Collagen types in healing alkali-burned corneal stroma in rabbits

We evaluated the change in the type of collagen found during healing in the alkali-burned corneal stroma of rabbits. We estimated the relative proportions of a chains in pepsin-solubilized collagen, using sodium dodecylsulfate polyacrylamide gel electrophoresis. Bands of alpha 1(I), alpha 2(I), alpha 1(V), and alpha 1(III) chains stained with Coomassie Blue were separated. The alpha 1(III) and a 1(V) chains showed a transient proportional increase in healing corneal stroma in the area exposed to alkali. No significant alterations in collagen a chains were detected in peripheral corneal stroma that had not been directly exposed to alkali. Our results suggest that the keratocytes which repopulate the alkali-injured corneal stroma early in healing synthesize a higher proportion of collagen types III and V than type I, and then switch to synthesizing predominantly type I collagen as stromal healing progresses. Collagen types III and V thus appear to be of primary importance in the healing of the corneal stroma.