HUMAN LENS EPITHELIAL-CELL PROLIFERATION IN A PROTEIN-FREE MEDIUM

Purpose. The ocular humors are relatively low in protein, yet cell gro wth in the human capsular bag still occurs after extracapsular catarac t extraction (ECCE) surgery. This resilient growth gives rise to poste rior capsule opacification (PCO) in a significant proportion (30%) of patients. This study compared the ability of human lens cells to proli ferate in serum-supplemented and protein-free medium, Methods, Sham ca taract operations were performed on human donor eyes. The capsular bag was dissected free, pinned flat on a petri dish, and incubated in Eag le's minimal essential medium (EMEM) alone or in EMEM supplemented wit h 10% fetal calf serum. Observations were made by phase-contrast micro scopy. At the endpoint, capsules were studied by fluorescence or elect ron microscopy. Mitotic activity was identified using Bromo-2-deoxyuri dine labeling and detection techniques. When required, an intraocular lens was implanted when surgery was performed. Results, It tvas found that human lens cells from a wide age spectrum of donors proliferate a nd migrate on the lens capsule in the absence of added protein. The ra te of growth was age-dependent, such that the posterior capsule nas co mpletely confluent after 8.0 +/- 0 days (n = 3) and 24.4 +/- 5.3 days (n = 8) for donor lenses aged <40 years and >60 years, respectively. T he outgrowth of epithelial cells gave rise to capsular contraction, wr inkling, and increased light scatter, Growth on the anterior surface o f the intraocular lens was less prolific than on the posterior capsule . Conclusion, The protein-free model replicates many features of clini cally-observed PCO. The resilient cell growth on the natural collagen capsule explains the high prevalence of PCO, especially in younger pat ients, and suggests that inflammation and external growth factors are not necessary for PCO. Furthermore, the protein-free capsular bag syst em can be used to explore fundamental questions concerning the autocri ne control of lens epithelial cell survival and growth.