Evaluation of the degradation, biocompatibility and osteogenesis behavior of lithium-doped calcium polyphosphate for bone tissue engineering

BACKGROUND: Calcium polyphosphate (CPP) is a commonly used biomaterial in bone tissue engineering, but CPP is insufficient in osteoinduction. This study aimed to fabricate lithium doped CPP (LiCPP) scaffolds and assess their characterization, degradation, biocompatibility and osteogenesis behavior for bone tissue engineering. METHODS: The novel scaffold was characterized by XRD, FTIR and SEM. The porosity, cell mediated degradation behavior and mechanical properties were also investigated. Meanwhile, cell proliferation activity and adhesion in vitro was exploited. Finally, osteogenesis the LiCPP scaffolds in vitro and in vivo was researched. RESULTS: The outcomes revealed that low-content Li doping had no significant influence on the structure of CPP. The results of cells mediated degradation experiments from the weight loss and the release of ions indicated that Li doped CPP improved biological degradation. The compressive strength of CPP with 66% porosity was improved to 7 MPa. Cells proliferation experiment and adhesion experiment demonstrated 2.0%LiCPP scaffold was most beneficial to cell growth and attachment. Furthermore, Li doped CPP up-regulated Wnt signal pathway when co-cultured with MG63 and increased osteogenic marker ALP expression and calcium phosphate deposition in vitro. At the same time, new bone formation in vivo was also enhanced by using LiCPP scaffolds and the 2.0%LiCPP scaffolds obtained best osteogenesis outcomes. CONCLUSION: The results obtained in our study suggest that 2.0%LiCPP scaffold could benefit from improving the osteogenesis behavior and is a promising biomaterial for bone repairing applications.