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Poole K, Iyer KS, Schmidtke DW, Petroll WM, Varner VD. Corneal keratocytes, fibroblasts, and myofibroblasts exhibit distinct transcriptional profiles in vitro. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582620. [PMID: 38464034 PMCID: PMC10925317 DOI: 10.1101/2024.02.28.582620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Purpose After stromal injury to the cornea, the release of growth factors and pro-inflammatory cytokines promotes the activation of quiescent keratocytes into a migratory fibroblast and/or fibrotic myofibroblast phenotype. Persistence of the myofibroblast phenotype can lead to corneal fibrosis and scarring, which are leading causes of blindness worldwide. This study aims to establish comprehensive transcriptional profiles for cultured corneal keratocytes, fibroblasts, and myofibroblasts to gain insights into the mechanisms through which these phenotypic changes occur. Methods Primary rabbit corneal keratocytes were cultured in either defined serum-free media (SF), fetal bovine serum (FBS) containing media, or in the presence of TGF-β1 to induce keratocyte, fibroblast, or myofibroblast phenotypes, respectively. Bulk RNA sequencing followed by bioinformatic analyses was performed to identify significant differentially expressed genes (DEGs) and enriched biological pathways for each phenotype. Results Genes commonly associated with keratocytes, fibroblasts, or myofibroblasts showed high relative expression in SF, FBS, or TGF-β1 culture conditions, respectively. Differential expression and functional analyses revealed novel DEGs for each cell type, as well as enriched pathways indicative of differences in proliferation, apoptosis, extracellular matrix (ECM) synthesis, cell-ECM interactions, cytokine signaling, and cell mechanics. Conclusions Overall, these data demonstrate distinct transcriptional differences among cultured corneal keratocytes, fibroblasts, and myofibroblasts. We have identified genes and signaling pathways that may play important roles in keratocyte differentiation, including many related to mechanotransduction and ECM biology. Our findings have revealed novel molecular markers for each cell type, as well as possible targets for modulating cell behavior and promoting physiological corneal wound healing.
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Iyer KS, Maruri DP, Schmidtke DW, Petroll WM, Varner VD. Treatment with both TGF-β1 and PDGF-BB disrupts the stiffness-dependent myofibroblast differentiation of corneal keratocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582803. [PMID: 38496568 PMCID: PMC10942298 DOI: 10.1101/2024.02.29.582803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
During corneal wound healing, stromal keratocytes transform into a repair phenotype that is driven by the release of cytokines, like transforming growth factor-beta 1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). Previous work has shown that TGF-β1 promotes the myofibroblast differentiation of corneal keratocytes in a manner that depends on PDGF signaling. In addition, changes in mechanical properties are known to regulate the TGF-β1-mediated differentiation of cultured keratocytes. While PDGF signaling acts synergistically with TGF-β1 during myofibroblast differentiation, how treatment with multiple growth factors affects stiffness-dependent differences in keratocyte behavior is unknown. Here, we treated primary corneal keratocytes with PDGF-BB and TGF-β1 and cultured them on polyacrylamide (PA) substrata of different stiffnesses. In the presence of TGF-β1 alone, the cells underwent stiffness-dependent myofibroblast differentiation. On stiff substrata, the cells developed robust stress fibers, exhibited high levels of ⍺-SMA staining, formed large focal adhesions (FAs), and exerted elevated contractile forces, whereas cells in a compliant microenvironment showed low levels of ⍺-SMA immunofluorescence, formed smaller focal adhesions, and exerted decreased contractile forces. When the cultured keratocytes were treated simultaneously with PDGF-BB however, increased levels of ⍺-SMA staining and stress fiber formation were observed on compliant substrata, even though the cells did not exhibit elevated contractility or focal adhesion size. Pharmacological inhibition of PDGF signaling disrupted the myofibroblast differentiation of cells cultured on substrata of all stiffnesses. These results indicate that treatment with PDGF-BB can decouple molecular markers of myofibroblast differentiation from the elevated contractile phenotype otherwise associated with these cells, suggesting that crosstalk in the mechanotransductive signaling pathways downstream of TGF-β1 and PDGF-BB can regulate the stiffness-dependent differentiation of cultured keratocytes. Statement of Significance In vitro experiments have shown that changes in ECM stiffness can regulate the differentiation of myofibroblasts. Typically, these assays involve the use of individual growth factors, but it is unclear how stiffness-dependent differences in cell behavior are affected by multiple cytokines. Here, we used primary corneal keratocytes to show that treatment with both TGF-β1 and PDGF-BB disrupts the dependency of myofibroblast differentiation on substratum stiffness. In the presence of both growth factors, keratocytes on soft substrates exhibited elevated ⍺-SMA immunofluorescence without a corresponding increase in contractility or focal adhesion formation. This result suggests that molecular markers of myofibroblast differentiation can be dissociated from the elevated contractile behavior associated with the myofibroblast phenotype, suggesting potential crosstalk in mechanotransductive signaling pathways downstream of TGF-β1 and PDGF-BB.
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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.
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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
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Cappitti A, Palmieri F, Garella R, Tani A, Chellini F, Salzano De Luna M, Parmeggiani C, Squecco R, Martella D, Sassoli C. Development of accessible platforms to promote myofibroblast differentiation by playing on hydrogel scaffold composition. BIOMATERIALS ADVANCES 2023; 155:213674. [PMID: 37922662 DOI: 10.1016/j.bioadv.2023.213674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 10/19/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023]
Abstract
Mechanomimetic materials are particularly attractive for modeling in vitro fibroblast to myofibroblast (Myof) transition, a key process in the physiological repair of damaged tissue, and recognized as the core cellular mechanism of pathological fibrosis in different organs. In vivo, mechanical stimuli from the extracellular matrix (ECM) are crucial, together with cell-cell contacts and the pro-fibrotic transforming growth factor (TGF)-β1, in promoting fibroblast differentiation. Here, we explore the impact of hydrogels made by polyacrylamide with different composition on fibroblast behavior. By appropriate modulation of the hydrogel composition (e.g. adjusting the crosslinker content), we produce and fully characterize three kinds of scaffolds with different Young modulus (E). We observe that soft hydrogels (E < 1 kPa) induced fibroblast differentiation better than stiffer ones, also in the absence of TGF-β1. This study provides a readily accessible biomaterial platform to promote Myof generation. The easy approach used and the commercial availability of the monomers make these hydrogels suitable to a wide range of biomedical applications combined with high reproducibility and simple preparation protocols.
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Affiliation(s)
- Alice Cappitti
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino, Italy
| | - Francesco Palmieri
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, 50134 Florence, Italy
| | - Rachele Garella
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, 50134 Florence, Italy
| | - Alessia Tani
- Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, Imaging Platform, University of Florence, 50134 Florence, Italy
| | - Flaminia Chellini
- Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, Imaging Platform, University of Florence, 50134 Florence, Italy
| | - Martina Salzano De Luna
- Department of chemical, materials and industrial production engineering, University of Naples Federico II, 80125 Napoli, Italy
| | - Camilla Parmeggiani
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino, Italy; European Laboratory for Non-Linear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - Roberta Squecco
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, 50134 Florence, Italy.
| | - Daniele Martella
- Department of Chemistry "Ugo Schiff", University of Florence, 50019 Sesto Fiorentino, Italy; European Laboratory for Non-Linear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy; Istituto Nazionale di Ricerca Metrologica (INRiM), 10135 Torino, Italy.
| | - Chiara Sassoli
- Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, Imaging Platform, University of Florence, 50134 Florence, Italy
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Zheng X, Xin Y, Wang C, Fan Y, Yang P, Li L, Yin D, Zhang E, Hong Y, Bao H, Wang J, Bao F, Zhang W, Chen S, Elsheikh A, Swain M. Use of Nanoindentation in Determination of Regional Biomechanical Properties of Rabbit Cornea After UVA Cross-Linking. Invest Ophthalmol Vis Sci 2023; 64:26. [PMID: 37850947 PMCID: PMC10593136 DOI: 10.1167/iovs.64.13.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 09/25/2023] [Indexed: 10/19/2023] Open
Abstract
Purpose To evaluate the regional effects of different corneal cross-linking (CXL) protocols on corneal biomechanical properties. Methods The study involved both eyes of 50 rabbits, and the left eyes were randomized to the five intervention groups, which included the standard CXL group (SCXL), which was exposed to 3-mW/cm2 irradiation, and three accelerated CXL groups (ACXL1-3), which were exposed to ultraviolet-A at irradiations of 9 mW/cm2, 18 mW/cm2, and 30 mW/cm2, respectively, but with the same total dose (5.4 J/cm2). A control (CO) group was not exposed to ultraviolet-A. No surgery was done on the contralateral eyes. The corneas of each group were evaluated by the effective elastic modulus (Eeff) and the hydraulic conductivity (K) within a 7.5-mm radius using nanoindentation measurements. Results Compared with the CO group, Eeff (in regions with radii of 0-1.5 mm, 1.5-3.0 mm, and 3.0-4.5 mm) significantly increased by 309%, 276%, and 226%, respectively, with SCXL; by 222%, 209%, and 173%, respectively, with ACXL1; by 111%, 109%, and 94%, respectively, with ACXL2; and by 59%, 41%, and 37%, respectively, with ACXL3 (all P < 0.05). K was also significantly reduced by 84%, 81%, and 78%, respectively, with SCXL; by 75%, 74%, and 70%, respectively, with ACXL1; by 64%, 62%, and 61%, respectively, with ACXL2; and by 33%, 36%, and 32%, respectively, with ACXL3 (all P < 0.05). For the other regions(with radii between 4.5 and 7.5 mm), the SCXL and ACXL1 groups (but not the ACXL2 and ACXL3 groups) still showed significant changes in Eeff and K. Conclusions CXL had a significant effect on corneal biomechanics in both standard and accelerated procedures that may go beyond the irradiated area. The effect of CXL in stiffening the tissue and reducing permeability consistently decreased with reducing the irradiance duration.
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Affiliation(s)
- Xiaobo Zheng
- School of Aeronautics, Northwestern Polytechnical University, Xi'an, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yue Xin
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- Dalian Medical University, Affiliated Dalian No. 3 People's Hospital, Dalian, China
| | - Chong Wang
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yiwen Fan
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Peng Yang
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Lingqiao Li
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Danping Yin
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Erchi Zhang
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yuxin Hong
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Han Bao
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Junjie Wang
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Fangjun Bao
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Weiwei Zhang
- School of Aeronautics, Northwestern Polytechnical University, Xi'an, China
| | - Shihao Chen
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Michael Swain
- AMME, Biomechanics Engineering, The University of Sydney, Sydney, Australia
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Petroll WM, Miron-Mendoza M, Sunkara Y, Ikebe HR, Sripathi NR, Hassaniardekani H. The impact of UV cross-linking on corneal stromal cell migration, differentiation and patterning. Exp Eye Res 2023; 233:109523. [PMID: 37271309 PMCID: PMC10825899 DOI: 10.1016/j.exer.2023.109523] [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: 01/23/2023] [Revised: 05/09/2023] [Accepted: 06/01/2023] [Indexed: 06/06/2023]
Abstract
Previous studies have demonstrated that UV cross-linking (CXL) increases stromal stiffness and produces alterations in extracellular matrix (ECM) microstructure. In order to investigate how CXL impacts both keratocyte differentiation and patterning within the stroma, and fibroblast migration and myofibroblast differentiation on top of the stroma, we combined CXL with superficial phototherapeutic keratectomy (PTK) in a rabbit model. Twenty-six rabbits underwent a 6 mm diameter, 70 μm deep phototherapeutic keratectomy (PTK) with an excimer laser to remove the epithelium and anterior basement membrane. In 14 rabbits, standard CXL was performed in the same eye immediately after PTK. Contralateral eyes served as controls. In vivo confocal microscopy through focusing (CMTF) was used to analyze corneal epithelial and stromal thickness, as well as stromal keratocyte activation and corneal haze. CMTF scans were collected pre-operatively, and from 7 to 120 days after the procedure. A subset of rabbits was sacrificed at each time point, and corneas were fixed and labeled in situ for multiphoton fluorescence microscopy and second harmonic generation imaging. In vivo and in situ imaging demonstrated that haze after PTK was primarily derived from a layer of myofibroblasts that formed on top of the native stroma. Over time, this fibrotic layer was remodeled into more transparent stromal lamellae, and quiescent cells replaced myofibroblasts. Migrating cells within the native stroma underneath the photoablated area were elongated, co-aligned with collagen, and lacked stress fibers. In contrast, following PTK + CXL, haze was derived primarily from highly reflective necrotic "ghost cells" in the anterior stroma, and fibrosis on top of the photoablated stroma was not observed at any time point evaluated. Cells formed clusters as they migrated into the cross-linked stromal tissue and expressed stress fibers; some cells at the edge of the CXL area also expressed α-SM actin, suggesting myofibroblast transformation. Stromal thickness increased significantly between 21 and 90 days after PTK + CXL (P < 0.001) and was over 35 μm higher than baseline at Day 90 (P < 0.05). Overall, these data suggest that cross-linking inhibits interlamellar cell movement, and that these changes lead to a disruption of normal keratocyte patterning and increased activation during stromal repopulation. Interestingly, CXL also prevents PTK-induced fibrosis on top of the stroma, and results in long term increases in stromal thickness in the rabbit model.
