Large-Scale Selection of CD34+ Peripheral Blood Progenitors and Expansion of Neutrophil Precursors for Clinical Applications

ABSTRACT Hematopoietic recovery after high-dose chemotherapy is characterized by an obligate period of neutropenia of approximately 8–10 days. It is postulated that if a pool of neutrophil precursors and progenitors were expanded in vitro and reinfused, the duration of neutropenia may be substantially shortened by these cells capable of providing mature neutrophils within days of reinfusion. In this study, peripheral blood progenitor cell products were obtained from six normal donors mobilized with rhG-CSF and two patients mobilized with cyclophosphamide and rhG-CSF. CD34+ cells were isolated using the Isolex® immunomagnetic bead method. A mean of 8.26 × 107 CD34+ cells with a mean purity of 74.5% were seeded at a concentration of 1 × 105/ml into a 12 day stroma-free liquid culture using gas-permeable bags. A serum-free growth medium supplemented with PIXY321 was used. On day 7, there was a mean cellular expansion of fourfold, at which time the cells were resuspended at the initial concentration, yielding...