The hydroxyapatite microtubes enhanced GelMA hydrogel scaffold with inner "pipeline framework" structure for bone tissue regeneration

The critical bone defect is a ubiquitous problem and attracts extensive research attentions. The artificial material GelMA hydrogels (GH) with high biocompatibility, biodegradability and light curing property is promising for treating bone defect, but hindered by its weak mechanical property and low interconnection of the inner pores. While the normal inorganic materials including hydroxyapatite (HA), mainly in the morphologies of micro-/ nanorods, wires and particles, have been composited with GH to enhance the mechanical properties, they can hardly improve porosity or their interconnections. In this study, a GH-based pipeline framework composite hydrogel scaffold was constructed by hybridizing hydroxyapatite microtube (HAMT) and GH. The tubular HAMT increases the mechanical properties of the scaffold, also interconnects the adjacent hole in the scaffold for the signal transmission performance and good breathability. Besides, the surface of the composite scaffold turns to much rougher with the addition of HAMT. Thus, this composite scaffold exhibits high adhesion performance, mechanical properties, breathability, and signal transmission function. Based on these properties, this pipeline framework composite scaffold displays excellent proliferation and differentiation ability of bone marrow mesenchymal stem cells (BMSCs) in vitro and bone repair capability in vivo. This research provides a new idea for multi-functional composite scaffold construction with a simple but practical strategy for bone defect repair.