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Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA; Department of Biomedical Engineering, UT Southwestern Medical Center, Dallas, TX, USA.
| | | | - Yukta Sunkara
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Hikaru R Ikebe
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Nishith R Sripathi
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
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Moore BA, Jalilian I, Kim S, Mizutani M, Mukai M, Chang C, Entringer AM, Dhamodaran K, Raghunathan VK, Teixeira LBC, Murphy CJ, Thomasy SM. Collagen crosslinking impacts stromal wound healing and haze formation in a rabbit phototherapeutic keratectomy model. Mol Vis 2023; 29:102-116. [PMID: 37859806 PMCID: PMC10584030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 07/14/2023] [Indexed: 10/21/2023] Open
Abstract
Purpose The purpose of this study was to evaluate the elastic modulus, keratocyte-fibroblast-myocyte transformation, and haze formation of the corneal stroma following combined phototherapeutic keratectomy (PTK) and epithelium-off UV-A/riboflavin corneal collagen crosslinking (CXL) using an in vivo rabbit model. Methods Rabbits underwent PTK and CXL, PTK only, or CXL 35 days before PTK. Rebound tonometry, Fourier-domain optical coherence tomography, and ultrasound pachymetry were performed on days 7, 14, 21, 42, 70, and 90 post-operatively. Atomic force microscopy, histologic inflammation, and immunohistochemistry for α-smooth muscle actin (α-SMA) were assessed post-mortem. Results Stromal haze formation following simultaneous PTK and CXL was significantly greater than in corneas that received PTK only and persisted for more than 90 days. No significant difference in stromal haze was noted between groups receiving simultaneous CXL and PTK and those receiving CXL before PTK. Stromal inflammation did not differ between groups at any time point, although the intensity of α-SMA over the number of nuclei was significantly greater at day 21 between groups receiving simultaneous CXL and PTK and those receiving CXL before PTK. The elastic modulus was significantly greater in corneas receiving simultaneous CXL and PTK compared with those receiving PTK alone. Conclusions We showed that stromal haze formation and stromal stiffness is significantly increased following CXL, regardless of whether it is performed at or before the time of PTK. Further knowledge of the biophysical cues involved in determining corneal wound healing duration and outcomes will be important for understanding scarring following CXL and for the development of improved therapeutic options.
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Affiliation(s)
- Bret A. Moore
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL
| | - Iman Jalilian
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
| | - Makiko Mizutani
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
| | - Madison Mukai
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
| | - Connor Chang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
| | - Alec M. Entringer
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX
| | - Kamesh Dhamodaran
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX
| | - Vijay Krishna Raghunathan
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX
| | - Leandro B. C. Teixeira
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI
| | - Christopher J. Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
- Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Sacramento, CA
| | - Sara M. Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA
- Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Sacramento, CA
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Akoto T, Cai J, Nicholas S, McCord H, Estes AJ, Xu H, Karamichos D, Liu Y. Unravelling the Impact of Cyclic Mechanical Stretch in Keratoconus-A Transcriptomic Profiling Study. Int J Mol Sci 2023; 24:7437. [PMID: 37108600 PMCID: PMC10139219 DOI: 10.3390/ijms24087437] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/04/2023] [Accepted: 04/16/2023] [Indexed: 04/29/2023] Open
Abstract
Biomechanical and molecular stresses may contribute to the pathogenesis of keratoconus (KC). We aimed to profile the transcriptomic changes in healthy primary human corneal (HCF) and KC-derived cells (HKC) combined with TGFβ1 treatment and cyclic mechanical stretch (CMS), mimicking the pathophysiological condition in KC. HCFs (n = 4) and HKCs (n = 4) were cultured in flexible-bottom collagen-coated 6-well plates treated with 0, 5, and 10 ng/mL of TGFβ1 with or without 15% CMS (1 cycle/s, 24 h) using a computer-controlled Flexcell FX-6000T Tension system. We used stranded total RNA-Seq to profile expression changes in 48 HCF/HKC samples (100 bp PE, 70-90 million reads per sample), followed by bioinformatics analysis using an established pipeline with Partek Flow software. A multi-factor ANOVA model, including KC, TGFβ1 treatment, and CMS, was used to identify differentially expressed genes (DEGs, |fold change| ≥ 1.5, FDR ≤ 0.1, CPM ≥ 10 in ≥1 sample) in HKCs (n = 24) vs. HCFs (n = 24) and those responsive to TGFβ1 and/or CMS. PANTHER classification system and the DAVID bioinformatics resources were used to identify significantly enriched pathways (FDR ≤ 0.05). Using multi-factorial ANOVA analyses, 479 DEGs were identified in HKCs vs. HCFs including TGFβ1 treatment and CMS as cofactors. Among these DEGs, 199 KC-altered genes were responsive to TGFβ1, thirteen were responsive to CMS, and six were responsive to TGFβ1 and CMS. Pathway analyses using PANTHER and DAVID indicated the enrichment of genes involved in numerous KC-relevant functions, including but not limited to degradation of extracellular matrix, inflammatory response, apoptotic processes, WNT signaling, collagen fibril organization, and cytoskeletal structure organization. TGFβ1-responsive KC DEGs were also enriched in these. CMS-responsive KC-altered genes such as OBSCN, CLU, HDAC5, AK4, ITGA10, and F2RL1 were identified. Some KC-altered genes, such as CLU and F2RL1, were identified to be responsive to both TGFβ1 and CMS. For the first time, our multi-factorial RNA-Seq study has identified many KC-relevant genes and pathways in HKCs with TGFβ1 treatment under CMS, suggesting a potential role of TGFβ1 and biomechanical stretch in KC development.
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Affiliation(s)
- Theresa Akoto
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Jingwen Cai
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Sarah Nicholas
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Hayden McCord
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Amy J. Estes
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Hongyan Xu
- Department of Population Health Sciences, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Yutao Liu
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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Chen J, Mo Q, Long Q, Sheng R, Chen Z, Luo Y, Liu C, Backman LJ, Zhang Y, Zhang W. Hydroxycamptothecin and Substratum Stiffness Synergistically Regulate Fibrosis of Human Corneal Fibroblasts. ACS Biomater Sci Eng 2023; 9:959-967. [PMID: 36705297 DOI: 10.1021/acsbiomaterials.2c01302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Corneal fibrosis is a common outcome of inappropriate repair associated with trauma or ocular infection. Altered biomechanical properties with increased corneal stiffness is a feature of fibrosis that cause corneal opacities, resulting in severe visual impairment and even blindness. The present study aims to determine the effect of hydroxycamptothecin (HCPT) and matrix stiffness on transforming growth factor-β1 (TGF-β1)-induced fibrotic processes in human corneal fibroblasts (HTK cells). HTK cells were cultured on substrates with different stiffnesses ("soft", ∼261 kPa; "stiff", ∼2.5 × 103 kPa) and on tissue culture plastic (TCP, ∼106 kPa) and simultaneously treated with or without 1 μg/mL HCPT and 10 ng/mL TGF-β1. We found that HCPT induced decreased cell viability and antiproliferative effects on HTK cells. TGF-β1-induced expression of fibrosis-related genes (FN1, ACTA2) was reduced if the cells were simultaneously treated with HCPT. Substrate stiffness did not affect the expression of fibrosis-related genes. The TGF-β1 induced expression of FN1 on both soft and stiff substrates was reduced if cells were simultaneously treated with HCPT. However, this trend was not seen for ACTA2, i.e., the TGF-β1 induced expression of ACTA2 was not reduced by simultaneous treatment of HCPT in either soft or stiff substrate. Instead, HCPT treatment in the presence of TGF-β1 resulted in increased gene expression of keratocyte phenotype makers (LUM, KERA, AQP1, CHTS6) on both substrate stiffnesses. In addition, the protein expression of keratocyte phenotype makers LUM and ALDH3 was increased in HTK cells simultaneously treated with TGF-β1 and HCPT on stiff substrate as compared to control, i.e., without HCPT. In conclusion, we found that HCPT can reduce TGF-β1-induced fibrosis and promote the keratocyte phenotype in a substrate stiffness dependent manner. Thus, HCPT stimulation might be an approach to stimulate keratocytes in the appropriate healing stage to avoid or reverse fibrosis and achieve more optimal corneal wound healing.
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Affiliation(s)
- Jialin Chen
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China.,Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210096, China.,China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou 310058, China
| | - Qingyun Mo
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China
| | - Qiuzi Long
- Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China.,Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Renwang Sheng
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China
| | - Zhixuan Chen
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China
| | - Yifan Luo
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China
| | - Chuanquan Liu
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China
| | - Ludvig J Backman
- Department of Integrative Medical Biology, Anatomy, Umeå University, Umeå SE-901 87, Sweden.,Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå SE-901 87, Sweden
| | - Yanan Zhang
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China
| | - Wei Zhang
- School of Medicine, Southeast University, Nanjing 210009, China.,Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing 210009, China.,Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210096, China.,China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou 310058, China
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10
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Zhang L, Liang L, Su T, Guo Y, Yu Q, Zhu D, Cui Z, Zhang J, Chen J. Regulation of the Keratocyte Phenotype and Cell Behavior Derived from Human Induced Pluripotent Stem Cells by Substrate Stiffness. ACS Biomater Sci Eng 2023; 9:856-868. [PMID: 36668685 DOI: 10.1021/acsbiomaterials.2c01003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Substrate stiffness has been indicated as an important factor to control stem cell fate, including proliferation and differentiation. To optimize the stiffness for the differentiation process from h-iPSCs (human induced pluripotent stem cells) into h-iCSCs (human corneal stromal cells derived from h-iPSCs) and the phenotypic maintenance of h-iCSCs in vitro, h-iPSCs were cultured on matrigel-coated tissue culture plate (TCP) (106 kPa), matrigel-coated polydimethylsiloxane (PDMS) 184 (1250 kPa), and matrigel-coated PDMS 527 (4 kPa) before they were differentiated to h-iCSCs. Immunofluorescence staining, quantitative real-time polymerase chain reaction (RT-qPCR), and western blot demonstrated that the stiffer substrate TCP promoted the h-iCSCs' differentiation from h-iPSCs. On the contrary, softer PDMS 527 was more effective to maintain the phenotype of h-iCSCs cultured in vitro. Finally, we cultured h-iCSCs on PDMS 527 until P3 and seeded them on a biomimetic collagen membrane to form the single-layer and multiple-layer bioengineered corneal stroma with high transparency properties and cell survival rate. In conclusion, the study is helpful for differentiating h-iPSCs to h-iCSCs and corneal tissue engineering by manipulating stiffness mechanobiology.
