+by+maintaining+close+association+with+their+niche+cells.">A new isolation method of human limbal progenitor cells by maintaining close association with their niche cells.</a> Tissue Engineering. Part C, Methods. 17 (5), 537-548 (2011).</li><li>Sato, T., Clevers, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SnapShot:+Growing+organoids+from+stem+cells.">SnapShot: Growing organoids from stem cells.</a> Cell. 161 (7), 1700-1701 (2015).</li></ol>

Corneal transparency is typically maintained by regular arrangement and distribution of small fibers (25-30 nm in diameter) in the corneal stroma, which is crucial for normal vision acuity16. There are 253 million visually impaired people worldwide, 36 million of whom are blind17. The world health organization (WHO) considers corneal blindness one of the most serious hazards to human eyesight, accounting for 5.1% of all blindness worldwide16. Corneal...

The incidence of corneal epithelial stem cell deficiency (CESD), also called limbal stem cells deficiency (LSCD)1, and&#160;corneal epithelial regeneration (CES) are&#160;becoming more and more urgent because of corneal infection&#160;and injury. If not properly treated, CESD can lead to blindness that requires corneal transplantation. As a result, CES regeneration is&#160;becoming more significant. There is a group of supportive cells called limbal niche cells (LNCs) that provide essential support for CES function. Limbal stromal stem cells were first isolated by Polisetty et al.2 and identified by Xie et al.3&#160;as LNCs which are localized in the limbal epithelium subjacent and stroma of the limbus. LNCs are the key supporting stem cell of the corneal rim&#160;and, with the function of bone marrow-derived MSC (BMMSCs), and could&#160;be induced to develop into corneal epithelial cells and corneal stromal cells, etc.3,4,5,6,7. Previous studies showed that the stem-cell qualities of LNCs are more primitive than BMMSCs8, which is already widely used in the clinic. LNCs may even become the next viable option after MSC, especially for treating CESD. As important supporting cells for CES, LNCs are also stem cells derived from the &#34;niche&#34; structure of the limbus. LNCs may play a key role in the dedifferentiation of mature corneal epithelial cells (MCEC) to CES9. However, studies on LNCs are still relatively insufficient, and there is no consensus on the terminology, isolation, purification, identification, and characteristics of LNCs. Some researchers have named LNCs limbal biopsy-derived stromal stem cells10, limbal mesenchymal stem cells11, limbal fibroblast stem cells12, and limbal mesenchymal stromal cells13. As the growth characteristics of LNCs have not been described in detail, and because of their promising scientific and clinical applications, and may be one of the most important clinical tools in the future, it is necessary to summarize the isolation, purification, identification, and characteristics of LNCs.
According to a previous study14, LNCs are mainly present at the limbal epithelium subjacent and stroma of the limbus. This protocol includes treating limbus tissue using collagenase A, obtaining a cluster consisting of LEPC and LNCs, and digesting it into single cells with 0.25% trypsin-EDTA (TE). LNCs were then selectively cultured in a modified embryonic stem cell medium (MESCM) to be purified. The protocol reported in this paper is simple and has high efficiency in obtaining human LNCs in large quantities.
The&#160;detailed procedure of LNC isolation, culture, and identification was recorded in the video for scientists who are interested in LNC&#160;study, and it can be conveniently repeated when needed.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>4&#39;,6-Diamidino-2-Phenylindole</td>
			<td>ThermoFisher</td>
			<td>D1306</td>
			<td>5&#956;g/mL</td>
		</tr>
		<tr>
			<td>Amphotericin B</td>
			<td>Sigma</td>
			<td>V900919</td>
			<td>1.25 &#956;g/mL</td>
		</tr>
		<tr>
			<td>Anti-CD73</td>
			<td>Abcam</td>
			<td>ab202122</td>
			<td>1:50</td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>MERCK</td>
			<td>A1933</td>
			<td>-</td>
		</tr>
		<tr>
			<td>CD105</td>
			<td>Proteintech</td>
			<td>67075-1-Ig</td>
			<td>1:200</td>
		</tr>
		<tr>
			<td>CD105</td>
			<td>Abcam</td>
			<td>ab114052</td>
			<td>1:50</td>
		</tr>
		<tr>
			<td>CD90</td>
			<td>Proteintech</td>
			<td>66766-1-Ig</td>
			<td>1:100</td>
		</tr>
