Objective To investigate the effect of hyperbaric-oxygen therapy on osteoprotegerin (OPG) and integrin β1 (Itgβ1 ) expression during mandibular distraction osteogenesis .Methods Forty New-Zealand rabbits were used .The animals were randomly divided into two groups (experimental group and control group) with 20 animals each ;after accomplished osteotomy and implant distraction devices on mandible bilaterally for 3 days of latency period ,the device was activated at the rate of 0 .8 mm per day for 10 days .All animals in the experimental group were subjected to hyperbaric oxy -gen for 90 minutes once a day since the beginning of distraction ,and lasted for four weeks .In control group ,all the distractors were activated following the same distraction protocol as the experimental group ,but without hyperbaric oxygen therapy .Five animals of each group were sacrificed at 10th day after distraction ,7th ,14th and 28th day of consolidation , respectively .The lengthened mandibles were harvested and processed for immunohistochemical examinations to detect OPG and Itg β1 expres-sion in the distraction gap .Semi-quantitative analysis was carried out by image analysis software . Results OPG staining was mainly located in the membrane and cytoplasm of osteoprogenitor cells and osteoblasts in the distraction zones .The expression of OPG increased after distraction accomplished and reached to the peak at 7th day of consolidation ,and then decreased gradually .At every time point , the level of expression of OPG in the experimental group was remarkably higher than those in control group .There were significant differences between the experimental group and control group ( P <0 .01) .Itgβ1 mainly located in actively proliferating osteoblasts ,fibroblasts and mesenchymal cells . The expression of Itgβ1 decreased significantly after reached to the peak at the 10th day distraction .At 10th day distraction ,7th and 14th day of consolidation ,Itgβ1 expressed more strongly than that in the experimental group ,which was remarkably higher than those in control group .There were significant differences between experimental group and control group (P < 0 .05) .At 28th day of consolidation , Itgβ1 expressed weakly ; there was no significant difference between the two groups ( P > 0 .05 ) . Conclusions Hyperbaric oxygen therapy can up-regulate the expression of OPG and Itgβ1 in the dis-traction gap ,which may promote osteoblast differentiation ,proliferation ,enhance osteoblast func-tion ,and new bone formation in distraction gap .

Objective: To explore the role of β-catenin in distraction osteogenesis of new bone formation, the expression of β-catenin in the distraction gap callus was detected during rabbit mandibular distraction osteogenesis. Methods: 26 New-Zealand rabbits were randomly divided into 3 groups. Group A is a normal control group with 2 rabbits, group B is the mandibular defect control group, and group C is the distraction group. Group B and C with 12 rabbits, respectively. The two rabbits in group A without surgery, their mandibles are normal control. In group B, vertical osteotomy was performed between the first molar and the mental foramen on the mandibles bilaterally, followed by rigid internal fixation with titanium plates and screw with 5 mm gap immediately. In group C, after the same osteotomy was performed, the fragments of mandibles were reduced and fixed with mandibular distractors bilaterally. On the fourth day postoperatively, the distraction started at a rate of 0.8 mm/d and lasted for 7 days, followed by consolidation period. Two rabbits of group B and C were sacrificed at 6th, 10th, 17th, 24th, 31st, 38th day postoperatively, respectively. The newly formed callus in the distraction gap of mandibles was harvested for Western blotting and immunohistochemistry examination to detect the distribution and expression of β-catenin. The experimental data were analyzed by SPSS 22.0 statistical software using Spearman function. Results: The result of Western blotting showed that the expression of β-catenin gradually increased at distraction period(6-10 days after surgery) and reached the peak at the end of the distraction period(10th day postoperatively), it gradually decreased during the consolidation period. However, the expression of β-catenin in group C was higher than that of group B. Immunohistochemistry stain showed that the expression of β-catenin mainly located in inflammatory cells(eg. monocyte), fibroblast of the granulation tissue, the osteoblasts, osteocyte on the surface of new formed trabecular, and the connective tissues surrounding the new bone in the new formed callus. Cytoplasmic and nuclear staining were positive. In group C, the expression of β-catenin was strong (3.245 8±0.132 3) after distraction (6th day postoperatively), and reached a peak (4.602 8±0.021 9) on the 10th day postoperatively. With the disappearance of the distraction stress, the expression of β-catenin gradually decreased since17th day postoperatively(3.639 8±0.125 5), but the staining was still positive. In group B, the strong positive staining of β-catenin on the 6th day after surgery (2.734 0±0.134 7), the strongest staining on the 10th day after surgery (3.101 3±0.104 8), and the expression of β-catenin on the 17th day after surgery (2.542 8±0.211 1) was weaker than that on the 10th day after surgery. At each time point, the expression of β-catenin in group C was significantly higher than that in group B, and the difference was statistically significant (r=0.943, P=0.005 6). Conclusions During mandibular distraction osteogenesis, the distraction stress activates the Wnt signal pathway to enhance the expression of β-catenin, it suggests that β-catenin plays an important role in the transformation of the mechanical signal to chemical signals during the process of distraction osteogenesis, and participates in the regulation of new bone formation during distraction osteogenesis.

