Optimization of CD34+ cell selection using immunomagnetic beads: implications for use in cryopreserved peripheral blood stem cell collections.

Isolation of CD34+ cells from bone marrow, umbilical cord blood, and mobilized peripheral blood stem cell (PBSC) collections has many potential clinical benefits. The aim of this study was to evaluate the use of the ISOLEX 300 system to select hematopoietic precursors and determine the effectiveness at depleting contaminating tumor cells from cryopreserved/thawed PBSC. Median recovery of CD34+ cells and CFU-GM colonies was 71% and 51.5%, respectively, using a protocol optimized for our laboratory. A mean 2.9 log10 decrease in contaminating breast carcinoma cells was seen after the selection process. Selected CD34+ cells underwent a second round of cryopreservation/thawing while retaining 85.6% viability and 72.3% recovery of CFU-GM colonies.