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Robertson SYT, Roberts JS, Deng SX. Regulation of Limbal Epithelial Stem Cells: Importance of the Niche. Int J Mol Sci 2021; 22:11975. [PMID: 34769405 PMCID: PMC8584795 DOI: 10.3390/ijms222111975] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 12/11/2022] Open
Abstract
Limbal epithelial stem/progenitor cells (LSCs) reside in a niche that contains finely tuned balances of various signaling pathways including Wnt, Notch, BMP, Shh, YAP, and TGFβ. The activation or inhibition of these pathways is frequently dependent on the interactions of LSCs with various niche cell types and extracellular substrates. In addition to receiving molecular signals from growth factors, cytokines, and other soluble molecules, LSCs also respond to their surrounding physical structure via mechanotransduction, interaction with the ECM, and interactions with other cell types. Damage to LSCs or their niche leads to limbal stem cell deficiency (LSCD). The field of LSCD treatment would greatly benefit from an understanding of the molecular regulation of LSCs in vitro and in vivo. This review synthesizes current literature around the niche factors and signaling pathways that influence LSC function. Future development of LSCD therapies should consider all these niche factors to achieve improved long-term restoration of the LSC population.
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Affiliation(s)
| | | | - Sophie X. Deng
- Jules Stein Eye Institute, University of California, Los Angeles, CA 94143, USA; (S.Y.T.R.); (J.S.R.)
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Differential gene expression of the healthy conjunctiva during the day. Cont Lens Anterior Eye 2021; 45:101494. [PMID: 34315655 DOI: 10.1016/j.clae.2021.101494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 07/16/2021] [Accepted: 07/19/2021] [Indexed: 02/07/2023]
Abstract
PURPOSE To determine if there is diurnal variation in gene expression in normal healthy conjunctival cells. METHODS Bulbar conjunctival swab samples were collected from four healthy subjects in the morning and evening of the same day. The two swab samples were taken from one eye of each participant, with a minimum of five hours gap between the two samples. RNA was extracted and analysed using RNA sequencing (RNA-Seq). RESULTS A total of 121 genes were differentially expressed between the morning and the evening conjunctival samples, of which 94 genes were upregulated in the morning, and 27 genes were upregulated in the evening. Many of the genes that were upregulated in the morning were involved in defence, cell turnover and regulation of gene expression, while the genes upregulated in the evening were involved in signalling and mucin production. CONCLUSIONS This study has identified several genes whose expression changes over the course of the day. Knowledge of diurnal variations of conjunctival gene expression provides an insight into the regulatory status of the healthy eye and provides a baseline for examining changes during ocular surface disease.
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Li JM, Kim S, Zhang Y, Bian F, Hu J, Lu R, Pflugfelder SC, Chen R, Li DQ. Single-Cell Transcriptomics Identifies a Unique Entity and Signature Markers of Transit-Amplifying Cells in Human Corneal Limbus. Invest Ophthalmol Vis Sci 2021; 62:36. [PMID: 34297801 PMCID: PMC8300054 DOI: 10.1167/iovs.62.9.36] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Purpose Differentiated from adult stem cells (ASCs), transit-amplifying cells (TACs) play an important role in tissue homeostasis, development, and regeneration. This study aimed to characterize the gene expression profile of a candidate TAC population in limbal basal epithelial cells using single-cell RNA sequencing (scRNA-seq). Methods Single cells isolated from the basal corneal limbus were subjected to scRNA-seq using the 10x Genomics platform. Cell types were clustered by graph-based visualization methods and unbiased computational analysis. BrdU proliferation assays, immunofluorescent staining, and real-time reverse transcription quantitative polymerase chain reaction were performed using multiple culture models of primary human limbal epithelial cells to characterize the TAC pool. Results Single-cell transcriptomics of 16,360 limbal basal cells revealed 12 cell clusters. A unique cluster (3.21% of total cells) was identified as a TAC entity, based on its less differentiated progenitor status and enriched exclusive proliferation marker genes, with 98.1% cells in S and G2/M phases. The cell cycle-dependent genes were revealed to be largely enriched by the TAC population. The top genes were characterized morphologically and functionally at protein and mRNA levels. The specific expression patterns of RRM2, TK1, CENPF, NUSAP1, UBE2C, and CDC20 were well correlated in a time- and cycle-dependent manner with proliferation stages in the cell growth and regeneration models. Conclusions For the first time, to the best of our knowledge, we have identified a unique TAC entity and uncovered a group of cell cycle-dependent genes that serve as TAC signature markers. The findings provide insight into ASCs and TACs and lay the foundation for understanding corneal homeostasis and diseases.
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Affiliation(s)
- Jin-Miao Li
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States.,State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Sangbae Kim
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Yun Zhang
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Fang Bian
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Jiaoyue Hu
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Rong Lu
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States.,State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Stephen C Pflugfelder
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Rui Chen
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - De-Quan Li
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
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Single-cell transcriptomics identifies limbal stem cell population and cell types mapping its differentiation trajectory in limbal basal epithelium of human cornea. Ocul Surf 2021; 20:20-32. [PMID: 33388438 DOI: 10.1016/j.jtos.2020.12.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/17/2020] [Accepted: 12/27/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE This study aimed to uncover novel cell types in heterogenous basal limbus of human cornea for identifying LSC at single cell resolution. METHODS Single cells of human limbal basal epithelium were isolated from young donor corneas. Single-cell RNA-Sequencing was performed using 10x Genomics platform, followed by clustering cell types through the graph-based visualization method UMAP and unbiased computational informatic analysis. Tissue RNA in situ hybridization with RNAscope, immunofluorescent staining and multiple functional assays were performed using human corneas and limbal epithelial culture models. RESULTS Single-cell transcriptomics of 16,360 limbal basal cells revealed 12 cell clusters belonging to three lineages. A smallest cluster (0.4% of total cells) was identified as LSCs based on their quiescent and undifferentiated states with enriched marker genes for putative epithelial stem cells. TSPAN7 and SOX17 are discovered and validated as new LSC markers based on their exclusive expression pattern and spatial localization in limbal basal epithelium by RNAscope and immunostaining, and functional role in cell growth and tissue regeneration models with RNA interference in cultures. Interestingly, five cell types/states mapping a developmental trajectory of LSC from quiescence to proliferation and differentiation are uncovered by Monocle3 and CytoTRACE pseudotime analysis. The transcription factor networks linking novel signaling pathways are revealed to maintain LSC stemness. CONCLUSIONS This human corneal scRNA-Seq identifies the LSC population and uncovers novel cell types mapping the differentiation trajectory in heterogenous limbal basal epithelium. The findings provide insight into LSC concept and lay the foundation for understanding the corneal homeostasis and diseases.
