In vitro generation of functional lens-like structures with relevance to age-related nuclear cataract

PURPOSE. To investigate the capacity of lens epithelial cells, maintained in a modified explant culture system, to mimic normal patterns of lens cell differentiation and to regenerate lens structure and function. METHODS. Lens epithetial explants were set up in pairs with their apical surfaces facing each other. These explant pairs (EPs) were then cultured in vitreous for up to 43 days to promote their growth and differentiation. Immunohistochemistry, and conventional tight and electron microscopy were used to assess structural and functional properties of the lens-like structures that developed from EPs. RESULTS. EPs that were asymmetrically exposed to vitreous routinely produced biconvex, lens-like structures composed of ordered epithelial and fiber cells that were transparent and had some focusing and magnifying ability. In addition, characteristic of the lens in vivo, fiberlike cells that were peripherally situated in EPs contained markers of the relatively early stages of fiber differentiation, whereas centrally situated cells contained markers of terminally differentiated fibers. During longterm culture of the EPs, a central opacity appeared that had structural features similar to those reported for the early stages of human, age-related nuclear cataract. CONCLUSIONS. This study shows that, given appropriate culture conditions, lens epithetial cells can regenerate ordered lens-like structures with functional proper-ties. This system represents a valuable new tool for the investigation of factors involved in the generation of normal lens structure and function and lens opacification.