The Research Of Bionic And Multiplex Artificial Chest Wall

BackgroundReconstruction of chest wall defects remains a great challenge for the reconstructive surgeons. Extensive chest wall defects, which result primarily from tumor, radiation necrosis, infection, or trauma, often require prosthetic repair to prevent flail chest and paradoxical breathing. The artificial prostheses have gained increasing popularity as it provides better stability with shorter and easier surgical procedure. Over the years, many different types of materials have been introduced and used to repair the chest wall. However, no product possesses the properties of the ideal material and late wound complications such as prosthesis dislocation, infection, fistulas or dense scar tissue formation, occur frequently in the chest wall reconstruction, due to the properties of the employed materials. As to the method of reconstruction, the sandwich structure "marlex mesh+bone cement+marlex mesh" is the most popular method in clinic use, but it can't reconstruct the chest wall defect both in anatomy and function which result in affecting the shape of chest wall and the observation of the organ in the chest cage.Now, tissue engineering technique has achieving tremendous success in clinic use, including bone, cartilage,skin reconstruction. Tissue engineering technique contains two critical factors, seed cell and scaffold. Bone marrow stem cell(BMSC) which can been induced to various cell is an acknowleded seed cell. As to the use of scaffolds, there are many different types and forms, but to now there is no ideal material and method. And long bone defect reconstruction is still a challenge problem.Objective1.On the base of early research, explore new method of weavement to improve the PDO mesh which would have two cages and to be the scaffold of soft tissue reconstruction; Choose the most suitable tissue engineered rib scaffold to reconstruct the rib defect;2. To prove the possibility of the method that using multiple scaffolds to reconstruct the long defect of rib,3. To prove the possibility of chest wall reconstruction using PDO mesh and tissue engineering ribMethods 1. The design, preparation of bionic chest wall prosthesisOn the base of early research, PDO suture will still be used as raw material for mesh. New method of weavement will be explored and the improved mesh will satisfy the following requirement:1) The size of the mesh is 8cm×5.5cm; 2) the mesh has two cages; 3)the mesh has many pores which allow the adhesion of tissue2. The selection of tissue engineering rib scaffoldthe biocompatibility and biological safety of the three materials for chest wall prosthesis were evaluated comprehensively in accordance with ISO10993-1:1998 and GB/T16886.1-2001, including in vitro cytotoxicity test, acute systemic toxicity test, hemolysis test, and pyrogen test, and in vivo biodegradation test. In the while, the structure and components of the scaffolds will be analyzed to select the most suitable scaffold.3. the research of long defect of rib reconstruction using multiple scaffoldsThe compound of the PDO cage containing two demineralized bone matrix(DBM) which seeded with osteogenically induced BMSCs was used to reconstruction the single long defect of rib defect. The radiographic examination and histological examination were used to observe the new bone regeneration.4. Establishing the animal model of the chest wall reconstruction using bionic,multiplex prothesisEstablish the animal model of chest wall defect, then reconstruct it with the bionic artificial chest wall designed by ourselves. Observe the regeneration of chest wall tissue including soft tissue and hard tissue by gross view of the sample, radiographic examination, histological examination and mechanical test. Explore the possibility of reconstruction of chest wall defect with biodegradable mesh and tissue engineering rib.ResultsPart 1 We successfully weaved a new PDO mesh which had two cages. The mesh's size is 8cm×5.5cm. The cages diameter is 1.25cm. The intervals between the two cages is 1cm in width. The mesh had a lot of pores whose size is 250um×250um. Besides, the mesh also can be optionally cut out.Part 2 DBM, CPC and PLGA/HA have good biocompatible and they are all nontoxic. The in vivo biodegradation test showed that the degradable speed of PLGA/HA was so fast that it lost its strength 8 weeks after it was inplant into the animal body, in the mean while, the other two materials had good mechanical strength. The structure test showed that DBM and CPC had good pore and HA content. But CPC is more fragile than DBM. So DBM is the most suitable scaffold for tissue engineering rib.Part 3 The result showed that the 4-cm long defect of rib is acknowleded as the long defect of bone as it exceeded the natural regeneration capability. Radiographic and histological examination showed that there were bone union not only in the connection of two scaffolds but also in the connection of scaffold and primary rib. Reconstruction of the long defect of bone using multiple pieces of scaffolds was a feasible method.Part 4 All the dogs survived after surgery while dogs in blank group died. As to the soft tissue reconstruction, PDO mesh completely degraded 6 months after surgery and the primary mesh was replaced by fibrous tissue whose thickness was nearly equal to the normal one.(No significant difference were found between the two groups (P>0.05). As to the rib reconstruction, Radiographic and histological examination showed that there were bone union not only in the connection of two scaffolds but also in the connection of scaffold and primary rib in the experimental group while they were fibrous union in other two groups which had no mechanical strength. The reconstruction rib' s radian was analogus to the primary rib. The result of mechanical test also proved that the strength of reconstructed rib was familiar to the primary one(No significant difference were found between the two groups (P>0.05).ConclusionsXenograft-DBM is a ideal scaffold for tissue engineering tib as it has good compatible and mechanical strength; Reconstucting the long defect of rib with multiple pieces of scaffolds seed with BMSCs is a promising method for the long defect of bone reconstruction; The bionic prothesis can reconstruct the chest wall not only in anatomy but also in function. It can reconstruct the soft tissue and hard tissue in the same time which make it a new and promising method for chest wall reconstruction.