Analysis of stress fiber orientation during corneal wound contraction

Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas 75235-9057.
Journal of Cell Science (Impact Factor: 5.43). 02/1993; 104 ( Pt 2)(2):353-63.
Source: PubMed


Previous studies of actin and actin-binding proteins in corneal myofibroblasts suggest the development of a contractile apparatus composed, in part, of F-actin micro-filament bundles, i.e. stress fibers. To better understand the mechanics of wound contraction and the relationship between microfilament bundles and wound closure, we have analyzed the spatial and temporal organization of stress fibers during the process of corneal wound healing. Rabbit corneas (26 eyes) received 6 mm full-thickness, central incisions and were studied at various times for F-actin organization using en bloc (whole cornea) staining with FITC-phalloidin, as well as conventional histological techniques. 3-D datasets (z-series of 40 en face optical sections, 1 micron steps) were collected using the Biorad MRC-600 laser scanning confocal microscope at various regions within the wound. At 7 days, 3-D analysis showed randomly oriented, interconnected F-actin filament bundles (stress fibers). Between 7 and 28 days, stress fibers appeared to organize gradually into planes parallel to the wound surface, with a large population achieving a final orientation nearly parallel to the long axis of the wound. Using Fourier Transform analysis techniques, an orientation index (OI) was calculated to quantitate global fiber orientation at each time point. Analysis of variance demonstrated a significant change (P < 0.001) in overall stress fiber orientation from a random distribution at day 7 to an alignment more parallel to the lateral wound borders at day 28. Overall, these data suggest that stress fibers undergo temporal changes in spatial organization that correlate with wound closure, and that wound closure does not involve the development of previously described contractile or tractional forces aligned directly across the wound.

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    • "It can simulate the growth of skin tumors (i.e. melanoma [9]) and biofilms [10] [11] as well as the contraction of the granulation tissue in the late stage of wound healing [2] [3] [4]. The contribution of collagen deposition in these processes is critical in addition to the isotropic counterpart. "
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    • "The accuracy of these methods is difficult to test due to the complete decoupling of the biological components of a filament network from the actual pixel-wise image properties. Karlon et al. (1999) propose an improved orientation measurement compared to (Petroll et al., 1993; Thomason et al., 1996) by accumulating image gradients into histograms defined over local image windows. Weichsel et al. (2010) propose a similar method to Karlon et al. (1999) where they calculate local coherency of the structure tensor in order to estimate the principal orientation of filaments. "
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    • "It is also somewhat different than the classical " collective " cell migration pattern used by cancer cells, in which lateral connections between invading cell clusters are not typically observed (Ilina and Friedl, 2009). Interestingly, in vivo studies have shown that following full thickness corneal incisions, fibroblasts form an interconnected mesh as they migrate into the wound space, and these interconnections are hypothesized to mediate force transduction during wound contraction (Jester et al., 1995a; Petroll et al., 1993). "
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