3D printed β-TCP scaffolds loaded with SVVYGLR peptide for promoting revascularization and osteoinduction

It is crucial for the successful transplantation of large segmental bone defects to achieve rapid vascularization within bone scaffolds. However, there are certain limitations including uncontrolled angiogenesis and inadequate vascular function. Therefore, there is an urgent need to develop bone scaffolds with functional vascular networks. In our study, porous<i>β</i>-tricalcium phosphate (<i>β</i>-TCP) scaffolds with varying pore sizes were prepared by 3D printing technology, loaded with osteopontin derived peptide Ser-Val-Val-Tyr-Gly-Leu-Arg (SVVYGLR) to induce osteoinduction and angiogenesis.<i>In vitro</i>, the proliferation and migration behaviors of human umbilical vein endothelial cell on scaffolds were assessed by Cell Counting Kit-8, confocal laser scanning microscopy and scanning electron microscopy. And the osteogenic ability of bone marrow mesenchymal stem cells was assessed using alkaline phosphatase staining and Alizarin Red S staining. The messenger ribonucleic acid (mRNA) expression levels of cell adhesion molecule (CD31), vascular endothelial growth factor and hypoxia inducible factor-1<i>α</i>in each group were detected by quantitative real-time fluorescence polymerase chain reaction (PCR) analysis.<i>In vivo</i>, cube scaffolds were subcutaneously implanted on the right hips of Sprague-Dawley (SD) rats for 6 weeks. Hematoxylin and Eosin staining, Masson's trichrome staining, and immunohistochemical analysis of osteocalcin and CD31 were performed on slices for every sample with three sections to explore the effect of SVVYGLR-loaded scaffolds on angiogenesis and osteogenic induction for bone reconstruction. The results indicate that 3D printed<i>β</i>-TCP scaffolds loaded with the SVVYGLR peptide offer superior revascularization and osteoinduction to the scaffolds without the SVVYGLR<i>in situ</i>. Moreover, scaffolds with a pore size of 400 µm demonstrate higher effectiveness compared to those with a 150 µm pore size. The distinct hollow channel scaffolds and the specific SVVYGLR peptide substantially improve cell adhesion, spreading, and proliferation, as well as promote angiogenesis and bone formation. Furthermore, scaffolds with a pore size of 400 µm may exhibit greater efficacy compared to those with a pore size of 150 µm. The results of this study provide an idea for the development of practical applications for tissue-engineered bone scaffolds.