Effects of cell concentration, time of fresh storage, and cryopreservation on peripheral blood stem cells

Peripheral blood stem cells are widely used in autologous or allogeneic transplantation. The quality of the product directly impacts clinical outcomes, and the cell quality and/or functionality may be influenced by the storage conditions as time, temperature, total nucleated cells (TNC) concentration and cryopreservation requirement.To verify the effects of time, cell concentration, and cryopreservation/thawing in the viability and functionality of stem cells for transplantation.We evaluated TNC, CD45+ viable cells, CD34+ viable cells, and cell viability and functionality of 11 samples. Measurements were performed immediately and 24 h, 48 h, 72 h, and 96 h after sample collection at high and low TNC concentrations. The same parameters were also evaluated after cryopreservation and thawing of the samples.Duration of storage and TNC concentration exhibited a negative effect on cell quality (CD45+ viable cells, CD34+ viable cells and functionality). Moreover, the association of these parameters increased the negative effect on graft quality. Cryopreservation and thawing also negatively affected the collected sample regarding viable CD34+ cells (recovery 66.2 %), viable CD45+ cells (recovery 56.8 %), and 7-AAD viability. No significant losses in viable CD45+/CD34+ cells and functionality were observed in the first 24 h in both TNC conditions.These results emphasize the importance to consider carefully the storage conditions until transplantation, measuring TNC/μL until 24 h after collection (diluting the product when TNC > 300 × 103/μL) and infusing fresh graft as soon as possible.