A Study Of In Situ Bone Tissue Engineering And Its Application

[Objective]To study the in situ bone tissue engineering technique and the ability of this technique to reconstruct the bone defects in special parts contained air, and to provid experimental evidence for reconstructing the bone defects in the aera of otolaryngology–head-neck.[Methods]1. Fundamental research for in situ bone tissue engineering: To prepare the acellcular cancellous bone, observe the structure and the biocompatibility of the materials; To culture the rabbit's bone marrow stem cells on the acellcular cancellous bone/BMP-2 in vitro, and then transplant the compound into partes subcutanea. We observed the osteogenesis ability of bone marrow stem cell induced by BMP-2 in situ; To add the BMP-2 into the acellcular cancellous bone, and trandplant into allotopia parts, then observe the osteogenesis ability of mesenchymal stem cell induced by BMP-2 in situ .2. Application study for in situ bone tissue engineering: To choose healthy rabbit to make skull bone specimen, observe the shape and position of the bullae. take fresh bullae to observe the detailed structure through endoscope and pathology technique. and then observe the landmarks of the retroauricular approach in a real surgery; Then from retroauricular approach, to make a hole in the posterolateral bone wall of the acoustic vesicle, and the prepared materials were implanted. After 3 month, we observed the osteogenesis of the prothesis with macroscopical anatomy and pathology; To prepare the acellular cancellous bone combined with BMP-2, and collagen sponges lamella were fixed on the material unilaterally by protein glue. The same material without BMP-2 were used in the control group. To remove part of the maxillary sinus lateral bone wall with mucosa, repair it with the prepared material, and the aspects of collagen sponge were put medially in situ. After 3 month, we observed the osteogenesis and reparation of the defects with macroscopical anatomy and pathology.[Results] 1. The acellular cancellous bone maintained porous structure just like sponge, the diameter of the pores were about 200-600μm, and the intension of the materials weren't significant change than the cancellous bone. No obvious immunological reaction occoured after the materials were transplanted in vivo; In the osteogenesis test, the implanted acellular cancellous bones maintained the shape after they were transplanted 3 month. There were some angiogenesis around the materials, no obvious immune reaction occured. In the acellcular cancellous bone/BMP-2/bone marrow stem cells and the acellcular cancellous bone/BMP-2 groups, osteogenesis were observed. In control groups, no osteogenesis occurred in simple acellular cancellous bone.2. There is a large cavity in the bullae. The rabbit's ossicle and inner ear are in the anterior of the bullae. From the retroauricular incision, following the posterior bone wall of the external auditory canal, we can find the processus styloideus-like structure. Trough the posterior wall , we can open the bullae with the important structure protected well; After 3 month, the implanted acellular cancellous bones were banded tightly with the bone of the acoustic vesicle bone wall. The surface of all materials were covered with mucosa. No obvious transformation of the materials were observe, and in the material with BMP-2, osteogenesis occurred; In the maxillary sinus wall defects repair test, the rabbits recovered soon after surgery, the implanted acellular cancellous bones were banded tightly with the bone around the defects, the medial aspects of the material were covered with mucosa., and new bone were formed after 3 month.[Conclusion]1. The acellcular cancellous bone can maintain its porous structure, no obvious antigenicity, and it is a suitable material for bone tissue engineering.2. BMP-2 can induce the mesenchymal stem cells differentiate into osteobalsts, and induce osteogenesis in allotopia.3. Through the retroauricular incision and surgical approach, we can enter the rabbit's bullae easily, and this technique can be used in the experiments based on rabbit's bullae. 4. The acellular cancellous bone with BMP-2 could induce osteogenesis in acoustic vesicle with primary shape, this material might be use to reconstruct the defects of ossicular chain.5. The BMP-2 could induce osteogenesis, the collagen sponges could support the mucosal regeneration, collagen sponge and acellular cancellous bone combined with BMP-2 could be used to repair the defects of the maxillary sinus bone wall and mucosa.[Significance]This study can provide the theoretic and experimental basis for the bone defects in special parts using in situ bone tissue engineering trchnique.