Long-term cryopreservation of bone marrow for autologous transplantation

Long-term cryopreservation of bone marrow for autologous transplantation

Little is known about the effect of long-term cryopreservation on the viability of hematopoietic stem cells (HSC) or on the success of autologous bone marrow transplantation. Although progenitor cell assays, such as the culture of CFU-GM after thawing, can be predictive of engraftment, the most rigorous assay for the cryosurvival of HSC is engraftment after reinfusion of stem cells.

Study Methodology and Patient Demographics

Researchers retrospectively evaluated the engraftment data for 36 patients with hematologic malignancies or solid tumors treated at the Fred Hutchinson Cancer Research Center between 1981 and 1993. These patients received bone marrows stored for 2 years or more. The median duration of cryopreservation for this study group was 2.7 years, with a range spanning 2.0 to 7.8 years.

Comparative Engraftment Results

• Granulocyte Recovery: 97% of the study group achieved a count of ≥ 0.5 x 1.0(9)/1 at a median of 19 days, compared to 86% of the control group at 20 days (P = 0.14).

• Platelet Recovery: 70% of the study group achieved a count ≥ 20 x 10(9)/1 at a median of 27 days, compared to 74% of the control group at 23 days (P = 0.47).

• Progenitor Culture: Samples from 28 marrows stored for a median of 4.4 years showed that storage length was not predictive for the quantity of colonies formed (BFU-E P = 0.57; CFU-GM P = 0.65).

Conclusion

The study found no consistent detrimental effect of long-term cryopreservation on the success rate of autologous bone marrow transplantation. This report confirms that marrow cells cryopreserved for several years remain capable of engrafting. Consequently, bone marrow cells may be stored at an early appropriate time before the cumulative side-effects of multiple cycles of chemotherapy and radiotherapy on hematopoietic tissues are incurred.