Objective To investigate the effects of supernatant liquid from cultured mesenchymal stem cells (MSCs) on the lipid accumulation, polarisation, inflammation and apoptosis of macrophages.

Methods The MSCs supernatant liquid (MSCs-SL) was co-cultured with THP-1 macrophages. The THP-1 macrophage activity were detected by MTT assay. The lipid accumulation of THP-1 macrophages were detected by oil red O staining. Real-time PCR was used to detect the expression levels of TNF-α, IL-1β, CD206 and ARG-1. The apoptosis of THP-1 macrophages were detected by TUNEL staining.

Results The 20% MSCs-SL could enhance the lipopolysaccharide-induced macrophage activity (F = 63.70, P ＜ 0.01). After treating the cells with 20% MSCs-SL, no significant effect on lipid accumulation in macrophages was observed (F = 2.26, P ＞ 0.05). The MSCs-SL co-culture group significantly upregulated the mRNA levels of TNF-α (F = 125.90, P ＜ 0.01) and IL-1β (F = 165.00, P ＜ 0.01) under inflammatory conditions, and TNF-α (t = 12.60, P ＜ 0.01) and IL-1β (t = 8.77, P ＜ 0.01) under M1 polarization conditions, and down-regulated the mRNA level of CD206 under M2 polarization conditions (t = 6.19, P ＜ 0.05). MSCs-SL treatment could significantly inhibit the macrophage apoptosis.

Conclusions MSCs-SL has no significant effect on lipid accumulation in macrophages, but it can promote the macrophage inflammation and M1 polarization, and inhibit the M2 polarization and apoptosis of macrophages.