Equine metabolic syndrome impairs adipose stem cells osteogenic differentiation by predominance of autophagy over selective mitophagy

Adipose-derived mesenchymal stem cells (ASC) hold great promise in the treatment of many disorders including musculoskeletal system, cardiovascular and/or endocrine diseases. However, the cytophysiological condition of cells, used for engraftment seems to be fundamental factor that might determine the effectiveness of clinical therapy. In this study we investigated growth kinetics, senescence, accumulation of oxidative stress factors, mitochondrial biogenesis, autophagy and osteogenic differentiation potential of ASC isolated from horses suffered from equine metabolic syndrome (EMS). We demonstrated that EMS condition impairs multipotency/pluripotency in ASCs causes accumulation of reactive oxygen species and mitochondria deterioration. We found that, cytochrome c is released from mitochondria to the cytoplasm suggesting activation of intrinsic apoptotic pathway in those cells. Moreover, we observed up-regulation of p21 and decreased ratio of Bcl-2/BAX. Deteriorations in mitochondria structure caused alternations in osteogenic differentiation of ASC(EMS) resulting in their decreased proliferation rate and reduced expression of osteogenic markers BMP-2 and collagen type I. During osteogenic differentiation of ASC(EMS), we observed autophagic turnover as probably, an alternative way to generate adenosine triphosphate and amino acids required to increased protein synthesis during differentiation. Downregulation of PGC1 alpha, PARKIN and PDK4 in differentiated ASC(EMS) confirmed impairments in mitochondrial biogenesis and function. Hence, application of ASC(EMS) into endocrinological or ortophedical practice requires further investigation and analysis in the context of safeness of their application.