1
|
Li S, Sun H, Chen L, Fu Y. Targeting limbal epithelial stem cells: master conductors of corneal epithelial regeneration from the bench to multilevel theranostics. J Transl Med 2024; 22:794. [PMID: 39198892 PMCID: PMC11350997 DOI: 10.1186/s12967-024-05603-y] [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: 01/25/2024] [Accepted: 08/10/2024] [Indexed: 09/01/2024] Open
Abstract
The cornea is the outermost layer of the eye and plays an essential role in our visual system. Limbal epithelial stem cells (LESCs), which are localized to a highly regulated limbal niche, are the master conductors of corneal epithelial regeneration. Damage to LESCs and their niche may result in limbal stem cell deficiency (LSCD), a disease confused ophthalmologists so many years and can lead to corneal conjunctivalization, neovascularization, and even blindness. How to restore the LESCs function is the hot topic for ocular scientists and clinicians around the world. This review introduced LESCs and the niche microenvironment, outlined various techniques for isolating and culturing LESCs used in LSCD research, presented common diseases that cause LSCD, and provided a comprehensive overview of both the diagnosis and multiple treatments for LSCD from basic research to clinical therapies, especially the emerging cell therapies based on various stem cell sources. In addition, we also innovatively concluded the latest strategies in recent years, including exogenous drugs, tissue engineering, nanotechnology, exosome and gene therapy, as well as the ongoing clinical trials for treating LSCD in recent five years. Finally, we highlighted challenges from bench to bedside in LSCD and discussed cutting-edge areas in LSCD therapeutic research. We hope that this review could pave the way for future research and translation on treating LSCD, a crucial step in the field of ocular health.
Collapse
Affiliation(s)
- Shiding Li
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Rd, Shanghai, 200011, China
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, 639 Zhizaoju Rd, Shanghai, 200011, China
| | - Hao Sun
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Rd, Shanghai, 200011, China
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, 639 Zhizaoju Rd, Shanghai, 200011, China
| | - Liangbo Chen
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Rd, Shanghai, 200011, China.
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, 639 Zhizaoju Rd, Shanghai, 200011, China.
| | - Yao Fu
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Rd, Shanghai, 200011, China.
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, 639 Zhizaoju Rd, Shanghai, 200011, China.
| |
Collapse
|
2
|
Thomasy SM, Leonard BC, Greiner MA, Skeie JM, Raghunathan VK. Squishy matters - Corneal mechanobiology in health and disease. Prog Retin Eye Res 2024; 99:101234. [PMID: 38176611 PMCID: PMC11193890 DOI: 10.1016/j.preteyeres.2023.101234] [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: 09/01/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/06/2024]
Abstract
The cornea, as a dynamic and responsive tissue, constantly interacts with mechanical forces in order to maintain its structural integrity, barrier function, transparency and refractive power. Cells within the cornea sense and respond to various mechanical forces that fundamentally regulate their morphology and fate in development, homeostasis and pathophysiology. Corneal cells also dynamically regulate their extracellular matrix (ECM) with ensuing cell-ECM crosstalk as the matrix serves as a dynamic signaling reservoir providing biophysical and biochemical cues to corneal cells. Here we provide an overview of mechanotransduction signaling pathways then delve into the recent advances in corneal mechanobiology, focusing on the interplay between mechanical forces and responses of the corneal epithelial, stromal, and endothelial cells. We also identify species-specific differences in corneal biomechanics and mechanotransduction to facilitate identification of optimal animal models to study corneal wound healing, disease, and novel therapeutic interventions. Finally, we identify key knowledge gaps and therapeutic opportunities in corneal mechanobiology that are pressing for the research community to address especially pertinent within the domains of limbal stem cell deficiency, keratoconus and Fuchs' endothelial corneal dystrophy. By furthering our understanding corneal mechanobiology, we can contextualize discoveries regarding corneal diseases as well as innovative treatments for them.
Collapse
Affiliation(s)
- Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, United States; Department of Ophthalmology & Vision Science, School of Medicine, University of California - Davis, Davis, CA, United States; California National Primate Research Center, Davis, CA, United States.
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, United States; Department of Ophthalmology & Vision Science, School of Medicine, University of California - Davis, Davis, CA, United States
| | - Mark A Greiner
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, United States; Iowa Lions Eye Bank, Coralville, IA, United States
| | - Jessica M Skeie
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, United States; Iowa Lions Eye Bank, Coralville, IA, United States
| | | |
Collapse
|
3
|
Ghosh N, Treisman JE. Apical cell expansion maintained by Dusky-like establishes a scaffold for corneal lens morphogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.17.575959. [PMID: 38293108 PMCID: PMC10827211 DOI: 10.1101/2024.01.17.575959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
The biconvex shape of the Drosophila corneal lens, which enables it to focus light onto the retina, arises by organized assembly of chitin and other apical extracellular matrix components. We show here that the Zona Pellucida domain-containing protein Dusky-like is essential for normal corneal lens morphogenesis. Dusky-like transiently localizes to the expanded apical surfaces of the corneal lens-secreting cells, and in its absence, these cells undergo apical constriction and apicobasal contraction. Dusky-like also controls the arrangement of two other Zona Pellucida-domain proteins, Dumpy and Piopio, external to the developing corneal lens. Loss of either dusky-like or dumpy delays chitin accumulation and disrupts the outer surface of the corneal lens. Artificially inducing apical constriction with constitutively active Myosin light chain kinase is sufficient to similarly alter chitin deposition and corneal lens morphology. These results demonstrate the importance of cell shape for the morphogenesis of overlying apical extracellular matrix structures.
Collapse
|
4
|
Kauppila M, Mörö A, Valle-Delgado JJ, Ihalainen T, Sukki L, Puistola P, Kallio P, Ilmarinen T, Österberg M, Skottman H. Toward Corneal Limbus In Vitro Model: Regulation of hPSC-LSC Phenotype by Matrix Stiffness and Topography During Cell Differentiation Process. Adv Healthc Mater 2023; 12:e2301396. [PMID: 37449943 DOI: 10.1002/adhm.202301396] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/29/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
A functional limbal epithelial stem cells (LSC) niche is a vital element in the regular renewal of the corneal epithelium by LSCs and maintenance of good vision. However, little is known about its unique structure and mechanical properties on LSC regulation, creating a significant gap in development of LSC-based therapies. Herein, the effect of mechanical and architectural elements of the niche on human pluripotent derived LSCs (hPSC-LSC) phenotype and growth is investigated in vitro. Specifically, three formulations of polyacrylamide gels with different controlled stiffnesses are used for culture and characterization of hPSC-LSCs from different stages of differentiation. In addition, limbal mimicking topography in polydimethylsiloxane is utilized for culturing hPSC-LSCs at early time point of differentiation. For comparison, the expression of selected key proteins of the corneal cells is analyzed in their native environment through whole mount staining of human donor corneas. The results suggest that mechanical response and substrate preference of the cells is highly dependent on their developmental stage. In addition, data indicate that cells may carry possible mechanical memory from previous culture matrix, both highlighting the importance of mechanical design of a functional in vitro limbus model.
Collapse
Affiliation(s)
- Maija Kauppila
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Anni Mörö
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Juan José Valle-Delgado
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Espoo, 02150, Finland
| | - Teemu Ihalainen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Lassi Sukki
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Paula Puistola
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Pasi Kallio
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Tanja Ilmarinen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| | - Monika Österberg
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Espoo, 02150, Finland
| | - Heli Skottman
- Faculty of Medicine and Health Technology, Tampere University, Tampere, 33520, Finland
| |
Collapse
|
5
|
Bhattacharya S, Mukherjee A, Pisano S, Dimri S, Knaane E, Altshuler A, Nasser W, Dey S, Shi L, Mizrahi I, Blum N, Jokel O, Amitai-Lange A, Kaganovsky A, Mimouni M, Socea S, Midlij M, Tiosano B, Hasson P, Feral C, Wolfenson H, Shalom-Feuerstein R. The biophysical property of the limbal niche maintains stemness through YAP. Cell Death Differ 2023:10.1038/s41418-023-01156-7. [PMID: 37095157 DOI: 10.1038/s41418-023-01156-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 04/26/2023] Open
Abstract
The cell fate decisions of stem cells (SCs) largely depend on signals from their microenvironment (niche). However, very little is known about how biochemical niche cues control cell behavior in vivo. To address this question, we focused on the corneal epithelial SC model in which the SC niche, known as the limbus, is spatially segregated from the differentiation compartment. We report that the unique biomechanical property of the limbus supports the nuclear localization and function of Yes-associated protein (YAP), a putative mediator of the mechanotransduction pathway. Perturbation of tissue stiffness or YAP activity affects SC function as well as tissue integrity under homeostasis and significantly inhibited the regeneration of the SC population following SC depletion. In vitro experiments revealed that substrates with the rigidity of the corneal differentiation compartment inhibit nuclear YAP localization and induce differentiation, a mechanism that is mediated by the TGFβ-SMAD2/3 pathway. Taken together, these results indicate that SC sense biomechanical niche signals and that manipulation of mechano-sensory machinery or its downstream biochemical output may bear fruits in SC expansion for regenerative therapy.
