Fluorescence labeling to study platelet and leucocyte deposition onto vascular grafts in vitro.

Platelets and leucocytes are important participants in the response of the body to small diameter vascular grafts implanted into the arterial circulation. A sensitive and quick method for measuring platelet and leucocyte deposition contributes to material evaluation. With a newly developed fluorescence labeling method we examined the deposition of platelets and leucocytes onto vascular grafts in vitro. Human platelets and leucocytes were isolated and labeled with the fluorescence label Europium trichloride (EuCl3). After reconstitution of the labeled cells in plasma their functionality appeared intact and competitive with unlabeled cells. Eu-labeled platelets or leucocytes were then incubated with expanded polytetrafluoroethylene (ePTFE), Dacron and polyurethane (PU) vascular grafts in autologous plasma. Beta-thromboglobin and thromboxane release from platelets and beta-glucuronidase release from leucocytes during the incubation experiments were measured. Platelets and leucocytes deposited significantly less onto ePTFE compared to Dacron and polyurethane (P < 0.01). Our results are in accordance with results of in vivo studies using radio-active labeling to study platelet and leucocyte deposition. However, a new finding was that this reduced cell deposition may in part be due to possible toxic effects of ePTFE, shown by increased haemolysis and beta-thromboglobin release.