Objective To investigate the optimal time and molecular mechanism of gene therapy for promoting distraction osteogenesis by observing the effect of gene transfecting at different time on expression of cyclins in mandibular distraction area.Methods Forty eight New-Zealand rabbits were employed.After accomplishing bilateral mandibular distraction osteogenesis model,the rabbits were randomly divided into the group A,B,C and D.The group A,B and C were transfected by recombinant plasmids pIRES-hBMP2-hVEGF165 2 μg(0.1 μg/μL)at the distraction area instantly after operation,on postoperative 4,14 d and given local electroporation stimulation.The four groups entered the consolidation stage after 10 d continuous traction at a rate of 1 mm/d on postoperative 4 d.Three rabbits in each group were respectively sacrificed on 7,14,28,56 d of the consolidation stage.The expression of cyclin A,D1,and E of fresh bone tissue in distraction area were detected by immunohistochemical staining.Results Cyclin A,D1,and E were strongly expressed in the traction gap on 7,14 d of consolidation stage found,which was strongest on 7 d,moreover the group A,B and C were stronger than the group D.The expression in each group was weakened on 28,56 d.The expression on 7 d in the group B was stronger than that in the4 group A,C and D(P<0.05),the expression had no statistical difference between the group A and C(P>0.05),but all were stronger than the group D(P<0.05);the expression in the group B and C on 14 d was stronger than that in the group A and D,but the expression had no statistical difference between the group B and C and between the group A and D(P>0.05).Conclusion The high expression of cyclin A,D1 and E can promote the cellular division,proliferation and differentiation in distraction area,thus accelerates the new bone formation in the distraction area,prompting that the distraction period is the best time for distraction osteogenesis under gene therapeutic intervention.

Objective To explore the clinical effect of endoscopic-assisted intraoral reduction mandibuloplasty.Methods From January 2010 to December 2014,a total of 186 patients with prominent mandibular angles underwent one stage long-curved ostectomy combined with splitting corticectomy through an intraoral approach with endoscopic assistence according to preoperative design for reduction mandible three-dimensionally,and achieved reduced width of the lower face with smooth curve of mandibular edge.The distance between both gonions was measured and the complications recorded to evaluate the clinical effect of the surgery during follow-up.Results All the 186 patients had no complications of bleeding and infection.The mean distance between both gonions measurement was (117.3±2.5) mm before surgery and (102.6±2.3) mm after operation;it was reduced (14.1 ±2.4)mm.After 1 month to 2 years of follow up,the width of the lower face was reduced in the frontal view and the mandibular angle appeared natural and inconspicuous in the lateral view.The patients were satisfied with both their frontal and lateral appearances.Conclusions Intraoral approach mandibular ostectomy with endoscopic-assisted allows surgeons to perform accurate,safe and reproducible ostectomies and to recontour mandible symmetrically and reduce the complications.

Objective Cephalometry has been used to measure the changes of mandibular shape before and after the surgery.The aim of this study was to evaluate the effect of mandibular angle osteotomy.Methods A lot of 42 cases with complete data were selected,cephalometric analysis were performed before operation and one week and 6 months after surgery,respectively.Furthermore,the data of six months postoperatively were compared to those of the beauty people reported in the literature.Results At one week after surgery,the average distance between the gonions decreased (17.70± 8.46) mm,the average length of the mandibular ramus reduced (5.84±3.26) mm,the average mandibular body length increased (4.61±2.74) mm,the average gonial angle increased (14.78±6.65)°,and the average mandibular plane angle increased (10.29±3.82)° (P＜0.05).At six months postoperatively,the first three linear measurements increased (3.68±2.91) mm,(1.66±2.51) mm and (2.10±2.37) mm,respectively;however,the last two angular measurements reduced (2.86±3.02)°and (1.77±2.62)° respectively.The data of six months postoperatively were compared to those of the beauty people reported in the literature,and there were statistically differences between the linear measurements,but no statistically differences between the angular measurements.Conclusions Re duction mandibuloplasty can modificate mandibular contouring three-dimensionally.Despite bone regeneration resuhs in linear or angular measurements change,postoperative angular shape is predominantly maintained,and so the patients can reach the level of beauty papulation.

