Background: Cryopreservation of hematopoietic cells with the rate-controlled method is used in the majority of centers. In recent years, there has been a trend toward the simplification of the process.
Study Design and Methods: A simplified method for cryopreservation was developed with 5-percent dimethyl sulfoxide (DMSO) as the sole cryoprotectant without rate-controlled freezing. Experiments were done with progressive concentrations of DMSO, ranging from 0 to 10 percent. With DMSO concentrations from 5- to 10-percent, the best recovery and viability for hematopoietic progenitor cells were observed. Hematopoietic progenitor cells with plasma and 5-percent DMSO were frozen and stored in a −80° C mechanical freezer. Ten patients with solid and hematologic malignancies underwent transplantation with autologous hematopoietic progenitor cells.
Results: The median number of transfused mononuclear cells and CD34+ cells was 3.70 (3.1–8.2) × 108 per kg and 1.70 (0.8-6.5) × 106 per kg, respectively. The median number of transfused colony-forming units-granulocyte-macrophage was 12.45 (3.4–55.3) × 104 per kg. All patients showed rapid and sustained engraftment. The mean times to reach a neutrophil count of 0.5 × 109 per L and a platelet count of 50 × 109 per L were 11.50 ± 1.70 and 13.90 ± 3.98 days, respectively. All patients are alive and without transfusion requirements in complete remission 2 to 8 months after transplantation.
Conclusion: This simplified cryopreservation technique will be useful for institutions without rate-controlled freezing facilities. Moreover, this method diminishes the amount of DMSO infused to patients, as well as its toxicity.