Growth requirements of calf lens epithelium in culture

Abstract

The in vitro life span and rate of growth of calf lens cells cultured in serum-supplemented 199 medium can be markedly increased by growing the cells with a layer of mitomycin-killed 3T6 feeders. In the absence of feeders, the epithelial cells are partially blocked in the S period of the cell cycle but show a normal distribution of cells in G₁ and G₂ when grown with fibroblasts. Increased growth rates and division potential can also be achieved by growing the lens in 199 medium containing 10⁻⁵ M thymidine, and cells grown under these conditions show a normal growth cycle. Our results suggest that lens epithelial cells cultured in medium 199 show a deficient endogenous synthesis of thymidylic acid, and fibroblast feeders or exogenously added thymidine enable them to overcome this deficiency. When grown in the presence of 10⁻⁵ M thymidine, the lens epithelial cells show a very low serum requirement for cell division in short term culture.