Conditioned Medium of Adipose-Derived Mesenchymal Stem Cells as a Promising Candidate to Protect High Glucose-Induced Injury in Cultured C28I2 Chondrocytes

Purpose: The aim of this study was to evaluate the protective effect of conditioned mediumderived from human adipose mesenchymal stem cells (CM-hADSCs) on C28I2 chondrocytesagainst oxidative stress and mitochondrial apoptosis induced by high glucose (HG).Methods: C28I2 cells were pre-treated with CM-hADSCs for 24 hours followed by HG exposure(75 mM) for 48 hours. MTT assay was used to assess the cell viability. Reactive oxygen species(ROS) and lipid peroxidation were determined by 2,7-dichlorofluorescein diacetate (DCFHDA)and thiobarbituric acid reactive substances (TBARS) assays, respectively. Expressionsof glutathione peroxidase 3 (GPX 3), heme oxygenase-1 (HO-1), and NAD(P)H quinonedehydrogenase 1 (NQO1) were analyzed by RT-PCR. Finally, western blot analysis was used tomeasure Bax, Bcl-2, cleaved caspase-3, and Nrf-2 expression at protein levels.Results: CM-hADSCs pretreatment mitigated the cytotoxic effect of HG on C28I2 viability.Treatment also markedly reduced the levels of ROS, lipid peroxidation, and augmented theexpression of HO-1, NQO1, and GPx3 genes in HG-exposed group. CM-ADSCs enhancedNrf-2 protein expression and reduced mitochondrial apoptosis through reducing Bax/Bcl-2 ratioand Caspase-3 activation.Conclusion: MSCs, probably through its paracrine effects, declined the deleterious effect ofHG on chondrocytes. Hence, therapies based on MSCs secretomes appear to be a promisingtherapeutic approaches to prevent joint complications in diabetic patients.