Inhibition of fibroblast proliferation by human iris pigment epithelial cells in vitro: preliminary results.

BACKGROUND

The interaction between different cells plays an important role in many physiological and pathological processes. Since the proliferation of fibroblasts is very much involved in the pathogenesis of eye diseases such as proliferative vitreoretinopathy, the failure of filtration in glaucoma surgery, etc., we attempted to ascertain whether iris pigment epithelial cells (IPE) have some modulating effect on fibroblast proliferation.

METHODS

Human IPE were explanted and the third-passage culture was transferred into serum-free RPMI-1640 medium. After 48 h of further incubation, the medium was collected and submitted to centrifugation; the supernatant was used as the conditioned medium of IPE (IPE-CM). Cultured fibroblasts from Tenon's capsule were seeded in a 96-well plate and incubated with IPE-CM in different concentrations. The proliferation of fibroblasts was estimated by thymidine incorporation and cell counting.

RESULTS

The incorporation of tritiated thymidine by fibroblasts was reduced to 56.68% of baseline with 1:16 diluted IPE-CM and to 13.63% and 8.20%, respectively, with 1:8 and 1:2 diluted IPE-CM. These findings were in good accordance with the results of cell counting, performed in parallel. SDS-PAGE of IPE-CM revealed two specific bands with molecular weight 65 kDa and 40 kDa.

CONCLUSION

IPE-CM showed an obvious dose-dependent inhibitory effect on fibroblast proliferation and was presumed to contain some active factors contributing to this effect.