Improved osteointegration and angiogenesis of strontium-incorporated 3D-printed tantalum scaffold via bioinspired polydopamine coating

Tantalum (Ta) is used in orthopedic implants because it has excellent biocompatibility. However, high elastic modulus, bio-inertness, and unsatisfactory osteointegration limits its wider use in clinical applications. Herein, a 3D porous Ta scaffold with low elastic modulus was fabricated using selective laser melting (SLM). Strontium (Sr) was incorporated on the surface of the scaffold with the aid of polydopamine (PDA) to further improve its osteointegration ability. The prepared scaffolds exhibited a stable Sr ion release in 14 d. Rat bone marrow stem cells (BMSCs) showed improved early adhesion and spreading after Sr was incorporated on the porous Ta surface. The osteogenic behavior, including extracellular matrix mineralization (ECM), alkaline phosphatase activity (ALP), and expression of bone-related RNA, were all enhanced. Furthermore, the Sr-incorporated porous Ta scaffolds exhibited better angiogenic behavior, such as promoting migration, tube formation, and angiogenesis-related RNA expression abilities of human vascular endothelial cells (HUVECs). Additionally, histological images (H&E, Masson and CD31 immunofluorescent staining) suggested that Sr-incorporated porous Ta scaffolds displayed enhanced osteointegration and angiogenesis after implantation in rat femur for 12 weeks. These findings prove that the PDA-based Sr-incorporated porous Ta scaffolds show promising use in orthopedic implants.