High Cellular Concentration of Peripheral Blood Progenitor Cells During Cryopreservation Adversely Affects CFU-GM but Not Hematopoietic Recovery

Abstract

The effects of bone marrow (BM) and peripheral blood progenitor cell (PBPC) concentration during cryopreservation on subsequent hematopoietic engraftment following high-dose chemotherapy were studied in 24 patients. Seventeen BM harvests and 71 PBPC collections were performed between July 1991 and June 1994. The PBPC were frozen at significantly higher cellular concentrations than the BM (medians of 243 × 10⁶/ml versus 73 × 10⁶/ml respectively, p = 0.0003). The recovery of committed progenitor cell colonies (CFU-GM) was significantly lower from PBPC frozen at concentrations above the median, compared with 116% from those frozen at concentrations below the median (p = 0.0467). This phenomenon was not seen in BM, which was generally frozen at a threefold lower concentration. Despite the lower recovery of CFU-GM when PBPC were frozen at a higher concentration, the patients receiving these grafts achieved good hematopoietic recovery. The higher number of PBPC probably compensated for the loss, and the patients still received a substantial number of clonogenic hematopoietic precursors.