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Verma S, Lin X, Coulson-Thomas VJ. The Potential Reversible Transition between Stem Cells and Transient-Amplifying Cells: The Limbal Epithelial Stem Cell Perspective. Cells 2024; 13:748. [PMID: 38727284 PMCID: PMC11083486 DOI: 10.3390/cells13090748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/18/2024] [Accepted: 04/24/2024] [Indexed: 05/13/2024] Open
Abstract
Stem cells (SCs) undergo asymmetric division, producing transit-amplifying cells (TACs) with increased proliferative potential that move into tissues and ultimately differentiate into a specialized cell type. Thus, TACs represent an intermediary state between stem cells and differentiated cells. In the cornea, a population of stem cells resides in the limbal region, named the limbal epithelial stem cells (LESCs). As LESCs proliferate, they generate TACs that move centripetally into the cornea and differentiate into corneal epithelial cells. Upon limbal injury, research suggests a population of progenitor-like cells that exists within the cornea can move centrifugally into the limbus, where they dedifferentiate into LESCs. Herein, we summarize recent advances made in understanding the mechanism that governs the differentiation of LESCs into TACs, and thereafter, into corneal epithelial cells. We also outline the evidence in support of the existence of progenitor-like cells in the cornea and whether TACs could represent a population of cells with progenitor-like capabilities within the cornea. Furthermore, to gain further insights into the dynamics of TACs in the cornea, we outline the most recent findings in other organ systems that support the hypothesis that TACs can dedifferentiate into SCs.
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Affiliation(s)
- Sudhir Verma
- College of Optometry, University of Houston, 4901 Calhoun Road, Houston, TX 77204, USA;
- Deen Dayal Upadhyaya College, University of Delhi, Delhi 110078, India
| | - Xiao Lin
- College of Optometry, University of Houston, 4901 Calhoun Road, Houston, TX 77204, USA;
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Sonam S, Bangru S, Perry KJ, Chembazhi UV, Kalsotra A, Henry JJ. Cellular and molecular profiles of larval and adult Xenopus corneal epithelia resolved at the single-cell level. Dev Biol 2022; 491:13-30. [PMID: 36049533 PMCID: PMC10241109 DOI: 10.1016/j.ydbio.2022.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 11/24/2022]
Abstract
Corneal Epithelial Stem Cells (CESCs) and their proliferative progeny, the Transit Amplifying Cells (TACs), are responsible for homeostasis and maintaining corneal transparency. Owing to our limited knowledge of cell fates and gene activity within the cornea, the search for unique markers to identify and isolate these cells remains crucial for ocular surface reconstruction. We performed single-cell RNA sequencing of corneal cells from larval and adult stages of Xenopus. Our results indicate that as the cornea develops and matures, there is an increase in cellular diversity, which is accompanied by a substantial shift in transcriptional profile, gene regulatory network and cell-cell communication dynamics. Our data also reveals several novel genes expressed in corneal cells and changes in gene expression during corneal differentiation at both developmental time-points. Importantly, we identify specific basal cell clusters in both the larval and adult cornea that comprise a relatively undifferentiated cell type and express distinct stem cell markers, which we propose are the putative larval and adult CESCs, respectively. This study offers a detailed atlas of single-cell transcriptomes in the frog cornea. In the future, this work will be useful to elucidate the function of novel genes in corneal epithelial homeostasis, wound healing and regeneration.
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Affiliation(s)
- Surabhi Sonam
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL, USA
| | - Sushant Bangru
- Department of Biochemistry, University of Illinois, Urbana-Champaign, IL, USA; Cancer Center@Illinois, University of Illinois, Urbana-Champaign, IL, USA
| | - Kimberly J Perry
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL, USA
| | - Ullas V Chembazhi
- Department of Biochemistry, University of Illinois, Urbana-Champaign, IL, USA
| | - Auinash Kalsotra
- Department of Biochemistry, University of Illinois, Urbana-Champaign, IL, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL, USA; Cancer Center@Illinois, University of Illinois, Urbana-Champaign, IL, USA.
| | - Jonathan J Henry
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL, USA.
