Possible mechanism of combining hyperbaric oxygen with parathyroid hormone to promote bone regeneration

Abstract

We read with great interest the paper published in your journal (Park et al., 2019). The authors highlighted that hyperbaric oxygen (HBO) combined with parathyroid hormone (PTH) could significantly increase the volume of new bone and decrease the residual material volume, thus reversing the radiation-induced bone-healing impairment. However, the mechanism behind the combined effects of HBO and PTH on bone regeneration following radiation exposure was not explored by Park et al. Therefore, this letter to the editor aims at discussing some of the mechanisms that may be playing a role in the healing process mediated by the synergistic effect of HBO and PTH. Animal experiments have showed that HBO could stimulate vascularization and new bone formation in rat calvarial defects and enhance the number of CD31-positive cells and its expression levels. Furthermore, HBO could also upregulate osteogenic marker gene expression and downregulate pro-inflammatory cytokine expression (Pedersen, Xing, Finne-Wistrand, Hellem,