EFFECTS OF ASCORBIC-ACID ON LEVELS OF FIBRONECTIN, LAMININ AND COLLAGEN TYPE-1 IN BOVINE TRABECULAR MESHWORK IN ORGAN-CULTURE

Purpose. Fibronectin, laminin and collagen type I are important extrac ellular matrix products of trabecular meshwork cells. This study was p erformed to examine the effects of ascorbic acid, a significant compon ent in the aqueous humor, on the levels of these proteins in trabecula r meshwork cells maintained in organ culture. Methods. The anterior se gment of freshly enucleated bovine eyes was perfused in a modified org an culture system. Three cultures were set up simultaneously. One rece ived serum-free medium containing 100 mu g/ml of ascorbic acid, one re ceived 250 mu g/ml of ascorbic acid and one served as a control. After 72 h, the tissues were processed for paraffin sections and immunostai ning was conducted using an avidin-biotin-peroxidase complex method. W estern blot and dot blot assays were performed on tissue extracts. Res ults. Compared with the controls, the staining for fibronectin and lam inin was markedly enhanced in trabecular meshwork tissues treated with both concentrations of ascorbic acid. Increased collagen type I produ ction by trabecular meshwork cells was also demonstrated in the presen ce of ascorbic acid. Western blot and dot blot results confirmed the i mmunostaining findings. Conclusions. Ascorbic acid promotes production of fibronectin, laminin and collagen type I by trabecular meshwork ce lls. The organ culture results are consistent with those obtained prev iously from tissue culture studies.