Collapse
Affiliation(s)
- Swarnabh Bhattacharya
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel.
- Department of Medical Oncology and Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
- Departments of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA.
| | - Abhishek Mukherjee
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Sabrina Pisano
- Université Côte d'Azur, INSERM, CNRS, IRCAN, 06107, Nice, France
| | - Shalini Dimri
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Eman Knaane
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Anna Altshuler
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Waseem Nasser
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Sunanda Dey
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Lidan Shi
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Ido Mizrahi
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Noam Blum
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Ophir Jokel
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Aya Amitai-Lange
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Anna Kaganovsky
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Michael Mimouni
- Department of Ophthalmology, Rambam Health Care Campus, 31096, Haifa, Israel
| | - Sergiu Socea
- Department of Ophthalmology, Rambam Health Care Campus, 31096, Haifa, Israel
| | - Mohamad Midlij
- Department of Ophthalmology, Hilel Yafe Medical Center, Hadera, Israel
| | - Beatrice Tiosano
- Department of Ophthalmology, Hilel Yafe Medical Center, Hadera, Israel
| | - Peleg Hasson
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel
| | - Chloe Feral
- Université Côte d'Azur, INSERM, CNRS, IRCAN, 06107, Nice, France
| | - Haguy Wolfenson
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel.
| | - Ruby Shalom-Feuerstein
- Department of Genetics & Developmental Biology, The Rappaport Faculty of Medicine & Research Institute, Technion Integrated Cancer Center, Technion - Israel Institute of Technology, 31096, Haifa, Israel.
| |
Collapse
|
6
|
Ra’oh NA, Man RC, Fauzi MB, Ghafar NA, Buyong MR, Hwei NM, Halim WHWA. Recent Approaches to the Modification of Collagen Biomatrix as a Corneal Biomatrix and Its Cellular Interaction. Polymers (Basel) 2023; 15:polym15071766. [PMID: 37050380 PMCID: PMC10097332 DOI: 10.3390/polym15071766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 03/21/2023] [Accepted: 03/30/2023] [Indexed: 04/05/2023] Open
Abstract
Over the last several decades, numerous modifications and advancements have been made to design the optimal corneal biomatrix for corneal epithelial cell (CECs) or limbal epithelial stem cell (LESC) carriers. However, researchers have yet to discover the ideal optimization strategies for corneal biomatrix design and its effects on cultured CECs or LESCs. This review discusses and summarizes recent optimization strategies for developing an ideal collagen biomatrix and its interactions with CECs and LESCs. Using PRISMA guidelines, articles published from June 2012 to June 2022 were systematically searched using Web of Science (WoS), Scopus, PubMed, Wiley, and EBSCOhost databases. The literature search identified 444 potential relevant published articles, with 29 relevant articles selected based on inclusion and exclusion criteria following screening and appraising processes. Physicochemical and biocompatibility (in vitro and in vivo) characterization methods are highlighted, which are inconsistent throughout various studies. Despite the variability in the methodology approach, it is postulated that the modification of the collagen biomatrix improves its mechanical and biocompatibility properties toward CECs and LESCs. All findings are discussed in this review, which provides a general view of recent trends in this field.
Collapse
Affiliation(s)
- Nur Amalia Ra’oh
- Department of Ophthalmology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Rohaina Che Man
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Mh Busra Fauzi
- Centre for Tissue Engineering and Regenerative Medicine (CTERM), Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Norzana Abd Ghafar
- Department of Anatomy, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Muhamad Ramdzan Buyong
- Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Ng Min Hwei
- Centre for Tissue Engineering and Regenerative Medicine (CTERM), Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Wan Haslina Wan Abdul Halim
- Department of Ophthalmology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| |
Collapse
|
7
|
Lin X, Mekonnen T, Verma S, Zevallos-Delgado C, Singh M, Aglyamov SR, Gesteira TF, Larin KV, Coulson-Thomas VJ. Hyaluronan Modulates the Biomechanical Properties of the Cornea. Invest Ophthalmol Vis Sci 2022; 63:6. [PMID: 36478198 PMCID: PMC9733656 DOI: 10.1167/iovs.63.13.6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose Hyaluronan (HA) is a major constituent of the extracellular matrix (ECM) that has high viscosity and is essential for maintaining tissue hydration. In the cornea, HA is enriched in the limbal region and is a key component of the limbal epithelial stem cell niche. HA is upregulated after injury participating in the formation of the provisional matrix, and has a key role in regulating the wound healing process. This study investigated whether changes in the distribution of HA before and after injury affects the biomechanical properties of the cornea in vivo. Methods Corneas of wild-type (wt) mice and mice lacking enzymes involved in the biosynthesis of HA were analyzed before, immediately after, and 7 and 14 days after a corneal alkali burn (AB). The corneas were evaluated using both a ring light and fluorescein stain by in vivo confocal microscopy, optical coherence elastography (OCE), and immunostaining of corneal whole mounts. Results Our results show that wt mice and mice lacking HA synthase (Has)1 and 3 present an increase in corneal stiffness 7 and 14 days after AB without a significant increase in HA expression and absence of scarring at 14 days after AB. In contrast, mice lacking Has2 present a significant decrease in corneal stiffness, with a significant increase in HA expression and scarring at 14 days after AB. Conclusions Our findings show that the mechanical properties of the cornea are significantly modulated by changes in HA distribution following alkali burn.
Collapse
Affiliation(s)
- Xiao Lin
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Taye Mekonnen
- Department of Biomedical Engineering, University of Houston, Houston, Texas, United States
| | - Sudhir Verma
- College of Optometry, University of Houston, Houston, Texas, United States,Department of Zoology, Deen Dayal Upadhyaya College, University of Delhi, Delhi, India
| | | | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, Texas, United States
| | - Salavat R. Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, Texas, United States
| | - Tarsis F. Gesteira
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Kirill V. Larin
- Department of Biomedical Engineering, University of Houston, Houston, Texas, United States
| | | |
Collapse
|
8
|
Di Girolamo N, Park M. Cell identity changes in ocular surface Epithelia. Prog Retin Eye Res 2022:101148. [DOI: 10.1016/j.preteyeres.2022.101148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/13/2022] [Accepted: 11/09/2022] [Indexed: 11/21/2022]
|
9
|
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.
Collapse
Affiliation(s)
| | | | - Sophie X. Deng
- Jules Stein Eye Institute, University of California, Los Angeles, CA 94143, USA; (S.Y.T.R.); (J.S.R.)
| |
Collapse
|
10
|
Bonnet C, González S, Roberts JS, Robertson SYT, Ruiz M, Zheng J, Deng SX. Human limbal epithelial stem cell regulation, bioengineering and function. Prog Retin Eye Res 2021; 85:100956. [PMID: 33676006 PMCID: PMC8428188 DOI: 10.1016/j.preteyeres.2021.100956] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 02/21/2021] [Accepted: 02/26/2021] [Indexed: 12/13/2022]
Abstract
The corneal epithelium is continuously renewed by limbal stem/progenitor cells (LSCs), a cell population harbored in a highly regulated niche located at the limbus. Dysfunction and/or loss of LSCs and their niche cause limbal stem cell deficiency (LSCD), a disease that is marked by invasion of conjunctival epithelium into the cornea and results in failure of epithelial wound healing. Corneal opacity, pain, loss of vision, and blindness are the consequences of LSCD. Successful treatment of LSCD depends on accurate diagnosis and staging of the disease and requires restoration of functional LSCs and their niche. This review highlights the major advances in the identification of potential LSC biomarkers and components of the LSC niche, understanding of LSC regulation, methods and regulatory standards in bioengineering of LSCs, and diagnosis and staging of LSCD. Overall, this review presents key points for researchers and clinicians alike to consider in deepening the understanding of LSC biology and improving LSCD therapies.
Collapse
Affiliation(s)
- Clémence Bonnet
- Cornea Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA; Cornea Department, Paris University, Cochin Hospital, AP-HP, F-75014, Paris, France
| | - Sheyla González
- Cornea Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - JoAnn S Roberts
- Cornea Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Sarah Y T Robertson
- Cornea Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Maxime Ruiz
- Cornea Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Jie Zheng
- Basic Science Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Sophie X Deng
- Cornea Division, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA.
| |
Collapse
|
11
|
Abdelftah Z, Gaber AR, Abo-Eleneen RE, EL-Bakry AM. Microstructure characteristics of cornea of some birds: a comparative study. BENI-SUEF UNIVERSITY JOURNAL OF BASIC AND APPLIED SCIENCES 2021. [DOI: 10.1186/s43088-021-00155-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Light is the critical factor that affects the eye's morphology and auxiliary plans. The ecomorphological engineering of the cornea aids the physiological activities of the cornea during connections between photoreceptor neurons and light photons. Cornea was dissected free from the orbit from three avian species as ibis (Eudocium albus), duck (Anas platyrhynchus domesticus) and hawk (Buteo Buteo) and prepared for light and scanning electron microscopy and special stain for structural comparison related to function.
