3D-Printed Poly (Lactic-Co-Glycolic Acid) and Graphene Oxide Nerve Guidance Conduit with Mesenchymal Stem Cells for Effective Axon Regeneration in a Rat Sciatic Nerve Defect Model

Meaghan E Harley-Troxell,1 Alisha P Pedersen,1 Steven D Newby,1 Eli Christoph,1 Stacy Stephenson,2 Thomas J Masi,3 Dustin L Crouch,4 David E Anderson,1 Madhu Dhar1 1Tissue Engineering and Regenerative Medicine Laboratory, Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, 37996, USA; 2Plastic and Reconstructive Surgery, University of Tennessee Medical Center, Knoxville, TN, 37920, USA; 3Department of Surgery, University of Tennessee Graduate School of Medicine, Knoxville, TN, 37996, USA; 4Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, TN, 37996, USACorrespondence: Madhu Dhar, University of Tennessee, 2407 River Drive, Knoxville, TN, 37996, USA, Tel +1 865 974 8387, Email [email protected]: Peripheral nerve injuries (PNIs) impact the quality of life of millions of people. The current gold standard of treatment, the autograft, fails to restore nerve function and is often associated with untoward effects. The alternative interventions available remain unable to ensure full functional recovery. For this study we developed a 3D printed nerve guidance conduit (NGC) composed of poly (lactic-co-glycolic acid) (PLGA) and 0.25% graphene oxide (GO), that can be seeded with human adipose-derived mesenchymal stem cells (MSCs), to develop a more effective treatment for PNI.Methods: We evaluated material degradation, surface topography, and MSC attachment in vitro. For the in vivo analyses, a 10-mm long sciatic nerve defect model was created, and rats were randomly divided into 4 treatment groups: autograft, PLGA, PLGA/GO, and PLGA/GO with 1× 106 MSCs. For a 6-month period: biomechanics were evaluated using a pressure mat walkway to determine functional repair; systemic toxicity was evaluated using transmission electron microscopy of kidney and lung tissue; immunohistochemistry evaluated local adverse effects, myelin sheath and axonal repair; and gross muscle analyses of the lateral gastrocnemius, medial gastrocnemius, and soleus evaluated muscle reinnervation.Results: In vitro results showed expected degradation rates, and the addition of GO exhibited cytocompatibility and favorable cell attachment. In vivo results showed biocompatibility with no translocation of the graphene nanoparticles. Histology showed evidence of axonal and myelin sheath repair. Biomechanics and gross muscle analyses had contradicting evidence of functional repair with the addition of GO. No differences were seen with the addition of MSCs.Conclusion: Our novel PLGA/GO NGC, both with and without MSCs, showed results comparable to or greater than the current gold standard, as well as ease of use surgically. With further studies to validate functional recovery, this specific combination of PLGA and GO may provide an effective biomimetic therapy to repair PNIs. Keywords: carbon-based nanoparticles, tissue engineering, nerve conduit, 3D printing