Platelet characteristic antigens of CD34 cells in cryopreserved cord blood: a study of platelet-derived microparticles in transplant processing.

摘要

Background and Objectives In previous studies, we found that platelet microparticles (PMPs) bind to cord blood (CB) CD34(+) cells and transfer adhesion molecules to them, which enhances their engraftment. Before applying this phenomenon in actual transplants, we investigated the effect of PMPs on cryopreserved CD34(+) cells in CB. Materials and Methods We cryopreserved 18 CB units, then evaluated the binding of PMPs to CD34(+) cells after thawing, by varying the expression of platelet characteristic antigens (CD41a, CD61, CD62P and CXCR4) on these cells. Adherence of the CD34(+) cells, coated with freeze/thaw-induced PMPs, to endothelium and fibronectin was also studied, as were the effects of thrombin-induced PMPs from both fresh and preserved CB platelets. Results PMPs induced by freezing and thawing adhered less well to CD34(+) cells than did those from fresh CB, and cells coated with these PMPs had poor adherence. However, thrombin-induced PMPs from both fresh and preserved CB platelets bound equally well to cryopreserved CD34(+) cells and improved their adhesion properties. Conclusions PMPs could be a useful tool for enhancing engraftment after CB transplantation.