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Adil MT, Henry JJ. Understanding cornea epithelial stem cells and stem cell deficiency: Lessons learned using vertebrate model systems. Genesis 2021; 59:e23411. [PMID: 33576188 DOI: 10.1002/dvg.23411] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 12/13/2022]
Abstract
Animal models have contributed greatly to our understanding of human diseases. Here, we focus on cornea epithelial stem cell (CESC) deficiency (commonly called limbal stem cell deficiency, LSCD). Corneal development, homeostasis and wound healing are supported by specific stem cells, that include the CESCs. Damage to or loss of these cells results in blindness and other debilitating ocular conditions. Here we describe the contributions from several vertebrate models toward understanding CESCs and LSCD treatments. These include both mammalian models, as well as two aquatic models, Zebrafish and the amphibian, Xenopus. Pioneering developments have been made using stem cell transplants to restore normal vision in patients with LSCD, but questions still remain about the basic biology of CESCs, including their precise cell lineages and behavior in the cornea. We describe various cell lineage tracing studies to follow their patterns of division, and the fates of their progeny during development, homeostasis, and wound healing. In addition, we present some preliminary results using the Xenopus model system. Ultimately, a more thorough understanding of these cornea cells will advance our knowledge of stem cell biology and lead to better cornea disease therapeutics.
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Affiliation(s)
- Mohd Tayyab Adil
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Jonathan J Henry
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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Sun C, Wang H, Ma Q, Chen C, Yue J, Li B, Zhang X. Time-course single-cell RNA sequencing reveals transcriptional dynamics and heterogeneity of limbal stem cells derived from human pluripotent stem cells. Cell Biosci 2021; 11:24. [PMID: 33485387 PMCID: PMC7824938 DOI: 10.1186/s13578-021-00541-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/15/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Human pluripotent stem cell-derived limbal stem cells (hPSC-derived LSCs) provide a promising cell source for corneal transplants and ocular surface reconstruction. Although recent efforts in the identification of LSC markers have increased our understanding of the biology of LSCs, much more remains to be characterized in the developmental origin, cell fate determination, and identity of human LSCs. The lack of knowledge hindered the establishment of efficient differentiation protocols for generating hPSC-derived LSCs and held back their clinical application. RESULTS Here, we performed a time-course single-cell RNA-seq to investigate transcriptional heterogeneity and expression changes of LSCs derived from human embryonic stem cells (hESCs). Based on current protocol, expression heterogeneity of reported LSC markers were identified in subpopulations of differentiated cells. EMT has been shown to occur during differentiation process, which could possibly result in generation of untargeted cells. Pseudotime trajectory analysis revealed transcriptional changes and signatures of commitment of hESCs-derived LSCs and their progeny-the transit amplifying cells. CONCLUSION Single-cell RNA-seq revealed time-course expression changes and significant transcriptional heterogeneity during hESC-derived LSC differentiation in vitro. Our results demonstrated candidate developmental trajectory and several new candidate markers for LSCs, which could facilitate elucidating the identity and developmental origin of human LSCs in vivo.
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Affiliation(s)
- Changbin Sun
- BGI-Shenzhen, Shenzhen, 518083, China.,BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, 518083, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, 518082, China
| | - Hailun Wang
- Department of Radiation Oncology, School of Medicine, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Qiwang Ma
- BGI-Shenzhen, Shenzhen, 518083, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, 518082, China
| | - Chao Chen
- BGI-Shenzhen, Shenzhen, 518083, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, 518082, China
| | - Jianhui Yue
- BGI-Shenzhen, Shenzhen, 518083, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, 518082, China.,Section of Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Bo Li
- BGI-Shenzhen, Shenzhen, 518083, China. .,China National GeneBank, BGI-Shenzhen, Shenzhen, 518082, China.
| | - Xi Zhang
- BGI-Shenzhen, Shenzhen, 518083, China. .,China National GeneBank, BGI-Shenzhen, Shenzhen, 518082, China.
