Kinetics of CFU-Mk after automated plateletpheresis

Background and Objectives Platelet count, thrombopoetin (TPO) level and the compartment of megakaryocyte progenitor cells (CFU-Mk) are major determinants in the regulation of thrombopoiesis. The aim of this study was to investigate the potential changes in the compartment of CFU-Mk and their correlation with serum TPO levels and platelet count after plateletpheresis. Materials and methods Twelve healthy individuals were randomly assigned to undergo single-donor plateletpheresis. A collagen-based in vitro culture system was used to determine the number of peripheral blood (PB) CFU-Mk before and after donation and on days 1, 4 and 7 thereafter. TPO levels were measured by a specific enzyme-linked immunosorbent assay and whole blood counts were performed using an automated cell counter. Results The pre-apheresis platelet count (mean ± SEM: 276 ± 13 × 109/l) decreased after plateletpheresis to a nadir of 194 ± 8 × 109/l (P < 0·001), showed a gradual increase on days 1 and 4, and reached pre-apheresis values by day 7 (280 ± 11). The serum TPO levels were found to be significantly increased on days 1 and 7 as compared to baseline levels (baseline value 103·3 ± 18·5 pg/ml versus day-1 value 135·8 ± 25·8 pg/ml and day-7 value 132 ± 30·19 pg/ml; P < 0·03 and P < 0·03, respectively). The numbers of CFU-Mk in PB were significantly elevated on day 4 only (125 ± 21 colonies/ml of PB versus pre-apheresis values of 68 ± 18 colonies/ml of PB, P < 0·005). Conclusions These findings suggest that platelet loss during plateletpheresis affects thrombopoiesis at the progenitor cell level, probably through alterations in TPO plasma concentrations.