Results
The three investigated avian species are composed of three identical layers; epithelium, stroma, and endothelium, and two basement membranes; bowman's and Descemet’s membrane, separating two cellular layers, except for B. buteo which only has a Descemet’s membrane. The corneal layers in the investigated species display different affinity to stain with Periodic Acid Schiff stain. The external corneal surface secured by different normal epithelial cells ran from hexagonal to regular polygonal cells. Those epithelial cells are punctured by different diameter microholes and microplicae and microvilli of various length. Blebs are scarcely distributed over their surface. The present investigation utilized histological, histochemical and SEM examination.
Conclusions
The study presents a brief image/account of certain structures of cornea for three of Avian’s species. Data distinguish the anatomic structures of the owl's eye. The discussion explains the role of some functional anatomical structures all through the vision.
Collapse
|
12
|
Li S, Ding C, Guo Y, Zhang Y, Wang H, Sun X, Zhang J, Cui Z, Chen J. Mechanotransduction Regulates Reprogramming Enhancement in Adherent 3D Keratocyte Cultures. Front Bioeng Biotechnol 2021; 9:709488. [PMID: 34568299 PMCID: PMC8460903 DOI: 10.3389/fbioe.2021.709488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/27/2021] [Indexed: 11/18/2022] Open
Abstract
Suspended spheroid culture using ultralow attachment plates (ULAPs) is reported to effect corneal fibroblast reprogramming. Polydimethylsiloxane (PDMS), with hydrophobic and soft substrate properties, facilitates adherent spheroid formation that promotes cellular physical reprogramming into stem-like cells without using transcription factors. However, it is still unknown whether the biophysical properties of PDMS have the same effect on adult human corneal keratocyte reprogramming. Here, PDMS and essential 8 (E8) medium were utilized to culture keratocyte spheroids and fibroblast spheroids, and the reprogramming results were compared. We provide insights into the probable mechanisms of the PDMS effect on spheroids. qPCR analysis showed that the expression of some stem cell marker genes (OCT4, NANOG, SOX2, KLF4, CMYC, ABCG2 and PAX6) was significantly greater in keratocyte spheroids than in fibroblast spheroids. The endogenous level of stemness transcription factors (OCT4, NANOG, SOX2, KLF4 and CMYC) was higher in keratocytes than in fibroblasts. Immunofluorescence staining revealed Klf4, Nanog, Sox2, ABCG2 and Pax6 were positively stained in adherent 3D spheroids but weakly or negatively stained in adherent 2D cells. Furthermore, OCT4, NANOG, SOX2, KLF4, HNK1, ABCG2 and PAX6 gene expression was significantly higher in adherent 3D spheroids than in adherent 2D cells. Meanwhile, SOX2, ABCG2 and PAX6 were more upregulated in adherent 3D spheroids than in suspended 3D spheroids. The RNA-seq analysis suggested that regulation of the actin cytoskeleton, TGFβ/BMP and HIF-1 signaling pathways induced changes in mechanotransduction, the mesenchymal-to-epithelial transition and hypoxia, which might be responsible for the effect of PDMS on facilitating reprogramming. In conclusion, compared to corneal fibroblasts, keratocytes were more susceptible to reprogramming due to higher levels of endogenous stemness transcription factors. Spheroid culture of keratocytes using PDMS had a positive impact on promoting the expression of some stem cell markers. PDMS, as a substrate to form spheroids, was better able to promote reprogramming than ULAPs. These results indicated that the physiological cells and culture conditions herein enhance reprogramming. Therefore, adherent spheroid culture of keratocytes using PDMS is a promising strategy to more safely promote reprogramming, suggesting its potential application for developing clinical implants in tissue engineering and regenerative medicine.
Collapse
Affiliation(s)
- Shenyang Li
- Aier School of Ophthalmology, Central South University, Changsha, China
| | | | - Yonglong Guo
- Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China
| | - Yanan Zhang
- Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China
| | - Hao Wang
- Aier School of Ophthalmology, Central South University, Changsha, China
| | - Xihao Sun
- Aier School of Ophthalmology, Central South University, Changsha, China
| | - Jun Zhang
- Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou, China
| | - Zekai Cui
- Aier School of Ophthalmology, Central South University, Changsha, China.,Aier Eye Institute, Changsha, China
| | - Jiansu Chen
- Aier School of Ophthalmology, Central South University, Changsha, China.,Aier Eye Institute, Changsha, China.,Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University, Guangzhou, China
| |
Collapse
|
13
|
Amit C, Padmanabhan P, Narayanan J. Deciphering the mechanoresponsive role of β-catenin in keratoconus epithelium. Sci Rep 2020; 10:21382. [PMID: 33288782 PMCID: PMC7721701 DOI: 10.1038/s41598-020-77138-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 10/19/2020] [Indexed: 12/30/2022] Open
Abstract
Keratoconus (KC) is a corneal dystrophy characterized by progressive ectasia that leads to severe visual impairment and remains one of the leading indications for corneal transplantation. The etiology is believed to be multifactorial and alterations have been documented in the biomechanical, biochemical and ultrastructural characteristics of the cornea. While the exact site of disease origin is still debated, changes in the corneal epithelium are believed to occur even before the disease is clinically manifested. In this study we investigate the possible role of β-catenin as mechanotransducer in KC corneal epithelium. The sheets of corneal epithelium removed from keratoconic eyes when they underwent collagen crosslinking as a therapeutic procedure were used for this study. The healthy corneal epithelium of patients undergoing Laser Refractive Surgery for the correction of their refractive error, served as controls. Immunoblotting and tissue immunofluorescence studies were performed on KC epithelium to analyse the expression and localization of β-catenin, E-cadherin, ZO1, α-catenin, Cyclin D1, α-actinin, RhoA, and Rac123. Co-immunoprecipitation of β-catenin followed by mass spectrometry of KC epithelium was performed to identify its interacting partners. This was further validated by using epithelial tissues grown on scaffolds of different stiffness. Histology data reported breaks in the Bowman’s layer in KC patients. We hypothesize that these breaks expose the epithelium to the keratoconic corneal stroma, which, is known to have a decreased elastic modulus and that β-catenin acts as a mechanotransducer that induces structural changes such as loss of polarity (Syntaxin3) and barrier function (ZO1) through membrane delocalization. The results of our study strongly suggest that β-catenin could be a putative mechanotransducer in KC epithelium, thus supporting our hypothesis.
Collapse
Affiliation(s)
- Chatterjee Amit
- Department of Nanobiotechnology, KNBIRVO Block, Vision Research Foundation, Sankara Nethralaya, 18/41, College Road Nungambakkam, Chennai, Tamil Nadu, India.,School of Chemical and Biotechnology, SASTRA, Deemed University, Tanjore, Tamil Nadu, India
| | - Prema Padmanabhan
- Department of Cornea, Medical Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India
| | - Janakiraman Narayanan
- Department of Nanobiotechnology, KNBIRVO Block, Vision Research Foundation, Sankara Nethralaya, 18/41, College Road Nungambakkam, Chennai, Tamil Nadu, India.
| |
Collapse
|
14
|
Gouveia RM, Connon CJ. Biomechanical Modulation Therapy-A Stem Cell Therapy Without Stem Cells for the Treatment of Severe Ocular Burns. Transl Vis Sci Technol 2020; 9:5. [PMID: 33240564 PMCID: PMC7671857 DOI: 10.1167/tvst.9.12.5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/07/2020] [Indexed: 12/16/2022] Open
Abstract
Ocular injuries caused by chemical and thermal burns are often unmanageable and frequently result in disfigurement, corneal haze/opacification, and vision loss. Currently, a considerable number of surgical and pharmacological approaches are available to treat such injuries at either an acute or a chronic stage. However, these existing interventions are mainly directed at (and limited to) suppressing corneal inflammation and neovascularization while promoting re-epithelialization. Reconstruction of the ocular surface represents a suitable but last-option recourse in cases where epithelial healing is severely impaired, such as due to limbal stem cell deficiency. In this concise review, we discuss how biomechanical modulation therapy (BMT) may represent a more effective approach to promoting the regeneration of ocular tissues affected by burn injuries via restoration of the limbal stem cell niche. Specifically, the scientific basis supporting this new therapeutic modality is described, along with our growing understanding of the role that tissue biomechanics plays in stem cell fate and function. The potential impact of BMT as a future treatment option for the management of injuries affecting tissue compliance is also further discussed.