Objective To observe the effect of hyperbaric oxygen therapy (HBOT) on mineral density and biomechanics of new-formed bone in distraction gap.Methods The mandibles were subjected to osteotomy and distractors were placed bilaterly in 30 rabbits,which were divided randomly into 2 groups.After 5 days for latency,the mandibles were distracted at a rate of 0.8 mm/day for 10 days,and then for consolidation.After surgery,group A received HBOT with daily distraction,whereas group B only distracted without HBOT served as control group.The animals in groups A and B were sacrificed 1 wk,2 wk,4 wk of consolidation,respectively.The mandibles were harvested and subjected to examination for new bone formation,and bone mineral density (BMD) and biomechanics of newly formed bone in the distraction gap.Results At one week of consolidation,no significant differences were observed between the BMD of newly formed bone in the two groups (P＞0.05);however,at the other time points,BMD of newly formed bone in group A was significantly higher than that in group B (P＜0.05).Moreover,at 4 weeks of consolidation,the strength,maximum fragile energy and modulus of elasticity of newly formed bone in group A were significantly higher than those in group B (P＜0.05).Conclusions The results suggest that HBOT improves mineral density and strength of new formed bone in distraction gap.

OBJECTIVETo investgate the expression patterns of bone morphogenetic protein-2 (BMP-2) in the distraction area following plRES-hBMP2-VEGFI65 gene transfection at different time during mandibular distraction osteogenesis in a rabbit model.

METHODS48 New-Zeland rabbits were employed to underwent osteotomy and distraction devices implantation on mandible bilaterly. After 3 days of latency period, the devices were activated at the rate of 0. 8 mm per day for 10 days. The rabbits were randomly divided into 4 groups (group A, B, C and D). Group A, B and C were transfected recombinant plasmids pIRES-hBMP2-hVEGF165 via electroporation-mediated approach at latency period, distraction period, consolidation period respectively. Group D was used as control group without gene transfection. Three rabbits in each group were sacrificed at 1, 2, 4 weeks of consolidation respectively. The mandibles were harvested for immunohistochemical staining detection of BMP-2 expression respectively, which were analyzed by CMIAS series multifunction color quantitative analysis of pathological image analysis system.

RESULTSBMP-2 expression was found to be mainly located in the monocyte, fibroblast of the granulation tissue, the osteoblasts, osteocyte on the surface of new formed trabecular, and the connective tissues surrounding the new formed bone. The expression in group B was superior to other groups. Image analysis showed that, at the first week and second week of consolidation, the expression abosordbance A in group B (0. 58 ± 0. 03 and 0. 34 ± 0. 02) was relatively higher, when compared with that in group A (0. 42 ± 0. 02 and. 31 ±0.01), C(0.32 ±0.01 and 0.30 ±0.01)and D(0.27 ±0.01 and 0.23 ±0.02), showing a significant difference(P <0. 05). It was also relatively higher in group A(0. 42 ± 0. 02 and 0. 31 ± 0. 01) and C(0. 32 ± 0.01 and 0.30 ± 0.01), when compared with that in group D(0. 27 ±0.01 and 0.23 ± 0. 02), showing a significant difference( P < 0. 05) , but there was no significant difference ( P > 0. 05) between group A and group C. At the fourth week of consolidation, the expression decreased and there was no significant difference among group A, B, C, D.

CONCLUSIONSThe electroporation-mediated gene transfection which is transfected at the beginning of traction can promote BMP-2 expression effectively, stimulate bone marrix synthesis and induce proliferation and differentiation of fibroblasts, osteoblasts, endothelial cells, which further effectively promote the new bone formation. It suggests that the distraction stage is the optimal time for gene therapy.

