Role of gingival mesenchymal stem cell exosomes in macrophage polarization under inflammatory conditions

Objective: Exosomes have been shown to play a strong role in intercellular communication. While GMSCs have been extensively studied, less research exists on exosomes derived from GMSCs, especially on how exosomes affect macrophages. This study aimed to investigate the impact of GMSC-derived exosomes on macrophage polarization and phenotype under inflammatory conditions. Methods: Exosomes were isolated from GMSCs-conditioned media by ultracentrifugation (UC) and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blot (WB). In vitro, GMSC-derived exosomes were co-incubated with macrophages for 24 h in the absence or presence of M1 polarizing conditions in the six-well plate. The protein and mRNA expression levels of M1 and M2 macrophage markers were detected and the supernatants were collected for an enzyme-linked immunosorbent assay (ELISA). Results: Exosomes were successfully isolated from GMSCs. Macrophages co-cultured with exosomes showed significantly decreased levels of the M1 markers Tumor Necrosis Factor-alpha (TNF-alpha), Interleukin-12 (IL-12), CD86 and Interleukin-15 (IL-1 beta). By contrast, M2 marker Interleukin-10 (IL-10) levels moderately increased. Meanwhile, similar results were acquired in the cell culture supernatants. Conclusion: GMSC-derived exosomes may promote M1 macrophage transformation into M2 macrophages, reducing the pro-inflammatory factors produced by M1 macrophages.