Collapse
Affiliation(s)
- Ricardo M Gouveia
- Biosciences Institute, Faculty of Medical Sciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Che J Connon
- Biosciences Institute, Faculty of Medical Sciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| |
Collapse
|
15
|
Efraim Y, Chen FYT, Stashko C, Cheong KN, Gaylord E, McNamara N, Knox SM. Alterations in corneal biomechanics underlie early stages of autoimmune-mediated dry eye disease. J Autoimmun 2020; 114:102500. [PMID: 32565048 PMCID: PMC8269964 DOI: 10.1016/j.jaut.2020.102500] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 12/11/2022]
Abstract
Autoimmune-mediated dry eye disease is a pathological feature of multiple disorders including Sjögren's syndrome, lupus and rheumatoid arthritis that has a life-long, detrimental impact on vision and overall quality of life. Although late stage disease outcomes such as epithelial barrier dysfunction, reduced corneal innervation and chronic inflammation have been well characterized in both human patients and mouse models, there is little to no understanding of early pathological processes. Moreover, the mechanisms underlying the loss of cornea homeostasis and disease progression are unknown. Here, we utilize the autoimmune regulatory (Aire)-deficient mouse model of autoimmune-mediated dry eye disease in combination with genome wide transcriptomics, high-resolution imaging and atomic force microscopy to reveal a potential extracellular matrix (ECM)-biomechanical-based mechanism driving cellular and morphological changes at early disease onset. Early disease in the Aire-deficient mouse model is associated with a mild reduction in tear production and moderate immune cell infiltration, allowing for interrogation of cellular, molecular and biomechanical changes largely independent of chronic inflammation. Using these tools, we demonstrate for the first time that the emergence of autoimmune-mediated dry eye disease is associated with an alteration in the biomechanical properties of the cornea. We reveal a dramatic disruption of the synthesis and organization of the extracellular matrix as well as degradation of the epithelial basement membrane during early disease. Notably, we provide evidence that the nerve supply to the cornea is severely reduced at early disease stages and that this is independent of basement membrane destruction or significant immune cell infiltration. Furthermore, diseased corneas display spatial heterogeneity in mechanical, structural and compositional changes, with the limbal compartment often exhibiting the opposite response compared to the central cornea. Despite these differences, however, epithelial hyperplasia is apparent in both compartments, possibly driven by increased activation of IL-1R1 and YAP signaling pathways. Thus, we reveal novel perturbations in corneal biomechanics, matrix organization and cell behavior during the early phase of dry eye that may underlie disease development and progression, presenting new potential targets for therapeutic intervention.
Collapse
Affiliation(s)
- Yael Efraim
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Feeling Yu Ting Chen
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Connor Stashko
- Center for Bioengineering and Tissue Regeneration, Department of Surgery, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Ka Neng Cheong
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Eliza Gaylord
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Nancy McNamara
- School of Optometry and Vision Science Graduate Program, University of California, Berkeley, CA, 94720, USA; Department of Anatomy, University of California San Francisco, San Francisco, CA, 94143, USA.
| | - Sarah M Knox
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA.
| |
Collapse
|
16
|
Li H, Zhao L, Wang F, Wang H, Dong M, Liu T, Ruan T, Zhou M, Zhou Q, Xie L. Natural cross-linker-stabilized acellular porcine corneal stroma for lamellar keratoplasty. Acta Biomater 2020; 114:270-284. [PMID: 32702529 DOI: 10.1016/j.actbio.2020.07.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/16/2020] [Accepted: 07/16/2020] [Indexed: 01/12/2023]
Abstract
Acellular porcine corneal stroma (APCS) is a promising alternative to human donor cornea for lamellar keratoplasty (LKP). However, the detergents, enzymes and physical forces used during decellularization unavoidably alter the cornea's extracellular matrix composition and disrupt its ultrastructure, making it less mechanically stable and liable to degradation both in vitro and in vivo. Herein, we systematically analyzed the low biomechanics and easy degradability of APCS in terms of structure and protein composition. Then, we introduced natural cross-linkers, namely proanthocyanidin (PA), epigallocatechin-3-gallate and genipin, to stabilize the APCS that exhibited color variations during crosslinking. Then, we developed a protective crosslinking system by combining cross-linkers with bovine serum albumin (BSA) to reduce color change, maintain transparency and improve the mechanical property of APCS. PA/BSA-crosslinked APCS (PA/BSA-APCS) shows favorable corneal transparency and swelling property; the improved overall and surface corneal biomechanics were comparable to those of human cornea, revealing strong resistance to enzymatic degradation and good biocompatibility. Results from LKP in the rabbit model showed complete re-epithelialization without graft melting, the stitches were scarcely loosened after the operation and more host keratocytes had migrated in PA/BSA-APCS at six months post-operation. Therefore, PA/BSA-APCS could be useful as a corneal substitute for tissue regeneration and the protective crosslinking system could be applicable in other bioengineering fields.
Collapse
Affiliation(s)
- Hua Li
- Department of Ophthalmology, Clinical Medical College of Shandong University, Jinan, China; State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Long Zhao
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Fuyan Wang
- Department of Ophthalmology, Clinical Medical College of Shandong University, Jinan, China; State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Hongwei Wang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Muchen Dong
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Eye Hospital of Shandong First Medical Universtiy, Jinan, China
| | - Ting Liu
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Ting Ruan
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China
| | - Mingming Zhou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Qingjun Zhou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China.
| | - Lixin Xie
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China.
| |
Collapse
|
17
|
Tseng SCG, Chen SY, Mead OG, Tighe S. Niche regulation of limbal epithelial stem cells: HC-HA/PTX3 as surrogate matrix niche. Exp Eye Res 2020; 199:108181. [PMID: 32795525 DOI: 10.1016/j.exer.2020.108181] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 06/15/2020] [Accepted: 07/31/2020] [Indexed: 12/13/2022]
Abstract
Homeostasis of the corneal epithelium is ultimately maintained by stem cells that reside in a specialized microenvironment within the corneal limbus termed palisades of Vogt. This limbal niche nourishes, protects, and regulates quiescence, self-renewal, and fate decision of limbal epithelial stem/progenitor cells (LEPCs) toward corneal epithelial differentiation. This review focuses on our current understanding of the mechanism by which limbal (stromal) niche cells (LNCs) regulate the aforementioned functions of LEPCs. Based on our discovery and characterization of a unique extracellular matrix termed HC-HA/PTX3 (Heavy chain (HC1)-hyaluronan (HA)/pentraxin 3 (PTX3) complex, "-" denotes covalent linkage; "/" denotes non-covalent binding) in the birth tissue, i.e., amniotic membrane and umbilical cord, we put forth a new paradigm that HC-HA/PTX3 serves as a surrogate matrix niche by maintaining the in vivo nuclear Pax6+ neural crest progenitor phenotype to support quiescence and self-renewal but prevent corneal fate decision of LEPCs. This new paradigm helps explain how limbal stem cell deficiency (LSCD) develops in aniridia due to Pax6-haplotype deficiency and further explains why transplantation of HC-HA/PTX3-containing amniotic membrane prevents LSCD in acute chemical burns and Stevens Johnson syndrome, augments the success of autologous LEPCs transplantation in patients suffering from partial or total LSCD, and assists ex vivo expansion (engineering) of a graft containing LEPCs. We thus envisage that this new paradigm based on regenerative matrix HC-HA/PTX3 as a surrogate niche can set a new standard for regenerative medicine in and beyond ophthalmology.
