DYNAMICS OF THE EXPRESSION OF CYTOSKELETON COMPONENTS AND ADHERENS MOLECULES BY FIBROBLASTIC CELLS IN ALKALI-BURNED AND LACERATED CORNEAS

To provide a better understanding of the role of fibroblastic cells du ring corneal wound-healing, we examined the expression of cytoskeleton components (i.e. smooth muscle alpha-actin (alpha-SMA), vimentin, des min), adherens molecules (vinculin and talin) and cellular fibronectin in alkali-burned and lacerated rabbit corneas. Alkali-burned and lace rated corneas, which had healed for various periods of time (1 day to 45 days), were excised and subjected to immunohistochemical studies wi th monoclonal antibodies against alpha-SMA, vimentin, desmin, vinculin , talin and cellular fibronection. Monoclonal antibody against alpha-S MA reacted with fibroblastic cells in injured corneas but did not reac t with keratocytes in normal corneas. Anti-desmin antibody did not rea ct with any corneal cells in normal or injured corneas except the musc le cells in the newly-formed capillary of injured corneas. The results indicate that the fibroblastic cells in injured corneas have the char acteristics of myofibroblasts. The number of myofibroblasts in granula tion tissues increased and peaked within 3 weeks of injury and then de clined. Electron microscopy revealed that some fibroblastic cells in t he lacerated cornea which had healed for 4 weeks contained dense chrom atins. In situ 3'-end labeling with terminal nucleotide transferase in dicating that some of the fibroblastic cells contained nicked genomic DNA. These observations imply that apoptosis plays a role in regulatin g the number of myofibroblasts in the injured corneas. Antibodies agai nst cellular fibronectin, vinculin and talin react with the fibroblast ic cells in the injured corneas, but not with the keratocytes of norma l corneas. Examination with transmission electron microscopy demonstra ted the presence of microtendon and fibronexis associated with fibrobl astic cells and the presence of stress fiber within fibroblastic cells . The results indicate that the fibroblastic cells may cause corneal w ound contraction, which in turn contributes to the formation of opaque scar tissues.