The effects on inhibition of corneal neovascularization after human amniotic membrane transplantation in severely damaged rabbit corneas

Human amniotic membrane isolated from the placenta contained basement membrane components such as type IV collagen, laminin, and 6 and 4 integrins, all of which remained detectable while preserved in glycerin for one week. One month after the n-heptanol removal of the total corneal epithelium and the limbal lamellar keratectomy, all rabbit eyes carried features of limbal deficiency, including conjunctival epithelial ingrowth, vascularization and chronic inflammation. Ten control eyes then received a total keratectomy, and 13 experimental eyes received an additional amniotic membrane transplantation. Three-month follow-ups revealed that all control corneas were revascularized to the center with granuloma and retained a conjunctival phenotype. In contrast, in the experimental groups, 5 corneas became clear with either minimal or no vascularization; the rest had either mild peripheral (5) or total (3) vascularization and more cloudy stroma. Using monoclonal antibodies for epithelial markers and matrix components, we concluded that the success correlated with the return of a cornea-like epithelial phenotype and the preservation of the amniotic membrane, whereas the failure maintained a conjunctival epithelial phenotype and the amniotic membrane was either partially degraded or covered by host fibrovascular stroma. Measures taken to facilitate the former might prove this procedure clinically useful for ocular surface reconstruction.

A Study on the Possibility of Reducing Corneal Haze with Topical Application of Human Amniotic Fluid in the Wounds Induced by Excimer Laser Keratectomy in Rabbits

Scarless wound healing with minimal inflammation obscured in the fetal skin rpay be due to the fact that amniotic fluid contains factors that may modulate the wound healing process. To examine this possibility, We examined the effect of topical application of human amniotic fluid on the healing of rabbit corneal wounds induced by excimer laser stromal ablation. The right eye received undiluted human amniotic fluid(AF) drops(13th week gestational age) and the left eye received the BSS as a control five times a day for one month. Epithelial healing completed within three days. The wound healing rate was not significant in the early phase but was significant in the late phase(p<0.05). Keratometric regression was significantly less in human amniotic fluid treated(AF group) eyes than BSS treated(control group) eyes. Corneal opacity was significantly less in AF group than control group at one and three months after laser ablation using Scheimpflug camera photography and MacDonald-Schadock class ification(p<0.05). Morphological examination revealed convoluted basement membrane, discontinued hemidesmosome and increased number of activated keratocytes in BSS-treated eyes. These results indicate that corneal scarring(haze) can be reduced by topical application of human amniotic fluid. We speculate that amniotic fluid may contain factors that can facilitate the restoration of fetal environment for wound healing by inhibiting fibroblast activation, thus preventing scar formation.