The Application Value Of Paclitaxel-eluting Stent In Preventing Restenosis After Tracheal Stent Implantation In Dogs

Objective:1.A canine tracheal stenosis model was established by electrocauterization of the dog airway with an electrical snare guided by a fiberoptic bronchoscope;2.Paclitaxel drug-eluting tracheal membrane stent was prepared using a special electrospray system for the preparation of bioinert polyurethane film;3.Paclitaxel-eluting tracheal stent implantation was used to find the treatment method and experimental evidence for inhibiting granulation tissue proliferation after tracheal stenosis stent implantation in dogs.Methods:1.The dog tracheal stenosis model was established by electric cauterization with an electric trapAfter general anesthesia,under the guidance of fiberoptic bronchoscopy,8 evenly distributed points were located on the c-shaped cartilage ring of the middle trachea 8cm from the glottis as burning points.The tracheal cartilage annulus to the cartilage layer is destroyed by burning with an electric trap.In order to assess postoperative complications and stenotic rate(SR)?weekly fiberoptic bronchoscopy and CT examination were performed.According to the CT results,the tracheal stenosis rate was calculated according to the formula SR=(s-s)/S 100%(SR:stenosis rate S:preoperative tracheal area S:lumen area during examination).Experimental dogs were sacrificed at 2 weeks,4 weeks or when the stenosis was greater than 90%.Gross specimens were taken for observation and histomorphology was observed by HE and Masson staining.2.Preparation of PTX drug-loaded tracheal stentFirstly,the polyurethane microspheres were dissolved in the solvent mixture of tetrahydrofuran(THF)and N,n-dimethylamide(DMF)(v/v 9:1)to make PTX drug-loading solution,and then PTX was dissolved in the solution to make predetermined drug concentration,and the drug-eluting stent was made by electrospray.The integrity of the film was examined by sem.3.The role of PTX stent in inhibiting restenosis after stent implantationEight dogs were randomly divided into the non-drug-loaded stents control group(n=4)and the PTX drug-loaded stents experimental group(n=4).After the establishment of the two groups of tracheal stenosis models,the stent putters were used to insert the drug-free Nitinol alloy polyurethane coated stent and polyurethane PTX drug-treated stent respectively.Fiberoptic bronchoscopy and CT examination were performed weekly after stent implantation to observe the stent status and degree of lumen stenosis in each group.The observation period was 3 months in both groups,and all dogs in the experimental group and the control group were sacrificed 3 months after stent implantation.After the animals were killed,the airway specimens were taken and observed by gross specimens,and histological changes of the experimental animals were observed by HE and Masson staining,and the degree of tracheal inflammatory infiltration of the specimens in each group was evaluatedResults:1.Establishment of dog tracheal stenosis model by trap electrocauteryAll experimental dogs were well able to withstand tracheal snare electrocauterization without obvious complications.CT examination of all experimental dogs on the 7th day after surgery showed a median stenosis of 26%without obvious respiratory symptoms.On the 14th day after surgery,shortness of breath and wheezing appeared.CT examination showed obvious proliferation of granulation tissue with a median stenosis of 72%.On the 21st day.all the experimental dogs began to show stridulations and hollow intercostal Spaces,with a narrowing degree of 86%.CT observation showed ring stenosis between tracheal rings 8cm from the middle trachea to the glottis,with a range of lcm.Gross specimens showed lumen stenosis and collapse of tracheal cartilage.Pathological sections showed cartilage destruction,granulation tissue formation,inflammatory cell infiltration,partial fibrosis and other pathological changes.2.Preparation of PTX drug-loaded tracheal stentPTX polyurethane carrier trachea stent can be prepared by electrospray.Scanning electron microscopy showed that the drug membrane was intact and the scaffold was intact without wear.3.Inhibitory effect of PTX drug-loaded stent on restenosis after stent implantation All experimental dogs were successfully implanted with stents at one time3 and all 8 dogs survived to the end point of observation for 3 months without adverse events.At 2 weeks after stent implantation,only a small amount of tissue hyperplasia was observed in part of the control group,and a small amount of ulceration was observed around the experimental groupAfter 1 month,granulation tissue hyperplasia was increased in the control group,and the trachea was narrowed to 2 degrees.Port tissue embedding was observed in the experimental group,and the trachea was narrowed to 1 degree.After the stent was placed for 3 months,the granulation tissue of the control group was proliferated in large quantity,and tissue growth burst into the stent.The-trachea was narrowed to more than 4 degrees.The tissue specimens were infiltrated with inflammatory cells at 1 degree and fibrosis at 3 degrees.In the experimental group,only moderate amount of granulation tissue hyperplasia was observed at the ports,and the trachea was stenosis of more than 2 degrees.The tissue specimens showed 2 degrees of inflammatory infiltration with 2 degrees of fibrosis.The differences were statistically significant.Conclusions:1.The dog tracheal stenosis model can be established by trap electrocautery,Safety,strong repeatability,good degree of consistency and high clinical similarity.2.PTX drug-loaded tracheal stent for animal experiments can be prepared by electrospray.3.PTX drug-loaded stent can effectively inhibit collagen fiber proliferation and granulation tissue formation after tracheal injury,and has certain inhibitory effect on restenosis after tracheal stenosis stent implantation.