Collapse
Affiliation(s)
- Scheffer C G Tseng
- Research & Development Department, TissueTech, Inc., Miami, FL, 33126, USA; Ocular Surface Center and Ocular Surface Research & Education Foundation, Miami, FL, 33126, USA.
| | - Szu-Yu Chen
- Research & Development Department, TissueTech, Inc., Miami, FL, 33126, USA
| | - Olivia G Mead
- Research & Development Department, TissueTech, Inc., Miami, FL, 33126, USA
| | - Sean Tighe
- Research & Development Department, TissueTech, Inc., Miami, FL, 33126, USA; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA; Department of Ophthalmology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 33199, USA
| |
Collapse
|
18
|
da Mata Martins TM, da Silva Cunha P, Rodrigues MA, de Carvalho JL, de Souza JE, de Carvalho Oliveira JA, Gomes DA, de Goes AM. Epithelial basement membrane of human decellularized cornea as a suitable substrate for differentiation of embryonic stem cells into corneal epithelial-like cells. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 116:111215. [PMID: 32806330 DOI: 10.1016/j.msec.2020.111215] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 06/13/2020] [Accepted: 06/18/2020] [Indexed: 12/11/2022]
Abstract
The ability to decellularize and recellularize the corneas deemed unsuitable for transplantation may increase the number of available grafts. Decellularized corneas (DCs) may provide a natural microenvironment for cell adhesion and differentiation. Despite this, no study to date has evaluated their efficacy as a substrate for the induction of stem cell differentiation into corneal cells. The present study aimed to compare the efficiency of NaCl and NaCl plus nucleases methods to decellularize whole human corneas, and to investigate the effect of epithelial basement membrane (EBM) of whole DCs on the ability of human embryonic stem cells (hESCs) to differentiate into corneal epithelial-like cells when cultured in animal serum-free differentiation medium. As laminin is the major component of EBM, we also investigated its effect on hESCs differentiation. The decellularization efficiency and integrity of the extracellular matrix (ECM) obtained were investigated by histology, electron microscopy, DNA quantification, immunofluorescence, and nuclear staining. The ability of hESCs to differentiate into corneal epithelial-like cells when seeded on the EBM of DCs or laminin-coated wells was evaluated by immunofluorescence and RT-qPCR analyses. NaCl treatment alone, without nucleases, was insufficient to remove cellular components, while NaCl plus nucleases treatment resulted in efficient decellularization and preservation of the ECM. Unlike cells induced to differentiate on laminin, hESCs differentiated on DCs expressed high levels of corneal epithelial-specific markers, keratin 3 and keratin 12. It was demonstrated for the first time that the decellularized matrices had a positive effect on the differentiation of hESCs towards corneal epithelial-like cells. Such a strategy supports the potential applications of human DCs and hESCs in corneal epithelium tissue engineering.
Collapse
Affiliation(s)
- Thaís Maria da Mata Martins
- Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Pricila da Silva Cunha
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil
| | - Michele Angela Rodrigues
- Department of Pathology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil
| | - Juliana Lott de Carvalho
- Department of Genomic Sciences and Biotechnology, Catholic University of Brasilia, QS 07 - Lote 01, EPCT - Taguatinga, Brasília, Distrito Federal 71966-700, Brazil; Faculty of Medicine, University of Brasilia, Campus Universitário Darcy Ribeiro, Brasília, Distrito Federal 70910-900, Brazil
| | - Joyce Esposito de Souza
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil
| | - Junnia Alvarenga de Carvalho Oliveira
- Department of Microbiology, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil
| | - Dawidson Assis Gomes
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil
| | - Alfredo Miranda de Goes
- Department of Pathology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Belo Horizonte 31270-901, Minas Gerais, Brazil
| |
Collapse
|
19
|
Prina E, Amer MH, Sidney L, Tromayer M, Moore J, Liska R, Bertolin M, Ferrari S, Hopkinson A, Dua H, Yang J, Wildman R, Rose FRAJ. Bioinspired Precision Engineering of Three-Dimensional Epithelial Stem Cell Microniches. ACTA ACUST UNITED AC 2020; 4:e2000016. [PMID: 32329968 DOI: 10.1002/adbi.202000016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/22/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
Maintenance of the epithelium relies on stem cells residing within specialized microenvironments, known as epithelial crypts. Two-photon polymerization (2PP) is a valuable tool for fabricating 3D micro/nanostructures for stem cell niche engineering applications. Herein, biomimetic gelatin methacrylate-based constructs, replicating the precise geometry of the limbal epithelial crypt structures (limbal stem cell "microniches") as an exemplar epithelial niche, are fabricated using 2PP. Human limbal epithelial stem cells (hLESCs) are seeded within the microniches in xeno-free conditions to investigate their ability to repopulate the crypts and the expression of various differentiation markers. Cell proliferation and a zonation in cell phenotype along the z-axis are observed without the use of exogenous signaling molecules. Significant differences in cell phenotype between cells located at the base of the microniche and those situated towards the rim are observed, demonstrating that stem cell fate is strongly influenced by its location within a niche and the geometrical details of where it resides. This study provides insight into the influence of the niche's spatial geometry on hLESCs and demonstrates a flexible approach for the fabrication of biomimetic crypt-like structures in epithelial tissues. This has significant implications for regenerative medicine applications and can ultimately lead to implantable synthetic "niche-based" treatments.
Collapse
Affiliation(s)
- Elisabetta Prina
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Mahetab H Amer
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Laura Sidney
- Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Maximilian Tromayer
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163, Vienna, 1060, Austria
| | - Jonathan Moore
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Robert Liska
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163, Vienna, 1060, Austria
| | - Marina Bertolin
- Fondazione Banca degli Occhi del Veneto Onlus, Padiglione Rama, Via Paccagnella 11, Zelarino-Venezia, 30174, Italy
| | - Stefano Ferrari
- Fondazione Banca degli Occhi del Veneto Onlus, Padiglione Rama, Via Paccagnella 11, Zelarino-Venezia, 30174, Italy
| | - Andrew Hopkinson
- Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Harminder Dua
- Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Jing Yang
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Ricky Wildman
- Institute of Advanced Manufacturing, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Felicity R A J Rose
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Nottingham Biodiscovery Institute, University of Nottingham, Nottingham, NG7 2RD, UK
| |
Collapse
|
20
|
Masterton S, Ahearne M. Influence of polydimethylsiloxane substrate stiffness on corneal epithelial cells. ROYAL SOCIETY OPEN SCIENCE 2019; 6:191796. [PMID: 31903218 PMCID: PMC6936283 DOI: 10.1098/rsos.191796] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/04/2019] [Indexed: 05/10/2023]
Abstract
Many cell types are known to modulate their behaviour in response to changes in material stiffness; however, little is known about how stiffness affects corneal epithelial cells. This study aims to investigate the response of a corneal epithelial cell line to polydimethylsiloxane (PDMS) substrates with a range of Young's moduli from 10 to 1500 kPa. Cellular morphology, proliferation, differentiation and mechanobiology were examined. Cells grown on PDMS adopted the typical cobblestone morphology exhibited by the corneal epithelium. Proliferative markers pERK and Ki67 were higher in cells cultured on stiffer substrates compared with those on softer substrates. Material stiffness was also found to influence the cell phenotype with cells on stiffer substrates having higher cytokeratin 3 gene expression, a mature epithelial marker, while cells on softer substrates expressed more cytokeratin 14, a basal epithelial marker. Cells grown on softer substrates also displayed higher levels of focal adhesions and intermediate filaments compared with cells on stiff substrates. This research will aid in designing novel biomaterials for the culture and transplantation of corneal epithelial cells.
Collapse
Affiliation(s)
- Sophia Masterton
- Department of Mechanical and Manufacturing Engineering, School of Engineering, University of Dublin, Dublin, Ireland
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Science Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Mark Ahearne
- Department of Mechanical and Manufacturing Engineering, School of Engineering, University of Dublin, Dublin, Ireland
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Science Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
| |
Collapse
|
21
|
YAP, ΔNp63, and β-Catenin Signaling Pathways Are Involved in the Modulation of Corneal Epithelial Stem Cell Phenotype Induced by Substrate Stiffness. Cells 2019; 8:cells8040347. [PMID: 31013745 PMCID: PMC6523807 DOI: 10.3390/cells8040347] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/05/2019] [Accepted: 04/10/2019] [Indexed: 12/11/2022] Open
Abstract
Recent studies have established that the phenotype of epithelial stem cells residing in the corneal periphery (the limbus) depends on this niche’s distinct biomechanical properties. However, the signaling pathways underlying this dependency are still poorly understood. To address this issue, we investigated the effect of substrate stiffness on the migration, proliferation, and molecular phenotype of human limbal epithelial stem cells (LESCs). Specifically, we demonstrated that cells grown on collagen-based substrates with limbus-like compliance showed higher proliferation and stratification and lower migration capabilities, as well as higher levels of pro-proliferative markers Ki67 and β-Catenin, and LESC markers ΔNp63, ABCG2, and CK15. In contrast, cells on stiffer substrates lost these stem/progenitor cell markers, but instead expressed the key mechanotransduction factor YAP, as well as elevated levels of BMP4, a promotor of cell differentiation known to be negatively regulated by Wnt/β-Catenin signaling. This data allowed us to propose a new model that integrates the various molecular pathways involved in LESC response to substrate stiffness. This model will potentially be a useful guide to future research on the mechanisms underlying LESC loss following fibrosis-causing injuries.