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Salih M, Shaharuddin B, Abdelrazeg S. A Concise Review on Mesenchymal Stem Cells for Tissue Engineering with a Perspective on Ocular Surface Regeneration. Curr Stem Cell Res Ther 2020; 15:211-218. [DOI: 10.2174/1574888x15666200129145251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/27/2019] [Accepted: 01/02/2020] [Indexed: 12/13/2022]
Abstract
Organ and tissue transplantation are limited by the scarcity of donated organs or tissue
sources. The success of transplantation is limited by the risk of disease transmission and immunological-
related rejection. There is a need for new strategies and innovative solutions to make transplantation
readily available, safer and with less complications to increase the success rates. Accelerating progress
in stem cell biology and biomaterials development have pushed tissue and organ engineering to a
higher level. Among stem cells repertoire, Mesenchymal Stem Cells (MSC) are gaining interest and
recognized as a cell population of choice. There is accumulating evidence that MSC growth factors, its
soluble and insoluble proteins are involved in several key signaling pathways to promote tissue development,
cellular differentiation and regeneration. MSC as multipotent non-hematopoietic cells with
paracrine factors is advantageous for regenerative therapies. In this review, we discussed and summarized
the important features of MSC including its immunomodulatory properties, mechanism of homing
in the direction of tissue injury, licensing of MSC and the role of MSC soluble factors in cell-free
therapy. Special consideration is highlighted on the rapidly growing research interest on the roles of
MSC in ocular surface regeneration.
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Affiliation(s)
- Mohamed Salih
- Regenerative Medicine Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Penang, Malaysia
| | - Bakiah Shaharuddin
- Regenerative Medicine Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Penang, Malaysia
| | - Samar Abdelrazeg
- Regenerative Medicine Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Penang, Malaysia
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Poly-l/dl-lactic acid films functionalized with collagen IV as carrier substrata for corneal epithelial stem cells. Colloids Surf B Biointerfaces 2019; 177:121-129. [PMID: 30716697 DOI: 10.1016/j.colsurfb.2019.01.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/10/2019] [Accepted: 01/26/2019] [Indexed: 12/13/2022]
Abstract
Limbal epithelial stem cells (LESCs) are responsible for the renewal of corneal epithelium. Cultivated limbal epithelial transplantation is the current treatment of choice for restoring the loss or dysfunction of LESCs. To perform this procedure, a substratum is necessary for in vitro culturing of limbal epithelial cells and their subsequent transplantation onto the ocular surface. In this work, we evaluated poly-L/DL-lactic acid 70:30 (PLA) films functionalized with type IV collagen (col IV) as potential in vitro carrier substrata for LESCs. We first demonstrated that PLA-col IV films were biocompatible and suitable for the proliferation of human corneal epithelial cells. Subsequently, limbal epithelial cell suspensions, isolated from human limbal rings, were cultivated using culture medium that did not contain animal components. The cells adhered significantly faster to PLA-col IV films than to tissue culture plastic (TCP). The mRNA expression levels for the LESC specific markers, K15, P63α and ABCG2 were similar or greater (significantly in the case of K15) in limbal epithelial cells cultured on PLA-col IV films than limbal epithelial cells cultured on TCP. The percentage of cells expressing the corneal (K3, K12) and the LESC (P63α, ABCG2) specific markers was similar for both substrata. These results suggest that the PLA-col IV films promoted LESC attachment and helped to maintain their undifferentiated stem cell phenotype. Consequently, these substrata offer an alternative for the transplantation of limbal cells onto the ocular surface.
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Kasinathan JR, Namperumalsamy VP, Veerappan M, Chidambaranathan GP. A novel method for a high enrichment of human corneal epithelial stem cells for genomic analysis. Microsc Res Tech 2016; 79:1165-1172. [PMID: 27862636 DOI: 10.1002/jemt.22771] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/11/2016] [Accepted: 08/18/2016] [Indexed: 12/13/2022]
Abstract
Understanding the molecular mechanisms that regulate the corneal epithelial stem cells (CESCs) in maintaining corneal homeostasis remains elusive largely due to the lack of a specific marker for their isolation. This study aims to enrich CESCs from human donor limbal epithelium and to evaluate the level of enrichment based on expression of ΔNp63α, a putative CESC marker. A two-stage enrichment of CESCs was carried out. (a) The limbal basal epithelial cells were isolated by differential enzymatic treatment and five-fold enrichment was achieved from 2% of CESCs present in the total limbal epithelium. The CESCs were quantified on the basis of two parameters-high expression of p63/ABCG2 and nucleus to cytoplasmic (N/C) ratio ≥0.7. (b) Cytospin smears of isolated basal cells were Giemsa stained and cells with N/C ratio ≥0.7 were separated by laser capture microdissection. This strategy resulted in an enrichment of CESCs to 78.57% based on two-parameter analysis using p63 and 76.66% using ABCG2. RT-PCR was carried out for ΔNp63 isoforms (α, β, and γ) and connexin-43, with GAPDH for normalization. The expression of ΔNp63α was restricted to the enriched population of CESCs in contrast to its absence in limbal basal cells with N/C ratio <0.7 and CCECs. The unique expression of ΔNp63α and 5.9-fold reduced connexin-43 expression in the enriched population of CESCs indicates its high purity. Further analysis of these cells will help in elucidating the molecular mechanisms associated with stemness and also in identifying a specific marker for CESCs.
