| Background： Distraction osteogenesis(DO) technology is a kind ofendogenous tissue engineering technology, using a specific mechanical device todistract the broken bone and promote the new bone formation progressively. It hasachieved some good therapeutic effects since McCarthy first used the DOtechnology in the correction of Cranial and maxillofacial deformity and bonedefect at the beginning of90s. However, A series of trauma responses exist in theprocess of DO therapy such as wound infection, bone fracture nonunion, fixedscrew loose, which have became the main obstacle of the technology for furtherpromote.Therefore, promoting a new kind of technology to help the newmandibular formation has become a hot spot and a difficulty in Cranial andmaxillofacial surgery research.According to related researches, hyperbaric oxygen(HBO) can boost the new blood vessels and collagen production of the fracturezone, and strengthen the calcium salt deposit on new bone and the procession ofmineralization, then prompt fracture healing and restoration.Objective: Observe the characteristics of the traction area bone tissue and theinfluence to the growth factor expression after giving HBOT. And further discussesthe possible molecular mechanism of the promoting function.Above all, we canfind the foundation and theory of bone tissue trauma, repair and treatment.Methods:120New Zealand white rabbits were randomly divided intoexperimental group and control group. The both mandibular traction models weremade, tracted with the fixed rate of0.8mm a day for10days. The experimentalgroup was given hyperbaric oxygen therapy(HBOT） at the beginning of tractionuntil rabbits were put to death,while the control group kept traction only in the same traction rate and way without HBOT.Fifteen rabbits were put to death afterin traction respectively, the mandibular specimens were taken on fixed1st, andthe1st,2nd,4th week to inspect the expression level of BMP-2(BMPS-2), BMP-7,CD34, vascular endothelial growth factor (VEGF) in the area of traction bonetissue by immunohistochemical detection and do the qualitative analysis ofimage.The samples of control group were taken in the same period.Results:1. HE stain reveals the traction fixed on the first day, whether thecontrol group in traction area or are visible inflammatory cells infiltrate, localblood capillary dilate fracture end both fibrous tissue to generate, and connectingdisruption, bone cell hyperplasia active. The first week after the traction fixed, bothgroups both fibrous tissue began to calcification and extended into a large numberof new blood vessels, a lot of the osteoblast and membrane formation in bone,fibroblasts synthesis secrete plenty collagen fiber and translated into fibrousconnective tissue, even the bone setting of two cut ends, bone trabeculae small,sparse, original callus formation, HBOT group fibrous tissue visible part betweencartilage cells island, and calcification form bone trabeculae, bone broken bonetrabeculae at the thick, bone matrix dyeing deepened. After the second week of thetraction fixed, a lot of blood capillary filling between bone trabeculae, fiberconnection already calcification, inside and outside callus formation, the callusdensity and calcification are higher than the control group.4weeks after traction,the increased traction bone trabeculae coarse neat, and has formed a completeosseous connection, inflammatory cell decreases, the decrease in the number ofcapillary and conversions, to resume normal blood flow.2.On the basis of immunohistochemical detection, all the expression ofBMP-2, BMP-7, VEGF, CD34were strong positive both in the experimental groupand the control group, which were detected in traction bone damage areagranulation tissue, the connective tissue of osteoblast and around. Compard theexpression between the two groups, there was no significant difference(p>0.05)during this time. In the first week, both expression of two groupsdecreased, the BMP-2level of experimental group higher than those in the control group, and there was significant difference between two groups (p<0.05),while inthis period there was no obvious differences between the two groups in thegrowth factors BMP-7, VEGF, CD34(p>0.05).During the second week, theexpression of BMP-7, VEGF, CD34of experimental group was significantlyhigher than the control group (p<0.05), and there was no obviously differences inBMP-2(p>0.05). Until the4th week, the expression of two groups decreasedobviously, and there was no significant differences between two groups (p>0.05).3.The level of VEGF、BMP-2、BMP-7and CD34expression are in positivecorrelation during the same period.Conclusion:1.HBO can raise the growth factors of BMP-2, BMP-7, VEGF, CD34in traction area, and promote the process of capillary endothelial cell proliferation,differentiation and the formation of new bone, thus strengthening the growth ofbone tissue injury and restoration in traction area.2. Under the effects of HBOT, the expression of BMP-2, VEGF BMP-7,CD34are in positive correlation in traction area. Therefore, there might exist aneffect of synergies or superposition in the process of bone repair. |
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