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Affiliation(s)
- Lan Zhang
- Ophthalmology Department, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Liying Liang
- Ophthalmology Department, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Ting Su
- Ophthalmology Department, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Yonglong Guo
- Ophthalmology Department, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China.,College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
| | - Quan Yu
- Centric Laboratory, Medical College, Jinan University, Guangzhou 510632, China
| | - Deliang Zhu
- Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, Guangdong, PR China
| | - Zekai Cui
- Aier Eye Institute, Changsha 410015, Hunan Province, China
| | - Jun Zhang
- Key Laboratory of Optoelectronic Information and Sensing Technologies, Guangdong Higher Educational Institutes, Jinan University, Guangzhou 510632, China
| | - Jiansu Chen
- Ophthalmology Department, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China.,Aier Eye Institute, Changsha 410015, Hunan Province, China.,Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou 510632, China.,Institute of Ophthalmology, Medical College, Jinan University, Guangzhou 510632, China
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11
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The TGM2 inhibitor cysteamine hydrochloride does not impact corneal epithelial and stromal wound healing in vitro and in vivo. Exp Eye Res 2023; 226:109338. [PMID: 36470430 PMCID: PMC10120528 DOI: 10.1016/j.exer.2022.109338] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
Corneal wound healing is integral for resolution of corneal disease or for post-operative healing. However, corneal scarring that may occur secondary to this process can significantly impair vision. Tissue transglutaminase 2 (TGM2) inhibition has shown promising antifibrotic effects and thus holds promise to prevent or treat corneal scarring. The commercially available ocular solution for treatment of ocular manifestations of Cystinosis, Cystaran®, contains the TGM2 inhibitor cysteamine hydrochloride (CH). The purpose of this study is to assess the safety of CH on corneal epithelial and stromal wounds, its effects on corneal wound healing, and its efficacy against corneal scarring following wounding. Quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) were first used to quantify and localize TGM2 expression in the cornea. Subsequently, (i) the in vitro effects of CH at 0.163, 1.63, and 16.3 mM on corneal epithelial cell migration was assessed with an epithelial cell migration assay, and (ii) the in vivo effects of application of 1.63 mM CH on epithelial and stromal wounds was assessed in a rabbit model with ophthalmic examinations, inflammation scoring, color and fluorescein imaging, optical coherence tomography (OCT), and confocal biomicroscopy. Post-mortem assessment of corneal tissue post-stromal wounding included biomechanical characterization (atomic force microscopy (AFM)), histology (H&E staining), and determining incidence of myofibroblasts (immunostaining against α-SMA) in wounded corneal tissue. TGM2 expression was highest in corneal epithelial cells. Application of the TGM2 inhibitor CH did not affect in vitro epithelial cell migration at the two lower concentrations tested. At 16.3 mM, decreased cell migration was observed. In vivo application of CH at 57 mM was well tolerated and did not adversely affect wound healing. No difference in corneal scarring was found between CH treated and vehicle control eyes. This study shows that the TGM2 inhibitor CH, at the FDA-approved dose, is well tolerated in a rabbit model of corneal wound healing and does not adversely affect epithelial or stromal wound healing. This supports the safe use of this medication in Cystinosis patients with open corneal wounds. CH did not have an effect on corneal scarring in this study, suggesting that Cystaran® administration to patients with corneal wounds is unlikely to decrease corneal fibrosis.
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12
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Chen F, Mundy DC, Le P, Seo YA, Logan CM, Fernandes-Cunha GM, Basco CA, Myung D. In Situ-Forming Collagen-Hyaluronate Semi-Interpenetrating Network Hydrogel Enhances Corneal Defect Repair. Transl Vis Sci Technol 2022; 11:22. [PMID: 36239965 PMCID: PMC9586141 DOI: 10.1167/tvst.11.10.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Purpose Millions worldwide suffer vision impairment or blindness from corneal injury, and there remains an urgent need for a more effective and accessible way to treat corneal defects. We have designed and characterized an in situ-forming semi-interpenetrating polymer network (SIPN) hydrogel using biomaterials widely used in ophthalmology and medicine. Methods The SIPN was formed by cross-linking collagen type I with bifunctional polyethylene glycol using N-hydroxysuccinimide ester chemistry in the presence of linear hyaluronic acid (HA). Gelation time and the mechanical, optical, swelling, and degradation properties of the SIPN were assessed. Cytocompatibility with human corneal epithelial cells and corneal stromal stem cells (CSSCs) was determined in vitro, as was the spatial distribution of encapsulated CSSCs within the SIPN. In vivo wound healing was evaluated by multimodal imaging in an anterior lamellar keratectomy injury model in rabbits, followed by immunohistochemical analysis of treated and untreated tissues. Results The collagen-hyaluronate SIPN formed in situ without an external energy source and demonstrated mechanical and optical properties similar to the cornea. It was biocompatible with human corneal cells, enhancing CSSC viability when compared with collagen gel controls and preventing encapsulated CSSC sedimentation. In vivo application of the SIPN significantly reduced stromal defect size compared with controls after 7 days and promoted multilayered epithelial regeneration. Conclusions This in situ-forming SIPN hydrogel may be a promising alternative to keratoplasty and represents a step toward expanding treatment options for patients suffering from corneal injury. Translational Relevance We detail the synthesis and initial characterization of an SIPN hydrogel as a potential alternative to lamellar keratoplasty and a tunable platform for further development in corneal tissue engineering and therapeutic cell delivery.
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Affiliation(s)
- Fang Chen
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA.,VA Palo Alto HealthCare System, Palo Alto, CA, USA
| | - David C Mundy
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Peter Le
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA.,VA Palo Alto HealthCare System, Palo Alto, CA, USA
| | - Youngyoon Amy Seo
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Caitlin M Logan
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | | | - Chris A Basco
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - David Myung
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA.,VA Palo Alto HealthCare System, Palo Alto, CA, USA.,Department of Chemical Engineering, Stanford University, Palo Alto, CA, USA
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13
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Yang S, Zhang J, Tan Y, Wang Y. Unraveling the mechanobiology of cornea: From bench side to the clinic. Front Bioeng Biotechnol 2022; 10:953590. [PMID: 36263359 PMCID: PMC9573972 DOI: 10.3389/fbioe.2022.953590] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 09/06/2022] [Indexed: 11/18/2022] Open
Abstract
The cornea is a transparent, dome-shaped structure on the front part of the eye that serves as a major optic element and a protector from the external environment. Recent evidence shows aberrant alterations of the corneal mechano-environment in development and progression of various corneal diseases. It is, thus, critical to understand how corneal cells sense and respond to mechanical signals in physiological and pathological conditions. In this review, we summarize the corneal mechano-environment and discuss the impact of these mechanical cues on cellular functions from the bench side (in a laboratory research setting). From a clinical perspective, we comprehensively review the mechanical changes of corneal tissue in several cornea-related diseases, including keratoconus, myopia, and keratectasia, following refractive surgery. The findings from the bench side and clinic underscore the involvement of mechanical cues in corneal disorders, which may open a new avenue for development of novel therapeutic strategies by targeting corneal mechanics.
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Affiliation(s)
- Shu Yang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China
- Department of Ophthalmology, The First People’s Hospital of Huzhou, Huzhou, Zhejiang, China
| | - Jing Zhang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China
- School of Optometry, Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Youhua Tan
- Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China
- Department of Biomedical Engineering, Hong Kong Polytechnic University, Hong Kong SAR, China
- *Correspondence: Youhua Tan, ; Yan Wang,
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China
- *Correspondence: Youhua Tan, ; Yan Wang,
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14
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BMP3 inhibits TGFβ2-mediated myofibroblast differentiation during wound healing of the embryonic cornea. NPJ Regen Med 2022; 7:36. [PMID: 35879352 PMCID: PMC9314337 DOI: 10.1038/s41536-022-00232-9] [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: 12/02/2021] [Accepted: 07/06/2022] [Indexed: 11/29/2022] Open
Abstract
Often acute damage to the cornea initiates drastic tissue remodeling, resulting in fibrotic scarring that disrupts light transmission and precedes vision impairment. Very little is known about the factors that can mitigate fibrosis and promote scar-free cornea wound healing. We previously described transient myofibroblast differentiation during non-fibrotic repair in an embryonic cornea injury model. Here, we sought to elucidate the mechanistic regulation of myofibroblast differentiation during embryonic cornea wound healing. We found that alpha-smooth muscle actin (αSMA)-positive myofibroblasts are superficial and their presence inversely correlates with wound closure. Expression of TGFβ2 and nuclear localization of pSMAD2 were elevated during myofibroblast induction. BMP3 and BMP7 were localized in the corneal epithelium and corresponded with pSMAD1/5/8 activation and absence of myofibroblasts in the healing stroma. In vitro analyses with corneal fibroblasts revealed that BMP3 inhibits the persistence of TGFβ2-induced myofibroblasts by promoting disassembly of focal adhesions and αSMA fibers. This was confirmed by the expression of vinculin and pFAK. Together, these data highlight a mechanism to inhibit myofibroblast persistence during cornea wound repair.
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15
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Iyer KS, Maruri DP, Peak KE, Schmidtke DW, Petroll WM, Varner VD. ECM stiffness modulates the proliferation but not the motility of primary corneal keratocytes in response to PDGF-BB. Exp Eye Res 2022; 220:109112. [PMID: 35595094 PMCID: PMC10163834 DOI: 10.1016/j.exer.2022.109112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/25/2022] [Accepted: 05/11/2022] [Indexed: 11/04/2022]
Abstract
During corneal wound healing, keratocytes present within the corneal stroma become activated into a repair phenotype upon the release of growth factors, such as transforming growth factor-beta 1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). The process of injury and repair can lead to changes in the mechanical properties of the tissue, and previous work has shown that the TGF-β1-mediated myofibroblast differentiation of corneal keratocytes depends on substratum stiffness. It is still unclear, however, if changes in stiffness can modulate keratocyte behavior in response to other growth factors, such as PDGF-BB. Here, we used a polyacrylamide (PA) gel system to determine whether changes in stiffness influence the proliferation and motility of primary corneal keratocytes treated with PDGF-BB. In the presence of PDGF-BB, cells on stiffer substrata exhibited a more elongated morphology and had higher rates of proliferation than cells in a more compliant microenvironment. Using a freeze-injury to assay cell motility, however, we did not observe any stiffness-dependent differences in the migration of keratocytes treated with PDGF-BB. Taken together, these data highlight the importance of biophysical cues during corneal wound healing and suggest that keratocytes respond differently to changes in ECM stiffness in the presence of different growth factors.
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Affiliation(s)
- Krithika S Iyer
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA
| | - Daniel P Maruri
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA
| | - Kara E Peak
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA
| | - David W Schmidtke
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA; Department of Surgery, UT Southwestern Medical Center, Dallas, TX, USA
| | - W Matthew Petroll
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA; Department of Surgery, UT Southwestern Medical Center, Dallas, TX, USA.