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Affiliation(s)
- Jhansi Rani Kasinathan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, Dr. G. Venkataswamy Eye Research Institute, Madurai, Tamil Nadu, India
| | | | - Muthukkaruppan Veerappan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, Dr. G. Venkataswamy Eye Research Institute, Madurai, Tamil Nadu, India
| | - Gowri Priya Chidambaranathan
- Department of Immunology and Stem Cell Biology, Aravind Medical Research Foundation, Dr. G. Venkataswamy Eye Research Institute, Madurai, Tamil Nadu, India
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Mikhailova A, Jylhä A, Rieck J, Nättinen J, Ilmarinen T, Veréb Z, Aapola U, Beuerman R, Petrovski G, Uusitalo H, Skottman H. Comparative proteomics reveals human pluripotent stem cell-derived limbal epithelial stem cells are similar to native ocular surface epithelial cells. Sci Rep 2015; 5:14684. [PMID: 26423138 PMCID: PMC4589773 DOI: 10.1038/srep14684] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/08/2015] [Indexed: 12/13/2022] Open
Abstract
Limbal epithelial stem cells (LESCs) are tissue-specific stem cells responsible for renewing the corneal epithelium. Acute trauma or chronic disease affecting LESCs may disrupt corneal epithelial renewal, causing vision threatening and painful ocular surface disorders, collectively referred to as LESC deficiency (LESCD). These disorders cannot be treated with traditional corneal transplantation and therefore alternative cell sources for successful cell-based therapy are needed. LESCs derived from human pluripotent stem cells (hPSCs) are a prospective source for ocular surface reconstruction, yet critical evaluation of these cells is crucial before considering clinical applications. In order to quantitatively evaluate hPSC-derived LESCs, we compared protein expression in native human corneal cells to that in hPSC-derived LESCs using isobaric tag for relative and absolute quantitation (iTRAQ) technology. We identified 860 unique proteins present in all samples, including proteins involved in cell cycling, proliferation, differentiation and apoptosis, various LESC niche components, and limbal and corneal epithelial markers. Protein expression profiles were nearly identical in LESCs derived from two different hPSC lines, indicating that the differentiation protocol is reproducible, yielding homogeneous cell populations. Their protein expression profile suggests that hPSC-derived LESCs are similar to the human ocular surface epithelial cells, and possess LESC-like characteristics.
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Affiliation(s)
| | - Antti Jylhä
- Department of Ophthalmology, School of Medicine, University of Tampere, Finland
| | | | - Janika Nättinen
- Department of Ophthalmology, School of Medicine, University of Tampere, Finland
| | | | - Zoltán Veréb
- Stem Cells and Eye Research Laboratory, Department of Ophthalmology, Faculty of Medicine, University of Szeged, Hungary
| | - Ulla Aapola
- Department of Ophthalmology, School of Medicine, University of Tampere, Finland
| | - Roger Beuerman
- Department of Ophthalmology, School of Medicine, University of Tampere, Finland.,Singapore Eye Research Institute and School of Medicine, Singapore
| | - Goran Petrovski
- Stem Cells and Eye Research Laboratory, Department of Ophthalmology, Faculty of Medicine, University of Szeged, Hungary
| | - Hannu Uusitalo
- Department of Ophthalmology, School of Medicine, University of Tampere, Finland.,Tampere University Hospital Eye Center, University of Tampere, Finland
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Mei H, Nakatsu MN, Baclagon ER, Deng SX. Frizzled 7 maintains the undifferentiated state of human limbal stem/progenitor cells. Stem Cells 2015; 32:938-45. [PMID: 24170316 DOI: 10.1002/stem.1582] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 09/14/2013] [Accepted: 09/18/2013] [Indexed: 12/15/2022]
Abstract
Wnt signaling pathway plays an important role in the regulation of human limbal stem/progenitor cells (LSCs). To examine the possible function of Frizzled (Fz) receptors in LSCs, the expression of 10 Fz receptors was profiled in the limbus and cornea. Only Fz7 had preferential expression in the basal limbal epithelium which contains the LSCs. The expression of Fz7 was colocalized with the putative LSC markers including p63α, N-cadherin and keratin (K) 14, and was minimum in cells expressing the corneal maturation marker K12. The expression of Fz7 was higher in the enriched LSCs population and decreased in cultured LSCs when there was a loss of progenitor phenotype. When the Fz7 was knocked down (Fz(KD)) using shRNA in primary LSCs, the expression of putative LSC markers ABCG2, ΔNp63α, and K14 was decreased significantly. The colony forming efficiency of the Fz7(KD) LSCs was significantly decreased in the subsequent passage 1 and 2 compared to the control. Our finding suggests that Wnt signaling is one of the factors of LSC niche, and Fz7 helps to maintain the undifferentiated state of LSCs.
