An Investigation Of Restoration Of Cleft Alveolar With Vascularised Engineered Bone

BackgroundAlveolus cleft is a congenital disease accompanied with cleft lip andpalate, which seriously affects the facial complexion and function. Thedefect will be repaired after the restoration of cleft lip and palate (whenpatient are 9-11 years old). There isn't any clinic verdict of the growth ofthe maxilla during the stage. As a general operative mode, autogolouscancellous (from the ilium or the mandible) is implanted into thedefective part to restore the continuity of the maxilla, to help thegeneration of canine, and to rectify the malformation of the nose. Manycomplications such as pain in the bone taking and bone reception area, etc,are reported during or after the operation. Engineered bone have beenused to restore the bone defect in the limbs during the past 10 years, butthe problem of vascularization remains unsolved, and it is rarely used inthe restoration of alveolus cleft.Therefore, it is necessary to study the growth of pre-maxilla after therestoration of cleft lip and palate, the use of engineered bone, and thechange of form after the use of vascular engineered bone to restorealveolus cleft, and to provide theoretical base for clinical application. Part 1 Influence of surgical induced bilateral cleft alveolus onmaxillary growth in dogsObjective To establish an animal model of bilateral alveolus cleftand study the influence of cleft on maxillary growth.Methods Eight dogs (12 weeks old ) were divided into unoperatedcontrol groups (n=4)and the model group (n=4) .The model dogs wereoperated onto establish a bilateral alveolus cleft. All the animals werekilled and the craniofacial morphology on clean skull was analyzed bythe direct detection and CT.Results The length ,the foreside width and the foreside height ofthe maxilla in the model group were shrunken than those of control group(P＜0.05)Conclusion The alveolus cleft plays an important role in themaxillary aberration.Part 2 An Investigation of Restoration of Alveolus Cleft withEngineered BoneObjective To investigate the feasibility of the restoration ofalveolus cleft with engineered bone constructed by sponge collagenprotein combined bone mesenchymal stem cells (BMSC).Methods Sixteen dogs were divided into 4 groupes, the thirdincisor and alveolus bone with peri0steum in bilateral maxilla wereremoved to form alveolus cleft model. The BMSCs were isolated from dog bone marrow. After being cultured and induced, the BMSCs wereseeded in sponge collagen protein and cultured for 72 hours. Thecomposites of BMSCs and collagen were implanted into the defect ofalveolus cleft. After being fed for 12 weeks, those dogs were killed.Three-dimensional CT and histological examination were used to observethe progress of bone formation.Results The defects healed 12 weeks after BMSCs-collagencomposites were implanted, the width of engineered bone resembledpositive control(implant with autologous cancellous), but the height isless than positive control(P＜0.05).Conclusion The engineered bone can restore the defect ofalveolus cleft, it may be used in the clinical treatment of the restoration ofalveolus cleft.Part 3 An Investigation of Restoration of Cleft Alveolus withVascularised Engineered BoneObjective To investigate the feasibility of the restoration of cleftalveolus with vascularised engineered bone constructed by collagencombined with vascular endothelial growth factor (VEGF) genetransfected bone mesenchymal stem cells.Methods The BMSCs were isolated by gradient densitycentrifugation with Percoll solution from dog bone marrow. After beingcultured and VEGF165 gene transfected, Verified by FCM, RT-PCR and IHC, BMSCs were seeded in collagen for 72 hours. The compositesof BMSCs and collagen were implanted into the defect of cleft alveolusof dog. After being fed for 12 weeks, those dogs were sacrificed. X-ray,three-dimensional CT and histological examination were used to observethe bone formation.Results 52% of BMSCs were transfected with VEGF165plasmid successfully. The defects of cleft alveolus healed at 12 weeksafter being implant collagen and VEGF 165 plasmid transfected BMSCcomposites and the forms of engineered bone resembled those implantedby autologous cancellous bone.Conclusion The vascularised engineered bone can repair thedefect of alveolus cleft effectively. It may be used in the clinic.Part 4 Application of Endothelial Progenitor Cell in Restoration ofCleft Alveolus with Engineered BoneObjective To investigate the feasibility of the restoration of cleftalveolus bridge with vascularised engineered bone which wereconstructed by collagen combined with endothelial progenitor cells(EPC)and bone mesenchymal stem cells (BMSC).Methods Twenty dogs were divided into 5 groups.The BMSC andEPC were isolated from dog bone marrow. EPC were purified bytime-limited digestive method. After being cultured and identified, BMSC and EPC were seeded in collagen for 72 hours. The composites wereimplanted into the defect of cleft alveolus model of dogs. After being fedfor 12 weeks, 20 dogs were sacrificed. X-ray, three-dimensional CT andhistological examination were used to observe the bone formation.Results The alveolus defects healed 12 weeks after beingimplanted composites and the forms of engineered bone resembled thoseimplanted by autologous cancellous bone. The engineered bone had morevessels than control groups in section.Conclusion EPC may promote the vascularization and ossificationof the engineered bone. Combined with BMSC, the vascular engineeredbone can repair the defect of alveolus cleft effectively, and it may be usedin clinical practice.