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16
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Sugioka K, Nishida T, Kodama-Takahashi A, Murakami J, Mano F, Okada K, Fukuda M, Kusaka S. Urokinase-type plasminogen activator (uPA) negatively regulates α-smooth muscle actin expression via Endo180 and the uPA receptor in corneal fibroblasts. Am J Physiol Cell Physiol 2022; 323:C104-C115. [PMID: 35649252 DOI: 10.1152/ajpcell.00432.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Corneal fibroblasts are embedded within an extracellular matrix composed largely of collagen type 1, proteoglycans, and other proteins in the corneal stroma, and their morphology and function are subject to continuous regulation by collagen. During wound healing and in various pathological conditions, corneal fibroblasts differentiate into myofibroblasts characterized by the expression of α-smooth muscle actin (α-SMA). Endo180, also known as urokinase-type plasminogen activator (uPA) receptor-associated protein (uPARAP), is a collagen receptor. Here we investigated whether targeting of Endo180 and the uPA receptor (uPAR) by uPA might play a role in the regulation of α-SMA expression by culturing corneal fibroblasts derived from uPA-deficient (uPA-/-) or wild-type (uPA+/+) mice in a collagen gel or on plastic. The expression of α-SMA was upregulated, the amounts of full-length Endo180 and uPAR were increased, and the levels of both transforming growth factor-b (TGF-β) expression and Smad3 phosphorylation were higher in uPA-/- corneal fibroblasts compared with uPA+/+ cells under the collagen gel culture condition. Antibodies to Endo180 inhibited these effects of uPA deficiency on a-SMA and TGF-b expression, whereas a TGF-b signaling inhibitor blocked the effects on Smad3 phosphorylation and a-SMA expression. Our results suggest that uPA deficiency might promote the interaction between collagen and Endo180 and thereby increase a-SMA expression in a manner dependent on TGF-β signaling. Expression of α-SMA is thus negatively regulated by uPA through targeting of Endo180 and uPAR.
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Affiliation(s)
- Koji Sugioka
- Department of Ophthalmology, Kindai University Nara Hospital, Ikoma City, Nara, Japan.,Department of Ophthalmology, Kindai University Hospital, Osakasayama City, Osaka, Japan
| | - Teruo Nishida
- Department of Ophthalmology, Kindai University Nara Hospital, Ikoma City, Nara, Japan.,Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.,Division of Cornea and Ocular Surface, Ohshima Eye Hospital, Fukuoka City, Fukuoka, Japan
| | - Aya Kodama-Takahashi
- Department of Ophthalmology, Kindai University Nara Hospital, Ikoma City, Nara, Japan
| | | | - Fukutaro Mano
- Department of Ophthalmology, Kindai University Hospital, Osakasayama City, Osaka, Japan
| | - Kiyotaka Okada
- Department of Arts and Science, Kindai University Faculty of Medicine, Osakasayama City, Osaka, Japan
| | - Masahiko Fukuda
- Department of Ophthalmology, Kindai University Nara Hospital, Ikoma City, Nara, Japan
| | - Shunji Kusaka
- Department of Ophthalmology, Kindai University Hospital, Osakasayama City, Osaka, Japan
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17
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Maruri DP, Iyer KS, Schmidtke DW, Petroll WM, Varner VD. Signaling Downstream of Focal Adhesions Regulates Stiffness-Dependent Differences in the TGF- β1-Mediated Myofibroblast Differentiation of Corneal Keratocytes. Front Cell Dev Biol 2022; 10:886759. [PMID: 35693927 PMCID: PMC9177138 DOI: 10.3389/fcell.2022.886759] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/06/2022] [Indexed: 12/05/2022] Open
Abstract
Following injury and refractive surgery, corneal wound healing can initiate a protracted fibrotic response that interferes with ocular function. This fibrosis is related, in part, to the myofibroblast differentiation of corneal keratocytes in response to transforming growth factor beta 1 (TGF-β1). Previous studies have shown that changes in the mechanical properties of the extracellular matrix (ECM) can regulate this process, but the mechanotransductive pathways that govern stiffness-dependent changes in keratocyte differentiation remain unclear. Here, we used a polyacrylamide (PA) gel system to investigate how mechanosensing via focal adhesions (FAs) regulates the stiffness-dependent myofibroblast differentiation of primary corneal keratocytes treated with TGF-β1. Soft (1 kPa) and stiff (10 kPa) PA substrata were fabricated on glass coverslips, plated with corneal keratocytes, and cultured in defined serum free media with or without exogenous TGF-β1. In some experiments, an inhibitor of focal adhesion kinase (FAK) activation was also added to the media. Cells were fixed and stained for F-actin, as well as markers for myofibroblast differentiation (α-SMA), actomyosin contractility phosphorylated myosin light chain (pMLC), focal adhesions (vinculin), or Smad activity (pSmad3). We also used traction force microscopy (TFM) to quantify cellular traction stresses. Treatment with TGF-β1 elicited stiffness-dependent differences in the number, size, and subcellular distribution of FAs, but not in the nuclear localization of pSmad3. On stiff substrata, cells exhibited large FAs distributed throughout the entire cell body, while on soft gels, the FAs were smaller, fewer in number, and localized primarily to the distal tips of thin cellular extensions. Larger and increased numbers of FAs correlated with elevated traction stresses, increased levels of α-SMA immunofluorescence, and more prominent and broadly distributed pMLC staining. Inhibition of FAK disrupted stiffness-dependent differences in keratocyte contractility, FA patterning, and myofibroblast differentiation in the presence of TGF-β1. Taken together, these data suggest that signaling downstream of FAs has important implications for the stiffness-dependent myofibroblast differentiation of corneal keratocytes.
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Affiliation(s)
- Daniel P. Maruri
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States
| | - Krithika S. Iyer
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States
| | - David W. Schmidtke
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States,Department of Surgery, UT Southwestern Medical Center, Dallas, TX, United States
| | - W. Matthew Petroll
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Victor D. Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX, United States,Department of Surgery, UT Southwestern Medical Center, Dallas, TX, United States,*Correspondence: Victor D. Varner,
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18
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19
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Fukuto A, Kim S, Kang J, Gates BL, Chang MW, Pinkerton KE, Van Winkle LS, Kiuchi Y, Murphy CJ, Leonard BC, Thomasy SM. Metal Oxide Engineered Nanomaterials Modulate Rabbit Corneal Fibroblast to Myofibroblast Transformation. Transl Vis Sci Technol 2021; 10:23. [PMID: 34661622 PMCID: PMC8525860 DOI: 10.1167/tvst.10.12.23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Corneal keratocyte-fibroblast-myofibroblast (KFM) transformation plays a critical role in corneal stromal wound healing. However, the impact of engineered nanomaterials (ENMs), found in an increasing number of commercial products, on this process is poorly studied. This study investigates the effects of metal oxide ENMs on KFM transformation in vitro and in vivo. Methods Cell viability of rabbit corneal fibroblasts (RCFs) was tested following treatment with 11 metal oxide ENMs at concentrations of 0.5 to 250 µg/ml for 24 hours. Messenger RNA (mRNA) and protein expression of αSMA, a marker of myofibroblast transformation, were measured using RCFs after exposure to 11 metal oxide ENMs at a concentration that did not affect cell viability, in media containing either 0 or 10 ng/ml of TGF-β1. Additionally, the effect of topical Fe2O3 nanoparticles (NPs) (50 ng/ml) on corneal stromal wound healing following phototherapeutic keratectomy (PTK) was determined. Results V2O5, Fe2O3, CuO, and ZnO ENMs were found to significantly reduce cell viability as compared to vehicle control and the other seven metal oxide ENMs tested. V2O5 nanoflakes significantly reduced mRNA and protein αSMA concentrations in the presence of TGF-β1. Fe2O3 NPs significantly increased αSMA mRNA expression in the presence of TGF-β1 but did not alter αSMA protein expression. Topically applied Fe2O3 NPs in an in vivo rabbit corneal stromal wound healing model did not delay healing. Conclusions Fe2O3 NPs promote corneal myofibroblast induction in vitro but do not impair corneal stromal wound healing in vivo. Translational Relevance These experimental results can apply to human nanomedical research.
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Affiliation(s)
- Atsuhiko Fukuto
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA.,Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Jennifer Kang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Brooke L Gates
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Maggie W Chang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Kent E Pinkerton
- Center for Health and the Environment, University of California-Davis, Davis, CA, USA.,Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Laura S Van Winkle
- Center for Health and the Environment, University of California-Davis, Davis, CA, USA.,Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA.,Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, CA, USA
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA.,Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, CA, USA
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20
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Kim S, Gates BL, Chang M, Pinkerton KE, Van Winkle L, Murphy CJ, Leonard BC, Demokritou P, Thomasy SM. Transcorneal delivery of topically applied silver nanoparticles does not delay epithelial wound healing. NANOIMPACT 2021; 24:100352. [PMID: 35559825 DOI: 10.1016/j.impact.2021.100352] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 08/10/2021] [Accepted: 08/17/2021] [Indexed: 06/15/2023]
Abstract
Silver nanoparticles (AgNPs) are a common antimicrobial additive for a variety of applications, including wound care. However, AgNPs often undergo dissolution resulting in release of silver ions, with subsequent toxicity to mammalian cells. The cornea is a primary exposure site to topically administered AgNPs in and around the eye but their impact on corneal wound healing is understudied. Thus, the purpose of this study was to determine in vitro toxicity of AgNPs on corneal epithelial cells and fibroblasts as well as their effects on corneal epithelial wound healing utilizing an in vivo rabbit model. Non-coated 20 nm sized AgNP (AgNP-20) as well as 1% and 10% silver silica NPs (AgSiO2NPs) were tested at concentrations ranging from 0.05-250 μg/mL. Immortalized human corneal epithelial (hTCEpi) cells and primary rabbit corneal fibroblasts (RCFs) were incubated for 24 h with AgNPs and cell viability was tested. Additionally, a round wound healing assay was performed to determine hTCEpi cell migration. Quantitative real-time PCR and western blot analysis was performed to determine α-smooth muscle actin (α-SMA, a myofibroblast marker) mRNA and protein expression, respectively, in RCFs treated with 50 μg/mL of AgNPs. Corneal epithelial wound healing was evaluated with 1%-AgSiO2NPs (10 and 250 μg/mL) using an in vivo rabbit model. Rabbits were subsequently euthanized, and histologic sections of the enucleated globes were used to determine corneal penetration of 1%-AgSiO2NPs with autometallography and hyperspectral darkfield microscopy. Cell viability of both the hTCEpi cells and fibroblasts was significantly decreased by the three AgNPs in a dose dependent manner. Migration of hTCEpi cells was significantly inhibited by the three AgNPs. Alpha-SMA mRNA expression was significantly inhibited with three AgNPs, but only the 1%-AgSiO2NPs inhibited protein expression of α-SMA. In vivo epithelial wound closure did not significantly differ between groups treated with 10 or 250 μg/mL of 1%-AgSiO2NPs or vehicle control. The 1%-AgSiO2NPs penetrated throughout all corneal layers and into the anterior chamber in all treated eyes with no histopathological changes observed. In conclusion, the 1%-AgSiO2NPs are safe and have potential therapeutic applications through its efficacy of the corneal penetration and reduced scar formation during corneal wound healing.
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Affiliation(s)
- Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA
| | - Brooke L Gates
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA
| | - Maggie Chang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA
| | - Kent E Pinkerton
- Center for Health and the Environment, University of California, Davis, CA 95616, USA
| | - Laura Van Winkle
- Center for Health and the Environment, University of California, Davis, CA 95616, USA; Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA; Department of Ophthalmology and Vision Science, School of Medicine, University of California, Davis, CA 95616, USA
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA
| | - Philip Demokritou
- Center for Nanotechnology and Nanotoxicology, HSPH-NIEHS Nanosafety Center, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, 665 Huntington, Boston, MA 02115, USA
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA; Department of Ophthalmology and Vision Science, School of Medicine, University of California, Davis, CA 95616, USA.
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21
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Xu Y, Koya R, Ask K, Zhao R. Engineered microenvironment for the study of myofibroblast mechanobiology. Wound Repair Regen 2021; 29:588-596. [PMID: 34118169 PMCID: PMC8254796 DOI: 10.1111/wrr.12955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/10/2021] [Accepted: 06/10/2021] [Indexed: 12/14/2022]
Abstract
Myofibroblasts are mechanosensitive cells and a variety of their behaviours including differentiation, migration, force production and biosynthesis are regulated by the surrounding microenvironment. Engineered cell culture models have been developed to examine the effect of microenvironmental factors such as the substrate stiffness, the topography and strain of the extracellular matrix (ECM) and the shear stress on myofibroblast biology. These engineered models provide well-mimicked, pathophysiologically relevant experimental conditions that are superior to those enabled by the conventional two-dimensional (2D) culture models. In this perspective, we will review the recent advances in the development of engineered cell culture models for myofibroblasts and outline the findings on the myofibroblast mechanobiology under various microenvironmental conditions. These studies have demonstrated the power and utility of the engineered models for the study of microenvironment-regulated cellular behaviours. The findings derived using these models contribute to a greater understanding of how myofibroblast behaviour is regulated in tissue repair and pathological scar formation.
