HUCMSC‐derived Exosomes Suppress the Titanium Particles‐induced Osteolysis in Mice through Inhibiting CCL2 and CCL3

OBJECTIVE: Wear particles induce inflammation and the further osteolysis around the prosthesis, has been proven to be the main cause of aseptic hip joint loosening. In this research, we aimed to clarify whether human umbilical cord mesenchymal stem cells (HUCMSCs) could inhibit the titanium particles‐induced osteolysis and shed light upon its mechanism. METHODS: The expression of chemokine (C‐C motif) ligand 2 (CCL2), chemokine (C‐C motif) ligand 3 (CCL3) and chemokine (C‐C motif) ligand 5 (CCL5) were examinjed in clinical specimens of aseptic hip prosthesis loosening patients. Local injection of lentivirus that knocked down CCL2 or CCL3 in a cranial osteolysis mice model were used to exam the effect of CCL2 and CCL3 on titanium particles‐induced osteolysis in vivo. Transwell assay was used to examine the effect of CCL2 and CCL3 on titanium particles‐induced activation of macrophage in vitro. Furthermore, the therapeutic effect of HUCMSCs, and exosomes from HUCMSCs were also examed in vivo and vitro. Immunohistochemical and real‐time PCR were used to examine the expression of relative pathways. Analysis of variance (ANOVA) and Student–Newman–Keuls post hoc t test were used to analyze the results and determine the statistical significance of the differences. RESULTS: Results showed that titanium particles caused the osteolysis at the mice cranial in vivo and a large number of macrophages that migrated, while local injection of HUCMSCs and exosomes did inhibit the cranial osteolysis and migration. An exosome inhibitor GW4869 significantly increased the osteolysis area in the mice cranium osteolysis model, and increased the number of migrated macrophages. Immunohistochemical results suggested that the expression of CCL2, CCL3 and CD68 in the cranial in Titanium particles mice increased significantly, but was significantly reduced by HUCMSCs or exosomes. HUCMSC and exosomes down‐regulate the expression of CCL3 in vitro and in vivo. CONCLUSION: HUCMSCs and HUCMSC‐derived exosomes could suppress the titanium particles‐induced osteolysis in mice through inhibiting chemokine (C‐C motif) ligand 2, chemokine (C‐C motif) ligand 3.