Antiproliferative role of 3-O-sulfate glucosamine in heparin on cultured pulmonary artery smooth muscle cells.

Heparin macromolecules inhibit vascular remodeling associated with hypoxic pulmonary hypertension. Heparin's antiproliferative effect on smooth muscle cells, based on studies of synthetic pentasaccharide fragments, has been attributed to 3-O-sulfate on the internal glucosamine. To determine the role of 3-O-sulfation in smooth muscle cell growth, we treated three heparins of varying potency with heparitinases I and II, which degrade heparin fragments containing 3-O-sulfate on the glucosamine residue to delta-tetrasaccharides only. Our most antiproliferative heparin gave the least amount of delta-tetrasaccharides. This heparin was then fractionated according to degree of sulfation using ETOH precipitation. Again we found no antiproliferative difference between the highly sulfated fractions and those with a lesser degree of sulfation. These studies suggest that 3-O-sulfate of glucosamine residue is not critical in whole heparins for antiproliferative activity.