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Affiliation(s)
- Ying Xu
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA
| | - Richard Koya
- Department of Obstetrics and Gynecology, University of Chicago Comprehensive Cancer Center, Biological Sciences Division, University of Chicago School of Medicine, Chicago, IL 60637, USA
| | - Kjetil Ask
- Department of Medicine, Div. Respirology, McMaster University, Hamilton, ON, Canada L8N 4A6
- The Research Institute of St. Joe’s Hamilton, Firestone Institute for Respiratory Health, Hamilton, ON, Canada L8N 4A6
| | - Ruogang Zhao
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA
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22
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Raghunathan V, Edwards SG, Leonard BC, Kim S, Evashenk AT, Song Y, Rewinski E, Marangakis Price A, Hoehn A, Chang C, Reilly CM, Muppala S, Murphy CJ, Thomasy SM. Differential effects of Hsp90 inhibition on corneal cells in vitro and in vivo. Exp Eye Res 2020; 202:108362. [PMID: 33220237 DOI: 10.1016/j.exer.2020.108362] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/30/2020] [Accepted: 11/13/2020] [Indexed: 10/23/2022]
Abstract
The transformation of quiescent keratocytes to activated fibroblasts and myofibroblasts (KFM transformation) largely depends on transforming growth factor beta (TGFβ) signaling. Initiation of the TGFβ signaling cascade results from binding of TGFβ to the labile type I TGFβ receptor (TGFβRI), which is stabilized by the 90 kDa heat shock protein (Hsp90). Since myofibroblast persistence within the corneal stroma can result in stromal haze and corneal fibrosis in patients undergoing keratorefractive therapy, modulation of TGFβ signaling through Hsp90 inhibition would represent a novel approach to prevent myofibroblast persistence. In vitro, rabbit corneal fibroblasts (RCFs) or stratified immortalized human corneal epithelial cells (hTCEpi) were treated with a Hsp90 inhibitor (17AAG) in the presence/absence of TGFβ1. RCFs were cultured either on tissue culture plastic, anisotropically patterned substrates, and hydrogels of varying stiffness. Cellular responses to both cytoactive and variable substrates were assessed by morphologic changes to the cells, and alterations in expression patterns of key keratocyte and myofibroblast proteins using PCR, Western blotting and immunocytochemistry. Transepithelial electrical resistance (TEER) measurements were performed to establish epithelial barrier integrity. In vivo, the corneas of New Zealand White rabbits were wounded by phototherapeutic keratectomy (PTK) and treated with 17AAG (3× or 6× daily) either immediately or 7 days after wounding for 28 days. Rabbits underwent clinical ophthalmic examinations, SPOTS scoring and advanced imaging on days 0, 1, 3, 7, 10, 14, 21 and 28. On day 28, rabbits were euthanized and histopathology/immunohistochemistry was performed. In vitro data demonstrated that 17AAG inhibited KFM transformation with the de-differentiation of spindle shaped myofibroblasts to dendritic keratocyte-like cells accompanied by significant upregulation of corneal crystallins and suppression of myofibroblast markers regardless of TGFβ1 treatment. RCFs cultured on soft hydrogels or patterned substrates exhibited elevated expression of α-smooth muscle actin (αSMA) in the presence of 17AAG. Treatment of hTCEpi cells disrupted zonula occludens 1 (ZO-1) adherens junction formation. In vivo, there were no differences detected in nearly all clinical parameters assessed between treatment groups. However, rabbits treated with 17AAG developed greater stromal haze formation compared with controls, irrespective of frequency of administration. Lastly, there was increased αSMA positive myofibroblasts in the stroma of 17AAG treated animals when compared with controls. Hsp90 inhibition promoted reversion of the myofibroblast to keratocyte phenotype, although this only occurred on rigid substrates. By contrast, in vivo Hsp90 inhibition was detrimental to corneal wound healing likely due to impairment in corneal epithelial closure and barrier function restoration. Collectively, our data demonstrated a strong interplay in vitro between biophysical cues and soluble signaling molecules in determining corneal stromal cell phenotype.
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Affiliation(s)
- VijayKrishna Raghunathan
- Department of Basic Sciences, United States; The Ocular Surface Institute, College of Optometry, University of Houston, Houston, TX, United States.
| | - Sydney Garrison Edwards
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Alexander T Evashenk
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Yeonju Song
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Eva Rewinski
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Ariana Marangakis Price
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Alyssa Hoehn
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Connor Chang
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Christopher M Reilly
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Santoshi Muppala
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States; Department of Ophthalmology and Vision Science, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, United States; Department of Ophthalmology and Vision Science, School of Medicine, University of California, Davis, Davis, CA, United States.
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23
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Petroll WM, Varner VD, Schmidtke DW. Keratocyte mechanobiology. Exp Eye Res 2020; 200:108228. [PMID: 32919993 PMCID: PMC7655662 DOI: 10.1016/j.exer.2020.108228] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 01/22/2023]
Abstract
In vivo, corneal keratocytes reside within a complex 3D extracellular matrix (ECM) consisting of highly aligned collagen lamellae, growth factors, and other extracellular matrix components, and are subjected to various mechanical stimuli during developmental morphogenesis, fluctuations in intraocular pressure, and wound healing. The process by which keratocytes convert changes in mechanical stimuli (e.g. local topography, applied force, ECM stiffness) into biochemical signaling is known as mechanotransduction. Activation of the various mechanotransductive pathways can produce changes in cell migration, proliferation, and differentiation. Here we review how corneal keratocytes respond to and integrate different biochemical and biophysical factors. We first highlight how growth factors and other cytokines regulate the activity of Rho GTPases, cytoskeletal remodeling, and ultimately the mechanical phenotype of keratocytes. We then discuss how changes in the mechanical properties of the ECM have been shown to regulate keratocyte behavior in sophisticated 2D and 3D experimental models of the corneal microenvironment. Finally, we discuss how ECM topography and protein composition can modulate cell phenotypes, and review the different methods of fabricating in vitro mimics of corneal ECM topography, novel approaches for examining topographical effects in vivo, and the impact of different ECM glycoproteins and proteoglycans on keratocyte behavior.
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Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - David W Schmidtke
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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24
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Maruri DP, Miron-Mendoza M, Kivanany PB, Hack JM, Schmidtke DW, Petroll WM, Varner VD. ECM Stiffness Controls the Activation and Contractility of Corneal Keratocytes in Response to TGF-β1. Biophys J 2020; 119:1865-1877. [PMID: 33080219 DOI: 10.1016/j.bpj.2020.08.040] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 07/31/2020] [Accepted: 08/31/2020] [Indexed: 12/19/2022] Open
Abstract
After surgery or traumatic injury, corneal wound healing can cause a scarring response that stiffens the tissue and impairs ocular function. This fibrosis is caused in part by the activation of corneal keratocytes from a native mechanically quiescent state to an activated myofibroblastic state. This transformation is tied to signaling downstream of transforming growth factor-β1 (TGF-β1). Here, to better understand how biochemical and biophysical cues interact to regulate keratocyte activation and contractility, we cultured primary rabbit corneal keratocytes on flexible substrata of varying stiffness in the presence (or absence) of TGF-β1. Time-lapse fluorescence microscopy was used to assess changes in keratocyte morphology, as well as to quantify the dynamic traction stresses exerted by cells under different experimental conditions. In other experiments, keratocytes were fixed after 5 days of culture and stained for markers of both contractility and myofibroblastic activation. Treatment with TGF-β1 elicited distinct phenotypes on substrata of different stiffnesses. Cells on soft (1 kPa) gels formed fewer stress fibers and retained a more dendritic morphology, indicative of a quiescent keratocyte phenotype. Keratocytes cultured on stiff (10 kPa) gels or collagen-coated glass coverslips, however, had broad morphologies, formed abundant stress fibers, exhibited greater levels of α-smooth muscle actin (α-SMA) expression, and exerted larger traction forces. Confocal images of phospho-myosin light chain (pMLC) immunofluorescence, moreover, revealed stiffness-dependent differences in the subcellular distribution of actomyosin contractility, with pMLC localized at the tips of thin cellular processes in mechanically quiescent cells. Importantly, keratocytes cultured in the absence of TGF-β1 showed no stiffness-dependent differences in α-SMA immunofluorescence, suggesting that a stiff microenvironment alone is insufficient to induce myofibroblastic activation. Taken together, these data suggest that changes in ECM stiffness can modulate the morphology, cytoskeletal organization, and subcellular pattern of force generation in corneal keratocytes treated with TGF-β1.
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Affiliation(s)
- Daniel P Maruri
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - Miguel Miron-Mendoza
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Pouriska B Kivanany
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joshua M Hack
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas
| | - David W Schmidtke
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas
| | - W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, Texas; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas.
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25
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Chen J, Backman LJ, Zhang W, Ling C, Danielson P. Regulation of Keratocyte Phenotype and Cell Behavior by Substrate Stiffness. ACS Biomater Sci Eng 2020; 6:5162-5171. [PMID: 33455266 DOI: 10.1021/acsbiomaterials.0c00510] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Corneal tissue engineering is an alternative way to solve the problem of lack of corneal donor tissue in corneal transplantation. Keratocytes with a normal phenotype and function in tissue-engineered cornea would be critical for corneal regeneration. Although the role of extracellular/substrate material stiffness is well-known for the regulation of the cell phenotype and cell behavior in many different cell types, its effects in keratocyte culture have not yet been thoroughly studied. This project studied the effect of substrate stiffness on the keratocyte phenotype marker expression and typical cell behavior (cell adhesion, proliferation, and migration), and the possible mechanisms involved. Human primary keratocytes were cultured on tissue culture plastic (TCP, ∼106 kPa) or on plates with the stiffness equivalent of physiological human corneal stroma (25 kPa) or vitreous body (1 kPa). The expression of keratocyte phenotype markers, cell adhesion, proliferation, and migration were compared. The results showed that the stiffness of the substrate material regulates the phenotype marker expression and cell behavior of cultured keratocytes. Physiological corneal stiffness (25 kPa) superiorly preserved the cell phenotype when compared to the TCP and 1 kPa group. Keratocytes had a larger cell area when cultured on 25 kPa plates as compared to on TCP. Treatment of cells with NSC 23766 (Rac1 inhibitor) mimicked the response in the cell phenotype and behavior seen in the transition from soft materials to stiff materials, including the cytoskeletal structure, expression of keratocyte phenotype markers, and cell behavior. In conclusion, this study shows that substrate stiffness regulates the cell phenotype marker expression and cell behavior of keratocytes by Rac1-mediated cytoskeletal reorganization. This knowledge contributes to the development of corneal tissue engineering.
