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 alpha 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 alpha 1(V) chains showed a transient proportional increase in healing corneal stroma in the area exposed to alkali. No significant alterations in collagen alpha 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.