Summary
Platelet compatibility after coating an artificial material with functionally active heparin was investigated. Blood was circulated in uncoated or heparin coated PVC tubing. In one hour platelet counts decreased from 155 (113-184) ×109/l to 124 (100-148) ×109/l with uncoated compared to 164 (132-192) ×109/l with heparin coated tubing (intergroup p = 0.02). β-thromboglobulin increased from 116 (80-148) μg/l to 1039 (757-1298) μg/l with uncoated and to 352 (229-638) μg/l with heparin coated tubing (intergroup p = 0.005). Platelet counts and β-thromboglobulin correlated closely with complement activation. Solid-phase enzyme immunoassay demonstrated substantial deposition of CD42a/GPIbIX and CD61/GPIIIa on uncoated, but not on heparin coated tubing (intergroup p <0.0005). Scanning electron microscopy demonstrated activated platelets and aggregates on uncoated in contrast to heparin coated tubing, where scattered, unactivated platelets were found. Changes in P-selectin and microparticles were minor. In conclusion, this heparin surface substantially improved platelet compatibility. Markers of choice for in vitro evaluation were platelet counts, β-thromboglobulin and platelet deposition.
Key words
Platelets - heparin - complement - artificial surface - β-thromboglobulin - P-selectin - microparticles - flow cytometry - biocompatibility