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Affiliation(s)
- Jialin Chen
- Department of Pathogenic Biology and Immunology, School of Medicine, Southeast University, Nanjing 210009, China.,Department of Integrative Medical Biology, Anatomy, Umeå University, Umeå SE-901 87, Sweden.,Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210009, China
| | - Ludvig J Backman
- Department of Integrative Medical Biology, Anatomy, Umeå University, Umeå SE-901 87, Sweden.,Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå SE-901 87, Sweden
| | - Wei Zhang
- Department of Integrative Medical Biology, Anatomy, Umeå University, Umeå SE-901 87, Sweden.,Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210009, China.,Department of Physiology, School of Medicine, Southeast University, Nanjing 210009, China
| | - Chen Ling
- Department of Orthopaedic Surgery, Institute of Digital Medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing 210000, China
| | - Patrik Danielson
- Department of Integrative Medical Biology, Anatomy, Umeå University, Umeå SE-901 87, Sweden.,Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå SE-901 87, Sweden
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26
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Kim S, Jalilian I, Thomasy SM, Bowman MAW, Raghunathan VK, Song Y, Reinhart-King CA, Murphy CJ. Intrastromal Injection of Hyaluronidase Alters the Structural and Biomechanical Properties of the Corneal Stroma. Transl Vis Sci Technol 2020; 9:21. [PMID: 32821518 PMCID: PMC7409307 DOI: 10.1167/tvst.9.6.21] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/05/2020] [Indexed: 12/27/2022] Open
Abstract
Purpose Glycosaminoglycans (GAGs) are important components of the corneal stroma, and their spatiotemporal arrangement regulates the organization of collagen fibrils and maintains corneal transparency. This study was undertaken to determine the consequences of hyaluronidase (HAse) injected into the corneal stroma on stromal stiffness and ultrastructure. Methods Equal volumes of HAse or balanced salt solution (vehicle) were injected intrastromally into the corneas of New Zealand white rabbits. Ophthalmic examination and multimodal imaging techniques, including Fourier-domain optical coherence tomography and in vivo confocal microscopy (IVCM), were performed at multiple time points to evaluate the impact of HAse treatment in vivo. Atomic force microscopy and transmission electron microscopy (TEM) were used to measure corneal stiffness and collagen's interfibrillar spacing, respectively. Results Central corneal thickness progressively decreased after HAse injection, reaching its lowest value at day 7, and then returned to normal by day 42. The HAse did not impact the corneal endothelium but transiently altered keratocyte morphology at days 1 and 7, as measured by IVCM. HAse-injected corneas became stiffer by day 1 postinjection, were stiffest at day 7, and returned to preinjection values by day 90. Changes in stromal stiffness correlated with decreased interfibrillar spacing as measured by TEM. Conclusions Degradation of GAGs by HAse decreases the corneal thickness and increases stromal stiffness through increased packing of the collagen fibrils in a time-dependent manner. Translational Relevance Intrastromal HAse injection appears relatively safe in the normal cornea, but its impact on corneal biomechanics and structure under pathologic conditions requires further study.
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Affiliation(s)
- Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Iman Jalilian
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.,Department of Ophthalmology & Vision Science, School of Medicine, University of California Davis, Davis, CA, USA
| | - Morgan A W Bowman
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Vijay Krishna Raghunathan
- Department of Basic Science, College of Optometry, University of Houston, Houston, TX, USA.,Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, USA
| | - Yeonju Song
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Cynthia A Reinhart-King
- Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, USA
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.,Department of Ophthalmology & Vision Science, School of Medicine, University of California Davis, Davis, CA, USA
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27
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Słoniecka M, Danielson P. Acetylcholine decreases formation of myofibroblasts and excessive extracellular matrix production in an in vitro human corneal fibrosis model. J Cell Mol Med 2020; 24:4850-4862. [PMID: 32176460 PMCID: PMC7176861 DOI: 10.1111/jcmm.15168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/11/2020] [Accepted: 02/15/2020] [Indexed: 02/06/2023] Open
Abstract
Acetylcholine (ACh) has been reported to play various physiological roles, including wound healing in the cornea. Here, we study the role of ACh in the transition of corneal fibroblasts into myofibroblasts, and in consequence its role in the onset of fibrosis, in an in vitro human corneal fibrosis model. Primary human keratocytes were obtained from healthy corneas. Vitamin C (VitC) and transforming growth factor‐β1 (TGF‐β1) were used to induce fibrosis in corneal fibroblasts. qRT‐PCR and ELISA analyses showed that gene expression and production of collagen I, collagen III, collagen V, lumican, fibronectin (FN) and alpha‐smooth muscle actin (α‐SMA) were reduced by ACh in quiescent keratocytes. ACh treatment furthermore decreased gene expression and production of collagen I, collagen III, collagen V, lumican, FN and α‐SMA during the transition of corneal fibroblasts into myofibroblasts, after induction of fibrotic process. ACh inhibited corneal fibroblasts from developing contractile activity during the process of fibrosis, as assessed with collagen gel contraction assay. Moreover, the effect of ACh was dependent on activation of muscarinic ACh receptors. These results show that ACh has an anti‐fibrotic effect in an in vitro human corneal fibrosis model, as it negatively affects the transition of corneal fibroblasts into myofibroblasts. Therefore, ACh might play a role in the onset of fibrosis in the corneal stroma.
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Affiliation(s)
- Marta Słoniecka
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | - Patrik Danielson
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden.,Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
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28
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Gelam honey promotes ex vivo corneal fibroblasts wound healing. Cytotechnology 2019; 71:1121-1135. [PMID: 31606844 DOI: 10.1007/s10616-019-00349-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 09/30/2019] [Indexed: 12/16/2022] Open
Abstract
This study evaluated the effects of Gelam honey (GH) on ex vivo corneal fibroblast ulcer model via wound healing assay, gene expression and immunocytochemistry. Corneal fibroblasts from New Zealand white rabbits were culture expanded. The corneal fibroblast wound healing capacity was observed by creating a circular wound onto confluent monolayer cells cultured in basal medium (BM), BM with GH, serum-enriched basal medium (BMS) and BMS with GH respectively. Wound healing assay and phenotypic characterization of the corneal fibroblast were performed at different stages of wound closure. Expression of aldehyde dehydrogenase (ALDH), vimentin, α-smooth muscle actin (α-SMA), lumican, collagen I and matrix metalloproteinase 12 (MMP 12) were measured at day 1, day 3 and complete wound closure day. Corneal fibroblast cultured in BMS with GH demonstrated the fastest wound closure, at day 5 post wounding. The gene expressions of ALDH and vimentin were higher than control groups while α-SMA expression was lower, in GH enriched media. The expressions of lumican, collagen I and MMP 12 were also higher in cells cultured in GH enriched media compared to the control groups. GH was shown to promote in vitro corneal fibroblast wound healing and may be a potential natural adjunct in the treatment of corneal wound.
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29
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Muppala S, Raghunathan VK, Jalilian I, Thomasy S, Murphy CJ. YAP and TAZ are distinct effectors of corneal myofibroblast transformation. Exp Eye Res 2018; 180:102-109. [PMID: 30578787 DOI: 10.1016/j.exer.2018.12.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/26/2018] [Accepted: 12/18/2018] [Indexed: 02/06/2023]
Abstract
PURPOSE Transforming growth factor β1 (TGFβ1) is elevated in wounds after injury and promotes the transdifferentiation of quiescent cells in the stroma (keratocytes, to activated fibroblasts and subsequently myofibroblasts-KFM transformation). Coactivators of transcription, YAP (Yes-associated protein) and TAZ (Transcriptional coactivator with PDZ-binding motif), are mechanotransducers that intersect with the TGFβ pathway via interactions with Smad proteins. Here, we examined the distinct role of YAP and TAZ on TGFβ1 induced myofibroblast transformation of primary human corneal fibroblasts (HCFs). METHODS A knockdown approach was used to silence YAP and TAZ individually in HCFs. Forty-eight hours post siRNA transfection, cells were cultured in the presence or absence of 2 ng/ml TGFβ1 for 24h. The cells were subjected to nuclear and cytoplasmic fractionation. The expression of α-smooth muscle actin (αSMA), Smad 2, 3 and 4, CTGF and phospho-Smad2, 3, and 4 were assessed by qPCR and Western blotting. RESULTS TGFβ1 stimulation resulted in the decreased phosphorylation of YAP in the cytosol, and increased levels of phosphorylated TAZ and Smad2/3/4 in the nucleus. Knockdown of TAZ resulted in elevated YAP expression but not vice versa. Additionally, knockdown of TAZ but not YAP resulted in upregulation of αSMA expression in the presence and absence of TGFβ1. In the presence of TGFβ1 YAP knockdown increased Smad2/3/4 expression and Smad4 phosphorylation, while TAZ knockdown had no effect on Smad2/3/4 expression and phosphorylation. YAP knockdown inhibited CTGF expression while TAZ knockdown resulted in its increased expression. Finally, simultaneous knockdown of YAP and TAZ resulted in cell death. CONCLUSION Our findings suggest that YAP and TAZ function as distinct modulators of TGFβ1 induced myofibroblast transformation and have different roles in signalling. Specifically, TAZ limits YAP's ability to mediate KFM transformation via Smad proteins. The data also suggest that while having distinct effects, YAP and TAZ have redundant or combinatorial functions critical to cell survival. These results suggest that a loss of TAZ may help drive corneal haze and fibrosis and that the balance between YAP/TAZ is essential in controlling myofibroblast differentiation.
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Affiliation(s)
- Santoshi Muppala
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Vijay Krishna Raghunathan
- Department of Basic Sciences, The Ocular Surface Institute, College of Optometry, USA; Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, TX, USA
| | - Iman Jalilian
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Sara Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California Davis, Davis, CA, USA.
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California Davis, Davis, CA, USA.
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Kivanany PB, Grose KC, Yonet-Tanyeri N, Manohar S, Sunkara Y, Lam KH, Schmidtke DW, Varner VD, Petroll WM. An In Vitro Model for Assessing Corneal Keratocyte Spreading and Migration on Aligned Fibrillar Collagen. J Funct Biomater 2018; 9:jfb9040054. [PMID: 30248890 PMCID: PMC6306816 DOI: 10.3390/jfb9040054] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/16/2018] [Accepted: 09/18/2018] [Indexed: 01/31/2023] Open
Abstract
Background: Corneal stromal cells (keratocytes) are responsible for developing and maintaining normal corneal structure and transparency, and for repairing the tissue after injury. Corneal keratocytes reside between highly aligned collagen lamellae in vivo. In addition to growth factors and other soluble biochemical factors, feedback from the extracellular matrix (ECM) itself has been shown to modulate corneal keratocyte behavior. Methods: In this study, we fabricate aligned collagen substrates using a microfluidics approach and assess their impact on corneal keratocyte morphology, cytoskeletal organization, and patterning after stimulation with platelet derived growth factor (PDGF) or transforming growth factor beta 1 (TGFβ). We also use time-lapse imaging to visualize the dynamic interactions between cells and fibrillar collagen during wound repopulation following an in vitro freeze injury. Results: Significant co-alignment between keratocytes and aligned collagen fibrils was detected, and the degree of cell/ECM co-alignment further increased in the presence of PDGF or TGFβ. Freeze injury produced an area of cell death without disrupting the collagen. High magnification, time-lapse differential interference contrast (DIC) imaging allowed cell movement and subcellular interactions with the underlying collagen fibrils to be directly visualized. Conclusions: With continued development, this experimental model could be an important tool for accessing how the integration of multiple biophysical and biochemical signals regulate corneal keratocyte differentiation.
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Affiliation(s)
- Pouriska B Kivanany
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Kyle C Grose
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Nihan Yonet-Tanyeri
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Sujal Manohar
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Yukta Sunkara
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Kevin H Lam
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
| | - David W Schmidtke
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Victor D Varner
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA.
