Mobilization and Apheresis Collection Strategies to Reduce Platelet Loss in G‐CSF Mobilized Healthy Adult Donors

Abstract

Granulocyte‐colony stimulating factor (G‐CSF) mobilizes hematopoietic progenitor cells (HPC) into the peripheral blood. Donor peripheral blood platelet loss has been observed during both G‐CSF mobilization and apheresis collection. This study evaluates two strategies to reduce donor platelet loss, preserve product CD34+ cell yield and collection efficiency and increase volume of whole blood (WB) processed. One hundred and two adults healthy donors were mobilized with either standard dose G‐CSF (9.5–12 mcg/kg/day × 4 days) or lower dose G‐CSF (7.5–10 mcg/kg/day × 4 days) according to their pre‐mobilization platelet count. Apheresis centrifugal force was adjusted by lowering the packing factor (PF) setting on the apheresis instrument. Between‐group differences were observed in absolute donor platelet loss (p = 0.04) favoring lower G‐CSF dosing, while percent donor platelet loss trended towards significance (p = 0.10). Lowering PF from the manufacturer's default of 4.5 to 4.0 demonstrated between‐group differences in absolute donor platelet loss (p < 0.05), percent donor platelet loss (p < 0.001), and apheresis product platelet content (p < 0.001). No differences were observed in the product CD34+ cell content and CD34+ cell collection efficiency when PF was reduced to 4.0. Additionally, a higher volume of WB could be processed due to reduced donor platelet loss. Together, these two strategies may mitigate the risk of cumulative platelet loss in G‐CSF mobilized healthy donors undergoing apheresis collection, thereby increasing the likelihood of completing the target total blood volume to be processed while maintaining donor safety.