Platelet Activation in Extracorporeal Circulation: Effects of Unfractionated Heparin on Damages Induced by Bio-incompatibility

Background. Interaction with biomaterials of non-endothelial surfaces of cardiopulmonary bypass circuit caused platelets activation.The aim of study was to evaluate the effects of unfractionated heparin (UH) on platelet activation induced by extracorporeal circulation (ECC). Methods. Analysis were performed on peripheral human blood (PB) obtained from 10 healthy adult blood donors.Markers were evaluated after in-vitro and after ECC stimulation, samples with and without UF were compared. In-vitro stimulation was tested on 10 ml of PB, at 37°C for 2 hours in Orbital Shaker SSL1 stirrer at flat speed. ECC stimulation was carried out on 100 ml of PB circulated 2 hours/37°C at a rate of 1.70 l/min.We tested Annexin V (marker of platelet activation) and CD41a (marker of platelet aggregation). Samples were analyzed on a flow cytometer. Results. We compared samples with UH and samples without (control=ctr) after in-vitro and ECC stimulation.We observed a greater positivity to Annexin V after ECC compared to in-vitro (25.9 vs 8.7%; p<0.01) in ctr samples. Similarly, CD41a+ was greater after ECC than in-vitro stimulation (68 vs 28.3%; p<0.01).In samples with UH, Annexin V was greater after ECC than in-vitro stimulation (25 vs 9%; p<0.001). A similar result was observed for CD41a (66 vs 23%; p<0.01). ECC induced a platelet activation compared to in-vitro stimulation. Addition of UH led to a reduction of platelet activation in vitro, and to a more marked reduction after ECC. Conclusions. ECC act on platelet activation.The addition of UH in the blood and in the circuit reduced activation, suggesting a positive action of the drug on the observed effects induced by biomaterials.