3D-bioprinted functional scaffold based on synergistic induction of i-PRF and laponite exerts efficient and personalized bone regeneration via miRNA-mediated TGF-β/Smads signaling

BACKGROUND: Limited stem cells, low vascularization efficiency, and weak osteoinductive activity plague the repair and reconstruction of bone defects with cell-free scaffolds. METHODS: Herein, injectable platelet-rich fibrin (i-PRF) was loaded into a alginate methacryloyl (AlgMA)/gelatin methacryloyl (GelMA)-methylcellulose (AGM) bioink system and constructed a porous hydrogel scaffold by 3D bioprinting. The addition of nanosilicate-laponite (Lap) further enhanced this scaffold and synergized with i-PRF to promote efficient and personalized cranial regeneration. RESULTS: At the biochemical level, Lap significantly enhanced the ability of the scaffold to retard growth factor release, and multiple physiologically proportional growth factors in the scaffold synergistically promoted rapid neoangiogenesis and concomitantly recruited endogenous bone marrow mesenchymal stem cells (BMSCs). More importantly, the bioactive ions released by Lap markedly promoted the proliferation of BMSCs and consistently induced the osteogenic differentiation of BMSCs. At the immunological level, i-PRF-AGM@Lap significantly attenuates the inflammatory response by promoting macrophage M2 polarization. Mechanistically, miRNA sequencing and functional validation experiments demonstrated that bioactive ions released by Lap could synergize with growth factors in i-PRF to promote osteogenic differentiation of BMSCs through the miR-21 and miR-125a-mediated transforming growth factor-β/Smads signaling pathway. CONCLUSION: The results of this study provide a new idea for the personalized treatment of bone defects.