Novel Nerve Guide Containing GDNF Microspheres Improves Recovery After Facial Nerve Injury In Rats
Fuat Baris Bengur, MD, Chiaki Komatsu, MD, Jocelyn S. Baker, BS, Caroline Nadia Fedor, BA, Aanchal Totwani, BS, Shawn Loder, MD, W. Vincent Nerone, BA, Mario G. Solari, MD, Kacey G. Marra, PhD.
University of Pittsburgh, Pittsburgh, PA, USA.
PURPOSE: Rapid functional recovery after facial nerve injury is critical to restoring expression. Tissue engineered nerve guides support enhanced recovery, acting as regenerative scaffolds. This can be improved by addition of exogenous neuro-supportive agents such as glial-derived neurotrophic factor (GDNF), which improves axonal growth and pathfinding. In this study, we evaluated efficacy of a composite poly(caprolactone) nerve guide containing double-walled GDNF microspheres on functional, electrophysiological, and histological outcomes in a rat facial nerve injury model.
METHODS: Male Lewis rats underwent transection and repair of the buccal branch of the facial nerve and were divided as follows: a) transection and repair only, b) empty guide, c) GDNF-guide. Weekly measurements of the whisking movements for protraction and retraction angles were recorded. At the endpoint of 12-weeks, compound muscle action potentials at the whisker pad were assessed and nerve, muscle, and whisker pad were collected for histomorphometric analysis, including Schwann cell analysis.
RESULTS: GDNF-guide treated rats displayed earliest peak and highest recovery in normalized whisking amplitude (p<0.001). Compound muscle action potentials were significantly higher after GDNF-guide placement vs. all others (p<0.001). Mean muscle fiber surface area was the highest (p<0.01) and the axonal integrity loss was less prominent with GDNF-guides. Gross morphology of the whisker pad was not different across the groups.
CONCLUSION: The novel tissue engineered nerve guide containing GDNF microspheres enhances recovery after facial nerve transection. Results support the clinical viability of these guides to enhance recovery after nerve injury and hold promise to facilitate recovery in defects with larger gaps.
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