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Miyagi H, Jalilian I, Murphy CJ, Thomasy SM. Modulation of human corneal stromal cell differentiation by hepatocyte growth factor and substratum compliance. Exp Eye Res 2018; 176:235-242. [PMID: 30193807 DOI: 10.1016/j.exer.2018.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/31/2018] [Accepted: 09/04/2018] [Indexed: 11/29/2022]
Abstract
Corneal wound healing is a complex process that consists of cellular integration of multiple soluble biochemical cues and cellular responses to biophysical attributes associated with the matrix of the wound space. Upon corneal stromal wounding, the transformation of corneal fibroblasts to myofibroblasts is promoted by transforming growth factor-β (TGFβ). This process is critical for wound healing; however, excessive persistence of myofibroblasts in the wound space has been associated with corneal fibrosis resulting in severe vision loss. The objective of this study was to determine the effect of hepatocyte growth factor (HGF), which can modulate TGFβ signaling, on corneal myofibroblast transformation by analyzing the expression of α-smooth muscle actin (αSMA) as a marker of myofibroblast phenotype particularly as it relates to biomechanical cues. Human corneal fibroblasts were cultured on tissue culture plastic (>1 GPa) or hydrogel substrates mimicking human normal or wounded corneal stiffness (25 and 75 kPa) in media containing TGFβ1 ± HGF. The expression of αSMA was analyzed by quantitative PCR, Western blot and immunocytochemistry. Cellular stiffness, which is correlated with cellular phenotype, was measured by atomic force microscopy (AFM). In primary human corneal fibroblasts, the mRNA expression of αSMA showed a clear dose response to TGFβ1. The expression was significantly suppressed when cells were incubated with 20 ng/ml HGF in the presence of 2 ng/ml of TGFβ1. The protein expression of αSMA induced by 5 ng/ml TGFβ1 was also decreased by 20 ng/ml of HGF. Cells cultured on hydrogels mimicking human normal (25 kPa) and fibrotic (75 kPa) cornea also showed an inhibitory effect of HGF on αSMA expression in the presence or absence of TGFβ1. Cellular stiffness was decreased by HGF in the presence of TGFβ1 as measured by AFM. In this study, we have demonstrated that HGF can suppress the myofibroblast phenotype promoted by TGFβ1 in human corneal stromal cells. These data suggest that HGF holds the potential as a therapeutic agent to improve wound healing outcomes by minimizing corneal fibrosis.
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Affiliation(s)
- Hidetaka Miyagi
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Iman Jalilian
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California, Davis, CA, USA.
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California, Davis, CA, USA.
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Thomasy SM, Raghunathan VK, Miyagi H, Evashenk AT, Sermeno JC, Tripp GK, Morgan JT, Murphy CJ. Latrunculin B and substratum stiffness regulate corneal fibroblast to myofibroblast transformation. Exp Eye Res 2018; 170:101-107. [PMID: 29421383 DOI: 10.1016/j.exer.2018.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 01/11/2018] [Accepted: 02/05/2018] [Indexed: 10/18/2022]
Abstract
The transformation of keratocytes and fibroblasts to myofibroblasts is important to corneal wound healing as well as formation of stromal haze. The purpose of this study was to determine the effect of latrunculin B, an actin cytoskeleton disruptor in conjunction with a fundamental biophysical cue, substrate stiffness, on myofibroblast transformation in vitro and in vivo. Rabbit corneal fibroblasts were cultured on substrates of differing compliance (1.5, 22, and 71 kPa) and tissue culture plastic (TCP; > 1 GPa) in media containing 0 or 10 ng/ml TGFβ1 for 72 h. Cells were treated with 0.4 μM Lat-B or DMSO for 30 min every 24 h for 72 h. RNA was collected from cells and expression of alpha-smooth muscle actin (α-SMA), keratocan, and ALDH1A1 determined using qPCR; immunocytochemistry was used to assess α-SMA protein expression. A rabbit phototherapeutic keratectomy (PTK) model was used to assess the impact of 0.1% Lat-B (n = 3) or 25% DMSO (vehicle control, n = 3) on corneal wound healing by assessment of epithelial wound size with fluorescein stain and semi-quantitative stromal haze scoring by an observer masked to treatment group as well as Fourier-domain optical coherence tomography (FD-OCT) at set time points. Statistical analysis was completed using one-way or two-way analysis of variance. Treatment with Lat-B versus DMSO resulted in significantly less αSMA mRNA (P ≤ 0.007) for RCF cells grown on 22 and 71 kPa substrates as well as TCP without or with TGFβ1, and significantly decreased α-SMA protein expression in RCFs cultured on the intermediate (22 kPa) stiffness in the absence (P = 0.028) or presence (P = 0.018) of TGFβ1. Treatment with Lat-B versus DMSO but did not significantly alter expression of keratocan or ALDH1A1 mRNA in RCFs (P > 0.05) in the absence or presence of TGFβ1, but RCFs grown on stiff hydrogels (71 kPa) had significantly more keratocan mRNA expression versus the 22 kPa hydrogel or TCP (P < 0.001) without TGFβ1. Administration of topical Lat-B BID was well tolerated by rabbits post-PTK but did not significantly alter epithelial wound closure, stromal haze score, stromal haze thickness as measured by FD-OCT in comparison to DMSO-treated rabbits. When corneal stromal cells are cultured on substrates possessing biologically relevant substratum stiffnesses, Lat-B modulates mRNA and protein expression of α-SMA and thus modulates myofibroblast transformation. At a dose and dose-frequency that reduced IOP in human glaucoma patients, Lat-B treatment did not substantially impact corneal epithelial or stromal wound healing in a rabbit PTK model. While a significant impact on wound healing was observed at the concentration and dose frequency reported here was not found, encouraging in vitro data support further investigations of topically applied Lat-B to determine if this compound can reduce stromal fibrosis.
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Affiliation(s)
- Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California, Davis, Davis, CA, USA.
| | - Vijay Krishna Raghunathan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Basic Sciences, The Ocular Surface Institute, College of Optometry, University of Houston, Houston, TX, USA
| | - Hidetaka Miyagi
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Minami-ku, Kasumi 1-2-3, Hiroshima, 7348551, Japan
| | - Alexander T Evashenk
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | - Jasmyne C Sermeno
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | - Geneva K Tripp
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | - Joshua T Morgan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California, Davis, Davis, CA, USA
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Miyagi H, Thomasy SM, Russell P, Murphy CJ. The role of hepatocyte growth factor in corneal wound healing. Exp Eye Res 2018; 166:49-55. [PMID: 29024692 PMCID: PMC5831200 DOI: 10.1016/j.exer.2017.10.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/19/2017] [Accepted: 10/08/2017] [Indexed: 11/28/2022]
Abstract
Hepatocyte growth factor (HGF) is a glycoprotein produced by mesenchymal cells and operates as a key molecule for tissue generation and renewal. During corneal injury, HGF is primarily secreted by stromal fibroblasts and promotes epithelial wound healing in a paracrine manner. While this mesenchymal-epithelial interaction is well characterized in various organs and the cornea, the role of HGF in corneal stromal and endothelial wound healing is understudied. In addition, HGF has been shown to play an anti-fibrotic role by inhibiting myofibroblast generation and subsequent production of a disorganized extracellular matrix and tissue fibrosis. Therefore, HGF represents a potential therapeutic tool in numerous organs in which myofibroblasts are responsible for tissue scarring. Corneal fibrosis can be a devastating sequela of injury and can result in corneal opacification and retrocorneal membrane formation leading to severe vision loss. In this article, we concisely review the available literature regarding the role of HGF in corneal wound healing. We highlight the influence of HGF on cellular behaviors in each corneal layer. Additionally, we suggest the possibility that HGF may represent a therapeutic tool for interrupting dysregulated corneal repair processes to improve patient outcomes.
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Affiliation(s)
- Hidetaka Miyagi
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave., Davis, CA, 95616, USA; Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Minami-ku, Kasumi 1-2-3, Hiroshima, 7348551, Japan.
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave., Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, 2315 Stockton Blvd, Sacramento, CA, 95817, USA.
| | - Paul Russell
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave., Davis, CA, 95616, USA.
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, 1 Shields Ave., Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, 2315 Stockton Blvd, Sacramento, CA, 95817, USA.
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Raghunathan VK, Thomasy SM, Strøm P, Yañez-Soto B, Garland SP, Sermeno J, Reilly CM, Murphy CJ. Tissue and cellular biomechanics during corneal wound injury and repair. Acta Biomater 2017; 58:291-301. [PMID: 28559158 DOI: 10.1016/j.actbio.2017.05.051] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 04/27/2017] [Accepted: 05/26/2017] [Indexed: 10/19/2022]
Abstract
Corneal wound healing is an enormously complex process that requires the simultaneous cellular integration of multiple soluble biochemical cues, as well as cellular responses to the intrinsic chemistry and biophysical attributes associated with the matrix of the wound space. Here, we document how the biomechanics of the corneal stroma are altered through the course of wound repair following keratoablative procedures in rabbits. Further we documented the influence that substrate stiffness has on stromal cell mechanics. Following corneal epithelial debridement, New Zealand white rabbits underwent phototherapeutic keratectomy (PTK) on the right eye (OD). Wound healing was monitored using advanced imaging modalities. Rabbits were euthanized and corneas were harvested at various time points following PTK. Tissues were characterized for biomechanics with atomic force microscopy and with histology to assess inflammation and fibrosis. Factor analysis was performed to determine any discernable patterns in wound healing parameters. The matrix associated with the wound space was stiffest at 7days post PTK. The greatest number of inflammatory cells were observed 3days after wounding. The highest number of myofibroblasts and the greatest degree of fibrosis occurred 21days after wounding. While all clinical parameters returned to normal values 400days after wounding, the elastic modulus remained greater than pre-surgical values. Factor analysis demonstrated dynamic remodeling of stroma occurs between days 10 and 42 during corneal stromal wound repair. Elastic modulus of the anterior corneal stroma is dramatically altered following PTK and its changes coincide initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Factor analysis demonstrates strongest correlation between elastic modulus, myofibroblasts, fibrosis and stromal haze thickness, and between edema and central corneal thickness. STATEMENT OF SIGNIFICANCE Tissue biomechanics during the course of corneal wound healing is documented for the first time through atomic force microscopy, and is correlated with advanced clinical imaging and immunohistochemistry. Parameters obtained from the study are applied in a multivariate statistical model to cluster the data for better classification and monitor the wound repair process. Elastic modulus of the anterior corneal stroma is dramatically altered following wounding and correlates initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Importantly, the occurrence of myofibroblasts is preceded by changes in tissue mechanics, which is important to consider in light of crosslinking procedures applied to treat corneal diseases.
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Molecular Hydrogen Effectively Heals Alkali-Injured Cornea via Suppression of Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:8906027. [PMID: 28400915 PMCID: PMC5376456 DOI: 10.1155/2017/8906027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 01/10/2017] [Accepted: 02/26/2017] [Indexed: 12/20/2022]
Abstract
The aim of this study was to examine the effect of molecular hydrogen (H2) on the healing of alkali-injured cornea. The effects of the solution of H2 in phosphate buffered saline (PBS) or PBS alone topically applied on the alkali-injured rabbit cornea with 0.25 M NaOH were investigated using immunohistochemical and biochemical methods. Central corneal thickness taken as an index of corneal hydration was measured with an ultrasonic pachymeter. Results show that irrigation of the damaged eyes with H2 solution immediately after the injury and then within next five days renewed corneal transparency lost after the injury and reduced corneal hydration increased after the injury to physiological levels within ten days after the injury. In contrast, in injured corneas treated with PBS, the transparency of damaged corneas remained lost and corneal hydration elevated. Later results-on day 20 after the injury-showed that in alkali-injured corneas treated with H2 solution the expression of proinflammatory cytokines, peroxynitrite, detected by nitrotyrosine residues (NT), and malondialdehyde (MDA) expressions were very low or absent compared to PBS treated injured corneas, where NT and MDA expressions were present. In conclusion, H2 solution favorably influenced corneal healing after alkali injury via suppression of oxidative stress.
