A printable bone repair scaffold with synergistic immune modulation and osteogenesis to enhance bone regeneration

Implantations of scaffold materials for bone lesion rectification involves multifaceted cascade reaction process, principally encompassing an initial inflammatory response followed by subsequent osteogenic restoration. The optimal bone scaffolds should possess not solely robust osteogenic potential, but also the control of the host's immune response towards the scaffolds. The development of bone repair scaffold materials boasting intelligent anti-inflammatory capabilities is of paramount importance. Herein, we constructed a novel 3D-printed drug delivery Hydroxyapatite+ κ-Carrageenan/Polyvinyl alcohol composite scaffold (HA+ κ-CA/PVA) incorporating mesoporous hydroxyapatite (MHA) loaded with icariin (ICA), for enhancing anti-inflammation and bone repair. Above all, the scaffolds with superior printability were developed by altering the proportion of polyvinyl alcohol (PVA) and κ-carrageenan (κ-CA). The HCP (HA+ κ-CA/PVA) scaffolds with the optimal organic compound ratio possessed a highly stable structure, characterized by excellent interconnected channels. Notably, the HCP scaffolds with 1:1–12% (1:1 represents the solid content ratio of κ-CA and PVA, and 12% means the mass fraction of PVA aqueous solution) exhibited marvelous hydrophilicity, swelling, mineralization in vitro and optimal mechanical properties. Furthermore, the drug ICA loaded with MHA was further incorporated to achieve the sustained release of the drug within the scaffolds. In vitro cell experiments verified that the ICA-laden scaffolds considerably stimulated the differentiation of osteoblasts MC3TC-E1 and regulated the polarization of macrophages RAW264.7 to M2 type. These findings suggest that 3D fabricated HCP scaffolds laden with ICA hold immense potential in bone tissue regeneration.