Expression of Alpha-smooth Muscle Actin During Wound Healing in UVR-exposed Rabbit Corneas

Abstract

Abstract: : Purpose: We have previously showed that UVR exposure leads to disappearance of corneal cells mediated by apoptosis. The damaged corneal stroma repopulates by new keratocytes during 1-2 weeks. The expression of alpha-smooth muscle actin (alpha-SMA) was examined to provide a better understanding of the corneal wound healing after UVR-induced keratitis. Methods: Six New Zealand albino rabbit corneas were exposed to 310 nm UVR at a dose producing photokeratitis (0.47 J/cm²). Animals were killed 3 and 7 days after exposure to UVR. The corneal tissue specimens were double stained and examined morphologically and immunohistochemically for alpha-SMA. Results: Corneas exposed to UVR showed disappearance of keratocytes through entire thickness of the corneal stroma at 3 days after exposure. At the same time, there was a front of keratocytes at the border to the damaged central stroma that showed positive staining for alpha-SMA. By 7 days after exposure, the damaged corneal stroma was already repopulated by new keratocytes. The alpha-SMA staining at 7 days was negative. Conclusions: During wound healing after UVR-induced keratitis, keratocytes that repopulate the damaged corneal stroma express alpha-SMA. That indicates the transformation of keratocytes into myofibroblasts. Keratocytes stop to express alpha-SMA when the repopulation is completed.

Keywords: cornea: stroma and keratocytes • wound healing • radiation damage: light/UV