X33 - Biodegradable Material and Geometry Improvement of Nerve Conduits

Saturday, October 11, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

NH

Nizhone R. Hickman

Student / Undergraduate researcher
University of Arizona
Tucson, Arizona, United States

Primary Investigator(s)

Mario I. Romero-Ortega, PhD

Department Head
University of Arizona
Tucson, Arizona, United States

Co-Author(s)

LS

Lindsay Stoy

Graduate Research Assistant
University of Arizona, United States
KJ

Kristen Jackson

Graduate Research Assistant
University of Arizona, United States
KN

Kenneth Nguyen

Biomedical Engineer
Pioneer Neurotech, United States

Introduction: :

Introduction:
Nerve injuries arising from trauma, disease, or as a surgical necessity, often lead to permanent loss of function. Approximately 3-5% of patients admitted to a Level I trauma center have peripheral nerve injury. Nerve gaps up to 2 cm can be repaired by decellularized allografts or biodegradable nerve conduits. Currently there are eight FDA-approved nerve conduits designed as single open tubes made of biodegradable materials (e.g. collagen, PCL, etc.). The more severe cases undergo complete transection with a resulting gap, which is often repaired by autologous nerve graft because commercial options can not achieve functional recovery and complete repair over 3cm. While polydioxanone (PDO) has been recognized as similar material as other polyesters used as commercial nerve conduits like poly(lactide-co-caprolactone (PLCL), it has not been evaluated for nerve injury repair. Furthermore, all available nerve conduits are hollow tubes. As nerve stumps are sutured to both ends, vessels only infiltrate from ends of the conduit towards the center of the gap. Here we designed nerve conduits using biodegradable materials with fenestrations to facilitate the vascularization of the regenerated nerve radially and simultaneously along the conduit, and compared their nerve regeneration efficacy compared to unfenestrated nerve conduits.

Materials and

Methods: : Materials and Methods
Nerve conduits were 3D printed using poly(lactide-co-caprolactone) (PLCL) with variable number and geometries of fenestrations and compared to hollow conduits made of FDA-approved materials (polyurethane (PU) and polydioxanone (PDO)).
The devices were implanted into the transected sciatic nerve of adult Lewis rats, bridging a 1.5cm gap. The animals were evaluated for functional regeneration using the DigiGate treadmill system and sensory testing using von Frey cutaneous stimulation. At eight weeks, evoked action potentials were evaluated (Plexon OmniPlex system). The regenerated nerves were stimulated proximally and recorded distally to the conduit using two bipolar hook electrodes. Stimulation pulses were 200µs wide biphasic at 1Hz frequency and the evoked EMG measured.

Results, Conclusions, and Discussions:: Results
Hollow conduits fabricated with PLCL, PU, and PDO enabled nerve regeneration. Nerve conduits with large fenestrations allowed nerve regeneration across the 1.5cm gap, including substantial amounts of vascularized tissue growth connecting the nerve in the lumen with the fibrotic scar wrapping the conduit. However, these fenestrations enabled nerve fascicles to grow out of the lumen and into adjacent muscles. Behavioral analysis, electrophysiological evaluation and muscle atrophy were qualitatively similar in all implanted animals. Quantitative analysis is currently underway.

Discussion
Preliminary results suggest that in vivo, PDO conduits degrade faster than their PLCL counterparts, becoming brittle, indicating PDO may not be an ideal choice for the time a nerve takes to bridge a 1.5cm gap. A PDO conduit that degrades slower would be better suited for this application and may enable the inclusion of engineered fenestrations. While large fenestrations encourage radial growth of vasculature to the nerve, smaller fenestrations may help prevent fascicular outgrowth and promote linear growth.

Conclusions
This in vivo study showed PDO conduits were slightly brittle at 8 weeks, degrading faster than PLCL conduits, but all conduits still supported nerve regeneration. A fenestrated design shows promising results by increasing vascularization of regenerating nerves across a long gap injury. In the future, fenestration geometry could be optimized to prevent innervation of non-target tissues.

Acknowledgements and/or References (Optional): : We thank Dr. Jeff Petruska and Pioneer Neurotech for help with the experimental design and conduit development. Research reported in this poster was supported by the National Institute Of Neurological Disorders And Stroke of the National Institutes of Health under Award Number R41NS130907.