miR-206 inhibits osteogenic differentiation of bone marrow mesenchymal stem cells by targetting glutaminase.

Osteoblast-mediated bone formation is a complex process involving various pathways and regulatory factors, including cytokines, growth factors, and hormones. Investigating the regulatory mechanisms behind osteoblast differentiation is important for bone regeneration therapy. miRNAs are known as important regulators, not only in a variety of cellular processes, but also in the pathogenesis of bone diseases. In the present study, we investigated the potential roles of miR-206 during osteoblast differentiation. We report that miR-206 expression was significantly down-regulated in human bone marrow mesenchymal stem cells (BMSCs) at days 7 and 14 during osteogenic induction. Furthermore, miR-206 overexpressing BMSCs showed attenuated alkaline phosphatase (ALP) activity, Alizarin Red staining, and osteocalcin secretion. The mRNA levels of osteogenic markers, Runx2 and Osteopontin (OPN), were significantly down-regulated in miR-206 overexpressing BMSCs. We observed that significantly increased glutamine uptake at days 7 and 14 during the osteogenic induction and inhibition of glutamine metabolism by knocking down glutaminase (GLS)-suppressed osteogenic differentiation of BMSCs. Here, we discover that miR-206 could directly bind to the 3'-UTR region of GLS mRNA, resulting in suppressed GLS expression and glutamine metabolism. Finally, restoration of GLS in miR-206 overexpressing BMSCs led to recovery of glutamine metabolism and osteogenic differentiation. In summary, these results reveal a new insight into the mechanisms of the miR-206-mediated osteogenesis through regulating glutamine metabolism. Our study may contribute to the development of therapeutic agents against bone diseases.

[Minimally invasive percutaneous plate osteosynthesis versus open reduction and internal fixation for distal tibial fractures in adults: a meta-analysis].

OBJECTIVE: To perform a meta-analysis on clinical outcomes of minimally invasive percutaneous plate osteosynthesis (MIPPO) or open reduction and internal fixation (ORIF) for distal tibial fractures in adults. METHODS: Pubmed database (from 1968 to March 2014), Cochrane library and CNKI database (from 1998 to March 2014) were searched. Case-control study on minimally invasive percutaneous plate osteosynthesis (MIPPO) or open reduction and internal fixation (ORIF) for distal tibial fractures in adults were chosen,and postoperative infection, operative time, blood loss, fracture nonunion rate, delayed union,fracture malunion rate were seen as evaluation index for meta analysis. The system review was performed using the method recommended by the Cochrane Collaboration. RESULTS: Totally 5 studies (366 patients) were enrolled. Meta-analysis showed that there were significant meaning in postoperative infection between MIPPO and ORIF [OR = 0.23,95% CI (0.06,0.92), P = 0.04]; fracture nonunion rate in MIPPO was lower than in ORIF group [OR = 0.16, 95% CI (0.03,0.76), P = 0.02]; operative time in MIPPO was shorter than in ORIF group, and had significant difference [MD = -14.42, 95% CI (-27.79, -1.05), P < 0.05]; blood loss in MIPPO was less than in ORIF group [MD= -87.17,95%CI (-99.20, -75.15), P < 0.05]; there was no obviously meaning in delayed union between two groups. CONCLUSION: For distal tibial fractures in adults, MIPPO has, advantages of short operative time, less blood loss, lower incidence of infection and fracture non-uniom, but with high fracture malunion rate. MIPPO for distal tibial fractures in adults is better than ORIF, and the best treatment should choose according to patient's condition.

Rotational acetabular osteotomy through an Ollier lateral U approach for early-stage osteoarthritis secondary to acetabular dysplasia.

OBJECTIVE: To explore the surgical technique and mid-term results of rotational acetabular osteotomy for early -stage osteoarthritis secondary to acetabular dysplasia. METHODS: Rotational acetabular osteotomies were performed on 14 hips of 12 patients from May 2000 to May 2006 and the patients followed up. All patients were female and their average age was 28.9 years (range, 13-46 years) at the time of surgery. The mean duration of clinical and roentgenographic follow-up was 6.0 years (range, 3.1-9.1 years). The lateral center-edge (CE) angle, acetabular roof angle and head lateralization index were measured on radiographs taken preoperatively, postoperatively and at the time of final follow-up. Clinical follow-up included use of the Harris hip score. The acetabular osteotomies were performed through an Ollier lateral U transtrochanteric approach and postoperative traction and cast immobilization were not used. RESULTS: All patients had satisfactory pain relief. The mean preoperative Harris score was 72 points; this had improved to a mean of 91 points at the time of last follow-up (P < 0.05). The mean CE angle improved from 0.9° preoperatively to 27° postoperatively (P < 0.05), the mean acetabular roof angle from 29° to 5° (P < 0.05) and the mean head lateralization index from 0.68 to 0.65. Solid bone-to-bone healing of the osteotomy sites and great trochanters occurred in all patients. CONCLUSIONS: Rotational acetabular osteotomy through an Ollier lateral U approach, which provides wide exposure and technical ease, for early-stage osteoarthritis secondary to acetabular dysplasia can relieve pain and delay the appearance or reduce the severity of osteoarthritis. Satisfactory mid-term results can be obtained.

