| Cornea is a disc-like avascular film in the most anterior of the eyeball. It composes five layers in histology from outside to inside, and the most outside layer is epithelial layer. Cornea is a component of the ocular dipotric system , it is the main reflecting interface of the eye ,its high diaphaneity is the basis for good visual acuity and inhibiting light from scattering.With the rapid development of the industry and agriculture in recent years, the chemical burn of cornea especially alkali burn becomes more and more serious. The most effective clinical therapy method to chemical burn is cornea transplantation, but its repair rate is the lowest in all corneal lesion transplantation. Also, the corneal donors are so rare as compared to the recipients, and the corneal tissue engineering progresses slowly, these conditions limit corneal transplantation. So it is urgent to thoroughly study the corneal tissue repair after alkali burn , especially to study the corneal limbus which is intimately related to corneal transplantation and corneal tissue engineering.The corneal epithelium has good proliferating ability under normal conditions, because of existing corneal stem cells in the corneal limbus basal layer , the corneal stem cells are the origin for corneal epithelial proliferation and differentiation. But after chemical burn especially alkali burn , the tissue repair processings and effects are different in different sites. There has little reports about these realms up to now.This paper studied in vivo and in vitro systematically the repair processing of rabbit central and limbal corneal alkali burn from cell culture and morphology, PA/PAI cascade's expression and stress gene screening . Also,?the corneal stem cells' function in burn repair was studied and some human embryos' cornea obtained legally were used.1. The cell culture and morphological changes of central and limbal cornea during alkali burn repairIn this part , corneal epithelial cells were cultured successfully, fusiform cells were found in cultured limbal corneal epithelium, by ICC they were presumed as TAG or TMC cells of differentiating corneal stem cells . The culture results also showed that corneal limbus cells grew better and more rapidly than central corneal cells.On the base of animal corneal alkali burn model ,corneal morphological characters were observed by HE,LM,SEM and TEM at different sites of the burned cornea and different intervals after burn . The results were as following: The corneal morphologies changed most about 24 hours after alkali burn; Second, The corneal repair processed synchronously with the alkali impair after alkali burn. And at last , the repairing rate and result of central corneal lesion were more rapid and better than that of the limbal corneal lesion.Also, the morphological study suggested that the comeal endodermis was also important for tissue repairing after alkali burn.2. The function of PA/PAI cascade in tissue repairing after corneal alkali burnThe expression of tPA, uPA, uPA-R and PAI-2 , the main members of PA/PAI cascade , were studied at different intervals after alkali burn in cultured corneal cells and animal corneal alkali burn model by ICC. The results suggested that PA/PAI cascade had almost the same function in corneal burn repair as it did in cutaneous repair, most members of the PA/PAI cascade were most active at about 24 hours after alkali burn.It's worthy to note that the expression of PAI-2 was a little later than the other three members, both uPA and uPA-R had a sub-highest phase, the reasonfor this phenomenon may be PAI-2's decrease and alkali' permanent impairment.3. Stress-mediated genes' screening and primary identification after corneal alkali burnOn the base of the first two parts, differentially expressed stress genes which controlled lesion repair after corneal limbus alkali burn were screened in cultured corneal cells ,the two time points were normal state and 24hours after alkali burn. The mainly screening t...
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