Résumé
Skeletal muscle demonstrates a force deficit after repair of injured peripheral nerves. We tested the hypothesis that the properties of reinnervated rabbit tibialis anterior (TA) muscles improves after transfer of adult myoblasts (satellite cells, SC). Adult rabbits underwent transection and immediate suture of the common peroneal nerve. In order to provide an environment favorable for cell transplantation, TA were then made to degenerate by cardiotoxin injection, either immediately (short term studies only) or after a 2-month delay, which is sufficient for muscle reinnervation. In both cases, the injured TA were transplanted with cultured SC 7 days after induction of muscle degeneration. Short term (4 months) studies show that when cells were transferred immediately after nerve repair, drastic morphological and functional muscle alterations were observed. When the muscles were allowed to become reinnervated before cell transplantation, muscles were heavier and the population of their fibers shifted towards increasing fiber sizes in comparison to controls. In addition, they developed a significantly higher maximal force compared to denervated-reinnervated muscles. However, application of cell therapy failed to improve properties of reinnervated muscles over a longer period (14 months). Although degenerated muscles were heavier and developed a significantly higher maximal force compared to denervated-reinnervated muscles, transfer of SC did not improve these parameters. Several conclusions can be drawn from these studies: First, application of the cell therapy protocol improved properties of denervated muscles only when they were allowed to become innervated. Second, its efficiency for only a short period indicates that myoblast transfer improves the reinnervation process. Third, the improvements of muscle properties observed over longer time intervals were independent of cell therapy. Taken together, these results which represent the first application of cell therapy to improve force recovery of reinnervated muscles, could be of significant interest in certain clinical contexts, particularly after immediate or delayed muscle reinnervation.