Summary
Heparin and other anticoagulant glycosaminoglycans were radiolabelled with 125I and their catabolism by human vascular endothelial cells in culture was studied.
Heparin, heparan sulphate and pentosan polysulphate were associated with the cellular
fraction and incorporated into the subendothelial matrix, but dermatan sulphate was
not found in either fraction. High molecular weight, fully desulphated carbohydrate
chains were major catabolic products of all those glycosaminoglycans which were taken
up by the cells. Pentosan polysulphate was not degraded further, but the catabolism
of heparan sulphate, and to a lesser extent that of heparin, also yielded small oligosaccharides.
Thus the first step in catabolism of exogenous glycosaminoglycans by human vascular
endothelial cells appears to be complete desul-phation, which destroys their biological
activity, followed by depolymerisation of the carbohydrate chain. This alternative
to the sequential action of lysosomal exoenzymes is dependent upon binding to the
cell; thus dermatan sulphate, which is not associated with the cellular fraction,
is not catabolised.
