FLOW CYTOMETRIC ANALYSIS OF MATERIAL-INDUCED PLATELET ACTIVATION IN ACANINE MODEL - ELEVATED MICROPARTICLE LEVELS AND REDUCED PLATELET LIFE-SPAN

Assessment of material-induced platelet activation is important given that it is thought to be a major mechanism of biomaterials thrombogeni city. We monitored, by flow cytometry, platelet microparticle (MP) lev els in the circulation during the connection of polyvinyl alcohol (PVA ) hydrogel and polyethylene (PE) test segments (3.18 mm ID, 20 and 50 cm L) to our chronically shunted beagle dogs. We report that circulati ng microparticle levels were dependent on test segment material, lengt h, and time. The connection of 50-cm lengths of PVA hydrogel test segm ents led to MP levels two to three times greater than background at 48 h, while the connection of polyethylene test segments did not lead to elevated microparticle levels. MP levels were near background 24 h af ter removal of the PVA test segment. To determine platelet life span d uring the connection of test segments, platelets were labeled in vivo with biotin and their disappearance monitored flow cytometrically. Whi le platelet life span for shunted dogs (no test segment) was 4.7 +/- 0 .2 days, the connection of PVA hydrogel test segments led to a platele t life span of <2 days. (C) 1997 John Wiley & Sons, Inc.