Primary skeletal muscle cells can be propagated for several generations. After a number of passages, cell senescence can be anticipated and the cells lose their myogenic phenotype, which might be caused by a progressive telomere shortening . It is therefore important to freeze as many cells as possible from early passages. An alternative would be the establishment of a permanent myogenic cell line. Several rodent myoblast or myoblast-like cell lines have been described that were obtained after cloning primary myogenic cells. Currently, continuous cell lines developed from mouse [74, 181, 182] and rat  skeletal muscle are available. Although these cells can fuse into myotubes and are used extensively to study several aspects of muscle differentiation, these cells must be considered as tumor cells and are no longer normal muscle cells. Furthermore, several cell lines have been described that have at least some characteristics of muscle cells. In all of these cell lines, one or more of the myogenic transcription factors is not expressed and terminal differentiation of the cells is inhibited .
The generation of human muscle cell clones was described by two groups [185, 186]. Cell lines were derived from individual cells by clonal growth of primary skeletal muscle cells and selection for myogenic potential. The G6 cell line differentiates rapidly and over 60% of the nuclei are found in myotubes after two days of differentiation in a low nutrition medium . Although several aspects of muscle cell differentiation can be examined using these cells [187-190], the fact that they lose a large part of their differentiation potential within three weeks of culture  is a major drawback. The RCMH cell line  has retained over 200 passages some characteristics of muscle cells, but little fusion occurs  and the suitability of this cell line for muscle differentiation studies seems rather limited.
Was this article helpful?