Long-Term Cryopreservation Does Not Affect Quality of PeripheralBlood Stem Cell Grafts: A Comparative Study of Native Short-Term and Long-TermCryopreserved Haematopoietic Stem Cells

摘要

Cryopreserved haematopoietic progenitor cells are used to restore autologoushaematopoiesis after high dose chemotherapy. Although the cells are routinelystored for a long period, concerns remain about the maximum storage time and thepossible negative effect of storage on their potency. We evaluated the effect ofcryopreservation on the quality of peripheral stem cell grafts stored for ashort (3 months) and a long (10 years) period and we compared it to nativeproducts.The viability of CD34+ cells remained unaffected during storage, theapoptotic cells were represented up to 10% and did not differ between groups.The clonogenic activity measured by ATP production has decreased with the lengthof storage (ATP/cell 1.28 nM in native vs. 0.63 in long term stored products,P < 0.05). Only borderline changes without statisticalsignificance were detected when examining mitochondrial and aldehydedehydrogenase metabolic activity and intracellular pH, showing their goodpreservation during cell storage. Our experience demonstrates that cryostoragehas no major negative effect on stem cell quality and potency, and thereforeautologous stem cells can be stored safely for an extended period of at least 10years. On the other hand, long term storage for 10 years and longer may lead tomild reduction of clonogenic capacity. When a sufficient dose of stem cells isinfused, these changes will not have a clinical impact. However, in productsstored beyond 10 years, especially when a low number of CD34+ cells isavailable, the quality of stem cell graft should be verified before infusionusing the appropriate potency assays.