Immunomodulatory 3D hybrid scaffolds functionalized with cytokine transfected stem cells for bone regeneration

• 3D-printed ColMA/CSMA/HA/BMSCs@IGF-1 scaffold exhibits superior biocompatibility, integrating natural-synthetic hybrid components for bone tissue engineering. • The scaffold promotes osteogenesis by inducing M2 macrophage polarization, establishing an immunoregulatory microenvironment conducive to bone regeneration. • IGF-1-transfected BMSCs act as functional seed cells, offering a novel immunomodulatory strategy to enhance bone biomaterial efficacy. Immunomodulatory bioactivity is critical for biomaterials to efficiently promote bone regeneration, which, however, remains a significant clinical challenge. Here, we develop a bioactive 3D-printed scaffold by encapsulating transfected bone marrow-derived mesenchymal stem cells (BMSCs) within a hybrid hydrogel, followed by UV crosslinking. While the hybrid hydrogel ColMA/CSMA/HA is composed of methacrylated type-I collagen, methacrylated chitosan, and nano-hydroxyapatite, encapsulating insulin-like growth factor-1 (IGF-1)-transfected BMSCs leads to the 3D scaffold ColMA/CSMA/HA/BMSCs@IGF-1. The in vitro evaluation demonstrates excellent biocompatibility and the capability of the scaffold to promote M2 macrophage polarization within an immunomodulatory microenvironment and thereby facilitate the osteogenic differentiation of BMSCs. Transcriptomic analyses reveal that the scaffold ColMA/CSMA/HA/BMSCs@IGF-1 regulates osteogenic differentiation and promote bone regeneration by modulating immune responses and suppressing inflammatory cytokines. Through the synergistic effects of immunomodulation, inflammation suppression, and osteogenic differentiation, the 3D-printed scaffold efficiently promotes the repair of bone defects. Overall, the 3D-printed hybrid scaffold exhibits synergistic effects under the interplay of the bone immune microenvironment to enhance bone regeneration. This study provides a new strategy for the development of bone biomaterials capable of mediating immunomodulation for bone tissue engineering and regeneration.