The Construction Of Vascular Tissue Engineering Bone

The jaw bone defection reparation's process is consist of revascularization, bone generation and fusion of the fracture. above these the most basic element is the revascularization. It can bring the pro-osteoblast, signaling molecule, nutritive material into the local microenvironment and Bring away the cellular necrosis production.so the revascularization can improve The regeneration of bone defect. With the development of the tissue-engineering's techique and theroy,there has been some way to construct the vascular bone: microsurgery technology, tissue-egineering bone with muscle flap, blood vessel fascia capsulate bone and contained many growth factor. but all of them have the shortcomings as the secondary trauma, origination is limited, uncontrolled of the speed of slow-released growth factor and the transplantable bone is uneasy to survive.The vascular endothelial cell's application in bone defect reparation can enhance the vascularization.lots of experiments have proved the vascular endothelial cell secret many growth factors like VEGF, BFGF.BFGF can induce the generation of blood vessel in many animal models. VEGF can affect BMP which is important in pro-osteoblast's proliferation and differentiation. The osteoblast also secrete BFGF and VEGF. Dr.Wang observed the osteoblast keep on expressing VEGFmRNA,and stimulate the prolification of VECs.most researchers considered that the two kinds of cells affect each other dependent of autocrine grow factor. Frenrich cultured the adipose cell on the scaffold with the VECs in collogen material. He observed new blood vessels in the ground substance. There has been the possibility of revascularization through mix culture two different cells.so we cocultured the VECs and MSCs as the bone tissue-engineering seed cells.the seed cells not only construct blood vessels which provide nutrient for the tissue-engineering bone,but also secret many grow factors to accelerate the speed of bone defect regenenaration.Dr.Qu has cocultured the rat kidney VECs and MSCs compared with only cultured MSCs on PLGA scaffold to investigate the connection between VECs and MSCs,And he investigated X ray density and quality of new bone of 8w and 12w cocultured exemplar are definitely higher than the control exemplar.in the microscope there was new blood capillary in the center of the PLGA at 2w.that proved that kidney VECs have the ability to construct blood capillary and fusion with each other as the blood vessel net. But the VECs acquired from rat kidney are the ripe VECs, the cytoactive is low and difficult to passage.more and more reserchers use the tissue-egineering bone to repair the defect of jaw bones. Tissue-egineering bones have many advantages especially can increase the histocompatibility and plasticity, be convenient to obtain and can repair quickly .but the key point is how to construct the local vascularization . In our research,we used the mesenchymal stem cells which is separated from rat as Tissue-egineering bones the seed cells have many advantages especially can increase the histocompatibility and plasticity, be convenient to obtain and can repair quickly .after passage we get enough cells .then the cells were cultured in vascular endothelial cell conditioned M199 medium, so the mecenchymal stem cells can induced to vascular endothelial cell. The induced VECs were identified by electron microscope and immunohistochemical staining with factorâ…§,CD34 to observe their function and morphous .and we cocultured the MSCs and VECs as the experimental group compared with only cultured MSCs. We detect the total protein and alkaline phosphatase(ALP) activity on 3d,6d,9d,12d,15d.and we observed the induced VECs's impact on ossification of MSCs through ALP and AZR staining.we sythesis the PLGA scaffold which containd typeâ… collagen as the 3D direct culture vetor to culture the MSCs and the induced vascular endothelial cells and then be planted into the rabbit mandibular defection .The control group use the PLGA only with MSCs.On the 4w and 8w we used the soft X ray and specimen slice method to evaluate under the induce of endothelial cells the function of vascular bone construction.Result: In vitro culture condition, under the inducement of conditional medium 2 weeks,the mesenchymal stem cell can diffrientiate into vascular endothelial cell.,â…§and CD34 immunohistochemical staining positive result are obviously high density than the control group.the 2 weeks cocultured cells express black extracellular calcification nodus in ALP dyeing and red calcification nodus in alizarin red dyeing. The total protein and ALP activity of experimental group was also higher than the control one.In vivo experiment we use soft X ray to observe the aberrance osteogensis function of PLGA scaffold with cocultured cells.Specimen HE dyeing found the area of angiopoiesis in experimental group is obviously larger than the control group.and the difference had statistical significance (P<0.05).Conclusion: the mesenchymal stem cell can induce into VECs ;the induced VECs have well to compatibility with MSCs and PLGA;The induced VECs can promote MSCs differentiate into osteroblast; the coculture 3D system can restore the defection of mandibular more effective and have more angiopoiesis efficiency than sigle cuture system.The research manbe provide the theory proof of using vascular artificial bone to rebuild the large jaw defection.