2023, Vol. 27 ›› Issue (6): 840-845

Effect of M2 macrophage-derived exosomes on osteogenic differentiation of bone marrow mesenchymal stem cells

Liu Wentao1, Feng Xingchao2, Yang Yi2, Bai Shengbin1   

Abstract: BACKGROUND: At present, studies have shown that M2 macrophages can promote osteogenic differentiation and regulate it in a network, and exosomes can carry a lot of information to participate in intercellular signal transduction. Whether M2 macrophage-derived exosomes can promote the osteogenic differentiation of bone marrow mesenchymal stem cells remains to be studied.  
OBJECTIVE: To investigate the effect of M2 macrophage-derived exosomes on osteogenic differentiation of bone marrow mesenchymal stem cells.
METHODS:   Rat derived macrophage line RAW264.7 was cultured with rat bone marrow mesenchymal cell line CP-M131 to the third generation. Interleukin 4 was used to induce macrophages to polarize into M2 macrophages. Exosomes were extracted from M2 macrophage culture supernatant. Exosomes at the final mass concentration of 0, 30, 60, 90 mg/L were cocultured with bone marrow mesenchymal stem cells for 72 hours, and 60 mg/L M2 macrophage-derived exosomes were cocultured with bone marrow mesenchymal stem cells for 24, 48 and 72 hours. The expression levels of osteogenic related factors RUNX2 and alkaline phosphatase protein in bone marrow mesenchymal stem cells were detected by western blot assay and the mineral deposition was detected by alizarin red staining.  
RESULTS AND CONCLUSION: (1) The expression levels of osteogenic related factors RUNX2 and alkaline phosphatase were closely related to the mass concentration of macrophage exosomes. Compared with the blank control group, the expression of RUNX2 and alkaline phosphatase in 60 mg/L exosome group increased significantly (P < 0.05), and the expression of RUNX2 and alkaline phosphatase after 72 hours of intervention increased significantly (P < 0.05). (2) The results of alizarin red experiment showed that compared with the blank control group, the content of calcium ion in 60 mg/L exosome group was higher (P < 0.05), and the content of calcium ion after 72 hours of intervention was higher (P < 0.05). (3) The results showed that the exosomes secreted by M2 macrophages in vitro could induce the differentiation of bone marrow mesenchymal stem cells into osteoblasts.
Key words: exosome, M2 macrophage, osteoblast, bone marrow mesenchymal stem cell, osteogenic differentiation