Cryo-printed collagen scaffolds reinforced with dentin-derived bioactive particles promote osteo-angiogenic bone regeneration

Critical-sized bone defects require grafts that combine structural integrity with biological cues. We processed extracted human teeth by decellularization, partial demineralization and cryogenic milling to obtain micron-scale dentin-derived particles (DDM-p) that retain low-crystalline bioapatite and matrix-bound factors. DDM-p (3, 5, or 7 wt%) or nano-hydroxyapatite (7 wt%) were blended with type I collagen and low-temperature 3D-printed into lattice scaffolds, then EDC/NHS-crosslinked. The printed scaffolds were highly porous; increasing DDM-p content raised mineral fraction, reduced water absorption, slowed collagenase-mediated mass loss, and enhanced compressive properties, with CDP-7 exhibiting the highest modulus. Pre-osteoblastic cells showed excellent viability, greater proliferation, deep 3D infiltration, and upregulated osteogenic markers and genes on DDM-p scaffolds compared with collagen and nano-hydroxyapatite controls. Endothelial cells formed denser tube networks and expressed higher CD31 and HIF-1α in the presence of DDM-p scaffolds, evidencing strong angiogenic stimulation. In a rat critical-sized calvarial defect, CDP-7 achieved the greatest bone mineral density, bone volume fraction, new bone area, and vessel density among all groups. Taken together, these findings suggest the potential of low-temperature printed collagen/DDM-p scaffolds as a structurally stable, osteo-angiogenic platform for bone regeneration.