Quantifying loss of CD34+ cells collected by apheresis after processing for freezing and post-thaw

Introduction: CD34+ cells collected for autologous bone marrow transplantation (BMT) are usually quantified in the apheresis product after collection, but the necessity to repeat these measures post-thaw is controversial.Methods: We examined the loss of CD34+ cells after collection, preparation for freezing and post-thaw in apheresis products collected for BMT.Results: Median number of CD34+ cells collected per unit was 1.61 × 106/kg, viability: 97–100%. This number decreased to 1.38 × 106/kg, viability: 96–100% before freezing and was 1.17 × 106/kg post-thaw. Viability decreased to 86–98%. The relative loss of viable PBHPC showed an inverse correlation with the ratio “CD34+ cells/total nucleated cells” (r = −0.45; p = <0.0005). This relative loss was largest in patients with Hodgkin’s lymphoma.Conclusion: Cryopreservation and thawing of PBHPCs in leukapheresis products provokes a small but significant stem cell loss. So, quantification of viable CD34+ cells post-thaw is important, especially in poorly mobilizing patients. Besides, the ratio “CD34+ cells/total nucleated cells” after leukapheresis is an important parameter for prediction of neutrophil recovery after BMT.