Abstract
Purpose: :
The purpose of this research is to demonstrate that antiapoptotic proteins (Hsp–27, Hsp–70 and Bcl–2 oncoprotein) are involved in the corneal wound healing process after surface and stromal laser excimer ablation and to explore the possibility that nerve growth factor (NGF) exerts its ant apoptotic effect through this proteins.
Methods: :
Lohmann Classic hens were divided into groups of 5 animals: Control (non manipulated animals), and laser–excimer treated hens (LASIK, LASEK and PRK). Each group were random assignees for topical administration of 0.2% murine NGF, balanced salt solution (BSS) and no topical treatment. At different time points (3h, 24h, 48 h day 3, 7, 15, 30 and 60), animals were euthanized and the corneas were fixed and stained for Light microscopy, Apoptosis detection were performed by TUNEL and Hsp–27, Hsp–70, and Bcl–2 oncoprotein were detected by immunostaining.
Results: :
Hsp–27 and 70 was observed in the new proliferative basal epithelium, keratocites and endothelium in PRK and LASEK corneas. These proteins were also detected in keratocites and endothelium in LASIK corneas. PRK–NGF treated corneas showed a higher increase of Bcl–2, Hsp–27 and 70 proteins compared with PRK–BSS treated and PRK–no topical treatment groups at the time points checked (12, 24, 48 and 72 hours after surgery). Surprising, total cell death was reduced in PRK–NGF treated corneas compared with the groups that underwent PRK and were treated with BSS and no topical drugs. Non–manipulated corneas (control group) showed no positive immunostaining for apoptosis and the proteins tested
Conclusions: :
Heat shock proteins and Bcl–2 oncoprotein are expressed during corneal wound healing after surface and stromal refractive surgery. Its antiapoptotic effect in corneal cells was modulated by topical administration of NGF that induces expression of antiapoptotic proteins, which probably cause a decrease of keratocite apoptosis.
Keywords: cornea: stroma and keratocytes • wound healing • refractive surgery