To determine the effects of tumor necrosis factor alpha (TNF-α) and transforming growth factor beta2 (TGF-β2) on retinal pigment epithelium (RPE) migration and proliferation in a simplified wound healing system in vitro.
Confluent and subconfluent human RPE cultures were centrally denuded and, the cultures were observed in the presence of TGF-β2 (10 ng/ml), TNF-α (10 ng/ml) or media alone (DMEM), after 24, 48, 72 and 96 hours. The migration was evaluated by counting the number of cells in the denuded area. The proliferation was assessed in situ by counting the percentage of positive cells by immunohistochemistry for the proliferation-related antigen Ki-67 in the denuded region and at the edge of the wound.
The control confluent cultures closed in approximately 72 hours, while the subconfluent cultures closed in approximately 96 hours. The closure occurred predominantly by migration although proliferation was increased at 24 hours both in the migrating cells and at the wound edge. TNF-α stimulated wound closure primarily by increasing migration in 24 and 48 hours. TGF-β2 decreased wound closure by inhibiting proliferation in 72 and 96 hours and migration in 48, 72 and 96 hours. The TNF-α effect was more intense in presence of subconfluent cultures, and the TGF-β2 effect was more intense in confluent cultures.
Healing of a denuded zone in RPE cultures was related predominantly to cellular by RPE migration although proliferation was also involved. RPE wound closure was stimulated by TNF-α and inhibited by TGF-β2.