Vitreous body-derived mitogenic activity for retinal pigment epithelial cells. A further characterization

To obtain a better insight into the possible role of vitreous body in proliferative vitreoretinopathy (PVR), we examined the influence of bovine vitreous body fractions separated by fast protein liquid chromatography (FPLC) on the growth of porcine retinal pigment epithelial (RPE) cells in vitro. Tetrazolium colorimetric assay (MTT assay) and cell counting were used for quantification. After fractionating proteins of the physiological vitreous body by FPLC gel chromatography (Superose 12/Superdex 75), we determined the mitogenic effect of the resulting fractions by either cell counting or MTT assay. With both columns we were capable of separating two fractions (20-40 kDa and 1-2 kDa) that induced RPE cell proliferation. A comparison of the mitogenesis and the protein content of the fractions indicated that we were not dealing with a nonspecific protein effect. The low-molecular fraction weighing less than 2 kDa was of particular interest to us. This was further separated by FPLC reversed-phase chromatography.