Recruited Cd68(+)Cd206(+)- Macrophages Orchestrate Graft Immune Tolerance To Prompt Xenogeneic-Dentin Matrix-Based Tooth Root Regeneration

Successful regenerative medicine strategies of xenogeneic extracellular matrix need a synergistic balance among inflammation, fibrosis, and remodeling process. Adaptive macrophage subsets have been identified to modulate inflammation and orchestrate the repair of neighboring parenchymal tissues. This study fabricated PPAR gamma-primed CD68(+)CD206(+)M2 phenotype (M2 gamma), and firstly verified their anti-inflammatory and tissue-regenerating roles in xenogeneic bioengineered organ regeneration. Our results showed that Th1-type CD3(+) CD8(+) T cell response to xenogeneic-dentin matrix-based bioengineered root complex (xeno-complex) was significantly inhibited by M2 gamma macrophage in vitro. PPARy activation also timely recruited CD68(+)CD206(+) tissue macrophage polarization to xeno-complex in vivo. These subsets alleviated proinflammatory cytokines (TNF-alpha, IFN-gamma) at the inflammation site and decreased CD3(+)CD8(+)T lymphocytes in the periphery system. When translated to an orthotopic nonhuman primate model, PPARy-primed M2 macrophages immunosuppressed IL-1 beta, IL-6, TNF-alpha, MMPs to enable xeno-complex to effectively escape immune-mediated rejection and initiate graft-host synergistic integrity. These collective activities promoted the differentiation of odontoblast-like and periodontal-like cells to guide pulp-dentin and cementum-PDLs-bone regeneration and rescued partially injured odontogenesis such as DSPP and periostin expression. Finally, the regenerated mot showed structure-biomechanical and functional equivalency to the native tooth. The timely conversion of M1-to-M2 macrophage mainly orchestrated odontogenesis, fibrogenesis, and osteogenesis, which represents a potential modulator for intact parenchymal-stromal tissue regeneration of targeted organs.