Attachment of proteoglycans to collagen fibrils. Effect on human platelet aggregation

We attached bovine aorta and cartilage proteoglycan fractions to extracted human skin collagen and studied the effect of such treatment on the platelet-aggregating activity of collagen. Attachment of bovine aorta and cartilage proteoglycan fractions to collagen was confirmed by electron microscopy and uronic acid analyses, Collagen attached with aorta proteoglycan retained its aggregating activity; collagen attached with cartilage proteoglycan caused a delayed platelet aggregation response. However, platelets preincubated with cartilage proteoglycan proceeded to normal aggregation when challenged by untreated collagen. Neither proteoglycan affected platelet aggregation induced by ADP. Preincubation of collagen with aorta proteoglycan did not protect the collagen from being inactivated by plasma. Of the proteoglycan fractions tested, only those from aorta were antithrombic and the antithrombic activity was plasma dependent.