Crystallins and their synthesis in human lens epithelial cells in tissue culture

Explants of epithelial cells from young human lenses of 5-12 months of age, obtained from patients who underwent surgery for retinopathy of prematurity, were cultured in Dulbecco's modified Eagle's medium supplemented with 20% fetal calf serum. Without exception, every piece of the anterior capsule explant showed cell outgrowth within 48-72 h and resulted in confluent monolayer culture within 2 weeks. From these monolayer cultures, two to three passages of subcultures were obtained by routinely seeding cells in a ratio of 1:4. The doubling times for these human lens epithelium (HLE) cultures during the first 4 weeks of two passages were found to be 24-36 h. In a majority of cultures through the first three passages, more than 12 population doublings were attained. However, no lentoid bodies were formed during this period. These cells were studied for the presence of crystallins and their synthesis. Using SDS-polyacrylamide gel electrophoresis, the presence of alpha- and beta-crystallins was demonstrated in HLE cells through three passages. The amount of alpha-crystallin in the first two passages amounted to nearly 13% of the total protein, but decreased significantly in the third passage. The presence of crystallins was corroborated by antibody reaction to the specific crystallins. Indirect immunofluorescence revealed the presence of actin and vimentin in these cell cultures. The synthesis of crystallins in HLE cultures was shown by the incorporation of [35S]methionine which was time dependent. The crystallin synthesis was found to decrease in third passage when the cell growth slowed down without consistent formation of confluent monolayer. These studies have demonstrated that primary cultures of HLE cells can be successfully grown from young lenses through several passages which continue to express the characteristic crystallins of the epithelial cells.