Skeletal muscle regeneration after injury is dependent on satellite cells (skeletal muscle stem cells) that, in response to local myofibre damage, proliferate to build up a supply of adult myoblasts that repair the damage. But do satellite cells relocate within the muscle to respond to distant myofibre damage? If so, how do they find their way? On p. 5279, D. D. W. Cornelison and co-workers investigate whether Ephs and ephrins – molecules that are usually associated with axon guidance but that are expressed by activated satellite cells – modulate satellite cell motility and patterning. Using an ephrin ‘stripe’ assay, they show that multiple ephrins elicit a repulsive migratory response in activated satellite cells and affect the patterning of differentiating satellite cells. Importantly, the same ephrins are present on the surface of healthy myofibres and increase during regeneration, which suggests that muscle regeneration could involve ephrin-mediated guidance. Given their results, the researchers propose that Eph/ephrin signalling might regulate multiple aspects of satellite cell behaviour during muscle regeneration.

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