Successful transplantation and engraftment of peripheral blood stem cells after cryopreservation, positive and negative purging procedures, and a second cryopreservation cycle

Transplantation of peripheral blood stem cells (PBSC), positively and/or ne gatively selected immediately after harvest, has become a widely applied th erapeutic option in hematological or oncological patients. The following ca se of peripheral blood stem cell transplantation represents the first case of successful transplantation of PBSC, cryopreserved twice and purged after cryopreservation. PBSC were harvested in a 44-year-old female patient with a low-grade non-Hodgkin's lymphoma stage IV after mobilization with chemot herapy and G-CSF. A total number of 15.2 x 10(6) CD34(+) cells/kg bodyweigh t was harvested with a 36.9% contamination of tumor cells coexpressing CD5 and CD20. After subsequent chemotherapy cycles and cyclophosphamide mobiliz ation, only 0.77 x 10(6) CD34(+) cells/kg bodyweight, not sufficient for tr ansplantation, were achieved after positive selection. Therefore, 10.8 x 10 (6) cryopreserved CD34(+) cells/kg bodyweight were thawed and a positive se lection was carried out with the BAXTER Isolex 300i machine. Before additio nal negative selection, the 0.77 x 10(6) positively selected CD34(+) cells/ kg bodyweight from the second mobilization were added. A total quantity of 4.4 x 10(6) CD34(+) cells/kg bodyweight with a purity of 93.1% representing a recovery of 38% was obtained. Cells were again cryopreserved, stored and retransfused after conditioning the patient with TBI and high-dose cycloph osphamide. The patient engrafted with a WBC count >1000/mul on day eight an d a platelet count > 20,000/mul without transfusion support on day 12 post- transplantation. This case indicates that purging procedures can successful ly be carried out with cryopreserved cell material and that purified CD34() cells can be cryopreserved a second time before transplantation, without affecting their hematopoietic capacity.