Viability, in Vitro Differentiation and Molecular Characterization of Equine Adipose Tissue-Derived Mesenchymal Stem Cells Cryopreserved in Serum and Serum-free Medium

BACKGROUND: The effect of freezing-thawing equine adipose tissue-derived mesenchymal stem cells (eATMSCs) have been poorly investigated. OBJECTIVE: This study is to test the influence of cryopreservation solution and temperature when adding the cryoprotectant for freezing eATMSCs, and to investigate the effects of cryopreservation on their stemness features. MATERIALS AND METHODS: Four freezing protocols were evaluated. Viability and proliferation ability of cryopreserved cells were investigated by MTT assay. Fresh and frozen thawed eATMSCs were compared for morphology, phenotypic characteristics (flow cytometry), and differentiation potential. RESULTS: A higher value of viable cells for samples frozen in FBS and a positive effect of CPA equilibration at low temperature in samples frozen in medium were observed. Morphology was similar for fresh and cryopreserved cells, such as CD expression and differentiation potential. CONCLUSION: eATMSCs can be safely stored for clinical use. FBS is superior to medium for freezing, but CPA equilibration at low temperature is beneficial when freezing in serumfree medium.