Objective: To investigate the effect of microvesicles from human embryonic stem cell derived-neural stem cells on macrophage polarization in vitro. Methods: The neural stem cell microvesicles were labeled by Dil to observe its internalization by THP-1 macrophages on microvesicles by flow cytometry and confocal microscopy; the optimal concentration of microvesicles was detected by real-time quantitative PCR; THP-1 cells were stimulated by 100 ng/mL lipopolysaccharide (LPS) for 6 h, then were treated with microvesicles for 12 h, the mRNA expression of macrophage pro-inflammatory factors, IL-1β, tumor necrosis factor-α (TNF-α), IL-6 were detected by real-time quantitative PCR; after treated with microvesicles for 24 h, the protein expression of inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-1) were detected by Western blotting; the expression of CD86 by M1 polarized macrophages was detected by flow cytometry. Results: THP-1 macrophages could significantly internalize neural stem cell microvesicles at both 12 h and 24 h; 0.12 μg/mL microvesicles had optimal regulatory effect; the mRNA expression of IL-1β, TNF-α, IL-6 and the protein expression of iNOS were greatly increased by 100 ng/mL LPS treatment compared with untreated cells (P<0.05); while the mRNA expression of IL-1β, TNF-α, IL-6 and the protein expression of iNOS were significantly decreased after treatment with neural stem cell microvesicles (P<0.05); the expression of CD86 in THP-1 macrophages induced by 100 ng/mL LPS had no statistical significance compared with untreated cells. Conclusion: Microvesicles from human embryonic stem cell-derived neural stem cells could reduce the expression of inflammatory cytokines and iNOS in THP-1 cells and inhibit M1 polarization of macrophages.

［Key words］neural stem cells; microvesicles; inflammation; macrophages; polarization