Effects of corneal extracts on rabbit corneal stromal cells in culture.

Rabbit corneal tissues were treated sequentially with phosphate buffered saline (PBS) and 4 M guanidine hydrochloride (GuHCl), dialyzed, and lyophilized. The interaction of the individual PBS and the GuHCl extracts with cultured rabbit corneal stromal cells was assessed. The PBS extract stimulated stromal cell growth. These cells had a thinner spindle-shaped appearance, a greater tendency toward multilayer formation, and a approximately 40-60% higher final density than the controls. The cells subjected to the GuHCl extract exhibited no such changes. When the PBS extract was heated to 80 degrees C, the stimulatory activity was replaced by an inhibitory activity, indicating that the PBS extract contained both the stimulatory and the inhibitory factors. Using a high performance liquid chromatograph system, such factors could be separated. The effects of corneal extracts on connective tissue synthesis were examined after labeling confluent stromal cultures with either (35S)sulfate or (3H)proline for 20 hr. The PBS and the GuHCl extracts significantly promoted the incorporation of (35S)sulfate into glycosaminoglycans. Neither extract altered the types of glycosaminoglycans synthesized or the collagen synthesis of stromal keratocytes in culture.