Surface morphology of circulating platelets: a suggested parameter for the monitoring of endothelial seeded grafts

For the clinical follow-up of endothelial cell seeded grafts, non-invasive but sensitive parameters are required in order to determine the extent and effectiveness of the endothelialization process. Such a very sensitive parameter was found by investigating the surface morphology of circulating platelets. This technique is based on the previous observation that characteristic alterations of platelet morphology are closely associated with the course of the aggregometer tracings. Applying these ultrastructural criteria we investigated 16 patients after distal femoro-popliteal and femoro-crural bypass surgery. Reinforced 6 mm non-seeded PTFE vascular grafts were compared with reversed autologous saphenous vein grafts. As early as 4 hours after graft implantation, a significant higher percentage of discoid platelets with marginal pseudopods--representing the earliest stage of platelet activation--as well as of spheroid "shape changed" platelets was found in patients with PTFE grafts. Moreover, perforated platelet membranes were exclusively found in the PTFE group. These findings were most distinguished 10 days postoperatively but persisted over the follow-up period of 1 year. Considering the sensitivity of the described technique it might provide a simple, reliable, and non-invasive means for the clinical assessment of successful graft endothelialization.