Retention of cellular properties of PBPCs following liquid storage and cryopreservation

G-CSF-mobilized PBPCs are routinely cryopreserved within 24 hours of collection. The ability to hold PBPCs for extended time would offer increased flexibility for patients and hospitals. Retention of PBPC properties following overnight shipping, extended liquid storage at 1 to 6 degrees C, and cryopreservation was evaluated.

PBPCs were stored in liquid at 1 to 6 degrees C up to 3 days, with and without shipping, and then cryopreserved in HES (6%), DMSO (5%), and HSA (4%). Thawed samples were assayed after two procedures, on dilution and after dilution and washing. Nucleated cells, viability, CD34+ cell number, committed progenitor colonies, and long-term culture-initiating cells were measured.

CD34+ cell number, committed colony-forming cells, and long-term culture-initiating cells were essentially maintained when samples were stored in liquid for 1, 2, or 3 days before cryopreservation or after thawing and dilution. Nevertheless, significant (p < 0.05, paired t test) losses in total nucleated cell numbers were observed if thawed PBPC samples were washed before assay.

PBPCs can be maintained at 1 to 6 degrees C for up to 3 days and can be cryopreserved after extended storage with properties minimally altered. Dilution alone, without centrifugation and washing, of thawed PBPC samples is a satisfactory procedure for preparing samples for in vitro assays.