COMPARATIVE-ANALYSIS OF ENGRAFTMENT AFTER CRYOPRESERVATION OF PERIPHERAL-BLOOD STEM-CELL AUTOGRAFTS BY CONTROLLED-RATE VERSUS UNCONTROLLED-RATE METHODS

Peripheral blood stem/progenitor cells (PBSC) were cryopreserved by di fferent methods and their clonogenic viabilities were compared. The tr aditional cryopreservation method involves controlled-rate freezing wi th 10% dimethyl sulfoxide (DMSO) and a programmed freezer (PF). The al ternative method incorporates 6% hydroxyethyl starch and 5% DMSO witho ut PF. In this non-randomized study, we analyzed the data of 24 patien ts (aged 1-17 years) who were in their first complete remission and wh o had undergone PBSC autograft (PBSCT) for high-risk acute lymphoblast ic leukemia, to determine the effects of these two different methods o f cryopreservation on time to engraftment and transfusion requirements after PBSCT. In all patients, PBSC were collected within 5 months of diagnosis and all had been conditioned with the high-dose MCVAC regime n (MCNU, cytosine arabinoside, etoposide and cyclophosphamide) without total body irradiation. Twelve patients received PBSC that had been c ryopreserved by the uncontrolled method without PF and the data were c ompared by actuarial analysis to those of 12 historical controls whose cells had been frozen by PF. No difference was observed in the time t o engraftment of granulocytes and platelets or the transfusion require ments between the two groups. Our results indicate that, in terms of p reserving engraftment potential, the simplified uncontrolled-rate cryo preservation method is at least as effective as the traditional contro lled-rate freezing procedure with PF.