PGE2 synthesis and response pathways in cultured corneal endothelial cells: the effects of in vitro aging

Abstract

PURPOSE. The purpose of these studies is to develop an in vitro model of corneal endothelial aging and to investigate age-related changes in morphology, mitosis, prostaglandin synthesis and prostaglandin response pathways. METHODS. First-passage rabbit corneal endothelial cells were grown in vitro for up to 30 days after subculture. PGE 2 synthesis was measured by radioimmunoassay. EP 2 receptors were evaluated by determination of PGE 2 stimulated cyclic AMP synthesis. Cell-cycle parameters were evaluated by flow cytometry and by bromodeoxyuridine (BrdU) incorporation in subconfluent, confluent and injured cultures. RESULTS. Rabbit corneal endothelial cells become less dense and more irregular in shape as they age in culture, thus resembling their in vivo counterparts. PGE 2 synthesis and response decrease with culture age. Injury results in enhanced PGE 2 synthesis in both younger and older cultures. In younger cultures, injury also results in mitosis of cells at the wound margin, and this response is greatly diminished in older cultures. CONCLUSIONS. The morphologic and mitotic changes seen in rabbit corneal endothelial cultures in vitro resemble those seen as a consequence of aging in humans and rabbits. Prostaglandin synthesis and response pathways are modified as a result of aging and may play a role in the autocrine regulation of wound repair, especially in younger cells.