Experimental Study Of¹²⁵Ⅰ Seeds Preventing Restenosis After Airway Stent Implantation Through TGFβ-NOX4-ROS Signaling Pathway

ObjectiveExogenous foreign body stimulation,reactive proliferation of endothelial cells and excessive formation of granulation tissue are common serious complications after tracheal stent implantation.Currently,there is no truly effective measure to inhibit proliferation in clinical practice.125Ⅰ seeds brachytherapy is an effective local program to inhibit the division and proliferation of normal cells and treat malignant tumors.Meanwhile,it can also inhibit the differentiation of normal cells to a certain extent,thus preventing the hyperplasia of granulation tissue.In this study,a healthy rabbit model was used to evaluate the inhibitory effect of 125Ⅰ seed scaffold on granulation tissue proliferation,and further explore the regulatory signaling pathway and its potential mechanism.Materials and Methods36 experimental rabbits were selected and randomly divided into:group A,bare stent group(control group);Group B,low-dose particle stent group for short,low-dose group;Group C,high-dose particle stent group referred to as high-dose group;12 experimental animals were included in each group.After anesthesia,different stents were placed into the trachea under the guidance of DSA.The rabbits were sacrificed at 2W,4W and 8W,respectively,and the samples were detected.The tissues were stained by HE,Masson,α-SMA,NOX4 and TGF-βimmunohistochemical staining,respectively.The pathological changes of tracheal tissue were observed by HE staining.Masson staining was used to observe the area of collagen deposition in tracheal epithelium and evaluate the degree of tracheal fibrosis in experimental rabbits in each group.The expression of different proteins was detected by immunohistochemistry.Using Image analysis software Image Pro Plus 6.0 to determine the tracheal basement membrane perimeter(Basement Membrane Perimeter,PBM),tube wall area(Total Wall Area,WAT)or Masson staining positive area(Masson(+)area/PBM),α-SMA staining positive area/PBM(α-SMA(+)area/PBM),NOX4 staining positive area/PBM(NOX4(+)area/PBM),TGF-βstaining positive area/PBM(TGF-β(+)area/PBM),and the measured data were standardized.In addition,ROS concentrations in rabbit tracheal tissue and serum were measured using ELISA kit.Results1.In gross specimens,obvious granulation tissue hyperplasia can be seen at both ends of the stent in the control group.In addition,the tracheal lumen is narrowed,and white purulent viscous secretion can be seen on the surface,combined with local edema of the airway mucosa.In the seeds stent group,the hyperplasia of granulation tissue in tracheal lumen was mild,superficial ulceration was observed in the particle chamber in the tracheal lumen,and fistula formation and tracheal perforation were not observed outside the tracheal lumen.2.Tracheal tissue HE staining and Masson staining:Compared with the bare stent control group(Group A),the fibrosis degree of tracheal tissue and the total thickness of tracheal wall in the low-dose group(Group B)and high-dose group(Group C)were lower at 2,4 and 8 weeks after irradiation(P<0.05).In addition,the high-dose group had stronger inhibitory effect on hyperplasia,lower tracheal wall thickness and less collagen fiber deposition under basement membrane.3.The intervention of 125Ⅰ seeds in the experimental group induced a series of pathological changes compared with the control group,which reduced the deposition of collagen fibers and α-SMA(extracellular matrix,ECM),decreased the production of transforming growth factor β induced by mechanical stimulation of scaffolds,and also significantly reduced the expression level of myofibroblast marker NOX4.α-SMA staining positive area/PBM(α-SMA(+Area/PBM),NOX4 staining positive area/PBM(NOX4(+)Area/PBM)and TGF-β staining positive area/PBM(TGF-β(+)Area/PBM)were significantly different in the particle stent group compared with the bare stent control group.Conclusion1.Tracheal stents carrying 125Ⅰ seeds,no matter at low dose or high dose,can inhibit the proliferation of granulation tissue on the edge of the stent and delay the restenosis of the stent compared with simple metal tracheal stents;But the particles in the high-dose group were more effective in inhibiting proliferation.2.The implantation of 125Ⅰ seed stent into the trachea of experimental rabbits was safe and feasible,and no serious complications such as tracheal perforation and tracheal fistula occurred within 8 weeks.3.The inhibitory effect of 125Ⅰ seed on granulation tissue proliferation and stent restenosis may be realized through TGFβ-NOX4-ROS signaling pathway.