Effects of surface-bound and intravenously administered heparin on cell-surface interactions: inflammation and coagulation.

Intravenous administration of heparin and heparin-bonded extracorporeal circuits are frequently used to mitigate the deleterious effects of blood contact with synthetic materials. The work described here utilized human blood in a micro-perfusion circuit to experimentally examine the effects of intravenous and surface-bound heparin on cellular activation. Activation markers of coagulation and of the inflammatory response were examined using flow cytometry; specifically, markers of platelet, monocyte, polymorphonuclear leukocyte (PMN), and lymphocyte activation were quantified. The results indicate that surface-bound heparin reduces the inflammatory response whereas systemically administered heparin does not. This finding has important implications for blood-contacting devices, particularly within the context of recently elucidated connections between inflammation pathways and coagulation disorders. Data presented indicate that surface-bound heparin and intravenously administered heparin play distinct, but vital roles in rendering biomaterial surfaces compatible with blood.