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Affiliation(s)
- Hua Mei
- Jules Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Qu Y, Chi W, Hua X, Deng R, Li J, Liu Z, Pflugfelder SC, Li DQ. Unique expression pattern and functional role of periostin in human limbal stem cells. PLoS One 2015; 10:e0117139. [PMID: 25658308 PMCID: PMC4319935 DOI: 10.1371/journal.pone.0117139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/19/2014] [Indexed: 11/19/2022] Open
Abstract
Periostin is a non-structural matricellular protein. Little is known about periostin in human limbal stem cells (LSCs). This study was to explore the unique expression pattern and functional role of periostin in maintaining the properties of human LSCs. Fresh donor corneal tissues were used to make cryosections for evaluation of periostin expression on ex vivo tissues. Primary human limbal epithelial cells (HLECs) were generated from limbal explant culture. In vitro culture models for proliferation and epithelial regeneration were performed to explore functional role of periostin in LSCs. The mRNA expression was determined by reverse transcription and quantitative real-time PCR (RT-qPCR), and the protein production and localization were detected by immunofluorescent staining and Western blot analysis. Periostin protein was found to be exclusively immunolocalized in the basal layer of human limbal epithelium. Periostin localization was well matched with nuclear factor p63, but not with corneal epithelial differentiation marker Keratin 3. Periostin transcripts was also highly expressed in limbal than corneal epithelium. In primary HLECs, periostin expression at mRNA and protein levels was significantly higher in 50% and 70% confluent cultures at exponential growth stage than in 100% confluent cultures at slow growth or quiescent condition. This expression pattern was similar to other stem/progenitor cell markers (p63, integrin β1 and TCF4). Periostin expression at transcripts, protein and immunoreactivity levels increased significantly during epithelial regeneration in wound healing process, especially in 16-24 hours at wound edge, which was accompanied by similar upregulation and activation of p63, integrin β1 and TCF4. Our findings demonstrated that periostin is exclusively produced by limbal basal epithelium and co-localized with p63, where limbal stem cells reside. Periostin promotes HLEC proliferation and regeneration with accompanied activation of stem/progenitor cell markers p63, integrin β1 and TCF4, suggesting its novel role in maintaining the phenotype and functional properties of LSC.
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Affiliation(s)
- Yangluowa Qu
- The Eye Institute, Xiamen University, Xiamen, China
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wei Chi
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
- Zhongshan Ophthalmic Center, State Key laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, China
| | - Xia Hua
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Ruzhi Deng
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jin Li
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zuguo Liu
- The Eye Institute, Xiamen University, Xiamen, China
- * E-mail: (ZL); (DQL)
| | - Stephen C. Pflugfelder
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
| | - De-Quan Li
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (ZL); (DQL)
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12
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Small-molecule induction promotes corneal epithelial cell differentiation from human induced pluripotent stem cells. Stem Cell Reports 2014; 2:219-31. [PMID: 24527395 PMCID: PMC3923224 DOI: 10.1016/j.stemcr.2013.12.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/23/2013] [Accepted: 12/23/2013] [Indexed: 12/21/2022] Open
Abstract
Human induced pluripotent stem cells (hiPSCs) offer unique opportunities for developing novel cell-based therapies and disease modeling. In this study, we developed a directed differentiation method for hiPSCs toward corneal epithelial progenitor cells capable of terminal differentiation toward mature corneal epithelial-like cells. In order to improve the efficiency and reproducibility of our method, we replicated signaling cues active during ocular surface ectoderm development with the help of two small-molecule inhibitors in combination with basic fibroblast growth factor (bFGF) in serum-free and feeder-free conditions. First, small-molecule induction downregulated the expression of pluripotency markers while upregulating several transcription factors essential for normal eye development. Second, protein expression of the corneal epithelial progenitor marker p63 was greatly enhanced, with up to 95% of cells being p63 positive after 5 weeks of differentiation. Third, corneal epithelial-like cells were obtained upon further maturation. Small-molecule induction directs early stage differentiation Subsequent maturation yields homogeneous populations of p63-positive cells p63-positive progenitor cells are capable of terminal differentiation The serum-free and feeder-free method can be upgraded to fully defined and xeno free
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Human limbal epithelial progenitor cells express αvβ5-integrin and the interferon-inducible chemokine CXCL10/IP-10. Stem Cell Res 2013; 11:888-901. [PMID: 23838123 DOI: 10.1016/j.scr.2013.05.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 05/29/2013] [Accepted: 05/29/2013] [Indexed: 02/08/2023] Open
Abstract
Stem cell (SC) therapy is the main treatment modality for patients with limbal stem cell deficiency. If limbal epithelial stem cells (LESC) can be more readily identified, isolated and maintained ex vivo, patients could be treated with better quality grafts. With prior knowledge that vitronectin (VN) is present within the LESC niche and that it supports LESC in vitro, we postulated that VN receptors (integrins αvβ3/5) are expressed by, and can be used to identify and isolate LESC. Immunolocalization studies were conducted on human corneas. Corneas were also used to expand limbal epithelial cells from either biopsies or enzyme-dissociated tissue and αvβ3/5 expression determined by flow cytometry. Integrin expressing cells were isolated by magnetic activated cell sorting then assessed by immunocytology, colony forming efficiency, RT-PCR and microarray analysis. Integrin αvβ5(+) cells co-localized to N-cadherin(+)/CK-15(+) putative LESC. αvβ5 was restricted to less than 4% of the total limbal epithelial cells, which expressed higher levels of CK-15 and formed more colonies compared to αvβ5(-) cells. Transcriptional profiling of αvβ5(+/-) cells by microarray identified several highly expressed interferon-inducible genes, which localize to putative LESC. Integrin αvβ5 is a candidate LESC marker since its expression is restricted to the limbus and αvβ5(+) limbal epithelial cells have phenotypic and functional properties of LESC. Knowledge of the niche's molecular composition and the genes expressed by its SC will facilitate isolation and maintenance of these cells for therapeutic purposes.
