Hyaluronate binding to intact corneas and cultured endothelial cells

Sodium hyaluronate (HA) protects the corneal endothelium during cataract surgery. Recently, HA receptors have been found on liver endothelial cells that play an important role in HA catabolism. It is unknown if similar receptors are present on the corneal endothelium. In this study we have used two different methods to follow the interaction of HA with corneal endothelial cells: (1) binding of 3H-HA to cells or intact corneas was determined in the presence or absence of unlabelled glycosaminoglycans after solubilization with KOH, and (2) the HA-binding region of bovine cartilage proteoglycan was used as a histochemical probe and visualized by an avidin-biotin method. 3H-HA bound both to intact rat corneas pretreated with Streptomyces hyaluronidase and to cultured monkey corneal endothelial cells. The fraction-bound 3H-HA increased with time and was saturable. Cultured endothelial cells were estimated to have 1700-2100 binding sites per cell with a binding constant of 5.6-8.5 X 10(9) liters/mol. Furthermore, unlabelled HA displaced the tritiated in a dose-dependent manner and the displacing efficiency was dependent on molecular weight. The histochemical method disclosed that HA forms a continuous layer on the endothelium. If Healon was injected into the anterior chamber, the thickness and staining intensity of this layer increased conspicuously.