Neuregulin-1 released by biodegradable gelatin hydrogels can accelerate facial nerve regeneration and functional recovery of traumatic facial nerve palsy.

Background And Aim: Neuregulin-1 is an essential axoglial signal required for peripheral nerve development, and evidence that neuregulin-1 is also required for effective nerve repair is growing. In this study, the effects of neuregulin-1-impregnated gelatin hydrogels on nerve regeneration and functional recovery after anastomosis of the facial nerve were investigated in a rat model of traumatic facial nerve paralysis.

Materials And Methods: Twenty-four adult male rats underwent complete resection of the facial nerve trunk, followed by end-to-end anastomosis with epineural sutures. The animals were then randomly allocated to one of three treatment groups (eight rats/group): no additional intervention (Group I), single-shot injection of neuregulin-1 into the epineurium of the facial nerve at the suture sites (Group II), or implantation of a hydrogel impregnated with neuregulin-1 at the injury site (Group III). After surgery, mimetic muscle movements were evaluated weekly. Eight weeks after surgery, the mimetic muscles were injected with a neural tracer (1,10-dioctadecyl-3,3,30,30-tetramethylindocarbocyanin perchlorate, DiI). Retrograde-labeled neurons were counted in the facial nuclei, and facial nerve specimens were stained with toluidine blue for histological examination of axon density.

Results: Group III exhibited significantly faster recovery of mimetic muscle function, a higher density of large-diameter axons (>5 μm) in the facial nerve, and greater numbers of retrogradely labeled neurons in the ipsilateral facial nucleus compared with Groups I and II.

Conclusions: Continuous release of neuregulin-1 from impregnated gelatin hydrogels can accelerate facial nerve regeneration.