CRYOPRESERVATION OF HEMATOPOIETIC PROGENITOR CELLS WITH 5-PERCENT DIMETHYL-SULFOXIDE AT -80-DEGREES-C WITHOUT RATE-CONTROLLED FREEZING

Background: Cryopreservation of hematopoietic cells with the rate-cont rolled method is used in the majority of centers. In recent years, the re has been a trend toward the simplification of the process. Study De sign and Methods: A simplified method for cryopreservation was develop ed with 5-percent dimethyl sulfoxide (DMSO) as the sole cryoprotectant without rate-controlled freezing. Experiments were done with progress ive concentrations of DMSO, ranging from 0 to 10 percent. With DMSO co ncentrations from 5- to 10-percent, the best recovery and viability fo r hematopoietic progenitor cells were observed. Hematopoietic progenit or cells with plasma and Ei-percent DMSO were frozen and stored in a - 80 degrees C mechanical freezer. Ten patients with solid and hematolog ic malignancies underwent transplantation with autologous hematopoieti c progenitor cells. Results: The median number of transfused mononucle ar cells and CD34+ cells was 3.70 (3.1-8.2) x 10(8) per kg and 1.70 (0 .8-6.5) x 10(6) per kg, respectively. The median number of transfused colony-forming was 12.45 (3.4-55.3) x 10(4) per kg. All patients showe d rapid and sustained engraftment. The mean times to reach a neutrophi l count of 0.5 x 10(9) per L and a platelet count of 50 x 10(9) per L were 11.50 +/- 1.70 and 13.90 +/- 3.98 days, respectively. All patient s are alive and without transfusion requirements in complete remission 2 to 8 months after transplantation. Conclusion: This simplified cryo preservation technique will be useful for institutions without rate-co ntrolled freezing facilities. Moreover, this method diminishes the amo unt of DMSO infused to patients, as well as its toxicity.