Long-term hematologic reconstitution after autologous peripheral blood progenitor cell transplantation: a comparison between controlled-rate freezing and uncontrolled-rate freezing at 80 degrees C.

Background: The most widely used system for peripheral blood progenitor cell (PBPC) cryopreservation is controlled-rate freezing (CRF). Uncontrolled-rate freezing (URF) at -80 degrees C has also been used, but its clinical impact has not been studied sufficiently yet.

Study Design And Methods: Two groups of patients were compared: Group A consisted of 69 patients autotransplanted with PBPCs cryopreserved with CRF; Group B consisted of 192 patients autotransplanted with PBPCs cryopreserved with URF at -80 degrees C. The same cryoprotectant solution and storage system were used.

Results: A significant delay of hematologic reconstitution (HR) in the URF group was observed for neutrophils greater than 0.5 x 10(9) per L and for platelets greater than 20 x 10(9) per L and greater than 50 x 10(9) per L; we did not observe any differences in the clinical course. The long-term HR was comparable in the two groups, all patients showed stable engraftment, and no late graft failures were observed.

Conclusion: Our study confirms that URF is safe and allows sustained long-term engraftment without increasing the risks of transplantation, even though the early engraftment after URF is slower.