Ginsenoside RB1 Influences Macrophage–DPSC Interactions in Inflammatory Conditions

Introduction and aims: Unresolved inflammation and tissue destruction are supposed to underlie the failure of dental pulp repair. As crucial regulators of the injury response, dental pulp stem cells (DPSCs) play a key role in pulp tissue repair and regeneration. M2 macrophages have been demonstrated to induce osteogenic/odontogenic differentiation of DPSCs. Ginsenoside Rb1 (GRb1) is the major component of ginseng and manifested an anti-inflammatory role by promoting M1 macrophage polarised into M2 macrophage in inflammatory disease. However, whether GRb1 facilitates odontogenic differentiation of DPSCs via promoting M2 macrophage polarisation under inflammatory conditions has yet to be established. Methods: Human monocyte leukemic cells (THP-1) differentiated macrophages were induced into M1 subsets and then treated with GRb1. After that, the conditioned medium was added to DPSCs. The cell co-cultured system was then subjected to odontogenic differentiation in osteogenic media. Effects of GRb1 on human dental pulp stem cells’ (hDPSCs’) osteogenic/odontogenic differentiation under inflammatory conditions were assessed by alkaline phosphatase (ALP) staining, Alizarin Red S (ARS) staining, and quantitative polymerase chain reaction testing. Results: Results demonstrated that GRb1 could facilitate the polarisation of macrophages from the M1 subtype to the M2 subtype. Conditioned medium from GRb1 + M1 macrophages, in comparison with M1 macrophages, may markedly increase the gene expression of ALP, DSPP, and DMP1. Moreover, ALP and ARS staining uncovered that the osteogenic/odontogenic differentiation ability of hDPSCs was strengthened in the M1 + GRb1 co-culture group. Conclusions: GRb1 plays a crucial role in the inflammatory response and reparative dentine formation after dental pulp injury. Findings show that GRb1 modulates the interaction between macrophages and DPSCs during inflammation. The current study discusses modifications of deep caries therapy.