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Bath C. Human corneal epithelial subpopulations: oxygen dependent ex vivo expansion and transcriptional profiling. Acta Ophthalmol 2013; 91 Thesis 4:1-34. [PMID: 23732018 DOI: 10.1111/aos.12157] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Corneal epithelium is being regenerated throughout life by limbal epithelial stem cells (LESCs) believed to be located in histologically defined stem cell niches in corneal limbus. Defective or dysfunctional LESCs result in limbal stem cell deficiency (LSCD) causing pain and decreased visual acuity. Since the first successful treatment of LSCD by transplantation of ex vivo expanded LESCs in 1997, many attempts have been carried out to optimize culture conditions to improve the outcome of surgery. To date, progress in this field of bioengineering is substantially hindered by both the lack of specific biomarkers of LESCs and the lack of a precise molecular characterization of in situ epithelial subpopulations. The aim of this dissertation was to optimize culture systems with regard to the environmental oxygen concentration for selective ex vivo expansion of LESCs and to analyse in situ subpopulations in human corneal epithelium using a combination of laser capture microdissection and RNA sequencing for global transcriptomic profiling. We compared dissociation cultures, using either expansion on γ-irradiated NIH/3T3 feeder cells in serum-rich medium or expansion directly on plastic in serum-free EpiLife medium, using a range of physiologically relevant oxygen concentrations (2%, 5%, 10%, 15% and 20%). Using immunocytochemistry and advanced fluorescence microscopy, cells were characterized regarding growth, cell cycle distribution, colony-forming efficiency (CFE), phenotypes and cytomorphometry. Limbal epithelial cells expanded in 2% O2 exhibited slow growth, low fraction of cells in S/G2 , high CFE, high expression of stem cell markers ABCG2 and p63α, and low fraction of differentiation marker CK3 resembling a LESC phenotype. The effect of hypoxia to maintain LESCs in culture was not dependent on the system used for propagation (Bath et al. 2013a). Laser capture microdissection was used to isolate cellular subpopulations in situ from the spatially defined differentiation pathway in human corneal epithelium according to an optimized protocol for maintenance of expression profiles. Isolated total RNA from basal limbal crypts (BLCs), superficial limbal crypts (SLCs), paracentral/central cornea and limbal stroma was amplified and converted to fragmented cDNA libraries for use in deep paired-end next-generation sequencing. Global transcriptional profiling was carried out using bioinformatics. The location of primitive cells in BLCs, migratory and activated cells in SLCs and differentiated cells in paracentral/central cornea was evident from mapping of significantly upregulated genes in each compartment to the gene ontology (GO). Interestingly, many GO terms in BLCs were also involved in neurogenic processes, whereas many GO terms in SLCs were related to vasculature. Mapping upregulated genes in BLCs to pathway annotations in Kyoto Encyclopedia of Genes and Genomes described many active pathways as signalling and cancer-associated pathways. We supply extensive information on possible novel biomarkers, reveal insight into both active pathways and novel regulators of LESCs such as Lrig1 and SOX9 and provide an immense amount of data for future exploration (Bath et al. 2013b). Selective ex vivo expansion of LESCs in hypoxia and the comprehensive molecular characterization of corneal epithelial subpopulations in situ are expected to be beneficial for the future treatment of LSCD by cultured limbal epithelial transplantation.
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Affiliation(s)
- Chris Bath
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
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Bath C, Muttuvelu D, Emmersen J, Vorum H, Hjortdal J, Zachar V. Transcriptional dissection of human limbal niche compartments by massive parallel sequencing. PLoS One 2013; 8:e64244. [PMID: 23717577 PMCID: PMC3661480 DOI: 10.1371/journal.pone.0064244] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Accepted: 04/10/2013] [Indexed: 12/13/2022] Open
Abstract
Corneal epithelium is maintained throughout life by well-orchestrated proliferation of limbal epithelial stem cells (LESCs), followed by migration and maturation centripetally towards the ocular surface. Disturbance of LESCs can potentially lead to a blinding condition, which can be reversed by reconstitution of a functional LESC pool. The current clinical procedures are effective to some degree, however, deeper knowledge of the molecular interplay within the limbal niche is necessary to achieve a fully satisfactory patient outcome. The present study was thus undertaken to carry out a comprehensive transcriptome analysis of four distinct human limbal compartments, including basal limbal crypts (BLCs), superficial limbal crypts (SLCs), cornea, and the supporting stroma, with the aid of laser capture microdissection and deep RNA sequencing. The tissue harvest pipeline was rigorously optimized so that the exposure to cold ischemia would be less than five minutes. The global gene ontology analysis confirmed existence of primitive cells in BLCs, migratory and activated cells in SLCs, and differentiated cells in cornea. Interestingly, many significantly upregulated genes in SLCs mapped to processes involved in regulation of vasculature, such as sFLT1. In contrast, BLCs exhibited many genes mapping to neurogenic processes and processes related to cell development. The primitive nature of BLCs was, furthermore, confirmed by the KEGG pathway analysis, and some potential regulators of LESCs were revealed, such as Lrig1 and SOX9. The analysis also yielded comprehensive lists of uniquely expressed genes in both BLCs and cornea, which may be useful to identify possible biomarkers. In conclusion, the current investigation provides new insight into the relationship between distinct cell populations within the limbal niche, identifies candidates to be verified for novel biological functions, and yields a wealth of information for prospective data mining.
