ABSTRACT
BACKGROUND:Fractures can induce bone cel hypoxia, and remarkably reduce the oxygen tension in cels. Hypoxia-inducible factor-2α is a key oxygen-dependent transcriptional activator to regulate the body function under hypoxia and mediate the release of various inflammatory factors after fractures. OBJECTIVE:To explore the role of Laquinimod in expression and function of hypoxia-inducible factor-2αin osteoblasts. METHODS: Mouse osteoblasts MC3T3-E1 (clone 14) were pretreated with Laquinimod at various concentrations(10-100μmol/L) before hypoxia in the presence or absence of specific proteasome inhibitors MG132 or N-acetyl-leucyl-leucyl-norleucine. Then, the media were pre-conditioned in 1% or 21% oxygen tension for 1 to 24 hours. RESULTS AND CONCLUSION: Under hypoxia, the expression of hypoxia-inducible factor-2α in osteoblasts was increased remarkably, and Laquinimod could inhibit the expression of hypoxia-inducible factor-2α and its target genes in mouse MC3T3-E1 cels. Mechanisticaly, Laquinimod promoted hypoxia-inducible factor-2α degradation in a proteasome-dependent but von Hippel-Lindau protein-independent manner. Importantly, we found that Laquinimod disrupted the interaction between hypoxia-inducible factor-2α and its chaperone heat shock protein 90, but promoted the interaction between hypoxia-inducible factor-2α and the receptor of activated protein kinase C. These findings suggest that Laquinimod may promote the degradation of hypoxia-inducible factor-2α by affecting its folding and maturation. Laquinimod is a novel inhibitor of hypoxia-inducible factor-2α by changing its functional interaction with chaperone proteins heat shock protein 90 and receptor of activated protein kinase C.
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Objective To investigate the immunologic properties of osteogenic differentiated bone mesenchymal stem cells (BMSCs). Methods BMSCs were isolated from normal volunteers and induced in osteogenic medium for two weeks. Then,non-differentiated/osteogenic differentiated BMSCs were co-cultured with allogenic T cells and phytohemagglutinin (PHA).The proliferation of T cells was examined by MTT method.The concentrations of TGF-β1 in osteogenic differentiated BMSCs supernatants at week 2 and mixed lymphocytes reaction (MLR) supernatants at day 5 were determined by ELISA.Also,anti-TGF-β antibody was added into the MLR to detect the response of the mixed T cells. Results Non-differentiated and osteogenic differentiated BMSCs did not induce proliferation of the allogeneic T cells but both suppressed the proliferation of the T cells mediated by PHA.The TGF-β1 concentrations had significant elevation in the MLR.Anti-TGF-β antibody could counteract the immunosuppressive function of the osteogenic differentiated BMSCs. Conclusion Osteogenic differentiated BMSCs possess low immunogenicity and immunosuppressive property.
ABSTRACT
BACKGROUND: Tissue engineering development brings a hope for articular cartilage defect repair. Current studies have demonstrated that bone marrow mesenchymal stem cells (MSCs) are the best cell source to repair full-thickness cartilage defects.OBJECTIVE: To induce MSCs to differentiate into chondrocytes with Ad-hTGF-pi in pellet culture system in vitro and identify the differentiated cells.DESIGN, TIME AND SETTING: Repetitive cellular measurements were performed at the Central Laboratory of Xinqiao Hospital,Third Military Medical University of Chinese PLA from June 2007 to January 2008.MATERIALS: Japanese rabbits, 2 months old, were provided by the Laboratory Animal Center of Third Military Medical University of Chinese PLA.METHODS: The rabbit MSCs were isolated, cultured and expanded in vitro. After transacted with Ad-hTGF-β1, the cells were cultured in pellet culture system. Chondrogenic differentiation was evaluated by histological, immunohistochemical and RT-PCR techniques.MAIN OUTCOME MEASURES: Cell morphological changes were observed by histological staining; proteoglycan and type Ⅱ collagen expression was detected by immunohistochemical and RT-PCR techniques.RESULTS: The induced cells exhibited a chondrocyte-like morphology by histological staining. Immunohistochemical and RT-PCR results showed that proteoglycan and type Ⅱ collagen were expressed in the induced cells.CONCLUSION: Bone marrow MSCs cultured in pellet culture system can differentiate into chondrocytes under the induction of Ad-hTGF-β1.
ABSTRACT
BACKGROUND:Tissue engineering development brings a hope for articular cartilage defect repair.Current studies have demonstrated that bone marrow mesenchymal stem cells (MSCs) are the best cell source to repair full-thickness cartilage defects.OBJECTIVE:To induce MSCs to differentiate into chondrocytes with Ad-hTGF-?1 in pellet culture system in vitro and identify the differentiated cells.DESIGN,TIME AND SETTING:Repetitive cellular measurements were performed at the Central Laboratory of Xinqiao Hospital,Third Military Medical University of Chinese PLA from June 2007 to January 2008.MATERIALS:Japanese rabbits,2 months old,were provided by the Laboratory Animal Center of Third Military Medical University of Chinese PLA.METHODS:The rabbit MSCs were isolated,cultured and expanded in vitro.After transfected with Ad-hTGF-?1,the cells were cultured in pellet culture system.Chondrogenic differentiation was evaluated by histological,immunohistochemical and RT-PCR techniques.MAIN OUTCOME MEASURES:Cell morphological changes were observed by histological staining;proteoglycan and type II collagen expression was detected by immunohistochemical and RT-PCR techniques.RESULTS:The induced cells exhibited a chondrocyte-like morphology by histological staining.Immunohistochemical and RT-PCR results showed that proteoglycan and type II collagen were expressed in the induced cells.CONCLUSION:Bone marrow MSCs cultured in pellet culture system can differentiate into chondrocytes under the induction of Ad-hTGF-?1.