CD34-positive cells isolated from cryopreserved peripheral-blood progenitor cells can be expanded ex vivo and used for transplantation with little or no toxicity

Abstract

Purpose: The objectives of this phase I study were to assess the feasibility of using cryopreserved peripheral-blood progenitor cells (PBPC) for large-scale CD34 selection and subsequent expansion, and the safety of their use for reinfusion following chemoradiotherapy.

Patients and methods: For 10 patients with nonmyeloid malignancy, an aliquot from a PBPC harvest was recovered from liquid nitrogen, and CD34 selected using the Isolex system (Baxter Healthcare, Newbury, United Kingdom) and expanded for 8 days ex vivo in a medium free of animal proteins but supplemented with autologous serum, stemcell factor (SCF), interleukin-1 beta (IL-1 beta), IL-3, IL-6, and erythropoietin.

Results: The mean increase for cell number was 21-fold, for colony-forming units-granulocyte/macrophage (CFU-GM) 139-fold, and for burst-forming units-erythroid (BFU-E) 114-fold. The expanded cells were reinfused in tandem with unmanipulated material (> or = 25 x 10(4) CFU-GM/kg). The patients did not experience any adverse effects immediately on cell infusion or within 48 hours. The 10 index patients were compared with 10 historical controls for parameters of myelosuppressive morbidity. In this small study, there were no differences in either neutrophil or platelet recovery between the patients who received expanded cells and historical controls.

Conclusion: These data demonstrate that CD34 cells can successfully be selected from cryopreserved material, expanded ex vivo on a large scale, and safely reinfused following myeloablative conditioning regimens.