ABSTRACT
Heparan sulfate isolated from mammalian arterial tissue inhibits the growth of homologous arterial smooth muscle cells when added to subconfluent cell cultures at a concentration of 50 to 100 micrograms/ml culture medium. Disintegration of the heparan sulfate molecule by hydrazinolysis that deacetylates N-acetylglucosaminyl residues and by subsequent treatment with nitrous acid at pH 3.9 results in the formation of a mixture of oligosaccharides which was further resolved into sulfate-enriched oligosaccharides with antiproliferative activity in an in vitro bioassay system. A decasaccharide and dodeca/tetradecasaccharide fraction had a significantly higher antiproliferative effect on arterial smooth muscle cells than the native heparan sulfate molecule. The antiproliferative oligosaccharides have a sulfate content of 0.9 to 1.2 sulfate groups/disaccharide unit and consist of 60 to 70% monosulfated, disulfated, and trisulfated disaccharide units. Up to 32% of the sulfate groups were in 2-position of the uronic acid. In contrast, nitrous acid degradation of heparan sulfate at pH 1.5, which cleaves glycosidic linkages of N-sulfoglucosaminyl residues, results in the formation of sulfate-poor or sulfate-free oligosaccharides without antiproliferative potency. The results indicate that (a) heparan sulfate has a heterogeneous molecular organization where sulfate-rich domains are separated by sulfate-poor sequences and that (b) the antiproliferative activity of heparan sulfate resides in domains enriched with 2-O-sulfated uronic acid residues.