Lack of fiber cell induction stops normal growth of rat lenses in organ culture.

PURPOSE

Lens organ culture has been widely used as a model system for studying cataract induction and prevention. While rat lenses remain transparent and viable for a week or longer in culture, they do not increase in weight. This study was undertaken to determine what accounts for the lack of weight increase.

METHODS

Lenses from 4-week-old Sprague-Dawley rats were cultured using standard methods. Histological analysis was performed on sections from methacrylate embedded tissue. 35S-labeled amino acids were used to metabolically label lenses in culture for the purpose of analyzing protein synthesis. BrdU labeling was used to assess synthesis of DNA in vivo and in vitro.

RESULTS

Lenses from young, rapidly growing rats do not increase in weight after being put into organ culture. Protein synthesis continues in the cultured lenses although at decreased levels as time in culture increases. Lens epithelial cells continue to synthesize DNA as indicated by BrdU labeling, however, the normal migration of epithelial cells from the proliferative zone to the equator does not occur in culture. In the cultured lens, the shape of the lens bow gradually changes, becoming compressed towards the capsule.

CONCLUSIONS

The differentiation of lens epithelial cells into fibers is arrested in the cultured lens; consequently lenses in organ culture do not grow normally.