Optimal Storage Conditions for Apheresis Research (OSCAR): a Biomedical Excellence for Safer Transfusion (BEST) Collaborative study

BACKGROUND: Cell therapy products are often stored and transported between sites. The aim of this study was to determine the effect of storage temperature, solution, and cell concentration on nonmobilized, peripheral blood–derived mononuclear cells (MNCs). STUDY DESIGN AND METHODS: This was a multicenter prospective study involving healthy volunteers who underwent nonmobilized MNC collection by apheresis. Products were processed at local laboratories and concentrated to either 100 × 10⁶ or 300 × 10⁶ nucleated cells/mL in 5% human serum albumin (HSA) or HypoThermosol FRS (HT; BioLife Solutions). Products were stored at room temperature (RT; 20-25°C) or refrigerated temperatures (2-8°C) with assessment at 0, 24, 48, and 72 hours. NC and MNC concentration, viability, and flow cytometric analysis for CD3, CD4, CD8, CD14, CD19, CD25, and CD56 were measured. RESULTS: Viability decreased over time for all conditions tested. Refrigerated storage preserved viability greater than RT storage, especially for products with a higher cell concentration. RT maintenance with a high cell concentration was associated with a relative loss of CD14- and CD4-positive cells, whereas the concentration of cells positive for other markers tested did not vary. Finally, there was delayed decrease in pH when using HT compared with HSA; however, there was no difference in viability between the two solutions. CONCLUSION: Low cell concentrations (approx. 100 × 10⁶ cells/mL), refrigerated temperatures, and HT storage solution appear to be the optimal conditions for storing nonmobilized, peripheral blood–derived MNC products.