Effects of a human microenvironment on the differentiation of human myoblasts.

Myogenic differentiation mechanisms are generally assessed using a murine cell line placed in low concentrations of an animal-derived serum. To more closely approximate in vivo pathophysiological conditions, recent studies have combined the use of human muscle cells with human serum. Nevertheless, the in vitro studies of the effects of a human microenvironment on the differentiation process of human myoblasts require the identification of the culture conditions that would provide an optimal and reproducible differentiation process of human muscle cells. We assessed the differentiation variability resulting from the use of human myoblasts and serums from healthy subjects by measuring the myotube diameter, fusion index and surface covered by myotubes. We showed the preserved cell-dependent variability of the differentiation response of myoblasts cultured in human serums compared to FBS. We found that using a pool of serums reduced the serum-dependent variability of the myogenic response compared to individual serums. We validated our methodology by showing the atrophying effect of pooled serums from COPD patients on healthy human myotubes. By replacing animal-derived tissues with human myoblasts and serums, and by validating the sensitivity of cultured human muscle cells to a pathological microenvironment, this human cell culture model offers a valuable tool for studying the role of the microenvironment in chronic disease.