The modulation of SHED-induced macrophage polarization and plasticity through paracrine mediators

Although the effect of stem cells from human exfoliated deciduous teeth (SHED) on macrophage polarization and plasticity has been studied in recent years, its mechanism needs to be elucidated. Here, we aimed to investigate how SHED-MSCs cross-talk with THP-1 cell-derived macrophages in a co-culture system. SHED- MSCs were indirectly co-cultured with polarized M0 and M1 macrophages using the six-well transwell culture system, and their effects on macrophage plasticity, surface molecule expression, cytokine secretion, oxidative stress indexes, and gene expression were evaluated. Using flow cytometry, we confirmed macrophage polarization and observed a significant shift toward the M2 phenotype (CD206) following co-culture with SHED-MSCs. Cytokine analysis revealed increased levels of anti-inflammatory factors (TGFB2, IL-10) and reduced pro-inflammatory cytokines (TNF-α, IL-12). Importantly, SHED-MSCs modulated the oxidative state of macrophages, significantly reducing Nitric oxide (NO) and Malondialdehyde (MDA) levels while enhancing antioxidant markers including Total antioxidant capacity (TAC), Superoxide dismutase (SOD), and Catalase (CAT). Gene expression analysis further supported this regulatory effect, with upregulation of ARG1 (Arginase 1 gene) and downregulation of IL-6R (Interleukin 6 receptor gene) in treated macrophages. our findings show that SHED-MSCs exert potent paracrine effects that not only reprogram inflammatory macrophages toward a reparative phenotype but also restore redox homeostasis. These results highlight the potential of SHED-MSCs as a therapeutic cell source for the treatment of inflammation- and oxidative stress-related diseases.