Abstract
BackgroundInfected 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.MethodsIn 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.ResultsAll 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.ConclusionOur results revealed that the Wnt11 gene plays an important role in hMSCs for enhancing the osteogenesis in an infectious environment.
Highlights
Infected bone defect poses a great challenge for orthopedists because it is difficult to cure
Quantitative PCR indicated that lentivirus-mediated Wnt11 RNAi in Human mesenchymal stem/stromal cell (hMSC) significantly diminished the Wnt11 gene expression level in comparison with the control, whereas the hMSCs designed to overexpress Wnt11 showed significantly higher expression levels than the control cells: the suppression or stimulation rate was 57 % and 260 % after transfection, respectively (Fig. 1c)
Histological analysis revealed that newly formed collagen I and trabecular bone in Wnt11 overexpressing hMSCs/scaffold group (WOSG) grafts were significantly higher than in the empty lentivirus-transduced hMSCs/scaffold group (ELSG) or Wnt11-RNAi hMSCs/scaffold group (WISG) grafts. These results further suggested that Wnt11 overexpression may enhance the osteogenesis of hMSCs in the infectious environment
Summary
Infected bone defect poses a great challenge for orthopedists because it is difficult to cure. Infected bone defect remains one of the greatest challenges for orthopedists because it is clinically difficult to treat and eradicate [1]. Because of the long treatment time and low cure rate, infected bone defects can be devastating and associated with physical and psychological damage for patients as well as economic loss [4]. Traditional antibiotic therapy has been employed generally, it is difficult to produce an effective local antibiotic concentration despite the high serum concentration [5, 6]. It is important to further investigate the potential mechanisms and therapies for bone formation in patients with infected bone defects
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