Development of Acellular Matrix-Based Bioprinted Scaffold for Inferior Alveolar Nerve Regeneration

The inferior alveolar nerve (IAN) is a sensory branch of the mandibular nerve that supplies sensation to teeth, the chin, and the lower lip. IAN injuries often result from trauma or iatrogenic causes, leading to the development of symptoms like difficulty in eating, smiling, pain, and paraesthesia. IAN regeneration is limited because of the confinement of the nerve within the mandibular canal. Current pharmacological and surgical interventions offer only partial recovery. Therefore, alternative approaches to enhance nerve repair and regeneration are required. To address this limitation, we developed a 3D-bioprinted scaffold composed of alginate, methylcellulose, and Schwann cell-derived acellular matrix (Alg/MC/ACM) for IAN regeneration. The Alg/MC hydrogel showed good mechanical stability and printability, and ACM provides biological cues for nerve regeneration. Proteomics analysis showed that there were 904 common proteins present when the Schwann cell lysate was compared with ACM. The rheological analysis demonstrated shear-thinning and viscoelastic properties of the Alg/MC/ACM hydrogel. In vitro cytocompatibility tests, such as MTT and Live/Dead assays using rat Schwann (RSC96) cells and neuronal (PC12) cells, demonstrated that Alg/MC/ACM2 significantly enhanced cell proliferation and viability when compared to Alg/MC and Alg/MC/ACM1 scaffolds. In vivo study in SD rat IAN crush injury model demonstrated that implantation of Alg/MC/ACM2 scaffolds improved the behavioral response when compared with injury control. Alg/MC/ACM2 scaffolds also promoted cellular infiltration, axonal organization, and remyelination, as observed in hematoxylin and eosin and Luxol fast blue staining. Overall, the incorporation of Schwann-cell-derived ACM within Alg/MC scaffolds provided a bioactive microenvironment that supported neural regeneration. This study presents the first evidence demonstrating the potential of Alg/MC/ACM bioprinted scaffolds as promising therapeutic strategies for IAN repair.