Endocrine Abstracts

Although mature skeletal muscle fibres are viewed as post-mitotic cells, they possess the ability to regenerate in pathological situations. Regeneration is mediated by satellite cells, which under appropriate conditions, will proliferate, then fuse and finally participate in the formation of regenerated fibres. Other cell types, including stem cells harvested from varied tissues, also fulfil the satellite cell role under certain conditions. Recent research has centred on identifying and isolating cells with at least multipotent, if not stem cell ability, that are capable of contributing to and rebuilding diseased muscle fibres. Such research has derived it impetus from the desire to develop cell based therapies to alleviate myopathic disease.

We have described a dermal cell which is capable of contributing to muscle fibre formation in vitro and in vivo. This cell will not enter the myogenic lineage and participate in fibre development unless treated with muscle conditioned medium. Therefore a soluble factor within the medium is necessary to allow such cells to become muscle. This commitment to muscle is mediated by the 15kD beta-galactoside binding protein, galectin-1. Exposure to galectin-1 significantly accelerated committed myogenic cells to terminally differentiate as well as allowing non-committed myogenic cells to enter the myogenic lineage. Muscles of the galectin-1 null mouse are less well formed than that of wild type mice at the early postnatal stage (1 week), although only subtle differences in muscle fibre morphology are evident by 3-4 weeks postnatally and there is a delay in the ability of galectin-1 deficient muscle fibres to regenerate after induction of trauma to muscles. Taken together, these results suggest to us that galectin-1 is a molecule involved in muscle cell determination and differentiation both in vitro and in vivo. Interestingly several reports indicate that galectin-1 affects the differentiation of other cell types such as astrocytes and neurons.