Investigations Into Tracheal Reconstruction With A Newly Developed Prosthesis Made From Biomedical Composite Materials

BackgroundStenosis,complete obstruction or tracheal defects may occur due to trauma,tumors, granulomatous disease,and long-term endotracheal intubation. Since the first tracheal resection and re-anastomosis was performed on humans in 1884,various surgical methods and techniques for tracheal reconstruction have been developed based on the degree and the cause of the tracheal diseases.Primary end-to-end anastomosis is preferred in the reconstruction of tracheal defects less than 50mm-60mm in humans. A large variety of allografts, prosthesis,autogenous tissue and tissue-engineered trachea have been extensively tried to repair larger,circumferential tracheal defects,but only limited success have been achieved experimentally and clinically.Graft ischemia and immunorejection have hindered the success of tracheal all ografts. Reconstruction with autogenous tissue have been found unsatisfactory due to inadequate airway function and poor sources. The research of the tissue-engineered trachea is still in initial stages,and remains numerous problems to be tackled.The development of the prosthetic tracheal grafts was,is and will be a challenging issue in tracheal surgery.In recent years, the perfect integration and development of polymeric sciences and life sciences provide necessary substitutes for restoring and improving the functions of the impaired tissues and oragens.Polymeric biomaterials comprise mainly synthetic and natural materials.The former such as polymers are characteristic of certain mechanical strengths and processing properties,which can provide appropriate scaffolds for cell growth and tissue regeneration.Compared with the former, the latter possessing excellent biocompatibility and biodegradability play a crucial role in inducing and facilitating cell growth and tissue regeneration. If the two kinds of different materials above could be integrated properly,it would be a great innovation theoretically and technically in designing and prefabricating tracheal prosthesis.Objective1. Screening and integrating perfectly the appropriate materials for the design and prefabrication of tracheal prosthesis.2. Evaluating comprehensively the biocompatibility and biological reliability of the selected materials in vitro & in vivo in accordance with ISO and GB/T of China.3.Prefabricating the tracheal prosthesis matching with the host physicochemically and biomechanically by the techniques of synthesizing and knitting;Measuring the bio-mechanical properties of the newly developed tracheal prosthesis.4.Establishing the animal model of the tracheal defects and reconstruction,and observing dynamically the situation of the implanted tracheal prosthesis and the functional changes of tissue structures surrounding the prosthesis.Methods1.Screening the appropriate biomaterials prepared for developing the tracheal prothesis. Biomaterials possessing excellent strength and elasticity were selected to prefabricate the mesh tube as a scaffold,whose inner lumen were coated by polymers and the exterior were laminated by bioactive materials.The biomechanical properties ofpolypropylene(PP), poly(lactic-co-glycolic acid)(PGLA) and Polyurethane(PU) were measured systematically by the use of the elongation test.dynamical thermadynamics, respectively.The structure of Collagen(Col)/Hydroxyapatite (HA) composites was analysed by scanning electron microscope(SEM).2.Evaluating comprehensively the biocompatibility and biological reliability of the selected materials in vitro & in vivo. The biocompatibility and biological reliability of the selected materials were evaluated comprehensively in accordance with ISO10993-1:1992 and GB/T16886.1-1997. The in vitro cytotoxicity test,acute systemic toxicity test ,hemolysis test,pyrogen test, skin hypersusceptibility test, genetic toxicity test and in vivo biodegra-dation test were all conducted.3.Prefabricating the tracheal prosthesis and measuring its biomechanical properties. A tubular mesh were developed by the specific micro-calibre kintting-machine,...