Preparation And Research Of A Bionic Tissue Engineering Woven Tracheal Stent

Severe tracheal stenosis,which commonly results from tumor of trachea,tracheal trauma and congenital deformity,constitutes a threat for patient life,thus needing for tracheal resection and reconstruction.A variety of materials and methods have been developed for the reconstruction of trachea,however,due to the special anatomical structure of trachea,now there are still no ideal tracheal replacements used for long segment(longer than 6 cm)tracheal defects.Tissue engineering is a new method for tracheal reconstruction in recent years.Reconstruction of short segment tracheal defect with tissue engineering tracheal prosthesis has achieved some successes.Based on the theory of ?segment fusion osteogenic reconstruction of segmental bone defect?,this study designed and prepared a bionic tissue engineering woven tracheal stent,aiming to provide a new idea and method for repairing and reconstruction of extensive tracheal defect and a good experimental foundation for the reconstruction of tracheal cartilage ring.First,this new type of bionic tracheal stent was designed according to the morphological characteristics of tracheal physiological structure.The stent was designed as a cylindrical hollow pipe,with three pipelines in its horizontal direction.Appropriate basic fabric structures were selected according to the designed structure of the tracheal stent,1/2 twill,1/5 twill,and 2/1 twill were respectively used for the outer,intermediate and inner layer of weave structure respectively,and the layers were interlocked with binding warps.The paper also designed the looming draft,and then carried out the pre-experiment of bionic tracheal scaffold with alternative materials to ensure that its structure could satisfy the design requirements.Second,materials of tracheal stents should meet requirements,including good biocompatibility and biodegradability,no side effects of degradation products on human body,and sufficient mechanical strength and flexural properties to support cell growth and tissue regeneration.In the paper,polydioxanone(PDO)monofilament was chosen as the material of inner and outer layers of stent,and ?-hydroxybutyrate and ?-hydroxyvalerate copolymers/ polylactic(PHBV/PLA)multifilament was used to woven relatively tight intermediate layer.Based on the performance requirements of the artificial tracheal stent,a serious of process parameters were set reasonably,such as the warp/weft density,width and weft insertion order,and this tissue engineering tracheal stent with horizontal pipe was successfully prepared in the special loom.For the sake of obtaining a certain size and shape,it is necessary to post-treat the tracheal stent billet,and the post-treatment process mainly included desizing,decontamination and heat setting.Then,the tracheal stent was undercoated with Chitosan solution at the concentration of 2%,which could temporarily seal pores and keep the pipe wall airtight.It also had the characteristics of promoting the growth of epithelial cells and selectively inhibiting the growth the fibroblasts,which could effectively prevent adhesion of internal organs with materials and anti-infection.Some basic physicochemical properties of this tracheal stent were investigated,including the warp/ weft density,wall thickness,radial supporting force and elastic recovery rate.The tracheal stent performed excellent radial strength that could provide adequate mechanical supports for cells and tissues of the tracheal cartilage ring and tracheal epithelium;it also has good elastic recovery that satisfies dynamic deformation of the stent.Finally,we carried out animal experiments on the tracheal stent,including cytotoxicity test and hemolysis test.The experimental results showed that this tracheal stent had low toxicity,no hemolysis.Good biocompatibility of the developed stent enabled it to meet the requirements of subsequent cell culture and biological transplantation.In the research,the novel bionic woven tracheal stent with horizontal pipelines was prepared in one step,and the longitudinal pipe combined with transverse pipe was woven.The stent performed excellent radial compressive property and biocompatibility,which could supply a good experimental foundation for the reconstruction of long segment tracheal defects and cartilage rings.