Impact Summary: This study demonstrates that medium conditioned by ex vivo human serum can regulate muscle protein synthesis in skeletal muscle cells in vitro via the mammalian Target of Rapomycin (mTOR) pathway, and this can be regulated differentially by fed and fasted ex vivo human serum. This allows us to investigate the efficacy of novel protein for muscle protein synthesis. A major strength of this ex vivo–in vitro approach is that human serum reflects the integrated systemic conditions. Therefore, treatment of skeletal muscle with ex vivo serum may be more physiologically relevant and therefore potentially more likely to translate to a human model. Culture medium can be conditioned accordingly to investigate the effects of different conditions, including nutrition, exercise and inflammation. One of the advantages of this approach for nutrient interventions is that the key nutrient regulators that appear in the circulation have undergone human digestion, in contrast to enzymatically simulated gastrointestinal digestion models. Furthermore, the humoral factors stimulated by feeding are also present. Therefore, the integrated effect of the nutrient and the physiological response to feeding is captured in the ex vivo serum sample and can elicit a pluripotent effect on MPS in skeletal muscle.
Carson, B.P., Patel, B., Amigo‐Benavent, M., Pauk, M., Kumar Gujulla, S., Murphy, S.M., Kiely, P.A. and Jakeman, P.M., 2018. Regulation of muscle protein synthesis in an in vitro cell model using ex vivo human serum. Experimental physiology.