ABSTRACT
BACKGROUND: Blood-foreign interaction cause activation of coagulation and inflammatory process that may lead to multiorgan dysfunction and determine the surgical outcomes.Of the methods for assessing the biocompatibility,the platelet adhesion study is considered as the most valuable evaluation step in blood-foreign interaction.As the most studies have used in-vitro or ex-vivo conditions,we have developed a technique of quantification for platelet adhesion on the blood contact surface by using in-vivo injection of radioactive platelets. MATERIAL AND METHOD: A coupled bypass circuit was designed to connect the proximal and descending thoracic aorta in 6 piglets(20~25 Kg).One side of the circuit tube was consisted of a heparin coated PVC tube(10mm in ID, n=6, Experimental group),and the other,a non-heparin coated PVC tube(10mm in ID, n=6, Control group).After cannulation,the blood was circulated through the circuit for 2 hours. Platelet concentrate was prepared from homologous pig blood 24 hours before the experiment.The platelet concentrate was incubated with Tc-99m-HMPAO for 30 min and then centrifuged for 10 min.The supernatant was discarded and the radio-labeling efficacy was measured.The radio-labeled platelet concentrate was mixed with the autologous plasma to make the volume 5 ml,and the mixture was injected intravenously into the experimental animal.After 2 hour circulation, 5 pieces of the specimen(10mm in length each)were obtained from each PVC tube.The radioisotopes were counted with a gamma counter(Cobra II,Packard,USA),and the ratio of radioisotope count was compared between the control and experimental group. RESULT: The radioisotope count number was 537.3221.1 Ci/min in the control group and 311.1 184.5 Ci/min in the experimental group(p=0.0104).The ratio between the groups was 1 to 0.58 (p=0.004). CONCLUSION: In vivo quantification using technetium-99m-HMPAO labeled platelets is simple and reproducible in evaluating platelet adhesion on a foreign surface.We suggest this technique to be a useful tool for blood compatibility test.