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Chen Q.,Chongqing Medical University | Chen Q.,Laboratory of Tissue Engineering in Chongqing City | Chen Q.,155 Hospital of PLA | Hou T.,Chongqing Medical University | And 9 more authors.
Inflammation | Year: 2016

Osteomyelitis is a common manifestation of invasive Staphylococcus aureus infection characterized by widespread bone loss and destruction. Phagocytes possess various receptors to detect pathogens, including the Toll-like receptors (TLRs). Previous studies have demonstrated that the S. aureus protein SpA binds directly to pre-osteoblastic cells via tumor necrosis factor receptor-1 (TNFR-1). In our present study, we investigated the relationship between TLR2 and TNFR-1 in S. aureus-infected osteoblasts. Our results showed that cell viability decreased, and apoptosis, expression of TLR2, and the secretion of inflammatory cytokines (TNF-α and IL-6) increased with increasing concentrations of S. aureus. The JNK pathway was also activated in response to S. aureus infection. Knockdown of TNFR1 not only inhibited the JNK pathway but also reduced TLR2 protein and RANKL levels in S. aureus-infected cells. Inhibition of the JNK pathway reduced the protein level of TLR2 and reduced TNF-α and IL-6 secretion in S. aureus-infected cells. © 2016, Springer Science+Business Media New York.


Chang Z.,Chongqing Medical University | Chang Z.,Laboratory of Tissue Engineering in Chongqing City | Chang Z.,General Hospital of Jinan Military Commanding Region | Hou T.,Chongqing Medical University | And 17 more authors.
International Journal of Medical Sciences | Year: 2013

A tissue-engineered construct (TEC) has previously been used for treating bone defects due to its strong osteogenic capability. However, transplantation of a TEC involves an open surgery that can cause infection. To overcome the potential risk of infection after TEC transplantation, we designed a system for the controlled release of antibiotics using fibrin gel-coated vancomycin alginate beads (FG-Vanco-AB) that can supply sustained antibiotics at the graft site. A TEC with FG-Vanco-AB was transplanted into critically sized bone defects of the right femur in a goat. As a control, the TEC without FG-Vanco-AB was transplanted into the left femur defect of the same goat. The breakpoint sensitivity of vancomycin for S. aureus (5 mg/L) was used as a known standard. Study results showed that the duration of time with vancomycin concentrations greater than 5 mg/L in the right graft site, blood, and left graft site were 28 days, 7 days, and 2 days, respectively. The bioactivity regarding vancomycin release was analysed by antibiotic disc diffusion. The vancomycin concentration was decreased from the centre of the graft to both ends of the femur. Radionuclide bone imaging showed no significant difference between the right and left TECs at either 28 or 56 days post-operation. Computed tomography and histological observation showed both sides' bone defects were healed by TEC at 1 12 days post-operation, and there was no significant difference in computed tomography value. These results suggest that FG-Vanco-AB in transplanted bone provided the ability to kill bacteria in local bone tissue while not interfering with the process of bone reconstruction and wound healing. © Ivyspring International Publisher.


Chen Q.,Chongqing Medical University | Chen Q.,Laboratory of Tissue Engineering in Chongqing City | Hou T.,Chongqing Medical University | Hou T.,Laboratory of Tissue Engineering in Chongqing City | And 8 more authors.
Cellular Physiology and Biochemistry | Year: 2014

Background and Aims: Osteomyelitis is a common manifestation of invasive Staphylococcus aureus infection characterized by bone loss and destruction. We investigated the role of toll-like receptor 2 (TLR2) in bacterial recognition and clearance in response to infection with an osteomyelitis isolate of S. aureus. Methods: Apoptosis was assessed in the osteoblastic cell line MC3T3-E1 by Annexin V-FITC/PI staining and flow cytometry. The expression of TLR2 and apoptosis-related and mitogen-activated protein kinase pathway proteins was assessed by qRT-PCR and western blotting. Alkaline phosphatase (ALP) activity and calcium deposition were assessed by ALP activity assay and Alizarin red staining. Results: S. aureus induced apoptosis, upregulated TLR2 expression, and activated mitogen-activated protein kinase pathways in a time dependent manner. Inhibition of the c-Jun N-terminal kinase (JNK) pathway downregulated TLR2 and suppressed the S. aureus induced activation of pro-apoptotic pathways. Short-hairpin RNA mediated silencing of TLR2 reversed S. aureus induced apoptosis and decrease in ALP activity and calcium deposition, and inhibition of JNK had a similar effect. Conclusion: We showed that osteoblast apoptosis and osteogenic differentiation in response to bacterial invasion are dependent on TLR2 expression and JNK activation, suggesting novel potential therapeutic targets for the treatment of osteomyelitis. © 2015 S. Karger AG, Basel.


