Regeneration of Paralyzed Vocal Fold by the Injection of Plasmid DNA Complex-Loaded Hydrogel Bulking Agent

Various growth factor delivery systems were used in the treatment of glottal insufficiency; however, relatively little attention has been paid to a gene delivery system for aspects of active vocal fold (VF) regeneration. Herein, we present a plasmid DNA (pDNA; bFGF gene encoding) complex-loaded alginate (ALG)/hyaluronic acid (HA) mixture hydrogel dispersed with polycaprolactone (PCL) microspheres that can enhance simultaneous regeneration of VF muscle and lamina propria, as well as have a bulking effect on atrophied VF. We have demonstrated long-term efficacy of bFGF synthesized from pDNA complex-transfected cells in vitro. PCL microspheres-dispersed ALG/HA hydrogel (with or without pDNA complex loading) are injected into rabbit VFs with recurrent laryngeal nerve denervation. The PCL microspheres dispersed in the hydrogel bulking agents remain stable at the applied site, leading to constant medialization of the paralyzed VF without significant initial volume loss even after 24 weeks. A regenerative effect for collagen deposition and HA synthesis around the injected site, which are major components of VF tissue, is well confirmed in the pDNA-complex-loaded hydrogel group. Moreover, the compensation of atrophied VFs also leads to the contact of bilateral VF and the remarkable recovery of voice function in the pDNA-complex-loaded group. Based on the results, pDNA (bFGF encoding) complex-loaded hydrogel dispersed with PCL microspheres may be employed as a bioactive bulking agent for the treatment of glottal insufficiency.