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Affiliation(s)
- Chris Bath
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
- Laboratory for Stem Cell Research, Aalborg University, Aalborg, Denmark
| | - Danson Muttuvelu
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
| | - Jeppe Emmersen
- Laboratory for Stem Cell Research, Aalborg University, Aalborg, Denmark
| | - Henrik Vorum
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
| | - Jesper Hjortdal
- Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark
| | - Vladimir Zachar
- Laboratory for Stem Cell Research, Aalborg University, Aalborg, Denmark
- * E-mail:
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Nakatsu MN, Vartanyan L, Vu DM, Ng MY, Li X, Deng SX. Preferential biological processes in the human limbus by differential gene profiling. PLoS One 2013; 8:e61833. [PMID: 23630617 PMCID: PMC3632514 DOI: 10.1371/journal.pone.0061833] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/14/2013] [Indexed: 12/14/2022] Open
Abstract
Corneal epithelial stem cells or limbal stem cells (LSCs) are responsible for the maintenance of the corneal epithelium in humans. The exact location of LSCs is still under debate, but the increasing need for identifying the biological processes in the limbus, where LSCs are located, is of great importance in the regulation of LSCs. In our current study we identified 146 preferentially expressed genes in the human limbus in direct comparison to that in the cornea and conjunctiva. The expression of newly identified limbal transcripts endomucin, fibromodulin, paired-like homeodomain 2 (PITX2) and axin-2 were validated using qRT-PCR. Further protein analysis on the newly identified limbal transcripts showed protein localization of PITX2 in the basal and suprabasal layer of the limbal epithelium and very low expression in the cornea and conjunctiva. Two other limbal transcripts, frizzled-7 and tenascin-C, were expressed in the basal epithelial layer of the limbus. Gene ontology and network analysis of the overexpressed limbal genes revealed cell-cell adhesion, Wnt and TGF-β/BMP signaling components among other developmental processes in the limbus. These results could aid in a better understanding of the regulatory elements in the LSC microenvironment.
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Affiliation(s)
- Martin N. Nakatsu
- Cornea Division, Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Lily Vartanyan
- Cornea Division, Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Daniel M. Vu
- Cornea Division, Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Madelena Y. Ng
- Cornea Division, Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Xinmin Li
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sophie X. Deng
- Cornea Division, Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California, United States of America
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Priya CG, Prasad T, Prajna NV, Muthukkaruppan V. Identification of Human Corneal Epithelial Stem Cells on the Basis of High ABCG2 Expression Combined With a LargeN/C Ratio. Microsc Res Tech 2012; 76:242-8. [DOI: 10.1002/jemt.22159] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 11/11/2012] [Indexed: 12/13/2022]
Affiliation(s)
- Chidambaranathan Gowri Priya
- Department of Immunology; Stem Cell Biology; Aravind Medical Research Foundation; Dr. G. Venkataswamy Eye Research Institute; Madurai; 625 020; Tamil Nadu; India
| | - Tilak Prasad
- Department of Immunology; Stem Cell Biology; Aravind Medical Research Foundation; Dr. G. Venkataswamy Eye Research Institute; Madurai; 625 020; Tamil Nadu; India
| | | | - Veerappan Muthukkaruppan
- Department of Immunology; Stem Cell Biology; Aravind Medical Research Foundation; Dr. G. Venkataswamy Eye Research Institute; Madurai; 625 020; Tamil Nadu; India
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Osei-Bempong C, Figueiredo FC, Lako M. The limbal epithelium of the eye - A review of limbal stem cell biology, disease and treatment. Bioessays 2012; 35:211-9. [DOI: 10.1002/bies.201200086] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Lu R, Qu Y, Ge J, Zhang L, Su Z, Pflugfelder SC, Li DQ. Transcription factor TCF4 maintains the properties of human corneal epithelial stem cells. Stem Cells 2012; 30:753-61. [PMID: 22232078 DOI: 10.1002/stem.1032] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
TCF4, a key transcription factor of Wnt signaling system, has been recently found to be essential for maintaining stem cells. However, its signaling pathway is not well elucidated. This study was to explore the functional roles and signaling pathway of TCF4 in maintaining adult stem cell properties using human corneal epithelial stem cells as a model. With immunofluorescent staining and real-time polymerase chain reaction, we observed that TCF4 was exclusively expressed in the basal layer of human limbal epithelium where corneal epithelial stem cells reside. TCF4 was found to be well colocalized with ABCG2 and p63, two recognized epithelial stem/progenitor cell markers. Using in vitro culture models of primary human corneal epithelial cells, we revealed that TCF4 mRNA and protein were upregulated by cells in exponential growth stage, and RNA interference by small interfering RNA-TCF4 (10-50 nM) transfection blocked TCF4 signaling and suppressed cell proliferation as measured by WST-1 assay. TCF4 silence was found to be accompanied by downregulated proliferation-associated factors p63 and survivin, as well as upregulated cyclin-dependent kinase inhibitor 1C (p57). By creating a wound healing model in vitro, we identified upregulation and activation of β-catenin/TCF4 with their protein translocation from cytoplasm to nuclei, as evaluated by reverse transcription-quantitative real-time polymerase chain reaction, immunostaining, and Western blotting. Upregulated p63/survivin and downregulated p57 were further identified to be TCF4 downstream molecules that promote cell migration and proliferation in wound healing process. These findings demonstrate that transcription factor TCF4 plays an important role in determining or maintaining the phenotype and functional properties of human corneal epithelial stem cells.
