Magnesium surface-activated 3D printed porous PEEK scaffolds for in vivo osseointegration by promoting angiogenesis and osteogenesis

Polyetheretherketone (PEEK) has been an alternative material for titanium in bone defect repair, but its clinical application is limited by its poor osseointegration. In this study, a porous structural design and activated surface modification were used to enhance the osseointegration capacity of PEEK materials. Porous PEEK scaffolds were manufactured via fused deposition modeling and a polydopamine (PDA) coating chelated with magnesium ions (Mg2+) was utilized on the surface. After surface modification, the hydrophilicity of PEEK scaffolds was significantly enhanced, and bioactive Mg2+ could be released. In vitro results showed that the activated surface could promote cell proliferation and adhesion and contribute to osteoblast differentiation and mineralization; the released Mg2+ promoted angiogenesis and might contribute to the formation of osteogenic H-type vessels. Furthermore, porous PEEK scaffolds were implanted in rabbit femoral condyles for in vivo evaluation of osseointegration. The results showed that the customized three-dimensional porous structure facilitated vascular ingrowth and bone ingrowth within the PEEK scaffolds. The PDA coating enhanced the interfacial osseointegration of porous PEEK scaffolds and the released Mg2+ accelerated early bone ingrowth by promoting early angiogenesis during the coating degradation process. This study provides an efficient solution for enhancing the osseointegration of PEEK materials, which has high potential for translational clinical applications.