title: Substrate Elastic Modulus Regulates the Morphology, Focal Adhesions, and α-Smooth Muscle Actin Expression of Retinal Müller Cells.
abstract: OBJECTIVE
  The stiffness of the extracellular matrix has been shown to regulate cell adhesion, migration, and transdifferentiation in fibrotic processes. Retinal Müller cells have been shown to be mechanosensitive; they are involved in fibrotic vitreoretinal diseases. Since fibrosis increases the rigidity of the extracellular matrix, our aim was to develop an in vitro model for studying Müller cell morphology and differentiation state in relation to matrix stiffness.
  
  
  METHODS
  A spontaneously immortalized human Müller cell line (MIO-M1) was cultured on type I collagen-coated polyacrylamide gels with Young's moduli ranging from 2 to 92 kPa. Cell surface area, focal adhesion, and the expression and morphology of α-smooth muscle actin induced by transforming growth factor β (TGF-β [10 ng/mL for 48 hours]) were analyzed by immunocytology. The images were documented by using fluorescence microscopy and confocal scanning laser microscopy.
  
  
  RESULTS
  MIO-M1 cells cultured on stiff substrates exhibited a significant increase in cell surface area, stress fiber, and mature focal adhesion formation. Furthermore, Müller cells treated with TGF-β1 and TGF-β2 and cultured on stiff substrates showed an increased incorporation of α-smooth muscle actin into stress fibers when compared to those grown on soft surfaces.
  
  
  CONCLUSIONS
  Compliance of the surrounding matrix seems to influence the morphology and contraction of retinal Müller cells in fibrotic conditions. Development of an in vitro model simulating both the normally compliant retinal tissue and the rigid retinal fibrotic tissue helps fill the gap between the results of petri-dish cell culture with rigid surfaces and in vivo findings.
authors.affiliation: Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands 2W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands 3Tianjin Medical Universi.
authors.forename: Shao-Chong
authors.initials: SC
authors.lastname: Bu
authors.affiliation: W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands 4Department of Biomedical Engineering-FB40, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Roel
authors.initials: R
authors.lastname: Kuijer
authors.affiliation: Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands 2W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Roelofje J
authors.initials: RJ
authors.lastname: van der Worp
authors.affiliation: W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands 5Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Sander M
authors.initials: SM
authors.lastname: van Putten
authors.affiliation: W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands 5Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Olaf
authors.initials: O
authors.lastname: Wouters
authors.affiliation: Tianjin Medical University Eye Centre, Tianjin Medical University, Tianjin, China.
authors.forename: Xiao-Rong
authors.initials: XR
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands 2W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Johanna M M
authors.initials: JM
authors.lastname: Hooymans
authors.affiliation: Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands 2W.J. Kolff Institute, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Leonoor I
authors.initials: LI
authors.lastname: Los
mesh_terms: D000199:Actins / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods; D054338:Cell Transdifferentiation / Q000502:physiology; D002478:Cells, Cultured; D055119:Elastic Modulus / Q000502:physiology*; D063928:Ependymoglial Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D022001:Focal Adhesions / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D016212:Transforming Growth Factor beta