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Affiliation(s)
- Rong Lu
- Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People's Republic of China
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Mort RL, Douvaras P, Morley SD, Dorà N, Hill RE, Collinson JM, West JD. Stem cells and corneal epithelial maintenance: insights from the mouse and other animal models. Results Probl Cell Differ 2012; 55:357-94. [PMID: 22918816 PMCID: PMC3471528 DOI: 10.1007/978-3-642-30406-4_19] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Maintenance of the corneal epithelium is essential for vision and is a dynamic process incorporating constant cell production, movement and loss. Although cell-based therapies involving the transplantation of putative stem cells are well advanced for the treatment of human corneal defects, the scientific understanding of these interventions is poor. No definitive marker that discriminates stem cells that maintain the corneal epithelium from the surrounding tissue has been discovered and the identity of these elusive cells is, therefore, hotly debated. The key elements of corneal epithelial maintenance have long been recognised but it is still not known how this dynamic balance is co-ordinated during normal homeostasis to ensure the corneal epithelium is maintained at a uniform thickness. Most indirect experimental evidence supports the limbal epithelial stem cell (LESC) hypothesis, which proposes that the adult corneal epithelium is maintained by stem cells located in the limbus at the corneal periphery. However, this has been challenged recently by the corneal epithelial stem cell (CESC) hypothesis, which proposes that during normal homeostasis the mouse corneal epithelium is maintained by stem cells located throughout the basal corneal epithelium with LESCs only contributing during wound healing. In this chapter we review experimental studies, mostly based on animal work, that provide insights into how stem cells maintain the normal corneal epithelium and consider the merits of the alternative LESC and CESC hypotheses. Finally, we highlight some recent research on other stem cell systems and consider how this could influence future research directions for identifying the stem cells that maintain the corneal epithelium.
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Alterations of epithelial stem cell marker patterns in human diabetic corneas and effects of c-met gene therapy. Mol Vis 2011; 17:2177-90. [PMID: 21866211 PMCID: PMC3159681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 08/08/2011] [Indexed: 11/21/2022] Open
Abstract
PURPOSE We have previously identified specific epithelial proteins with altered expression in human diabetic central corneas. Decreased hepatocyte growth factor receptor (c-met) and increased proteinases were functionally implicated in the changes of these proteins in diabetes. The present study examined whether limbal stem cell marker patterns were altered in diabetic corneas and whether c-met gene overexpression could normalize these patterns. METHODS Cryostat sections of 28 ex vivo and 26 organ-cultured autopsy human normal and diabetic corneas were examined by immunohistochemistry using antibodies to putative limbal stem cell markers including ATP-binding cassette sub-family G member 2 (ABCG2), N-cadherin, ΔNp63α, tenascin-C, laminin γ3 chain, keratins (K) K15, K17, K19, β(1) integrin, vimentin, frizzled 7, and fibronectin. Organ-cultured diabetic corneas were studied upon transduction with adenovirus harboring c-met gene. RESULTS Immunostaining for ABCG2, N-cadherin, ΔNp63α, K15, K17, K19, and β(1) integrin, was significantly decreased in the stem cell-harboring diabetic limbal basal epithelium either by intensity or the number of positive cells. Basement membrane components, laminin γ3 chain, and fibronectin (but not tenascin-C) also showed a significant reduction in the ex vivo diabetic limbus. c-Met gene transduction, which normalizes diabetic marker expression and epithelial wound healing, was accompanied by increased limbal epithelial staining for K17, K19, ΔNp63α, and a diabetic marker α(3)β(1) integrin, compared to vector-transduced corneas. CONCLUSIONS The data suggest that limbal stem cell compartment is altered in long-term diabetes. Gene therapy, such as with c-met overexpression, could be able to restore normal function to diabetic corneal epithelial stem cells.
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Nieto-Miguel T, Calonge M, de la Mata A, López-Paniagua M, Galindo S, de la Paz MF, Corrales RM. A comparison of stem cell-related gene expression in the progenitor-rich limbal epithelium and the differentiating central corneal epithelium. Mol Vis 2011; 17:2102-17. [PMID: 21850186 PMCID: PMC3156782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 07/28/2011] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Corneal epithelium is maintained by a population of stem cells (SCs) that have not been identified by specific molecular markers. The objective of this study was to find new putative markers for these SCs and to identify associated molecular pathways. METHODS Real time PCR (rt-PCR) was performed in 24 human limbal and central corneal epithelial samples to evaluate the gene expression profile of known corneal epithelial SC-associated markers. A pool of those samples was further analyzed by a rt-PCR array (RT²-PCR-A) for 84 genes related to the identification, growth, maintenance, and differentiation of SCs. RESULTS Cells from the corneal epithelium SC niche showed significant expression of ATP-binding cassette sub-family G member 2 (ABCG2) and cytokeratin (KRT)15, KRT14, and KRT5 genes. RT²-PCR-A results indicated an increased or decreased expression in 21 and 24 genes, respectively, in cells from the corneal SC niche compared to cells from the central corneal epithelium. Functional analysis by proprietary software found 4 different associated pathways and a novel network with the highest upregulated genes in the corneal SC niche. This led to the identification of specific molecules, chemokine (C-X-C motif) ligand 12 (CXCL12), islet-1 transcription factor LIM/homeodomain (ISL1), collagen-type II alpha 1 (COL2A), neural cell adhesion molecule 1 (NCAM1), aggrecan (ACAN), forkhead box A2 (FOXA2), Gap junction protein beta 1/connexin 32 (GJB1/Cnx32), and Msh homeobox 1 (MSX1), that could be used to recognize putative corneal epithelial SCs grown in culture and intended for transplantation. Other molecules, NCAM1 and GJB1/Cnx32, potentially could be used to positively purify them, and Par-6 partitioning defective 6 homolog alpha (PARD6A) to negatively purify them. CONCLUSIONS Knowledge of these gene and molecular pathways has provided a better understanding of the signaling molecular pathways associated with progenitor-rich limbal epithelium. This knowledge potentially could give support to the design and development of innovative therapies with the potential to reverse corneal blindness arising from ocular surface failure.