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Guo ZH, Zeng YM, Lin JS. Dynamic spatiotemporal expression pattern of limbal stem cell putative biomarkers during mouse development. Exp Eye Res 2020; 192:107915. [PMID: 31911164 DOI: 10.1016/j.exer.2020.107915] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 12/20/2019] [Accepted: 01/02/2020] [Indexed: 02/07/2023]
Abstract
Limbal stem cells (LSCs), a subpopulation of limbal epithelial basal cells, are crucial to the homeostasis and wound healing of corneal epithelium. The identification and isolation of LSCs remains a challenge due to lack of specific LSCs biomarkers. In this study, Haematoxylin-eosin (HE), 4', 6-diamidino-2-phenylindole (DAPI), and immunohistochemistry (IHC) stains were performed on the pre- and post-natal limbus tissues of mice which has the advantage of more controllable in term of sampling age relative to human origin. By morphological analysis, we supported that there is an absence of the Palisades of Vogt (POV) in the mouse. The development of prenatal and neonatal cornea was dominated by its stroma, whereas after eyelids opened at P14, the corneal epithelial cells (CECs) quickly go stratification in response to the liquid-air interface. Based on IHC staining, we found that the expression of LSCs putative biomarkers in limbal epithelial basal cells appeared in chronological order as follows: Vim = p63 > CK14 > CK15 (where = represents same time; > represents earlier), and in corneal epithelial basal cells were weakened in chronological order as follows: Vim > p63 > CK15 > CK14, which might also represent the stemness degree. Furthermore, the dynamic spatial expression of the examined LSCs putative biomarkers during mouse development also implied a temporal restriction. The expression of Vim in epithelial cells of mouse ocular surface occurred during E12-E19 only. The expression of CK15 was completely undetectable in CECs after P14, whereas the others putative molecular markers of LSCs, such as p63 and CK14, still remained weak expression, suggesting that CK15 was suitable to serve as the mouse LSCs biomarkers after P14. In this study, our data demonstrated the dynamic spatiotemporal expression pattern of LSCs putative biomarkers in mouse was age-related and revealed the time spectrum of the expression of LSCs in mouse, which adds in our knowledge by understanding the dynamic expression pattern of biomarkers of stem cells relate to maintenance of their stemness.
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Affiliation(s)
- Zhi Hou Guo
- School of Medicine, Huaqiao University, Quanzhou, 362021, Fujian, China; Stem Cell Laboratory, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, China.
| | - Yi Ming Zeng
- The Second Affiliated Hospital of Fujian Medical University, China.
| | - Jun Sheng Lin
- School of Medicine, Huaqiao University, Quanzhou, 362021, Fujian, China.
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Adil MT, Simons CM, Sonam S, Henry JJ. Understanding cornea homeostasis and wound healing using a novel model of stem cell deficiency in Xenopus. Exp Eye Res 2019; 187:107767. [PMID: 31437439 DOI: 10.1016/j.exer.2019.107767] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/25/2019] [Accepted: 08/16/2019] [Indexed: 12/13/2022]
Abstract
Limbal Stem Cell Deficiency (LSCD) is a painful and debilitating disease that results from damage or loss of the Corneal Epithelial Stem Cells (CESCs). Therapies have been developed to treat LSCD by utilizing epithelial stem cell transplants. However, effective repair and recovery depends on many factors, such as the source and concentration of donor stem cells, and the proper conditions to support these transplanted cells. We do not yet fully understand how CESCs heal wounds or how transplanted CESCs are able to restore transparency in LSCD patients. A major hurdle has been the lack of vertebrate models to study CESCs. Here we utilized a short treatment with Psoralen AMT (a DNA cross-linker), immediately followed by UV treatment (PUV treatment), to establish a novel frog model that recapitulates the characteristics of cornea stem cell deficiency, such as pigment cell invasion from the periphery, corneal opacity, and neovascularization. These PUV treated whole corneas do not regain transparency. Moreover, PUV treatment leads to appearance of the Tcf7l2 labeled subset of apical skin cells in the cornea region. PUV treatment also results in increased cell death, immediately following treatment, with pyknosis as a primary mechanism. Furthermore, we show that PUV treatment causes depletion of p63 expressing basal epithelial cells, and can stimulate mitosis in the remaining cells in the cornea region. To study the response of CESCs, we created localized PUV damage by focusing the UV radiation on one half of the cornea. These cases initially develop localized stem cell deficiency characteristics on the treated side. The localized PUV treatment is also capable of stimulating some mitosis in the untreated (control) half of those corneas. Unlike the whole treated corneas, the treated half is ultimately able to recover and corneal transparency is restored. Our study provides insight into the response of cornea cells following stem cell depletion, and establishes Xenopus as a suitable model for studying CESCs, stem cell deficiency, and other cornea diseases. This model will also be valuable for understanding the nature of transplanted CESCs, which will lead to progress in the development of therapeutics for LSCD.
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Affiliation(s)
- Mohd Tayyab Adil
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, 601 S. Goodwin Ave. Urbana, IL, 61801, USA.
| | - Claire M Simons
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, 601 S. Goodwin Ave. Urbana, IL, 61801, USA.
| | - Surabhi Sonam
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, 601 S. Goodwin Ave. Urbana, IL, 61801, USA.
| | - Jonathan J Henry
- Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, 601 S. Goodwin Ave. Urbana, IL, 61801, USA.
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