Cryoprotection in Human Mesenchymal Stromal/Stem Cells: Synergistic Impact of Urea and Glucose

Standard freezing protocols of clinically relevant cell lines commonly employ agents such as fetal bovine serum and dimethyl sulfoxide, which are a potential concern from both a regulatory and a patient safety per-spective. The aim of this work was to develop formulations with safe and well tolerated excipients for the (cryo-) preservation of cell therapy products. We evaluated the cryoprotective capabilities of urea and glu-cose through measurements of cell metabolic activity. Freezing of clinically relevant human mesenchymal stromal/stem cells and human dermal fibroblasts at <= -65 degrees C at equimolar ratios of urea and glucose resulted in comparable viabilities to established dimethyl sulfoxide. Pre-incubation of human mesenchymal stromal/ stem cells in trehalose and addition of mannitol and sucrose to the formulation further enhanced cell viabil-ity after freeze-thaw stress. Other cell types assessed (A549 and SK-N-AS) could not satisfactorily be pre-served with urea and glucose, highlighting the need for tailored formulations to sustain acceptable cryopreservation.(c) 2023 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.