CHARACTERIZATION OF SV40-TRANSFECTED CELL STRAINS FROM RABBIT KERATOCYTES

The process of corneal wound healing involves the transformation of ad jacent corneal keratocytes to myofibroblast-like cells characterized b y the development of prominent microfilament bundles containing alpha- smooth muscle-specific actin (alpha-SM), a contractile protein thought to be important in mediating wound contraction. Recent studies have s hown that the expression of alpha-SM in cultured corneal keratocytes c an be induced by serum and TGF To study the cellular and molecular mec hanisms underlying this transformation process and to been to identify the role of alpha-SM in wound contractile events, we generated immort alized rabbit corneal cell strains with extended life by using SV40 tr ansfection. Two unique strains were isolated (TRK-36 and TRK-43). TRK- 36, which appears similar to normal corneal keratocytes, maintains a s tellate, keratocyte morphology when grown in the absence of serum and transforms to a myofibroblast-like cell when treated with TGF beta 1 ( 1 ng/ml) as indicated by the induced expression of alpha-SM actin. TRK -43 exhibits features characteristic of myofibroblasts in that it cons titutively expresses or-SM actin under serum-free conditions. Both str ains show in vitro contraction of collagen gels less than or equal to 80% in 24 h in serum-containing medium. Interestingly, under serum-fre e conditions, TRK-43 cells showed significantly greater contraction of collagen gels compared with those of TRK-36. Overall, the establishme nt and further study of these cell strains may provide important insig hts into the molecular mechanisms underlying myofibroblast transformat ion.