Prolonged Thrombocytopenia Following Allogeneic Hematopoietic Stem Cell Transplantation: Association with Reduced Ploidy and Immaturation of Megakaryocytes

Abstract 4695

Prolonged thrombocytopenia is a frequent complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT), but its pathogenesis has remained obscure. In present study, by using a flow cytometry technique, we determined the frequency of bone marrow megakaryocytes (MKs) and MKs ploidy distributions in allo-HSCT recipients with or without prolonged thrombocytopenia (n=32 and 27, respectively) and in 13 healthy volunteers. Along with that, the expression of c-Mpl in MKs was measured. The result showed a significant difference in MKs ploidy distributions between the 3 groups. Both the allo-HSCT patients with or without prolonged thrombocytopenia showed a significant shift to low ploidy cells (left shift) with 55.63±18.62% and 44.63±19.38% of their MKs in ploidy classes 2N to 8N, respectively. In contrast, the healthy volunteers had only 25.97±10.70% of their MKs in ploidy classes 2N to 8N. And the patients with prolonged thrombocytopenia showed a marked increase in cells ≤8N, a significant decrease in the 16N and ≥32N cells comparing to patients without prolonged thombocytopenia, which told us there were more less mature MKs in the allo-HSCT recipients with prolonged thrombocytopenia. We concluded that prolonged thrombocytopenia and slow platelet engraftment after allo-HSCT may be related to reduced ploidy and immaturation of MKs.