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Ali M, Raghunathan V, Li JY, Murphy CJ, Thomasy SM. Biomechanical relationships between the corneal endothelium and Descemet's membrane. Exp Eye Res 2016; 152:57-70. [PMID: 27639516 DOI: 10.1016/j.exer.2016.09.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 09/13/2016] [Indexed: 12/28/2022]
Abstract
The posterior face of the cornea consists of the corneal endothelium, a monolayer of cuboidal cells that secrete and attach to Descemet's membrane, an exaggerated basement membrane. Dysfunction of the endothelium compromises the barrier and pump functions of this layer that maintain corneal deturgesence. A large number of corneal endothelial dystrophies feature irregularities in Descemet's membrane, suggesting that cells create and respond to the biophysical signals offered by their underlying matrix. This review provides an overview of the bidirectional relationship between Descemet's membrane and the corneal endothelium. Several experimental methods have characterized a richly topographic and compliant biophysical microenvironment presented by the posterior surface of Descemet's membrane, as well as the ultrastructure and composition of the membrane as it builds during a lifetime. We highlight the signaling pathways involved in the mechanotransduction of biophysical cues that influence cell behavior. We present the specific example of Fuchs' corneal endothelial dystrophy as a condition in which a dysregulated Descemet's membrane may influence the progression of disease. Finally, we discuss some disease models and regenerative strategies that may facilitate improved treatments for corneal dystrophies.
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Affiliation(s)
- Maryam Ali
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
| | - VijayKrishna Raghunathan
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, TX, 77204, USA.
| | - Jennifer Y Li
- Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, Sacramento, CA, 95817, USA.
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA; Department of Ophthalmology & Vision Science, School of Medicine, UC Davis Medical Center, Sacramento, CA, 95817, USA.
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA.
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Kumar P, Pandit A, Zeugolis DI. Progress in Corneal Stromal Repair: From Tissue Grafts and Biomaterials to Modular Supramolecular Tissue-Like Assemblies. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:5381-5399. [PMID: 27028373 DOI: 10.1002/adma.201503986] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 12/31/2015] [Indexed: 06/05/2023]
Abstract
Corneal injuries and degenerative conditions have major socioeconomic consequences, given that in most cases, they result in blindness. In the quest of the ideal therapy, tissue grafts, biomaterials, and modular engineering approaches are under intense investigation. Herein, advancements and shortfalls are reviewed and future perspectives for these therapeutic strategies discussed.
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Affiliation(s)
- Pramod Kumar
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Biosciences Research Building, National University of Ireland Galway (NUI Galway), Galway, Ireland
- Center for Research in Medical Devices (CÚRAM), Biosciences Research Building, National University of Ireland Galway (NUI Galway), Galway, Ireland
| | - Abhay Pandit
- Center for Research in Medical Devices (CÚRAM), Biosciences Research Building, National University of Ireland Galway (NUI Galway), Galway, Ireland
| | - Dimitrios I Zeugolis
- Regenerative, Modular & Developmental Engineering Laboratory (REMODEL), Biosciences Research Building, National University of Ireland Galway (NUI Galway), Galway, Ireland
- Center for Research in Medical Devices (CÚRAM), Biosciences Research Building, National University of Ireland Galway (NUI Galway), Galway, Ireland
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Chen TC, Tsai TY, Chang SW. Molecular mechanism of fluoroquinolones modulation on corneal fibroblast motility. Exp Eye Res 2016; 145:10-16. [DOI: 10.1016/j.exer.2015.10.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 10/20/2015] [Accepted: 10/22/2015] [Indexed: 11/26/2022]
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Abstract
Myofibroblasts are activated in response to tissue injury with the primary task to repair lost or damaged extracellular matrix. Enhanced collagen secretion and subsequent contraction - scarring - are part of the normal wound healing response and crucial to restore tissue integrity. Due to myofibroblasts ability to repair but not regenerate, accumulation of scar tissue is always associated with reduced organ performance. This is a fair price to pay by the body for not falling apart. Whereas myofibroblasts typically vanish after successful repair, dysregulation of the normal repair process can lead to persistent myofibroblast activation, for instance by chronic inflammation or mechanical stress in the tissue. Excessive repair leads to the accumulation of stiff collagenous ECM contractures - fibrosis - with dramatic consequences for organ function. The clinical need to terminate detrimental myofibroblast activities has stimulated researchers to answer a number of essential questions: where do myofibroblasts come from, what are the factors leading to their activation, how do we discriminate myofibroblasts from other cells, what is the molecular basis for their contractile activity, and how can we stop or at least control them? This article reviews the current state of the myofibroblast literature by emphasizing their role in ocular repair and fibrosis. It appears that although the eye is quite an extraordinary organ, ocular myofibroblasts behave or misbehave just like their siblings in other organs.
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Affiliation(s)
- Boris Hinz
- Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, 150 College Street, FitzGerald Building, Room 234, Toronto, M5S 3E2 Ontario, Canada.
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Petroll WM, Lakshman N. Fibroblastic Transformation of Corneal Keratocytes by Rac Inhibition is Modulated by Extracellular Matrix Structure and Stiffness. J Funct Biomater 2015; 6:222-40. [PMID: 25874856 PMCID: PMC4493509 DOI: 10.3390/jfb6020222] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/06/2015] [Accepted: 04/08/2015] [Indexed: 01/06/2023] Open
Abstract
The goal of this study was to investigate how alterations in extracellular matrix (ECM) biophysical properties modulate corneal keratocyte phenotypes in response to specific wound healing cytokines and Rho GTPases. Rabbit corneal keratocytes were plated within standard collagen matrices (2.5 mg/mL) or compressed collagen matrices (~100 mg/mL) and cultured in serum-free media, PDGF BB, IGF, FGF2 or TGFβ1, with or without the Rac1 inhibitor NSC23766 and/or the Rho kinase inhibitor Y-27632. After 1 to 4 days, cells were labeled for F-actin and imaged using confocal microscopy. Keratocytes within standard collagen matrices (which are highly compliant) maintained a dendritic phenotype following culture in serum-free media, PDGF, IGF and FGF, but developed stress fibers in TGFβ1. Keratocytes within compressed collagen (which has high stiffness and low porosity) maintained a dendritic phenotype following culture in serum-free media, PDGF and IGF, but developed stress fibers in both FGF and TGFβ1. The Rac inhibitor had no significant impact on growth factor responses in compliant matrices. Within compressed collagen matrices however, the Rac inhibitor induced fibroblastic transformation in serum-free media, PDGF and IGF. Fibroblast and myofibroblast transformation was blocked by Rho kinase inhibition. Overall, keratocyte growth factor responses appear to be regulated by both the interplay between Rho and Rac signaling, and the structural and mechanical properties of the ECM.
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Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX 75390-9057, USA.
| | - Neema Lakshman
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX 75390-9057, USA.
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Petroll WM, Miron-Mendoza M. Mechanical interactions and crosstalk between corneal keratocytes and the extracellular matrix. Exp Eye Res 2015; 133:49-57. [PMID: 25819454 PMCID: PMC4379425 DOI: 10.1016/j.exer.2014.09.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 12/13/2022]
Abstract
The generation of cellular forces and the application of these physical forces to the ECM play a central role in mediating matrix patterning and remodeling during fundamental processes such as developmental morphogenesis and wound healing. In addition to growth factors and other biochemical factors that can modulate the keratocyte mechanical phenotype, another key player in the regulation of cell-induced ECM patterning is the mechanical state of the ECM itself. In this review we provide an overview of the biochemical and biophysical factors regulating the mechanical interactions between corneal keratocytes and the stromal ECM at the cellular level. We first provide an overview of how Rho GTPases regulate the sub-cellular pattern of force generation by corneal keratocytes, and the impact these forces have on the surrounding ECM. We next review how feedback from local matrix structural and mechanical properties can modulate keratocyte phenotype and mechanical activity. Throughout this review, we provide examples of how these biophysical interactions may contribute to clinical outcomes, with a focus on corneal wound healing.
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Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9057, USA.
| | - Miguel Miron-Mendoza
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9057, USA
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Cheung JW, McCulloch CA, Santerre JP. Establishing a gingival fibroblast phenotype in a perfused degradable polyurethane scaffold: Mediation by TGF-β1, FGF-2, β1-integrin, and focal adhesion kinase. Biomaterials 2014; 35:10025-32. [DOI: 10.1016/j.biomaterials.2014.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/26/2014] [Accepted: 08/30/2014] [Indexed: 11/30/2022]
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Stepp MA, Zieske JD, Trinkaus-Randall V, Kyne BM, Pal-Ghosh S, Tadvalkar G, Pajoohesh-Ganji A. Wounding the cornea to learn how it heals. Exp Eye Res 2014; 121:178-93. [PMID: 24607489 DOI: 10.1016/j.exer.2014.02.007] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 02/07/2014] [Accepted: 02/10/2014] [Indexed: 12/12/2022]
Abstract
Corneal wound healing studies have a long history and rich literature that describes the data obtained over the past 70 years using many different species of animals and methods of injury. These studies have lead to reduced suffering and provided clues to treatments that are now helping patients live more productive lives. In spite of the progress made, further research is required since blindness and reduced quality of life due to corneal scarring still happens. The purpose of this review is to summarize what is known about different types of wound and animal models used to study corneal wound healing. The subject of corneal wound healing is broad and includes chemical and mechanical wound models. This review focuses on mechanical injury models involving debridement and keratectomy wounds to reflect the authors' expertise.
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Affiliation(s)
- Mary Ann Stepp
- Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, Washington, DC 20037, USA; Department of Ophthalmology, The George Washington University Medical Center, Washington, DC 20037, USA.
| | - James D Zieske
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114-2500, USA
| | - Vickery Trinkaus-Randall
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA 02118, USA; Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Briana M Kyne
- Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Sonali Pal-Ghosh
- Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Gauri Tadvalkar
- Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Ahdeah Pajoohesh-Ganji
- Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, Washington, DC 20037, USA
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Guo L, Frost MR, He L, Siegwart JT, Norton TT. Gene expression signatures in tree shrew sclera in response to three myopiagenic conditions. Invest Ophthalmol Vis Sci 2013; 54:6806-19. [PMID: 24045991 DOI: 10.1167/iovs.13-12551] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE We compared gene expression signatures in tree shrew sclera produced by three different visual conditions that all produce ocular elongation and myopia: minus-lens wear, form deprivation, and dark treatment. METHODS Six groups of tree shrews (n = 7 per group) were used. Starting 24 days after normal eye-opening (days of visual experience [DVE]), two minus-lens groups wore a monocular -5 diopter (D) lens for 2 days (ML-2) or 4 days (ML-4); two form-deprivation groups wore a monocular translucent diffuser for 2 days (FD-2) or 4 days (FD-4). A dark-treatment (DK) group was placed in continuous darkness for 11 days after experiencing a light/dark environment until 17 DVE. A normal colony-reared group was examined at 28 DVE. Quantitative PCR was used to measure the relative differences in mRNA levels for 55 candidate genes in the sclera that were selected, either because they showed differential expression changes in previous ML studies or because a whole-transcriptome analysis suggested they would change during myopia development. RESULTS The treated eyes in all groups responded with a significant myopic shift, indicating that the myopia was actively progressing. In the ML-2 group, 27 genes were significantly downregulated in the treated eyes, relative to control eyes. In the treated eyes of the FD-2 group, 16 of the same genes also were significantly downregulated and one was upregulated. The two gene expression patterns were significantly correlated (r(2) = 0.90, P < 0.001). After 4 days of treatment, 31 genes were significantly downregulated in the treated eyes of the ML-4 group and three were upregulated. Twenty-nine of the same genes (26 down- and 3 up-regulated) and six additional genes (all downregulated) were significantly affected in the FD-4 group. The response patterns were highly correlated (r(2) = 0.95, P < 0.001). When the DK group (mean of right and left eyes) was compared to the control eyes of the ML-4 group, the direction and magnitude of the gene expression patterns were similar to those of the ML-4 (r(2) = 0.82, P < 0.001, excluding PENK). Similar patterns also were found when the treated eyes of the ML-4, FD-4, and DK groups were compared to the age-matched normal eyes. CONCLUSIONS The very similar gene expression signatures produced in the sclera by the three different myopiagenic visual conditions at different time points suggests that there is a "scleral remodeling signature" in this mammal, closely related to primates. The scleral genes examined did not distinguish between the specific visual stimuli that initiate the signaling cascade that results in axial elongation and myopia.
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Affiliation(s)
- Lin Guo
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama
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