Morphological examination is more effective than cell viability assays in the characterization of myotube atrophy

Abstract

Skeletal muscle atrophy is a significant health problem associated particularly with aging, cancer, and metabolic diseases, leading to a decline in quality of life and responses to treatment. During skeletal muscle atrophy, the balance between protein synthesis and degradation in the tissue is disrupted in favor of protein degradation. This condition results in a reduction in muscle mass and loss of strength and function in the muscles. In order to elucidate the molecular mechanisms causing skeletal muscle atrophy, prevent the processes leading to atrophy, and test the effectiveness of emerging therapeutics, in vitro models that mimic atrophic conditions are commonly used. In these models, typically utilizing primary myoblasts obtained from tissues or myoblast cell lines, either cell viability assays or myotube morphology analyses are employed to determine the degree of atrophy occurring during differentiation. Here, the commonly used MTT cell viability assay and myotube diameter analysis were mutually evaluated to determine which one better characterizes myotube atrophy. While myotube diameter measurement can grade the extent of atrophy in myotubes, the MTT assay, although unable to directly assess the degree of myotube atrophy, demonstrated that the decrease in cell viability indicates the cause of myoblast atrophy.