A Prospective Study of Platelets Function During the Process of Stem Cells Mobilisation in Healthy, Allogeneic Blood Stem Cell Donors Using the Method of Impedance Aggregometry.

Abstract 5079

Potential haemostasis disturbances accompanying the process of peripheral stem cells harvest are still underestimated. Although the last two decades have witnessed an important increase in the use of peripheral blood stem cells (PBSC) for allogeneic transplantations, we are still lacking a satisfactory analysis of mobilization related risk of thrombosis or an unexpected bleeding. It was previously proved, that G-CSF administration may induce a hypercoagulable state by increasing levels of FVIII;C. On the other hand, platelet aggregation is reduced after cytokine application. Numerous, remaining unsolved questions in this matter prompted us to study prospectively 26 PBSC healthy donors. All donors were medically evaluated initially to eliminate any identifiable pathology in their medical history, especially concerning cardiovascular system. Any concomitant medication was excluded. All donors studied were excluded if they had an abnormal platelet count, activated partial thromboplastin time (APTT) or prothrombin time(PT) prior to cytokine administration.

All donors received G-CSF (Neupogen, Amgen) at 5ug/kg of body weight subcutaneously twice daily for nine consecutive doses. We were analyzing the group of donors in the context of hemostasis alteration using the method of impedance aggregometry. The basic device used was “MULTIPLATE' aggregometer produced by DYNABYTE (Munich). We analyzed the primary hemostasis measuring the reaction of platelets to collagen (COL-TEST), ADP (ADP-test) and TRAP –test.

We performed platelets aggregation analysis before G-CSF administration, and subsequently on the first day of stem cells mobilization, three times. The first sample was obtained just before the beginning of separation, the second in the half time point of the procedure and the last sample was drawn immediately after the cessation of stem cell collection procedure. We found reduced platelet aggregation after G-CSF administration, comparing the data before cytokine stimulation and preceding the leukapheresis (p<0,05).

In contrast to this finding, there was a considerable increase in platelet activation parameters in the course of apheresis procedure, concerning both COL-test (p<0,04) nad TRAP-test (p<0,05).

The clinical implications of these findings confirm important and significant coagulation system stimulation during separation procedure.