Rebuilding Muscle

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Science  16 Dec 2011:
Vol. 334, Issue 6062, pp. 1475
DOI: 10.1126/science.334.6062.1475-b

Skeletal muscle injury can be debilitating and potentially lethal. Factors released by the damaged muscle can stimulate local skeletal muscle stem cells (satellite cells) to become motile, proliferate, and differentiate into replenishing myofibers. Stark et al. now suggest that even satellite cells distant from a site of injury could be recruited to help. The authors found that satellite cell motility was controlled by cell surface proteins called Ephrins that are expressed by healthy and regenerating muscle cells. Ephrins and their Eph receptors function as a guidance system in a variety of developmental processes. Ephrins elicited a repulsive signal that caused satellite cells to alter their migratory course. Mouse satellite cells grafted into either the developing hindbrain or limb bud of quail embryos respected Ephrin-defined boundaries as they migrated in vivo. The authors propose that Eph-Ephrin interactions may modulate satellite cell migration and patterning during muscle fiber development.

Page et al. have used microthreads of fibrin to restore muscle function in mice with substantial leg muscle injury. When placed into the damaged area, the microthread scaffolds, seeded with adult human muscle cells that were coaxed into a stem cell–like state, restored healthy muscle fibers. Suprisingly, most of the new muscle was generated from recruited mouse satellite cells. Together, these studies point to potential therapies for treating major muscle injuries.

Development 138, 5279 (2011); Tissue Eng. Part A 17, 2629 (2011).

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