Cryopreserved mobilized autologous blood progenitors stored for more than 2 years successfully support blood count recovery after high-dose chemotherapy

Abstract

Background aims. The ability of hematopoietic progenitor cells–apheresis (HPC-A) that have been stored for many years after cryopreservation to reconstitute hematopoiesis following high-dose chemo/radiotherapy has not been well-documented. Methods. In this retrospective study, eight Canadian centers contributed data from 53 autologous stem cell transplants (ASCT) performed using HPC-A that had undergone long-term storage (>2 years, range 2–7 years) and 120 ASCT using HPC-A stored for <6 months (short-term storage). Results. The doses of nucleated and CD34⁺ cells per kilogram recipient weight were similar between the short- (mean ± SD, 4.7 ± 4.9 × 10⁸ and 6.8 ± 4.3 × 10⁶, respectively) and long- (4.0 ± 4.9 × 10⁸ and 6.1 ± 3.4 × 10⁶, respectively) term storage groups. The median days to neutrophils (absolute neutrophil count; ANC) >0.5 × 10⁹/L (median 11 days for both short- and long-term storage) and platelets >20 × 10⁹/L (median 12 and 11 for short- and long-term storage, respectively) post-ASCT were not significantly different between the two groups. When ASCT performed with <5 × 10⁶/kg CD34⁺ cells was compared there was also no difference in ANC or platelet recovery (median 12 days for both after short-term storage, and 12 and 11 days, respectively, after long-term storage). Fourteen HPC-A products stored for >5 years also showed similar count recoveries as the entire long-term storage group (median 11 days for both ANC and platelets). Conclusions. Cryopreserved HPC-A can be stored for at least 5 years with no apparent loss in their ability to support hematopoietic reconstitution after high-dose chemotherapy.

Key Words::

• cryopreserved
• engraftment
• long-term storage
• short-term storage

Acknowledgments

The authors thank the members of the Laboratory Practices Committee of the Canadian Blood and Marrow Transplant Group (CBMTG) for their co-operation with this study and the CBMTG for funding through a ‘small research grant’, which facilitated this research.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.