Role of Bone Marrow Mesenchymal Stem Cell-Conditioned Media Combined with Polystyrene Nanoparticles in Rat Osteomyelitis and Macrophage Polarization

This study aimed at investigating the potential role of bone marrow mesenchymal stem cell-conditioned media (BMSC-CM) incorporated with polystyrene nanoparticles (PS-NPs) in inflammatory response in osteomyelitis and clarifying its underlying mechanism. BMSCs were collected from 25 osteomyelitis and healthy rats, and their conditioned media (CM) were collected. Enzyme-linked Immunosorbent Assay (ELISA) was used to determine the expression levels of inflammatory factor IL-10, while the BMSCs were identified by surface antigens. After treatment of BMSCs, BMSC-CM, and BMSC-CM with PS-NPs, flow cytometry was conducted to assess apoptosis of inflammatory cells and macrophage polarization-specific protein, and mRNA expressions were detected. The expression level of IL-10 was up-regulated in the osteomyelitis rats. With primary BMSCs in a long spindle shape, the MSCs were positive for CD44 (99.87%) and negative for antigen CD34 (4.32%). The BMSC-CM combined with PS-NPs caused increased macrophage polarization-related genes (BMP-2, MCP-1, iNOS, CD206, Arg-1, TGF-β) with decreased IL-10 expression. The BMSC-CM combined with PSNPs might inhibit the polarization of BMSCs to macrophages and alleviate inflammation in osteomyelitis.