Proangiogenic Role of Matrix Metalloproteinase (MMP) 14 in Cornea

Abstract

Abstract: : Purposes: MMP-14 is a member of the matrix metalloproteinase family of structurally related enzymes that plays important role in tissue morphogenesis, differentiation, development, homeostasis, wound healing, and disease. MMP-14 knockout mice did not display corneal neovascularization (NV) following corneal implantation of the bFGF pellet. Our study aims to investigate the roles of MMP-14 in NV of cornea. Methods: We performed Western blot analysis to assess the production of MMP-14 in the bFGF pellet model. The corneas were harvested on day 21 after bFGF pellet implantation. The protein lysates from bFGF treated and normal corneas were subjected to SDS gel electrophoresis and immunobloted with anti-MMP-14 antibody. Immunohistochemistry of the cornea samples were used to localize MMP-14 expression on day 1, 4, 7, 14, and 21 (n ≥ 2 per time point). The corneas were immunostained with MMP-14 antibody and visualized by confocal microscopy. To study the in vivo role of MMP-14, we injected the MMP-14 naked DNA (2 µg) or vector control (2 µg) into mice corneal stroma in combination with limbal scrape wounds (n = 4 per group). Corneal vessels were visualized and photographed on day 4 and 14 under the slit lamp biomicroscopy. The amount of vessels were quantified. Results: Western blot analysis demonstrated enhanced production of MMP-14 in the cornea of the bFGF pellet implanted mice but not in the control animals. The apparent molecular weight of 43 kD and 20 kD were consistent with shedding fragments of MMP-14. Confocal microscopic analysis demonstrated that MMP-14 was mainly immunolocalized to the anterior stroma of the bFGF treated mice. The expression peaked on day 7 to 14. MMP-14 naked DNA intrastromal injections elicited significant corneal NV following hemilimbal injury. The vessels were seen on day 14 but not day 4. No vessels were found in controls (limbal scrape only, or naked DNA injection alone). Conclusions: Our data suggest that MMP-14 may play important roles in wound healing and corneal NV.

Keywords: cornea: basic science • wound healing • molecular biology