Wnt7a promotes muscle regeneration in branchiomeric orbicularis oris muscle

Background: The orbicularis oris muscle exhibits a deficiency in cleft lip patients. Compared with the somite-derived limb muscles, the regeneration performance of the branchiomeric orofacial muscle has seldom been investigated. Objective: This study aims to explore the possibility of augmenting the orbicularis oris muscle through the stimulus of Wnt7a. Methods: Adult rat orbicularis oris muscle and tibialis anterior muscle were injected with recombinant human Wnt7a protein. The muscles were harvested at different time points after Wnt7a delivery. Muscle regeneration related activity, including cell proliferation, stem cell proportion, myofiber plasticity, and total fiber number, was examined. Results: Adult rat orbicularis oris muscle and tibialis anterior muscle exhibit similar regeneration related activities after Wnt7a administration. Recombinant human Wnt7a administration resulted in enhanced cell proliferation, stem cell expansion, and fiber type remodelling in rat orbicularis oris muscle. In addition, newly formed myofibers were detected, contributing to an increased total fiber number. Conclusion: Wnt7a induces vigorous regeneration in rat orbicularis oris muscle. This study helps lay a foundation for developing biotherapies to combat orofacial muscle deficiency.