Biodegradable Nerve Guide with Glial Cell Line-Derived Neurotrophic Factor Improves Recovery After Facial Nerve Injury in Rats.

Bioengineered nerve guides with glial cell line-derived neurotrophic factor (GDNF) support recovery after facial nerve injury by acting as regenerative scaffolds. To compare functional, electrophysiological, and histological outcomes after repair of rat facial nerve transection in control, empty nerve guide, and nerve guide with GDNF conditions. Rats underwent transection and primary repair of the buccal branch of the facial nerve and were divided into (1) transection and repair only, (2) transection and repair augmented with empty guide, (3) transection and repair augmented with GDNF-guide groups. Weekly measurements of the whisking movements were recorded. At 12 weeks, compound muscle action potentials (CMAPs) at the whisker pad were assessed, and samples were collected for histomorphometric analysis. Rats in GDNF-guide group displayed the earliest peak in normalized whisking amplitude. CMAPs were significantly higher after GDNF-guide placement. Mean fiber surface area of the target muscle, axonal count of the injured branch, and the number of Schwann cells were highest with GDNF guides. The biodegradable nerve guide containing double-walled GDNF microspheres enhanced recovery after facial nerve transection and primary repair.