Lanthanum doped octacalcium phosphate/polylactic acid scaffold fabricated by 3D printing for bone tissue engineering

Lanthanum (La) has tremendous potential in the treatment and prevention of bone diseases especially osteoporosis and metabolic disorders. However, controlling its distribution and keeping the release of La3+ ions sustained and steady in the body is still a big challenge. In this study, we prepared La-OCP powders via co-precipitation method, and further prepared La-OCP/PLA porous scaffolds by 3D printing. La3+ was successfully introduced into the OCP crystal structure and substituted Ca2+ at the Ca-5 and Ca-8 sites. In particular, some La3+ ions were deposited on the crystal surface in the form of nanoparticles. Both octacalcium phosphate (OCP, Ca8H2(PO4)6·5H2O) crystals and nanoparticles played as the carriers for La3+ ions. The La-OCP/PLA scaffolds displayed obvious mineralization effects and sustained release of La3+. The scaffolds contained a uniform structure with rough micro surface topography which acted as a suitable pathway for BMSCs cells to adhere, grow and proliferation. At a certain La3+ concentration, the extracts from La-OCP/PLA scaffolds increased the expression of osteogenesis-related genes, thus promoting the osteogenic differentiation of BMSCs. Moreover, the extracts regulated the immune responses. The experiment in vivo proved that La-OCP/PLA porous scaffolds were safe and could enhance bone defect regeneration in vivo. These findings suggest that 3D printed La-OCP/PLA porous scaffolds have promising potentials in bone tissue engineering.