3D printing of lithium osteogenic bioactive composite scaffold for enhanced bone regeneration

The repair of large bone defects is still a challenge in clinical orthopedics. The combination of composite materials and 3D printing is expected to produce ideal bone defect scaffolds. This research studied the combined polylactic acid (PLA), nano-hydroxyapatite (n-HA), and lithium (Li) bone tissue scaffold via 3D printing. The n-HA/PLA/Li composite scaffold was proposed by screening the optimal proportion, biocompatibility, and osteoinductive activity. The degradation and mechanical properties of the proposed specimens were evaluated. Osteogenesis and vasculogenesis were detected in vitro, and the regulatory pathways were explored to screen the doping amount of lithium ions. In vivo, the PLA/n-HA/Li composited scaffold was used for the beagle dog heterotopic and rabbit femur orthotopic osteogenesis studies. Results indicated that the mechanical strength of PLA/n-HA/Li composited scaffold decreased with the increase of the n-HA ratio. The 30% n-HA scaffold group showed a good comprehensive performance of printability and mechanical strength. Based on the osteoinductive activity, 0%, 0.5%, and 1% lithium-doped scaffolds were studied and screened. The 1% lithium group exhibited the best degradation, osteogenesis, and angiogenesis properties in vitro than other groups and could induce ectopic osteogenesis and in situ osteogenesis in vivo. This PLA/n-HA/Li composite biomaterial shows good printability, biocompatibility, degradability, and osteogenic inducibility, it has application potential in the personalized repair of large bone defects.