title: Regulation of corneal fibroblast morphology and collagen reorganization by extracellular matrix mechanical properties.
abstract: OBJECTIVE
  To investigate how extracellular matrix mechanical properties influence cell and matrix patterning in three-dimensional culture.
  
  
  METHODS
  Human corneal fibroblasts were seeded within 30 x 10 mm collagen matrices that were unconstrained (UN), fully constrained (CO) along the long axis by attaching the construct to two immobilized plastic bars, or partially constrained (PC) by allowing linear elastic displacement of one bar. After 24 hours, constructs were labeled with phalloidin and were imaged using fluorescent and reflected light (for collagen) confocal microscopy. Cell morphology and local collagen fibril density and alignment were measured using digital image processing.
  
  
  RESULTS
  Corneal fibroblasts in UN matrices were less elongated (UN < PC < CO; P < 0.05) than those in constrained matrices. Cells were aligned parallel to the long axis in the anisotropic region of constrained matrices but were randomly aligned in unconstrained (isotropic) matrices (UN < PC = CO; P < 0.05). Both the local collagen density and the degree of cell/collagen coalignment were higher in constrained matrices (UN < PC < CO; P < 0.05). In regions of higher cell density, additional bands of aligned collagen were often observed between individual cells.
  
  
  CONCLUSIONS
  These data suggest that cell spreading, alignment, and contractile force generation are directly influenced by the mechanical properties of the surrounding extracellular matrix (ECM). Corneal fibroblasts generally align and compact collagen parallel to the axis of greatest ECM stiffness. Mechanical cross-talk between adjacent cells leads to enhancement of matrix reorganization, and results in additional, more complex matrix patterning.
authors.affiliation: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9057, USA.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Karamichos
authors.forename: Neema
authors.initials: N
authors.lastname: Lakshman
authors.forename: W Matthew
authors.initials: WM
authors.lastname: Petroll
mesh_terms: D000199:Actins / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D002452:Cell Count; D018929:Cell Culture Techniques; D049109:Cell Proliferation; D048430:Cell Shape / Q000502:physiology; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000166:cytology* / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence
chemical_list: D000199:Actins; D003094:Collagen