Early and middle term results after surgical treatment for slipped capital femoral epiphysis.

OBJECTIVE: To evaluate the early and middle-term results of in situ single screw fixation and subtrochanteric osteotomy of the femur with external fixator for slipped capital femoral epiphysis (SCFE). METHODS: From June 1998 to July 2008, 11 patients (seven male [eight hips] and four female [four hips]) of average age 14.3 years (range, 9-18 years) were treated in our hospital. According to the Southwick measurement, seven hips were mildly affected (<30°), two moderately (30-50°), and three severely (>50°). The average body mass index (BMI) was 31.1 g/m(2) (range, 27-35 g/m(2) ). All the mild and moderate cases underwent in situ single screw fixation, and the three severe cases subtrochanteric osteotomy of femur with external fixator. All cases were evaluated both clinically and radiographically at 3 months, 6 months and every year postoperatively. RESULTS: All cases were followed up for 2-12 years (average 5.6 years). The Harris hip score increased from a mean of 74.8 (70 ∼ 85) points preoperatively to 90.6 (70 ∼ 100) points postoperatively. X-ray films showed epiphyseal closure in the in situ single screw fixation cases, and no further increase in epiphyseal-shaft angle. Partial reduction of slipped epiphysis with normal joint spaces was observed after subtrochanteric osteotomy of the femur in the external fixator cases. CONCLUSION: In situ single screw fixation for treating mild and moderate SCFE has a satisfactory clinical outcome, and the advantage of prevention of further slippage. Subtrochanteric osteotomy of the femur with external fixator is suitable for severe SCFE with late deformity; the realignment procedure can correct deformity and postpone or prevent subsequent osteoarthritis.

Experimental study on phase-contrast imaging with synchrotron hard X-ray for repairing osteonecrosis of the femoral head.

Synchrotron radiation light is 1 of 4 artificial light sources, the others being electric light, X-ray, and laser. Phase-contrast imaging with hard X-ray has achieved wide application in many scientific fields, such as biomedicine and material science. This article compares the effectiveness of nanohydroxyapatite/collagen (nHAC) and autologous mesenchymal stem cell for the repair of defects in a rabbit model with osteonecrosis of the femoral head under the monitoring of phase-contrast imaging with synchrotron hard X-ray. We established models of bilateral osteonecrosis of the femoral head defect using New Zealand rabbits and divided them into 3 groups. Imaging techniques such as phase-contrast imaging and diffraction enhanced imaging with synchrotron hard X-ray were applied to assess the degradation and repair process of nHAC and mesenchymal stem cell at 4, 8, and 12 weeks postoperatively. We found phase-contrast imaging with synchrotron hard X-ray displayed the reparative process of the bone defect, degradation of nHAC, and osteocyte substitution. There were significant differences in the repair of the bone defect and osteogenesis in groups B and C compared with group A (control). Osteogenesis was more significant in group C. We provided experimental data for the development and application of synchrotron hard X-ray imaging techniques and concluded that phase-contrast microimaging with synchrotron hard X-ray displays the reparative process of bone tissue at a micro-level and plays an important role in the development of tissue engineering.

[Repair of articular cartilage defects by autologous adipose derived mesenchymal stem cell: experiment with rabbits].

OBJECTIVE: To evaluate the effectiveness of autologous adipose derived mesenchymal stem cells (ADSCs) transduced by adenovirus-mediated human transforming growth factor 2 (Ad-hTGF-beta2) gene in the repair of articular cartilage defects. METHODS: Rabbit ADSCs were obtained, cultured, and transfected with Ad-hTGF-beta2 containing human transforming growth factor (hTGF)-beta2. Three days later RT-PCR was used to detect the mRNA expression of hTGF-beta2 in the ADSCs, and ELISA was used to detect the protein expression of hTGF-beta2 in the supernatant. phosphorylation of Smad was examined by Western blotting. Articular cartilage defects at the femoral trochlea were made on 20 rabbits (40 sides) so as to establish animal models. The culture-expanded rabbit ADSCs transfected with Ad-hTGF-2 were seeded on poly (L-lactic-co-glycolic acid) (PLGA) scaffolds. The cell-adhered PLGA scaffolds were implanted into the articular cartilage defects. Plain PLGA was implanted into the left-side defects of 10 rabbits as control group and the defects of 10 sides remained untreated as blank control group. The rabbits were sacrificed 4, 12, and 24 weeks after the operation respectively. The specimens of defects were examined histologically and stained immunohistochemically for type II collagen. RESULTS: After transfection the ADSCs expressed mRNA and protein expression of hTGF-beta2 and Western blotting showed bands of phosphorylated Smad. The cartilage specimens harvested from the experimental group rabbits demonstrated hyaline cartilage formation mingled closely with the nearby tissues and expression of type II collagen. However, only fibroblasts, not cartilage-like cells, were seen in the control groups that lacked the expression of type II collagen too. CONCLUSION: Culture-expanded autologous ADSCs adhered with PLGA composites facilitate the formation of hyaline-cartilage.