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.

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.

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.

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.

Minimally invasive surgery has become a trend in modern orthopedic surgery,and the demand for intraoperative imaging has gradually increased.Good intraoperative imaging can assist the orthopaedic surgeon in accurately positioning the anatomy and placing the internal fixation.However,intraoperative imaging inevitably exposes the orthopaedic surgeon and patient to ionizing radiation,and radiation exposure can induce DNA damage and reactive oxygen species.Production results in cell damage that often leads to cell death or genomic instability leading to increased risk of various radiation-related conditions,including malignancy.Although the traditional intraoperative fluoroscopy operating room will be equipped with lead clothing and lead collar to reduce radiation exposure,it is not known whether the lead clothing and lead-covered parts are safe.Therefore,radiation safety has become an inevitable problem for orthopedic surgeons in intraoperative imaging,and how to effectively reduce and avoid unnecessary exposure to ionizing radiation is particularly important for bone surgeons and patients.This article aims to review the occupational exposure and radiation safety of intraoperative imaging in orthopaedic surgery.