Collapse
|
22
|
Gouveia RM, Lepert G, Gupta S, Mohan RR, Paterson C, Connon CJ. Assessment of corneal substrate biomechanics and its effect on epithelial stem cell maintenance and differentiation. Nat Commun 2019; 10:1496. [PMID: 30944320 PMCID: PMC6447573 DOI: 10.1038/s41467-019-09331-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 03/01/2019] [Indexed: 12/13/2022] Open
Abstract
Whilst demonstrated extensively in vitro, the control of cell behaviour via modulation of substrate compliance in live tissues has not been accomplished to date. Here we propose that stem cells can be regulated solely through in situ modulation of tissue biomechanics. By first establishing, via high-resolution Brillouin spectro-microscopy, that the outer edge (limbus) of live human corneas has a substantially lower bulk modulus compared to their centre, we then demonstrate that this difference is associated with limbal epithelial stem cell (LESC) residence and YAP-dependent mechanotransduction. This phenotype-through-biomechanics correlation is further explored in vivo using a rabbit alkali burn model. Specifically, we show that treating the burnt surface of the cornea with collagenase effectively restores the tissue's mechanical properties and its capacity to support LESCs through mechanisms involving YAP suppression. Overall, these findings have extended implications for understanding stem cell niche biomechanics and its impact on tissue regeneration.
Collapse
Affiliation(s)
- Ricardo M Gouveia
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle-upon-Tyne, NE1 3BZ, UK
| | - Guillaume Lepert
- The Blackett Laboratory, Imperial College London, London, SW7 2BW, UK
| | - Suneel Gupta
- Harry S. Truman Memorial Veterans Hospital, Columbia, MO 65201, MO, USA
- College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, MO, USA
| | - Rajiv R Mohan
- Harry S. Truman Memorial Veterans Hospital, Columbia, MO 65201, MO, USA
- College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, MO, USA
| | - Carl Paterson
- The Blackett Laboratory, Imperial College London, London, SW7 2BW, UK
| | - Che J Connon
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle-upon-Tyne, NE1 3BZ, UK.
| |
Collapse
|
23
|
|
24
|
Masterton S, Ahearne M. Mechanobiology of the corneal epithelium. Exp Eye Res 2018; 177:122-129. [PMID: 30086260 PMCID: PMC6280025 DOI: 10.1016/j.exer.2018.08.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 07/16/2018] [Accepted: 08/03/2018] [Indexed: 12/16/2022]
Abstract
There has been a drive to develop new cell based therapies to treat corneal blindness, one of the most common causes of blindness worldwide. Mechanical and physical cues are known to regulate the behavior of many cell types, however studies examining these effects on corneal epithelial cells have been limited in number and their findings have not previously been amalgamated and contrasted. Here, we provide an overview of the different types of mechanical stimuli to which the corneal epithelium is exposed and the influence that these have on the cells. Shear stress from the tear film motion and blinking, extracellular matrix stiffness and external physical forces such as eye rubbing and contact lens wear are among some of the forms of mechanical stimuli that the epithelium experiences. In vivo and in vitro studies examining the mechanobiology on corneal epithelial cells under differing mechanical environments are explored. A greater understanding of the mechanobiology of the corneal epithelium has the potential to lead to improved tissue engineering and cell based therapies to repair and regenerate damaged cornea.
Collapse
Affiliation(s)
- Sophia Masterton
- Dept of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, University of Dublin, Ireland; Trinity Centre for Bioengineering, Trinity Biomedical Science Institute, Trinity College Dublin, University of Dublin, Ireland
| | - Mark Ahearne
- Dept of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, University of Dublin, Ireland; Trinity Centre for Bioengineering, Trinity Biomedical Science Institute, Trinity College Dublin, University of Dublin, Ireland.
| |
Collapse
|
25
|
Zhu JY, Lin S, Ye J. YAP and TAZ, the conductors that orchestrate eye development, homeostasis, and disease. J Cell Physiol 2018; 234:246-258. [PMID: 30094836 DOI: 10.1002/jcp.26870] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/08/2018] [Accepted: 05/18/2018] [Indexed: 12/25/2022]
Abstract
Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are transcriptional coactivators established as a nexus in numerous signaling pathways, notably in Hippo signaling. Previous research revealed multifarious function of YAP and TAZ in oncology and cardiovasology. Recently, the focus has been laid on their pivotal role in eye morphogenesis and homeostasis. In this review, we synthesize advances of YAP and TAZ function during eye development in different model organisms, introduce their function in different ocular tissues and eye diseases, and highlight the potential for therapeutic interventions.
Collapse
Affiliation(s)
- Jing-Yi Zhu
- Department of Ophthalmology and Institute of Surgery Research, Daping Hospital, Army Medical University, Chongqing, China
| | - Sen Lin
- Department of Ophthalmology and Institute of Surgery Research, Daping Hospital, Army Medical University, Chongqing, China
| | - Jian Ye
- Department of Ophthalmology and Institute of Surgery Research, Daping Hospital, Army Medical University, Chongqing, China
| |
Collapse
|
26
|
Menzel-Severing J, Zenkel M, Polisetti N, Sock E, Wegner M, Kruse FE, Schlötzer-Schrehardt U. Transcription factor profiling identifies Sox9 as regulator of proliferation and differentiation in corneal epithelial stem/progenitor cells. Sci Rep 2018; 8:10268. [PMID: 29980721 PMCID: PMC6035181 DOI: 10.1038/s41598-018-28596-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/26/2018] [Indexed: 02/08/2023] Open
Abstract
Understanding transcription factor (TF) regulation of limbal epithelial stem/progenitor cells (LEPCs) may aid in using non-ocular cells to regenerate the corneal surface. This study aimed to identify and characterize TF genes expressed specifically in LEPCs isolated from human donor eyes by laser capture microdissection. Using a profiling approach, preferential limbal expression was found for SoxE and SoxF genes, particularly for Sox9, which showed predominantly cytoplasmic localization in basal LEPCs and nuclear localization in suprabasal and corneal epithelial cells, indicating nucleocytoplasmic translocation and activation during LEPC proliferation and differentiation. Increased nuclear localization of Sox9 was also observed in activated LEPCs following clonal expansion and corneal epithelial wound healing. Knockdown of SOX9 expression in cultured LEPCs by RNAi led to reduced expression of progenitor cell markers, e.g. keratin 15, and increased expression of differentiation markers, e.g. keratin 3. Furthermore, SOX9 silencing significantly suppressed the proliferative capacity of LEPCs and reduced levels of glycogen synthase kinase 3 beta (GSK-3ß), a negative regulator of Wnt/ß-catenin signaling. Sox9 expression, in turn, was significantly suppressed by treatment of LEPCs with exogenous GSK-3ß inhibitors and enhanced by small molecule inhibitors of Wnt signaling. Our results suggest that Sox9 and Wnt/ß-catenin signaling cooperate in mutually repressive interactions to achieve a balance between quiescence, proliferation and differentiation of LEPCs in the limbal niche. Future molecular dissection of Sox9-Wnt interaction and mechanisms of nucleocytoplasmic shuttling of Sox9 may aid in improving the regenerative potential of LEPCs and the reprogramming of non-ocular cells for corneal surface regeneration.
Collapse
Affiliation(s)
- Johannes Menzel-Severing
- Department of Ophthalmology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Matthias Zenkel
- Department of Ophthalmology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Naresh Polisetti
- Department of Ophthalmology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Elisabeth Sock
- Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Michael Wegner
- Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Friedrich E Kruse
- Department of Ophthalmology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | |
Collapse
|
27
|
Lepert G, Gouveia RM, Connon CJ, Paterson C. Assessing corneal biomechanics with Brillouin spectro-microscopy. Faraday Discuss 2018; 187:415-28. [PMID: 27051893 DOI: 10.1039/c5fd00152h] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A new Brillouin spectro-microscope was designed and built to investigate the mechanical properties of bovine and human corneas. This instrument integrates a single-stage virtually imaged phased array spectrometer with a novel adaptive-optics interferometric filter to achieve unprecedented rejection of the elastic background signal. As a result, highly-resolved, reproducible data from both thin and thick collagen-based materials were obtained. In particular, this technique is capable of rigorously measuring the relative stiffness of different areas of human corneas, thus providing a true non-contact method to characterise the fundamental mechanical features of both live and fixed biological tissue samples.
Collapse
Affiliation(s)
- Guillaume Lepert
- Imperial College London, Blackett Laboratory, London, SW7 2BW, UK.
| | - Ricardo M Gouveia
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Che J Connon
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Carl Paterson
- Imperial College London, Blackett Laboratory, London, SW7 2BW, UK.
| |
Collapse
|
28
|
Prina E, Mistry P, Sidney LE, Yang J, Wildman RD, Bertolin M, Breda C, Ferrari B, Barbaro V, Hopkinson A, Dua HS, Ferrari S, Rose FRAJ. 3D Microfabricated Scaffolds and Microfluidic Devices for Ocular Surface Replacement: a Review. Stem Cell Rev Rep 2018; 13:430-441. [PMID: 28573367 DOI: 10.1007/s12015-017-9740-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In recent years, there has been increased research interest in generating corneal substitutes, either for use in the clinic or as in vitro corneal models. The advancement of 3D microfabrication technologies has allowed the reconstruction of the native microarchitecture that controls epithelial cell adhesion, migration and differentiation. In addition, such technology has allowed the inclusion of a dynamic fluid flow that better mimics the physiology of the native cornea. We review the latest innovative products in development in this field, from 3D microfabricated hydrogels to microfluidic devices.
