Denervation During Mouse and Human Mandibular Distraction Osteogenesis Results in Impaired Osteogenesis

Abstract

INTRODUCTION: Mandibular DO is mediated by skeletal stem cells (SSCs) in mice, which enact bone regeneration via neural crest reactivation. Because peripheral nerves are essential to progenitor function during development and regeneration, we question whether denervation impairs mandibular DO. METHODS: C57Bl6 mice were divided into 2 groups, DO with inferior alveolar nerve (IAN) denervation (“DO-Den”) and DO with IAN intact (“DO-Inn”), and underwent gradual DO. Specimens were harvested for analysis of stem/ progenitor cell populations using fluorescence-activated cell sorting, microCT, histology, and single cell RNA sequencing (scRNAseq). A unique opportunity arose to question whether our animal findings were conserved in a clinical specimen. A young patient underwent bilateral mandibular DO and was noted postoperatively to have a new unilateral IAN clinical deficit. Osteogenesis was then examined using CT, histology, and scRNAseq. Using anchor transfer, we compared human and mouse SSC populations to identify congruent cell clusters. RESULTS: In mice, DO-Den resulted in reduced histological and radiological osteogenesis and SSC expansion relative to DO-Inn (*p = 0.018). Impaired histological and radiological DO in the setting of denervation was also conserved in the human specimen. Anchor transfer of mouse and human SSCs demonstrated congruency of transcriptional pathways in mouse and human samples. CONCLUSION: Together these data suggest that peripheral nerves maintain a salient role in DO by promoting nonneuronal tissue repair, a pattern that is conserved in mice and humans. Harnessing the underlying biology of nerve-dependent DO may aid clinical innovation in craniofacial skeletal regeneration.