Xing J.,Chongqing Medical University | Xing J.,Laboratory of Tissue Engineering in Chongqing City | Jin H.,Chongqing Medical University | Jin H.,Laboratory of Tissue Engineering in Chongqing City | And 15 more authors.
Journal of Surgical Research | Year: 2014

Background: To understand the cellular mechanism underlying bone defect healing in the context of tissue engineering, a reliable, reproducible, and standardized loadbearing large segmental bone defect model in small animals is indispensable. The aim of this study was to establish and evaluate a bilateral femoral defect model in mice. Materials and methods: Donor mouse bone marrow mesenchymal stem cells (mBMSCs) were obtained from six mice (FVB/N) and incorporated into partially demineralized bone matrix scaffolds to construct tissue-engineered bones. In total, 36 GFP+ mice were used for modeling. Titanium fixation plates with locking steel wires were attached to the femurs for stabilization, and 2-mm elong segmental bone defects were created in the bilateral femoral midshafts. The defects in the left and right femurs were transplanted with tissue-engineered bones and control scaffolds, respectively. The healing process was monitored by x-ray radiography, microcomputed tomography, and histology. The capacity of the transplanted mBMSCs to recruit host CD31+ cells was investigated by immunofluorescence and real-time polymerase chain reaction. Results: Postoperatively, no complication was observed, except that two mice died of unknown causes. Stable fixation of femurs and implants with full load bearing was achieved in all animals. The process of bone defect repair was significantly accelerated due to the introduction of mBMSCs. Moreover, the transplanted mBMSCs attracted more host CD31+ endothelial progenitors into the grafts. © 2014 Elsevier Inc. All rights reserved.


Wu X.,Southwest University | Wu X.,Chongqing Medical University | Wu X.,Laboratory of Tissue Engineering in Chongqing City | Hou T.,Southwest University | And 20 more authors.
Tissue Engineering - Part A | Year: 2013

Angiogenesis and osteogenesis are essential for healing bone injuries, especially those related to critically sized bone defect (CSBD). Bone tissue engineering is a promising method for repairing bone defect, but the inherently poor nutrient supply and the slow osteogenesis of large size defect are two obstacles. This leads to an urgent need to understand how to orchestrate angiogenesis and osteogenesis for promoting bone defect healing. In this article, poly-L-lysine-coated vascular endothelial growth factor/alginate controlled releasing microspheres (VEGF-AG-PLL) were fabricated in tissue-engineered bone (TEB), and then the composite was implanted into the CSBD of goat femurs. Dynamic intramedullary rod was utilized to fixate the femur and produce an analogous physiological axial compression. We found that VEGF released in early stage not only promoted angiogenesis, but also brought benefit to osteogenesis. Meanwhile, in early stage physiological axial compression could regulate angiogenesis and facilitate VEGF release from the composite. In later stage, compression could accelerate reconstruction of TEB. In conclusion, this study demonstrated that the collaborative application of VEGF and compression could accelerate the reconstruction of TEB; thus, providing a new strategy for clinically repairing large bone defect in future. © Mary Ann Liebert, Inc.


Xing J.,Southwest Hospital | Xing J.,Chongqing Medical University | Xing J.,Laboratory of Tissue Engineering in Chongqing City | Hou T.,Southwest Hospital | And 20 more authors.
Tissue Engineering - Part A | Year: 2013

Bone defect complicated by infection remains a major challenge in orthopedic surguries, and bone grafting for primary repair often associates with high failure rate. The rapid progress in the research spectrums of tissue-engineered bone and antibiotic delivery systems bring hope to solve this issue. Herein, we evaluated the local anti-infective and osteogenic potential of an injectable anti-infection tissue-engineered construct, which includes a fibrin gel scaffold and vancomycin alginate beads (Vanco-AB) to form composites, in the treatment of chronic osteomyelitis with bone defect in rabbit tibia. The infected bone defect model of rabbit tibia was established. Then, the bone defects in the proximal tibial metaphysis were implanted with the constructed composites, containing different combinations of mesenchymal stem cells and Vanco-AB. The in vivo capacities of anti-infection and local osteogenesis of the grafts were determined using radiographic assessment, histopathological observation, and microorganism cultures. Results showed that the injectable anti-infection tissue-engineered construct, comprising a fibrin gel scaffold and Vanco-AB led to efficient eradication of bacteria. At 1 and 3 months after transplantation, the radiographic assessment and microbiological examination demonstrated that the sustained antibiotic release by Vanco-AB significantly decreased the Norden scores of osteomyelitis, generated negative results for the presence of bacteria, and reduced the relapse of osteomyelitis. Meanwhile, tissue-engineered construct implanted in one-stage promoted local bone repair and reconstruction, and it exhibited more apparent osteogenic potential, compared to the control group (without Vanco-AB). In conclusion, the current study achieved the primary repair of bone defect with infection, thus providing an alternative treatment strategy for infected bone defect, which occurs commonly in chronic osteomyelitis. © Mary Ann Liebert, Inc.

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