		<tr>
			<td>CD90</td>
			<td>Abcam</td>
			<td>ab307736</td>
			<td>1:50</td>
		</tr>
		<tr>
			<td>Cell Incubator</td>
			<td>Shanghai Lishen</td>
			<td>K1119K4644</td>
			<td>HF90(HT)</td>
		</tr>
		<tr>
			<td>Centrifuge system</td>
			<td>StatSpin&#160;</td>
			<td>StatSpin CytoFuge 12</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Collagenase A</td>
			<td>Roche</td>
			<td>10103578001</td>
			<td>2 mg/mL</td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>Zeiss&#160;</td>
			<td>LSM700</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Culture plate</td>
			<td>virya</td>
			<td>3500356</td>
			<td>35 mm</td>
		</tr>
		<tr>
			<td>DME/F-12 1:1 (1x)&#160;</td>
			<td>cytiva</td>
			<td>SH30023.01</td>
			<td>90%</td>
		</tr>
		<tr>
			<td>Donkey anti-Mouse IgG (H+L) Secondary Antibody</td>
			<td>ThermoFisher</td>
			<td>A16016</td>
			<td>1:1000</td>
		</tr>
		<tr>
			<td>Donkey anti-rabbit IgG (H+L) Secondary Antibody</td>
			<td>ThermoFisher</td>
			<td>31568</td>
			<td>1:1000</td>
		</tr>
		<tr>
			<td>FACS Diva sofware</td>
			<td>BD Biosciences</td>
			<td>Tree Star</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Flow Cytometer</td>
			<td>BD Biosciences</td>
			<td>Becton Dickinson LSRII</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>olympus</td>
			<td>cx31&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Gentamicin</td>
			<td>Sigma</td>
			<td>G1914</td>
			<td>50 &#956;g/mL</td>
		</tr>
		<tr>
			<td>Hemocytometer</td>
			<td>MERCK</td>
			<td>Z359629</td>
			<td>Bright-Line</td>
		</tr>
		<tr>
			<td>High-capacity cDNA Transcription Kit</td>
			<td>ThermoFisher</td>
			<td>4374966</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted phase-contrast microscope</td>
			<td>&#160;UOP</td>
			<td>DSZ2000X</td>
			<td></td>
		</tr>
		<tr>
			<td>ITS (insulin, transferrin, sodium selenite)</td>
			<td>Sigma</td>
			<td>I3146</td>
			<td>5 &#956;g/mL insulin, 5 &#956;g/mL transferrin, 5 ng/mL sodium selenite</td>
		</tr>
		<tr>
			<td>KnockOut SR Serum Replacement for ESCs/iPSCs</td>
			<td>gibco</td>
			<td>10828-028</td>
			<td>10%</td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>BioCoat</td>
			<td>356234</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Pan-CK</td>
			<td>Abcam</td>
			<td>ab7753</td>
			<td>1:1000</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>NoninBio</td>
			<td>NBS0135</td>
			<td>4.00%</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>MKBio</td>
			<td>MM-1505</td>
			<td>4%</td>
		</tr>
		<tr>
			<td>PDGFR&#946;</td>
			<td>Abclonal</td>
			<td>A1444</td>
			<td>1:100</td>
		</tr>
		<tr>
			<td>Real-time fluorescence quantitative PCR instrument</td>
			<td>Applied Biosystems</td>
			<td>Step One Plus</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Recombinant Human FGF-basic</td>
			<td>Peprotech</td>
			<td>100-18B</td>
			<td>4 ng/mL</td>
		</tr>
		<tr>
			<td>Recominant Human Leukemia Inhibitory Factor(Lif)</td>
			<td>Peprotech</td>
			<td>300-05</td>
			<td>10 ng/mL</td>
		</tr>
		<tr>
			<td>RNeasy Mini RNA Isolation Kit</td>
			<td>Qiagen</td>
			<td>74104</td>
			<td>-</td>
		</tr>
		<tr>
			<td>SCF</td>
			<td>Bioss</td>
			<td>bs-0545R</td>
			<td>1:100</td>
		</tr>
		<tr>
			<td>SCF</td>
			<td>Abcam</td>
			<td>ab52603</td>
			<td>1:50</td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>ZEISS</td>
			<td>SteREO Discovery. V8</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile surgical round blade</td>
			<td>Careforde</td>
			<td>29500</td>
			<td>size 10</td>
		</tr>
		<tr>
			<td>TaqMan Gene Expression Assay Mix</td>
			<td>Applied Biosystems</td>
			<td>4448489</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>MERCK</td>
			<td>X100</td>
			<td>0.20%</td>
		</tr>
		<tr>
			<td>Trypan blue</td>
			<td>ThermoFisher</td>
			<td>15250061</td>
			<td>0.40%</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA</td>
			<td>Genview</td>
			<td>GP3108</td>
			<td>0.25%</td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>MERCK</td>
			<td>P9416</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Ultra Clean Bench</td>
			<td>LaiTe</td>
			<td>LT20200705</td>
			<td>SW-CJ-IFDG</td>
		</tr>
		<tr>
			<td>Universal PCR Master Mix</td>
			<td>Applied Biosystems</td>
			<td>4304437</td>
			<td></td>
		</tr>
		<tr>
			<td>Vim&#160;</td>
			<td>Abcam</td>
			<td>ab92547</td>
			<td>1:100</td>
		</tr>
	</tbody>
</table>

