Age dependence of the human skeletal muscle stem cell in forming muscle tissue.

Human skeletal muscle stem cells from healthy donors aged 2-82 years (n = 13) and from three children suffering from Duchenne Muscular Dystrophy (DMD) were implanted into soleus muscles of immunoincompetent mice and were also expanded in vitro until senescence. Growth of implanted cells was quantified by structural features and by the amount of human DNA present in a muscle. Proliferative capacity in vitro and in vivo was inversely related to age of the donor.

The vast majority of bone-marrow-derived cells integrated into mdx muscle fibers are silent despite long-term engraftment.

Bone-marrow-derived cells can contribute nuclei to skeletal muscle fibers. However, serial sectioning of muscle in mdx mice implanted with GFP-labeled bone marrow reveals that only 20% of the donor nuclei chronically incorporated in muscle fibers show dystrophin (or GFP) expression, which is still higher than the expected frequency of "revertant" fibers, but there is no overall increase above controls over time. Obviously, the vast majority of incorporated nuclei either never or only temporarily turn on myogenic genes; also, incorporated nuclei eventually loose the activation of the beta-actin::GFP transgene.

On the regenerative capacity of human skeletal muscle.

The proliferative capacity of organotypic muscle stem cells, the satellite cells, from nine healthy human donors aged between 2 and 78 years was investigated. There was a loss in proliferative capacity with age, but the oldest donors (76, 78 years) would still be able to replace their musculature several times. Depending on frequency of desmin-positive (i.

Migration and differentiation of myogenic precursors following transplantation into the developing rat brain.

There is increasing evidence that muscle-derived precursor cells can, under appropriate conditions, give rise to other than myogenic cell types. Transplantation into the embryonic ventricular zone provides a unique opportunity to study the migration and differentiation of non-neural somatic progenitor cells in response to instructive cues within the developing neuroepithelium. Here, we demonstrate that myogenic cell lines grafted into the ventricles of rat embryos showed widespread migration into several host brain compartments.