The Reconstruction Of Tracheal Defect With Bionic Tissue Engineering Trachea

The trachea is an important organ of the human body.Tracheal tumors,trauma,thyroid cancer,congenital tracheal stenosis can cause problems such as tracheal stenosis and life-threatening,so in the clinical practice,it is necessary to remove the diseased trachea and perform tracheal reconstruction.Due to the special anatomical structure of the trachea,if the tracheal resection length of adults is greater than 50% or the tracheal resection length of children is greater than 30%,the end-to-end direct anastomosis of the trachea cannot be performed.Therefore,reconstruction of long tracheal defects requires replacement.However,there is currently no ideal tracheal graft,and tracheal reconstruction is a very challenging task for clinicians.At present,tissue engineering is a hot method to study tracheal reconstruction.The main principle is that a small amount of autologous cells are implanted in a pre-constructed three-dimensional scaffold after in vitro expansion,and finally a tracheal graft without rejection is cultured,so that it has a good research prospect.Research purposes1.On the basis of the previous research of the research group,the tissue engineering tracheal stent with a cross tube was woven with PDO monofilament and PHBV/PLA multifilament,and it was coated and modified to provide seed cells for later stage;2.In vitro the tracheal stent was co-cultured with chondrogenesis induction BMSCs,and exploring methods for in vitro co-construction of BMSCs and tracheal stents to provide materials for the repair of tracheal defects in the next step.3.We used a bionic tracheal stent to repair the animal's tracheal defect and observe the effect of its repair.Research content and method1.Material selection,design,weaving and mechanical evaluation of biomimetic tissue engineering tracheal stentBased on the original research of the research group,the PDO monofilament and the PHBV/PLA multifilament are used to weave a bionic tissue engineering scaffold with a cross tube.The weaving method of forming a pipe structure is explored,and the PGA is inserted into the cross tube.Finally,the inner wall of the stent is coated with chitosan to prepare a tracheal stent for later experiments.2.Biological evaluation of tissue engineering tracheal scaffoldA set of experiments was designed according to GB/T16886 and ISO10993 standard for medical device biology evaluation.The biocompatibility experiments of five biomaterials(PDO,PHBV/PLA,PGA,chitosan)were carried out,and the mechanical properties of the scaffold was tested to provide a good experimental basis for the safety of the next study..3.In vitro experimental study on the construction of tracheal stent and seed cellIn this part of the experiment,we conducted an in vitro co-culture study of seed cells and tracheal scaffolds on the basis of previous experimental studies and explored the conditions and methods of co-culture of seed cells and three-dimensional tracheal scaffolds to provide conditions for the next step of in-situ and orthotopic transplantation of tissue engineered tracheal grafts.4.In-vivo preset for bionic structure tracheal stent and establishment of an animal model of tracheal defectThis section describes in detail the experimental method of the biomimetic structure tracheal scaffold preset in the animal body,and the histological examination of the tracheal stent after preset in the body.The tracheal reconstruction of the tracheal defect in the animal was performed by using the preset tracheal scaffold.The feasibility of repairing the tracheal defect with the bionic tracheal stent was demonstrated by observing the outcome of the tracheal reconstruction and the histological changes of the tracheal stent after reconstruction.It provides ideas and references for future research.Result1.A tracheal scaffold with a cross tube structure was prepared by using PDO monofilament and PHBV/PLA multifilament.The diameter of the tube was 15 mm and 10 mm,and the pore size was 200?m.The inner wall of the bionic tracheal scaffold is then coated with chitosan to increase the airtightness and radial support of the tracheal stent.The radial support force of the two types of tracheal stents(?15mm ?10mm)that have been woven is determined to be 800 cN or more,and the elastic recovery rate is about 90%.2.Cytotoxicity test,systemic acute toxicity test,hemolysis test,heat source test and delayed type hypersensitivity test were carried out on the mixture of five biological materials(PDO,PHBV/PLA,PGA,chitosan)which finally formed the tracheal stent.The test proved the good biocompatibility of the above mixed materials,which laid a good foundation for the next experiment.3.In the experimental study of the construction of the tracheal scaffold and the seed cell,we successfully induced cultured cells to osteoblasts and chondrocytes,and proved that the cells isolated and purified by the adherence method were BMSCs.It provides cell mass and quality assurance for co-culture of seed cells and tracheal scaffolds.We inserted PGA filaments into the cross tube of the tracheal scaffold,and implanted the cartilage-induced BMSCs into the three-dimensional network formed by PGA filaments.The BMSCs could be grown in three-dimensional structure by scanning electron microscopy.4.The bionic graft of the tracheal scaffold with the seed cells was pre-set in the gap between the tracheal and cervical muscles of the dog.The histological analysis of the preset tracheal scaffold proved that the tracheal scaffold has excellent histocompatibility.A large number of capillaries were found in the scaffold,and chondrocytes were found in the scaffold,indicating the effectiveness of the scaffold design.However,it has also been found that the radial support force of the tracheal scaffold after body presetted is reduce,so that intratracheal stents are required to maintain airway patency when repairing tracheal defects.Tracheal reconstruction was performed on the tracheal defect model of the dog.The tracheal intubation was used as an endotracheal stent to maintain airway patency.Two weeks after the repair experiment,the grafts were taken out for tissue section study,and it was found that the anastomosis of the graft and the trachea healed well.Conclusion1.The 1:2 twill,1:5 twill,and 2:1 twill are selected as the basic structure of the three-layer structure of the tracheal stent.The segmental perforation method can be used to prepare the tracheal stent with the cross tube.2.The biomaterials selected by the research team have good biocompatibility,and the successfully woven tracheal scaffold has a certain mechanical strength in vitro test.3.In vitro,a tracheal scaffold was constructed with a complex of cartilage-induced BMSCs,and a method for constructing a cartilage-scaffold complex in vitro was clarified.4.Through the histological evaluation of the preset scaffold,the excellent tissue compatibility of the scaffold was confirmed and the revascularization ability was achieved,and the tracheal defect model of the dog was repaired.The tracheal defect model of the dog was repaired by the scaffold.Through the evaluation of graft histology and mechanics,it provides new ideas and new methods for the study of tracheal repair.