Abstract
Abstract: :
Purpose: To study the effect of transforming growth factor-ß2 (TGF-ß2) on the growth of iris pigment epithelial cells (IPE) in vitro, and to compare dose-dependent inhibitory effect of TGF-ß2 with known concentrations of TGF-ß2 in aqueous humor. Methods: Adult human IPE were isolated and cultured using methods described previously (Invest Ophthalmol Vis Sci 33:2443, 1992). The IPE were plated into 24-well plates at a density of 1 x 104 cells/well and cultured with F12 medium supplemented with 10% serum. After 24 hours, TGF-ß2 was added to the medium in various concentrations (0.01-30 ng/ml). After 6 days, the cells were detached, counted and compared to the controls. The effect of TGF-ß2 on DNA synthesis by IPE (as evaluated by uptake of bromodeoxyuridine) incubated in serum-free culture medium was also tested. Results: TGF-ß2 inhibited growth and DNA synthesis of cultured IPE in a dose-dependent manner at concentrations from 0.3-30.0 ng/ml. TGF-ß2 inhibited the growth of IPE by up to 64% in 6 days of culture and inhibited the uptake of bromodeoxyuridine of UM by up to 52% in 48 hours. Conclusions: It has been reported that the pigment epithelium contain cathepsin, which is able to activate latent TGF- ß2. The amount of TGF-ß2 in aqueous humor (intrinsically active TGF ß2, 0.2-0.4 ng/ml; total TGF- ß2, 0.4-2.2 ng/ml. Exp Eye Res 59:723-728, 1994) is sufficient to inhibit the growth of IPE. Therefore, TGF-ß2 may play an important role in maintaining the non-proliferative, relatively quiescence status of IPE in vivo.
Keywords: iris • growth factors/growth factor receptors