Magnesium Ammonium Phosphate Composite Cell-Laden Hydrogel Promotes Osteogenesis and Angiogenesis In Vitro

[Image: see text] Injectable hydrogels provide an effective strategy for minimally invasive treatment on irregular bony defects in the maxillofacial region. To improve the osteoinduction of gelatin methacrylate (GelMA), we fabricated a three-dimensional (3D) culture system based on the incorporation of magnesium ammonium phosphate hexahydrate (struvite) into GelMA. The optimal concentration of struvite was investigated using the struvite extracts, and 500 μg mL(–1) was found to be the most suitable concentration for the osteogenesis of dental pulp stem cells (DPSCs) and angiogenesis of human umbilical vein endothelial cells (HUVECs). We prepared the GelMA composite (MgP) with 500 μg mL(–1) struvite. Struvite did not affect the cross-linking of GelMA and released Mg(2+) during degradation. The cell delivery system using MgP improved the laden-cell viability, upregulated the expression of osteogenic and angiogenic-differentiation-related genes, and promoted cell migration. Overall, the modifications made to the GelMA in this study improved osteoinduction and demonstrated great potential for application in vascularized bone tissue regeneration.