Animals ; Bone Morphogenetic Protein 2 ; metabolism ; Electroporation ; methods ; Genetic Therapy ; methods ; Mandible ; surgery ; Osteogenesis ; Osteogenesis, Distraction ; Osteotomy ; Rabbits ; Time Factors ; Transfection ; methods

Objective To investigate the effect of gene therapy which was mediated by electroporation on the expression of basic fibroblast growth factor (bFGF) duning mandible distraction.Methods Bilateral mandibular osteotomies were performed in New-Zealand rabbit.After a latency of 3 days,the mandibles were elongated using distractors with a rate of 0.8 mm/d for 7 days.The rabbits were randomly divided into 5 groups:2 μtg recombinant plasmids pIRES-hVEGF165-hBMP2,pIRES-hBMP2,pIRES-hVEGF165,pIRES and normal saline (NS) were injected into the distraction area of groups A,B,C,D and E,after completion of distraction,respectively.The lengthened mandibles were harvested and processed for immunohistochemical detection of bFGF,and the mean optic densities and integral optical density of bFGF positive cells were measured by computerized image analyzer.Results bFGF mainly located in fibroblasts,giant monocytes,polynuclear phagocytes,osetocytes,and osetoblasts in the connective tissue around bone tissue.The strongest expression was observed at the 7th day,and weakened at 14th day of consolidation stage,there were no significant difference among groups A,B and C,at the 7th day of consolidation.However,there were significant differences between gene therapy groups (A,B and C) and control groups (D and E) (P＜0.01).Conclusions Gene therapy can enhance and prolong the expression of bFGF in distraction gap,which promotes the cell differentiation and proliferation,extracellular matrix synthesis and new bone formation during distraction osteogenesis.This is probably one of the molecular mechanisms of the gene therapy promoting new bone formation in distraction gap.

Objective To observe the effect of continuous elastic outside distraction on the expression of basic fibroblast growth factor (bFGF) and transforming growth factor-beta 1 (TGF-β1) in the female porcine nipples,and to further investigate the mechanism of continuous elastic outside distraction stimulation on the proliferation of supporting tissue in nipples.Methods Three female minipigs were employed,each of them had 12 nipples.Four nipples of each minipig were used as control group,while the other eight nipples were continuously distracted with prefabricated instruments.One nipple without distraction and two distracted nipples of each minipig were excised at 2,4,8,and 12 weeks after operation under general anesthesia respectively.The excised nipples were prepared for immunohistochemical staining to observe the expression of bFGF and TGF-β1.Image analysis software was employed for quantitative analysis.Results bFGF and TGF-β1 expression of control groups was weaker than those of the distracted groups at any time (P＜0.01).The expression of bFGF increased gradually after tracted and reached the peak at 4 weeks.There was significant difference (P＜0.05) in the expression of bFGF between 4 weeks and 12 weeks groups.The expression of TGF-β1 was increased to the peak after 2 weeks.The expression of TGF-β1 between 8 weeks and 12 weeks groups and 2 weeks group had statistical significance (P＜0.05).The expression of bFGF and TGF-β1 had a positive correlation during the traction.Conclusions Continuous elastic outside distraction can promote female minipig nipple to synthesis and secretion of b-FGF and TGF-β1.

Objective To investigate the expression patterns of major bone growth factors and bone morphogenetic protein-2 (BMP2) in the distracted calluses following transfected gene during mandibular distraction osteogenesis in a rabbit model.Methods Bilateral mandibular osteotomies were performed in New-Zeland rabbits.After a latency of 3 days,the mandibles were elongated using distractors for 7 days.After the completion of distraction,the rabbits were randomly divided into 5 groups.Three animals each were sacrificed at the end of the delay phase,at 7,14,and 28 days after completion of distraction,respectively.The lengthened mandibles were harvested and processed for immunohistochemical detection of BMP2 expression,the mean optic densities and integral optical density of BMP2 positive cells were measured by computerized image analyzer.Results Elevated cellular expression of BMP2,in the distraction gap,was observed following mandibular distraction.BMP2 staining was mainly located in inflammatory cells,and the connective tissues arrounding the new bone.Their strongest expression was the 7th day,some of those growth factors expressed weakly or negatively.Conclusions Electroporation-mediated gene transfection can promote BMP2 expression effectively,which plays an important role in cell differentiation and proliferation during distraction osteo genesis.The BMP2 stimulates extracellular matrix synthesis,induces the proliferation and differentiation of fibroblasts and osteoblasts,which then promotes the new bone formation and repair.