Enhanced osteogenesis of 3D printed β-TCP scaffolds with Cissus Quadrangularis extract-loaded polydopamine coatings

Abstract Growing demand in bone tissue replacement has shifted treatment strategy from pursuing traditional bone-bone grafting to tissue replacement with bioactive biomaterials. Constructs that exhibit the ability to support the bone structure while encouraging tissue regeneration, integration, and replacement represent the future of bone tissue engineering. The present study aimed to understand the osteogenic and mechanical effects of binder-jet 3D printed, porous β-tricalcium phosphate scaffolds modified with a natural polymer/drug coating of polydopamine and Cissus Quadrangularis extract. Compression testing was used to determine the effect the polydopamine coating process had on the mechanical strength of the scaffolds. 3D printed scaffolds without and with polydopamine coatings fractured at 3.84 ± 1.01 MPa and 3.88 ± 0.51 MPa, respectively, suggesting no detrimental effect on strength due to the coating process. The osteogenic potential of the extract-loaded coating was tested in vitro, under static and dynamic flow conditions, and in vivo in a rat distal femur model. Osteoblast cell cultures showed polydopamine resulted in increased proliferation and alkaline phosphatase expression under dynamic flow, which was further enhanced by the addition of Cissus Quadrangularis extract. Histological analysis of implanted scaffolds showed significantly more new bone growth throughout the implant pores at 4 weeks post-op in polydopamine and extract-loaded implants compared to pure β-tricalcium phosphate. These results indicate that implants modified with polydopamine and Cissus Quadrangularis extract considerably outperform pure β-tricalcium phosphate scaffolds in facilitating early bone formation and ingrowth.