3D-printed PCL/nHA/SA/COL loaded with M2 macrophage-derived exosomes alleviates the senescence of bone marrow mesenchymal stem cells

BACKGROUND: The communication between bone marrow mesenchymal stem cells (BMSCs) and macrophages in implant microenvironment is crucial for implantation prognosis. This study explores the potential of PCL/nHA/SA/COL loaded with M2 macrophage-derived exosomes (PCL/nHA/SA/COL@EXOs) on the functions of BMSCs. METHODS: PCL/nHA/SA/COL structure is generated by 3D printing. M2 macrophage-derived exosomes (EXOs) are analyzed by TEM and NTR. Gene expression is determined by RT-qPCR, Western blot, and immunofluorescence. KDM4B-induced WNT/P53 signaling-controlled transcription was analyzed using ChIP assay. Cellular behaviors of BMSCs were analyzed by CCK-8, EdU, alizarin red staining, ALP staining, and SAβ-gal staining. 3D-printed PCL/nHA/SA/COL@Exo implantation is performed in mice as well as aged rats. RESULTS: PCL/nHA/SA/COL@EXOs exerts more remarkable effects on promoting the proliferation and osteogenic differentiation of BMSCs. Furthermore, PCL/nHA/SA/COL@EXOs inhibits the senescence of BMSCs. Mechanistically, PCL/nHA/SA/COL@EXOs upregulates KDM4B, which mediates histone demethylation and drives WNT/P53 signaling-controlled transcription. In vivo assays confirm that PCL/nHA/SA/COL@EXOs inhibits senescence and mediates new bone regeneration. CONCLUSION: PCL/nHA/SA/COL@EXOs effectively inhibits BMSC senescence as well as endows with bone integration performance, which holds great potential for future clinical applications.