TRANSPLANTED CORNEAL STROMAL CELLS IN VITREOUS REPRODUCE EXTRACELLULAR-MATRIX OF HEALING CORNEAL STROMA

Purpose. To characterize the extracellular matrix (ECM) formed by corn eal stromal cells after injection into the vitreous. This will provide a basis for future studies on the function of corneal ECM macromolecu les. Methods. Cell line from rabbit dermal fibroblasts (RAB9) and prim ary cultures of rabbit corneal stroma fibroblasts (NRCF) were grown to confluence. For each cell type, approximately 1 X 10(6) cells suspend ed in basal medium were injected into the vitreous of normal rabbits a nd observed periodically with a slit lamp. After 1, 2, and 4 weeks, ey es were processed for transmission electron microscopy (TEM), immunohi stochemistry, immunocytochemistry, and in situ hybridization. Results. All cells showed gradual growth within the vitreous along the needle track. Occurrence of retinal detachment and inflammation was variable. Transmission electron microscopy of NRCF confirmed the deposition of ECM reminiscent of the organization of normal fetal corneal stroma. Si milar matrices were produced by RAB9. NRCF deposited collagen fibrils similar in diameter to those seen in normal developing and healing cor neal stroma. RAB9 produced collagen fibrils with larger diameters. NRC F-transplanted cells synthesized proteoglycans and collagen-immunologi cally identical to decorin proteins and type VI collagen, indicating t hat the expression of specific ECM is maintained after transplantation . In addition, in situ hybridization showed that type XII collagen mRN A is synthesized by transplanted NRCF similar to healing corneas. Conc lusions. Corneal stroma cells transplanted into vitreous produce a mat rix morphologically and biochemically similar to that in healing corne al stroma.