Polydopamine-Induced BMP7-Poly (Lactic-Co-Glycolic Acid)-Nanoparticle Coating Facilitates Osteogenesis in Porous Tantalum Scaffolds

Bone defects are difficult to treat clinically and most often require bone grafting for repair. However, the source of autograft bone is limited, and allograft bone carries the risk of disease transmission and immune rejection. As tissue engineering technology advances, bone replacement materials are playing an increasingly important role in the treatment of bone defects. Porous tantalum (PT) scaffolds have shown beneficial clinical effects in the repair of bone defects, surface modification of PT to induce osteogenic differentiation of mesenchymal stem cells (MSC) is the key to optimizing this material. Poly (lactic-co-glycolic acid) nanoparticle (PLGA NPs) encapsulating bone morphogenetic protein 7 (BMP7) (BPNPs) was prepared by a double emulsion (water/oil/water [W/O/W]) method and adhered on polydopamine (PDA)-coated PT (PPT) that was prepared by biomimetic method to prepare BPNPs-coated PPT (BPPT). The successful preparation of BPPT was monitored by scanning electron microscopy (SEM) and energy spectrum. Murine calvarial preosteoblasts (MC3T3-E1) cells were co-cultured with BPPT, vitro experiments showed that BPPT promoted cell proliferation and osteogenic differentiation. BPPT was further implanted into the bone defect of the distal femoral epiphysis of the rabbit. At 4 weeks postoperatively, in the BPPT group, high-resolution CT reconstruction indicated that bone volume/total volume (BV/TV) was near 50%, and the hard tissue section indicated that the depth of new bone ingrowth into the scaffolds was nearly 2 mm. The immunofluorescence staining of bone tissue around the bone defects indicated that the expression of osteogenic-related proteins was higher in the BPPT group than the other groups. Taken together, our results suggest that BPPT promoted early osteointegration, which may provide a novel approach for the clinical treatment of bone defects.