Collapse
Affiliation(s)
- Elisabetta Prina
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | - Pritesh Mistry
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | - Laura E Sidney
- Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham, Nottingham, UK
| | - Jing Yang
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | - Ricky D Wildman
- Faculty of Engineering, University of Nottingham, Nottingham, UK
| | - Marina Bertolin
- Fondazione Banca degli Occhi del Veneto, c/o Padiglione G. Rama - Via Paccagnella 11, 30174 Zelarino, Venice, Italy
| | - Claudia Breda
- Fondazione Banca degli Occhi del Veneto, c/o Padiglione G. Rama - Via Paccagnella 11, 30174 Zelarino, Venice, Italy
| | - Barbara Ferrari
- Fondazione Banca degli Occhi del Veneto, c/o Padiglione G. Rama - Via Paccagnella 11, 30174 Zelarino, Venice, Italy
| | - Vanessa Barbaro
- Fondazione Banca degli Occhi del Veneto, c/o Padiglione G. Rama - Via Paccagnella 11, 30174 Zelarino, Venice, Italy
| | - Andrew Hopkinson
- Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham, Nottingham, UK
| | - Harminder S Dua
- Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham, Nottingham, UK
| | - Stefano Ferrari
- Fondazione Banca degli Occhi del Veneto, c/o Padiglione G. Rama - Via Paccagnella 11, 30174 Zelarino, Venice, Italy.
| | - Felicity R A J Rose
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| |
Collapse
|
29
|
Figueiredo GS, Bojic S, Rooney P, Wilshaw SP, Connon CJ, Gouveia RM, Paterson C, Lepert G, Mudhar HS, Figueiredo FC, Lako M. Gamma-irradiated human amniotic membrane decellularised with sodium dodecyl sulfate is a more efficient substrate for the ex vivo expansion of limbal stem cells. Acta Biomater 2017; 61:124-133. [PMID: 28760619 PMCID: PMC5598144 DOI: 10.1016/j.actbio.2017.07.041] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 11/25/2022]
Abstract
The gold standard substrate for the ex vivo expansion of human limbal stem cells (LSCs) remains the human amniotic membrane (HAM) but this is not a defined substrate and is subject to biological variability and the potential to transmit disease. To better define HAM and mitigate the risk of disease transmission, we sought to determine if decellularisation and/or γ-irradiation have an adverse effect on culture growth and LSC phenotype. Ex vivo limbal explant cultures were set up on fresh HAM, HAM decellularised with 0.5M NaOH, and 0.5% (w/v) sodium dodecyl sulfate (SDS) with or without γ-irradiation. Explant growth rate was measured and LSC phenotype was characterised by histology, immunostaining and qRT-PCR (ABCG2, ΔNp63, Ki67, CK12, and CK13). Ƴ-irradiation marginally stiffened HAM, as measured by Brillouin spectromicroscopy. HAM stiffness and γ-irradiation did not significantly affect the LSC phenotype, however LSCs expanded significantly faster on Ƴ-irradiated SDS decellularised HAM (p<0.05) which was also corroborated by the highest expression of Ki67 and putative LSC marker, ABCG2. Colony forming efficiency assays showed a greater yield and proportion of holoclones in cells cultured on Ƴ-irradiated SDS decellularised HAM. Together our data indicate that SDS decellularised HAM may be a more efficacious substrate for the expansion of LSCs and the use of a γ-irradiated HAM allows the user to start the manufacturing process with a sterile substrate, potentially making it safer. STATEMENT OF SIGNIFICANCE Despite its disadvantages, including its biological variability and its ability to transfer disease, human amniotic membrane (HAM) remains the gold standard substrate for limbal stem cell (LSC) culture. To address these disadvantages, we used a decellularised HAM sterilised by gamma-irradiation for LSC culture. We cultured LSCs on fresh HAM, HAM decellularised with NaOH, HAM decellularised with sodium dodecyl sulfate (SDS) and HAM decellularised with SDS and sterilised with gamma-irradiation. We demonstrated that although HAM decellularised with SDS and sterilised with gamma-irradiation is significantly stiffer this does not affect LSC culture growth rate or the phenotype of cultured LSCs. We therefore recommend the use of SDS decellularised gamma-irradiated HAM in future LSC clinical trials.
Collapse
Affiliation(s)
- G S Figueiredo
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK; Department of Ophthalmology, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK.
| | - S Bojic
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| | - P Rooney
- Tissue Services, NHS Blood and Transplant, 14 Estuary Banks, Speke, Liverpool L24 8RB, UK.
| | - S-P Wilshaw
- School of Pharmacy and Medical Sciences, Faculty of Life Sciences, University of Bradford, Bradford BD7 1DP, UK.
| | - C J Connon
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| | - R M Gouveia
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| | - C Paterson
- The Blackett Laboratory, South Kensington Campus, Imperial College, London SW7 2AZ, UK.
| | - G Lepert
- The Blackett Laboratory, South Kensington Campus, Imperial College, London SW7 2AZ, UK.
| | - H S Mudhar
- National Specialist Ophthalmic Pathology Service, Department of Histopathology, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, UK.
| | - F C Figueiredo
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK; Department of Ophthalmology, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK.
| | - M Lako
- Institute for Genetic Medicine, International Centre for Life, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK.
| |
Collapse
|
30
|
Gouveia RM, González-Andrades E, Cardona JC, González-Gallardo C, Ionescu AM, Garzon I, Alaminos M, González-Andrades M, Connon CJ. Controlling the 3D architecture of Self-Lifting Auto-generated Tissue Equivalents (SLATEs) for optimized corneal graft composition and stability. Biomaterials 2017; 121:205-219. [PMID: 28092777 PMCID: PMC5267636 DOI: 10.1016/j.biomaterials.2016.12.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/02/2016] [Accepted: 12/21/2016] [Indexed: 12/26/2022]
Abstract
Ideally, biomaterials designed to play specific physical and physiological roles in vivo should comprise components and microarchitectures analogous to those of the native tissues they intend to replace. For that, implantable biomaterials need to be carefully designed to have the correct structural and compositional properties, which consequently impart their bio-function. In this study, we showed that the control of such properties can be defined from the bottom-up, using smart surface templates to modulate the structure, composition, and bio-mechanics of human transplantable tissues. Using multi-functional peptide amphiphile-coated surfaces with different anisotropies, we were able to control the phenotype of corneal stromal cells and instruct them to fabricate self-lifting tissues that closely emulated the native stromal lamellae of the human cornea. The type and arrangement of the extracellular matrix comprising these corneal stromal Self-Lifting Analogous Tissue Equivalents (SLATEs) were then evaluated in detail, and was shown to correlate with tissue function. Specifically, SLATEs comprising aligned collagen fibrils were shown to be significantly thicker, denser, and more resistant to proteolytic degradation compared to SLATEs formed with randomly-oriented constituents. In addition, SLATEs were highly transparent while providing increased absorption to near-UV radiation. Importantly, corneal stromal SLATEs were capable of constituting tissues with a higher-order complexity, either by creating thicker tissues through stacking or by serving as substrate to support a fully-differentiated, stratified corneal epithelium. SLATEs were also deemed safe as implants in a rabbit corneal model, being capable of integrating with the surrounding host tissue without provoking inflammation, neo-vascularization, or any other signs of rejection after a 9-months follow-up. This work thus paves the way for the de novo bio-fabrication of easy-retrievable, scaffold-free human tissues with controlled structural, compositional, and functional properties to replace corneal, as well as other, tissues.
