The Bridging Effect of Controlled-Release Glial Cell-Derived Neurotrophic Factor Microcapsules within Nerve Conduits on Rat Facial Nerve Regeneration

Objectives. The study is aimed at exploring the effect of the controlled release of the glial-derived neurotrophic factor (GDNF) on nerve regeneration. Methods. The PLGA/chitosan composite nerve conduit was used to bridge the dissected trunk of the rat facial nerve. GDNF microcapsules were loaded into the nerve conduit. Nine weeks after surgery, the facial nerve zygomatic and buccal branches were labeled with fluorescent indicators. The incorrectly grown facial neurons were reversed and counted. The facial nerve functional recovery was assessed by measuring the maximum evoked potential. Results. The nerve conduit was filled with different regenerating factors, such as the GDNF, GDNF microcapsules, or saline (control). The number of incorrectly regenerated neurons was lower with the nerve conduits filled with GDNF microcapsules than with those supplied with just the GDNF. However, neither the GDNF nor GDNF microcapsules affected the number of regenerated neurons. The functional recovery of the facial nerve was the best, with the nerve conduit filled with GDNF microcapsules closest to the healthy uncut facial nerve. Conclusion. The stable slow-release GNDF microcapsule inside the biodegradable nerve conduit can reduce the extent of incorrect growth of the facial nerve neuron when bridging the dissected rat facial nerve trunk The technique has a good effect on functional nerve recovery.