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Affiliation(s)
- Teresa Nieto-Miguel
- Institute for Applied Ophthalmobiology (IOBA), University of Valladolid, Valladolid, Spain,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain
| | - Margarita Calonge
- Institute for Applied Ophthalmobiology (IOBA), University of Valladolid, Valladolid, Spain,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain
| | - Ana de la Mata
- Institute for Applied Ophthalmobiology (IOBA), University of Valladolid, Valladolid, Spain,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain
| | - Marina López-Paniagua
- Institute for Applied Ophthalmobiology (IOBA), University of Valladolid, Valladolid, Spain,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain
| | - Sara Galindo
- Institute for Applied Ophthalmobiology (IOBA), University of Valladolid, Valladolid, Spain,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain
| | | | - Rosa M. Corrales
- Institute for Applied Ophthalmobiology (IOBA), University of Valladolid, Valladolid, Spain,Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Valladolid, Spain
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Enhanced functional properties of corneal epithelial cells by coculture with embryonic stem cells via the integrin β1-FAK-PI3K/Akt pathway. Int J Biochem Cell Biol 2011; 43:1168-77. [PMID: 21550417 DOI: 10.1016/j.biocel.2011.04.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/08/2011] [Accepted: 04/18/2011] [Indexed: 12/16/2022]
Abstract
Adult stem cells are important cell sources in regenerative medicine, but isolating them is technically challenging. This study employed a novel strategy to generate stem-like corneal epithelial cells and promote the functional properties of these cells by coculture with embryonic stem cells. The primary corneal epithelial cells were labelled with GFP and cocultured with embryonic stem cells in a transwell or by direct cell-cell contact. The embryonic stem cells were pre-transfected with HSV-tk-puro plasmids and became sensitive to ganciclovir. After 10 days of coculture, the corneal epithelial cells were isolated by treating the cultures with ganciclovir to kill the embryonic stem cells. The expression of stem cell-associated markers (ABCG2, p63) increased whereas the differentiation mark (Keratin 3) decreased in corneal epithelial cells isolated from the cocultures as evaluated by RT-PCR and flow cytometry. Their functional properties of corneal epithelial cells, including cell adhesion, migration and proliferation, were also enhanced. These cells could regenerate a functional stratified corneal epithelial equivalent but did not form tumors. Integrin β1, phosphorylated focal adhesion kinase and Akt were significantly upregulated in corneal epithelial cells. FAK Inhibitor 14 that suppressed the expression of phosphorylated focal adhesion kinase and Akt inhibited cell adhesion, migration and proliferation. LY294002 that suppressed phosphorylated Akt but not phosphorylated focal adhesion kinase inhibited cell proliferation but had no effect on cell adhesion or migration. These findings demonstrated that the functional properties of stem-like corneal epithelial cells were enhanced by cocultured embryonic stem cells via activation of the integrin β1-FAK-PI3K/Akt signalling pathway.
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Lu R, Bian F, Zhang X, Qi H, Chuang EY, Pflugfelder SC, Li DQ. The β-catenin/Tcf4/survivin signaling maintains a less differentiated phenotype and high proliferative capacity of human corneal epithelial progenitor cells. Int J Biochem Cell Biol 2011; 43:751-9. [PMID: 21292023 DOI: 10.1016/j.biocel.2011.01.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 01/18/2011] [Accepted: 01/24/2011] [Indexed: 01/07/2023]
Abstract
It is clear that the microenvironment or niche plays an important role in determining the fate of stem cells: being stem cells or differentiated. However, the intrinsic pathways controlling the fate of adult stem cells in different niches are largely unknown. This study was to explore the role of β-catenin/Tcf4/survivin signaling in determining the fate of human corneal epithelial stem cells in different media. We observed that the low calcium serum-free media, especially CnT-20, promoted proliferative capacity, colony forming efficiency and stem cell-like phenotype of human corneal epithelial cells (HCECs) when compared with the cells cultured in a high calcium serum-containing medium SHEM. Three key factors in Wnt signaling, β-catenin, Tcf4 and survivin, were found to be expressed higher by HCECs grown in CnT-20 than those cultured in SHEM, as evaluated by real-time PCR, Western blotting and immunostaining. Transfection of siRNA-Tcf4 at 10-50nM knocked down Tcf4, and also significantly suppressed its down stream molecule survivin at both mRNA and protein levels in HCECs. Furthermore, Tcf4 silencing significantly suppressed the proliferative capacity of HCECs, measured by WST-1 assay, compared with the control groups, untreated or transfected with non-coding sequence siRNA-fluorescein. These findings demonstrate that low calcium serum free media promote ex vivo expansion of corneal epithelial progenitor cells that retain a less differentiated phenotype and high proliferative capacity via β-catenin/Tcf4/survivin signaling, a novel intrinsic pathway. This study may have high impact and clinic implication on the expansion of corneal epithelial stem cells in regenerative medicine, especially for ocular surface reconstruction.
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Affiliation(s)
- Rong Lu
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
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Davies SB, Di Girolamo N. Corneal stem cells and their origins: significance in developmental biology. Stem Cells Dev 2010; 19:1651-62. [PMID: 20629538 DOI: 10.1089/scd.2010.0201] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Adult corneal stem cells (SCs) have been the subject of substantial research over the past 2 decades, with promising clinical applications being devised, refined, and tried. However, there have been few studies on the early development of these cells in humans, perhaps due to ethical and practical constraints. This review highlights work that has yielded significant insights from developmental studies in the cornea and other SC repositories. This field merits further research to improve our current knowledge of the origin of SCs, their location, phenotype, function, and niche structure, as well as providing fresh insight into the pathogenesis of congenital diseases and new therapeutic avenues for treating a range of blinding corneal diseases.
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Affiliation(s)
- Sarah B Davies
- Department of Pathology, School of Medical Sciences, Inflammation and Infection Research Centre, The University of New South Wales, Sydney, Australia
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