Collapse
Affiliation(s)
- Ricardo M Gouveia
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle-upon-Tyne, UK
| | - Elena González-Andrades
- Tissue Engineering Group, Department of Histology, Faculty of Medicine and Dentistry, University of Granada, Granada, Spain
| | - Juan C Cardona
- Laboratory of Biomaterials and Optics, Optics Department, Faculty of Sciences, University of Granada, Granada, Spain
| | | | - Ana M Ionescu
- Laboratory of Biomaterials and Optics, Optics Department, Faculty of Sciences, University of Granada, Granada, Spain
| | - Ingrid Garzon
- Tissue Engineering Group, Department of Histology, Faculty of Medicine and Dentistry, University of Granada, Granada, Spain
| | - Miguel Alaminos
- Tissue Engineering Group, Department of Histology, Faculty of Medicine and Dentistry, University of Granada, Granada, Spain
| | - Miguel González-Andrades
- Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
| | - Che J Connon
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle-upon-Tyne, UK.
| |
Collapse
|
31
|
Schlötzer-Schrehardt U, Freudenberg U, Kruse FE. Zukunftstechnologie Tissue-Engineering. Ophthalmologe 2017; 114:327-340. [DOI: 10.1007/s00347-017-0468-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
32
|
Findlay AS, Panzica DA, Walczysko P, Holt AB, Henderson DJ, West JD, Rajnicek AM, Collinson JM. The core planar cell polarity gene, Vangl2, directs adult corneal epithelial cell alignment and migration. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160658. [PMID: 27853583 PMCID: PMC5099008 DOI: 10.1098/rsos.160658] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 09/15/2016] [Indexed: 05/13/2023]
Abstract
This study shows that the core planar cell polarity (PCP) genes direct the aligned cell migration in the adult corneal epithelium, a stratified squamous epithelium on the outer surface of the vertebrate eye. Expression of multiple core PCP genes was demonstrated in the adult corneal epithelium. PCP components were manipulated genetically and pharmacologically in human and mouse corneal epithelial cells in vivo and in vitro. Knockdown of VANGL2 reduced the directional component of migration of human corneal epithelial (HCE) cells without affecting speed. It was shown that signalling through PCP mediators, dishevelled, dishevelled-associated activator of morphogenesis and Rho-associated protein kinase directs the alignment of HCE cells by affecting cytoskeletal reorganization. Cells in which VANGL2 was disrupted tended to misalign on grooved surfaces and migrate across, rather than parallel to the grooves. Adult corneal epithelial cells in which Vangl2 had been conditionally deleted showed a reduced rate of wound-healing migration. Conditional deletion of Vangl2 in the mouse corneal epithelium ablated the normal highly stereotyped patterns of centripetal cell migration in vivo from the periphery (limbus) to the centre of the cornea. Corneal opacity owing to chronic wounding is a major cause of degenerative blindness across the world, and this study shows that Vangl2 activity is required for directional corneal epithelial migration.
Collapse
Affiliation(s)
- Amy S. Findlay
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
| | - D. Alessio Panzica
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
| | - Petr Walczysko
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
| | - Amy B. Holt
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
| | - Deborah J. Henderson
- Institute of Genetic Medicine, Newcastle University, Centre for Life, Newcastle upon Tyne NE1 3BZ, UK
| | - John D. West
- Genes and Development Group, Centre for Integrative Physiology, Clinical Sciences, University of Edinburgh Medical School, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Ann M. Rajnicek
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
| | - J. Martin Collinson
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
- Author for correspondence: J. Martin Collinson e-mail:
| |
Collapse
|
33
|
Gouveia RM, Hamley IW, Connon CJ. Bio-fabrication and physiological self-release of tissue equivalents using smart peptide amphiphile templates. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2015; 26:242. [PMID: 26411438 DOI: 10.1007/s10856-015-5581-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/21/2015] [Indexed: 06/05/2023]
Abstract
In this study we applied a smart biomaterial formed from a self-assembling, multi-functional synthetic peptide amphiphile (PA) to coat substrates with various surface chemistries. The combination of PA coating and alignment-inducing functionalised substrates provided a template to instruct human corneal stromal fibroblasts to adhere, become aligned and then bio-fabricate a highly-ordered, multi-layered, three-dimensional tissue by depositing an aligned, native-like extracellular matrix. The newly-formed corneal tissue equivalent was subsequently able to eliminate the adhesive properties of the template and govern its own complete release via the action of endogenous proteases. Tissues recovered through this method were structurally stable, easily handled, and carrier-free. Furthermore, topographical and mechanical analysis by atomic force microscopy showed that tissue equivalents formed on the alignment-inducing PA template had highly-ordered, compact collagen deposition, with a two-fold higher elastic modulus compared to the less compact tissues produced on the non-alignment template, the PA-coated glass. We suggest that this technology represents a new paradigm in tissue engineering and regenerative medicine, whereby all processes for the bio-fabrication and subsequent self-release of natural, bio-prosthetic human tissues depend solely on simple template-tissue feedback interactions.
Collapse
Affiliation(s)
- Ricardo M Gouveia
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - Ian W Hamley
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - Che J Connon
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK.
| |
Collapse
|
34
|
Moving epithelia: Tracking the fate of mammalian limbal epithelial stem cells. Prog Retin Eye Res 2015; 48:203-25. [DOI: 10.1016/j.preteyeres.2015.04.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/10/2015] [Accepted: 04/16/2015] [Indexed: 12/13/2022]
|
35
|
West JD, Dorà NJ, Collinson JM. Evaluating alternative stem cell hypotheses for adult corneal epithelial maintenance. World J Stem Cells 2015; 7:281-99. [PMID: 25815115 PMCID: PMC4369487 DOI: 10.4252/wjsc.v7.i2.281] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/26/2014] [Accepted: 10/14/2014] [Indexed: 02/07/2023] Open
Abstract
In this review we evaluate evidence for three different hypotheses that explain how the corneal epithelium is maintained. The limbal epithelial stem cell (LESC) hypothesis is most widely accepted. This proposes that stem cells in the basal layer of the limbal epithelium, at the periphery of the cornea, maintain themselves and also produce transient (or transit) amplifying cells (TACs). TACs then move centripetally to the centre of the cornea in the basal layer of the corneal epithelium and also replenish cells in the overlying suprabasal layers. The LESCs maintain the corneal epithelium during normal homeostasis and become more active to repair significant wounds. Second, the corneal epithelial stem cell (CESC) hypothesis postulates that, during normal homeostasis, stem cells distributed throughout the basal corneal epithelium, maintain the tissue. According to this hypothesis, LESCs are present in the limbus but are only active during wound healing. We also consider a third possibility, that the corneal epithelium is maintained during normal homeostasis by proliferation of basal corneal epithelial cells without any input from stem cells. After reviewing the published evidence, we conclude that the LESC and CESC hypotheses are consistent with more of the evidence than the third hypothesis, so we do not consider this further. The LESC and CESC hypotheses each have difficulty accounting for one main type of evidence so we evaluate the two key lines of evidence that discriminate between them. Finally, we discuss how lineage-tracing experiments have begun to resolve the debate in favour of the LESC hypothesis. Nevertheless, it also seems likely that some basal corneal epithelial cells can act as long-term progenitors if limbal stem cell function is compromised. Thus, this aspect of the CESC hypothesis may have a lasting impact on our understanding of corneal epithelial maintenance, even if it is eventually shown that stem cells are restricted to the limbus as proposed by the LESC hypothesis.
Collapse
Affiliation(s)
- John D West
- John D West, Natalie J Dorà, Genes and Development Group, Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Natalie J Dorà
- John D West, Natalie J Dorà, Genes and Development Group, Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - J Martin Collinson
- John D West, Natalie J Dorà, Genes and Development Group, Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| |
Collapse
|
36
|
Abidin FZ, Gouveia RM, Connon CJ. Application of retinoic acid improves form and function of tissue engineered corneal construct. Organogenesis 2015; 11:122-36. [PMID: 26496651 PMCID: PMC4879898 DOI: 10.1080/15476278.2015.1093267] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 07/22/2015] [Accepted: 09/04/2015] [Indexed: 12/13/2022] Open
Abstract
Retinoic acid has recently been shown to control the phenotype and extracellular matrix composition of corneal stromal cells cultured in vitro as monolayers. This study set out to investigate the effects of retinoic acid on human corneal keratocytes within a 3D environment. Human corneal keratocytes were encapsulated in collagen gels, which were subsequently compressed under load, and cultured in serum-free media supplemented with 10 µM retinoic acid or DMSO vehicle for 30 days. Cell proliferation was quantified on selected days, while the expression of several important keratocytes markers was evaluated at day 30 using RT-PCR and immunoblotting. The weight and size of the collagen constructs were measured before and after hydration and contraction analyses. Retinoic acid enhanced keratocyte proliferation until day 30, whereas cells in control culture conditions showed reduced numbers after day 21. Both gene and protein expressions of keratocyte-characteristic proteoglycans (keratocan, lumican and decorin), corneal crystallins and collagen type I and V were significantly increased following retinoic acid supplementation. Retinoic acid also significantly reduced the expression of matrix metalloproteases 1, 3 and 9 while not increasing α-smooth muscle actin and fibronectin expression. Furthermore, these effects were also correlated with the ability of retinoic acid to significantly inhibit the contractility of keratocytes while allowing the build-up of corneal stromal extracellular matrix within the 3D constructs. Thus, retinoic acid supplementation represents a promising strategy to improve the phenotype of 3D-cultured keratocytes, and their usefulness as a model of corneal stroma for corneal biology and regenerative medicine applications.
Collapse
Affiliation(s)
- Fadhilah Z Abidin
- Institute of Genetic Medicine; Newcastle University; Center for Life; Newcastle, UK
| | - Ricardo M Gouveia
- Institute of Genetic Medicine; Newcastle University; Center for Life; Newcastle, UK
| | - Che J Connon
- Institute of Genetic Medicine; Newcastle University; Center for Life; Newcastle, UK
| |
Collapse
|
37
|
|