Wnt11 plays an important role in the osteogenesis of human mesenchymal stem cells in a PHA/FN/ALG composite scaffold: possible treatment for infected bone defect

BACKGROUND: Infected bone defect poses a great challenge for orthopedists because it is difficult to cure. Tissue-engineered bone based on the human mesenchymal stem cells (hMSCs), has currently taken a promising treatment protocol in clinical practice. In a previous study, a porous hydroxyapatite/fibronectin/alginate (PHA/FN/ALG) composite scaffold displayed favorable biological properties as a novel scaffold, which was considered better than single-material scaffolds. In addition, Wnt11 has been demonstrated to play an important role in the development of osteoblasts, but until recently, its role in the osteogenic differentiation of hMSCs in infectious environment remained unclear. METHODS: In this study, we constructed a PHA/FN/ALG composite scaffold with layer-by-layer technology. Furthermore, we also constructed Wnt11-silenced (RNAi) and -overexpressing hMSCs by lentiviral transduction. The gene transduction efficacy was confirmed by quantitative PCR assay and Western blot analysis. Tissue-engineered bone was constructed with hMSCs and PHA/FN/ALG composite scaffolds, and then was implanted into an infected bone defect model for evaluating the osteogenic capacity by quantitative PCR, gross observation, micro-CT and histology analysis. RESULTS: All those cells showed similar adhesion abilities and proliferation capacities in scaffolds. After tissue-engineered bone implantation, there were high levels of systemic inflammatory factors in vivo, which significantly declined three days after antibiotic therapy. One or two months after implantation, the results of osteogenic-related gene analyses, gross observation, micro-CT and histology consistently showed that the Wnt11 over-expression hMSC group displayed the strongest osteogenesis capacity, whereas the Wnt11-RNAi hMSC group displayed inferior osteogenesis capacity, when compared with the other cell-containing groups. However, the blank control group and the only composite scaffold without cell implantation group both showed extremely weak osteogenesis capacity. CONCLUSION: Our results revealed that the Wnt11 gene plays an important role in hMSCs for enhancing the osteogenesis in an infectious environment.