Comparison of Freshly-Cultured versus Cryopreserved Mesenchymal Stem Cells in Animal Models of Inflammation: A Pre-Clinical Systematic Review

Abstract Background: Mesenchymal stem cells (MSCs) are multipotent cells that demonstrate therapeutic potential for the treatment of acute and chronic inflammatory-mediated conditions. Although controversial, some studies suggest that MSCs may lose their functionality with cryopreservation which could render them non-efficacious.Objective: In comparative pre-clinical models of inflammation, to determine if there are differences in in-vivo measures of pre-clinical efficacy (primary outcomes) and in-vitro potency (secondary outcomes) between freshly-cultured and cryopreserved MSCs. Methods: A systematic search on OvidMEDLINE, EMBASE, BIOSIS, and Web of Science (until June 5, 2020) was conducted. The primary outcome included measures of in-vivo pre-clinical efficacy; secondary outcomes included measures of in-vitro MSC potency. Risk of bias was assessed by the SYRCLE “Risk of Bias” assessment tool for pre-clinical studies. Results: 15 studies were included. A total of 194 in-vivo pre-clinical efficacy experiments represented 72 distinct outcome measures. 2.6% (5/194) of these outcomes were significantly different at the 0.05 level or less; 2 favoured freshly-cultured and 3 favoured cryopreserved MSCs. A total of 63 in-vitro experiments represented 26 different potency measures; 11.1% (7/63) of the experiments were significantly different at the 0.05 level or less, with 5 experiments favouring freshly-cultured MSC and 2 favouring cryopreserved MSCs.Conclusions: The majority of preclinical in-vivo outcomes and in-vitro potency outcomes did not detect significant differences (p<0.05) in pre-clinical efficacy between freshly-cultured and cryopreserved MSCs. Our systematic summary of the current evidence base may provide MSC research scientists as well as regulatory bodies additional rationale and justification for considering a cryopreserved MSC product in their clinical trials.Registration: Protocol has been registered with PROSPERO (CRD42020145833).