RECOMBINANT TIMP-1 AND TIMP-2 ENHANCE THE PROLIFERATION OF RABBIT CORNEAL EPITHELIAL-CELLS IN-VITRO AND THE SPREADING OF RABBIT CORNEAL EPITHELIUM IN-SITU

Purpose. The repair of the corneal epithelium is modulated by matrix m etalloproteinases. The present study examined the effects of recombina nt (r-) tissue inhibitors of metalloprotein ases-1 and -2 (TIMP-1 and -2) on the proliferation of cultured epithelial cells from rabbit corn ea, and on the spreading of a sheet of squamous epithelium of rabbit c ornea placed in an organ culture system.Methods. DNA synthesis of the cells, with or without r-TIMPs, was determined by an immunoassay for B rdU incorporation. Cell proliferation was assayed by measuring MTT mit ochondrial activity. Epithelial spreading was evaluated by culturing s mall corneal blocks for 24 h in the presence or absence of each agent. Cryosections were prepared and the epithelial growth on the cut strom al surface was measured. Results. Each agent, r-TIMP-1 (at 50 and 100 ng/ml) and r-TIMP-2 (at 50 ng/ml) significantly enhanced the DNA synth esis and MTT activity of the corneal epithelial cells in vitro. Relati ve to the untreated control cells, DNA synthesis was increased 2.4-fol d by r-TIMP-1 and 2.3-fold by r-TIMP-2. r-TIMP-1 (at 100 and 200 ng/ml ) and r-TIMP-2 (at 10 and 50 ng/ml) each significantly enhanced the sp reading of the corneal epithelium. Relative to the untreated control t issue, spreading of the epithelial sheet was increased 1.7-fold by r-T IMP-1 and 1.4-fold by r-TIMP-2. Higher concentrations of r-TIMP-1 and r-TIMP-2 did not further enhance either the DNA synthesis of the cultu red cells or the spreading of the epithelium. Conclusions. Exogenous T IMPs enhanced the spreading of the corneal epithelium and proliferatio n of cultured corneal epithelial cells. Findings suggest that endogeno us TIMPs may influence the healing of corneal epithelium in vivo.