isolation and identification of limbal niche cells

Here we report a standard procedure for the isolation and identification of limbal niche cells (LNCs). Limbus tissue obtained from an eye bank was used for LNCs isolation. The tissue was divided into 12 pieces under aseptic conditions and digested for 18 h at 37 &#176;C in the cell culture incubator using collagenase A to obtain cell clusters with LNCs and limbal&#160;epithelial progenitor cells. The cell clusters were further digested for 15 min at 37 &#176;C using 0.25% trypsin-EDTA to obtain single cells and then cultured in modified embryonic stem cell medium (MESCM) on a plastic surface coated with 5% Matrigel. Cells were passaged upon 70% confluence, and LNCs were identified using immunofluorescence, real-time quantitative PCR (qPCR), and flow cytometry. Primary LNCs were isolated and passaged more than 12 times. The proliferation activity of LNCs from P4 to P6 was the highest. LNCs expressed higher stem cell markers than BMMSCs (SCF, Nestin, Rex1, SSEA4, CD73, CD90, MSX1, P75NTR, and PDGFR&#946;). Furthermore, results showed that P4 LNCs uniformly expressed VIM, CD90, CD105, and PDGFR&#946;, but not Pan-CK, which could be used as a marker for the identification of LNCs. Flow cytometric analysis showed that approximately 95%, 97%, 92%, and 11% of LNCs expressed CD73, CD90, CD105, and SCF respectively, while they were&#160;68%, 99%, 20%, and 3% in&#160;BMMSCs. The standard process for LNC&#160;isolation and identification could provide&#160;a reliable laboratory basis for the widespread use of LNCs.

Isolation and Identification of Limbal Niche Cells

Growth of LNC 
The LNCs were successfully isolated according to the method of digestion of collagenase A (2 mg/mL) digestion of corneoscleral rim tissue, as described above (Figure 1). Consistent with a previously reported study3, after collagenase A digestion, caterpillar-like clusters were visualized under the microscope (Figure 2). The proportion of spindle cells increased gradually with the&#160;cell passage. Spi...

Watch this Scientific Journal Video about Standardizing Limbal Niche Cell LNC Isolation and Characterization to Support Widespread LNC Research at JoVE.com

Standardizing Limbal Niche Cell (LNC) Isolation and Characterization to Support Widespread LNC Research (Video) | JoVE

Here, we present a protocol to isolate and identify the human limbal niche cells.

Here we report a standard procedure for the isolation and identification of limbal niche cells (LNCs). Limbus tissue obtained from an eye bank was used ...