Biosynthesis of glycosaminoglycans by mammalian corneal epithelium and fibroblasts in vitro. II. Approach to specify the GAG from the two cell types.

35S- as well as 3H-labeled glycosaminoglycans (GAG) produced by cultivated epithelium and fibroblasts of the rabbit cornea were treated with testicular hyaluronidase, leech hyaluronidase and chondroitinase-ABC or -AC. The fractionation-patterns of enzyme-treated GAG were compared with blanks not exposed to enzymes. The epithelial GAG revealed to be generally more resistant to the enzymatic degradation than the GAG synthesized by the fibroblasts, but--depending on the enzyme--in the GAG of both cell types the same fractions were attacked. The decline of the radioactivity in the fractions of enzyme-treated GAG allows the conclusions that both cell types produce relatively small amount of keratan sulfate but mainly chondroitin sulfates with a different degree of sulfation. In addition GAG, not present in the normal cornea, are synthesized: hyaluronic acid chiefly by fibroblasts and probably dermatan sulfate. The possible role of the fibroblastic and epithelial GAG in corneal wound repair is discussed.