PURPOSE: To compare three experimental models of limbal stem cell (SC) removal in rabbits in relation to morphologic aspects. METHODS: In the present study, 54 rabbits (108 eyes) were divided into 3 experimental groups - (G1), (G2) and (G3). Each group consisted of 18 rabbits whose left eyes were submitted to 3 different experimental techniques - (T1), (T2) and (T3), respectively. A control group was formed with the 54 remaining eyes (RE) of the G1, G2 and G3 rabbits. Four morphological parameters were assessed: epithelium, inflammatory response, vascularization and fibroblastic response. RESULTS: The limbal epithelium was not completely removed by T1, was almost totally removed by T2, and thoroughly removed by T3. Corneal surface was healed by conjunctival phenotype (conjunctivalization) in the three groups. Goblet cells started to appear on days 14 and their density peaked on day 28. The inflammatory response was more intense in G3 than in G1 and G2. Regression was faster in G1 and similar in G2 and G3 contributing to corneal opacity specially on days 14 and 28. It was mainly concentrated at the stromal anterior half, whereas the posterior half was spared. It peaked on day 28 and decreased from that moment on. In the beginning, it was characterized by a predominantly polymorphonuclear infiltrate, which, on day 56, changed to mononuclear. The new vessels started appearing on days 7. At first, they permeated the stromal upper half and progressed toward the surface as the stromal edema decreased. In the three groups, at the end of the experiment, vascularization was superficial in the stroma; but no thick sclerotic-fibrous tissue nor actual scars, distinct from the corneal stroma, were formed. CONCLUSIONS: Conjunctivalization and neovascularization occurred in all experimental models. T2 and T3 seemed to be adequate models for the removal of limbal SC and most studied parameters showed similar results. T1 was found to be an adequate model for the partial-thickness removal of limbal SC.
Limbus corneae; Germ cells; Epithelium corneal; Stem cells; Corneal neovascularization; Rabbits
