Biomechanical Properties And Cellular Biocompatibility Of 3D Printed Tracheal Graft

Tracheal resection and end-to-end anastomosis,which is currently the "gold standard"clinical approach to tracheal reconstruction,is impossible when more than half of the total tracheal length in adults or a third in children is diseased.When the diseased trachea exceeds the maximum range,tracheal reconstruction is a very challenging procedure because the trachea is not a simple cylinder,but a complex,multilayered structure.The trachea is composed of 15-20 C-shaped cartilages,covered with ciliated epithelium on the inside and connective tissue,including smooth muscles and supporting blood supply,on the outside.The cylindrical shape is supported by the tracheal cartilages,while mucociliary clearance is the essential role of the respiratory epithelium.The connective tissues surrounding the cartilages allows the trachea to bend,expand,or contract.Therefore,there is no method to reconstruct this multilayered trachea and all its functions at once.However,in recent years,the development of 3D printing technology provides a new way for for tracheal reconstruction.3D printing technology which has relied on computer-aided imaging and widely used biological materials as the print medium,can quickly and accurately copy and reconstruct defective tissue or complex structure of organ,so the application in the field of tissue engineering has received extensive attention.Bone marrow mesenchymal stem cells are easily isolated and cultured,and have the potential of multi-directional differentiation,which are the preferred seed cells for tracheal tissue engineering.The purpose of this study is to use PCL as the material,through 3D printing technology to print the tracheal scaffold and to study its cellular compatibility and biomechanical properties,in order to find a suitable tissue engineering tracheal scaffold material.Part1 Preparation and biomechanical Properties of 3D printed tracheal graftObjectivePolycaprolactone was printed as a tracheal graft using 3D printing techniques and in order to study its biomechanical properties.Methods1.Preparation of 3D printed tracheal graft.2.Structure of 3D printed tracheal graft observed by means of scanning electron microscopy.3.Biomechanical testing of 3D printed tracheal graft.Results1.Scanning electron microscopy(SEM)showed that the 3D print tracheal graft had a suitable pore size of 300 to 500μm.2.Biomechanical test results confirmed that the maximum stress and elastic modulus of 3D tracheal graft was significantly better than in vitro fresh trachea,which had good biomechanical properties.Conclusion1.Polycaprolactone was printed as a tracheal graft using 3D printing techniques.2.3D printed tracheal graft shows a reasonable three-dimensional shape,pore structure and structure.3.3D printed tracheal graft shows favorable cellular biocompatibility and biomechanical properties.Part 2 In vitro culture of bone marrow mesenchymal stemcells and cellular biocompatibility of 3D printed tracheal graftObjective1.In vitro culture of bone marrow mesenchymal stem cells.2.3D printed tracheal graft and bone marrow mesenchymal stem cells were co-cultured,and then observed its cellular biocompatibility.Methods1.Obtainment of rabbit bone marrow mesenchymal stem cells.2.Culture of rabbit bone marrow mesenchymal stem cells.3.Identification of rabbit bone marrow mesenchymal stem cells.4.3D printed tracheal graft and bone marrow mesenchymal stem cells were co-cultured,and then observed its cellular biocompatibility.Results1.Bone marrow mesenchymal stem cells obtained by whole bone marrow culture and adherence purification method were cultured to the third generation.The cells were spindle-shaped and polygonal,which could differentiate into chondrocytes and adipocytes.2.The results of cellular compatibility test after co-culture with bone marrow mesenchymal stem cells showed that the 3D printed tracheal patch had good cellular compatibility.Conclusion3D printed trachea graft shows favorable cellular biocompatibility,and therefore can be used as a scaffold material for tissued-engineered trachea.