Three-dimensional printed PCL/nHA/SA/COL structure-mediated M2 macrophage polarization enhances angiogenesis and...

Reconstruction of tooth defects remains a substantial clinical challenge. Herein, we used 3D bioprinting biotechnology for tooth tissue engineering. M2 macrophage-derived exosomes were loaded with a three-dimensional-printed poly (ε-caprolactone) (PCL)/nano-hydroxyapatite (nHA)/sodium alginate (SA)/collagen (COL) hydrogels. Mechanical properties were analyzed. New bone regeneration was detected using H&E and Masson trichrome staining. Gene expression was determined using RT-qPCR, immunohistochemistry, immunofluorescence, and Western blot. Cellular mineralization was determined using alizarin red. Osteogenic differentiation was determined using ALP staining. Cell proliferation was determined using CCK-8 and EdU assay. Angiogenesis was determined using tube formation assay. Macrophage function and internalization of exosomes were detected using flow cytometry. We found that PCL/nHA/SA/COL promoted the angiogenic and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), manifested by the upregulation of angiogenesis and osteogenic markers. Moreover, PCL/nHA/SA/COL reprogrammed microenvironment and stimulated anti-inflammatory M2 macrophage polarization. PCL/nHA/SA/COL loaded with M2 macrophage-derived exosomes cultured with rIL10 (PCL/nHA/SA/COL@Exo) enhanced the angiogenic and osteogenic differentiation of BMSCs. In vivo assays confirmed that PCL/nHA/SA/COL@Exo drove macrophage M2 polarization as well as enhanced angiogenesis and osteogenic differentiation. In summary, PCL/nHA/SA/COL@Exo mediates M2 macrophage polarization, which provide a favorable environment for angiogenesis and osteogenic differentiation.