| Purpose:To evaluate the safety and feasibility of a newly designed 125I brachytherapy ureteral stent(BUS)in normal dogs.Materials and Methods:Ten radioactive 125I seeds were loaded into the integrated seed-carrying ureteral scaffold,and 27 normal beagles were randomly divided into three groups:group A,high activity radioactive 125I seeds group(0.8mci group),ureteral scaffold loaded with 10 0.8 mCI125I seeds;Group B,low activity radioactive 125I seeds group,referred to as low activity group(0.4mci group),ureteral stent loaded with 10 0.4mCi 125I seeds;Group C,simple ureteral stent group(0mci group),the group without any 125I seeds in the ureteral stent.The contralateral normal ureter was the control group.In postoperative 2,4 and 8 respectively went blood biochemical and blood routine examination,weight test,gross observation,the cumulative dose,hematoxylin eosin staining,mason dyeing and cysteine protease-3(Caspase-3),Collagen I,proliferating cell nucleus antigen(PCNA)and alpha smooth muscle actin(α-SMA)in different groups of mRNA and protein expression level.Results:1.BUS was successfully implanted in all dogs(27/27),the technical success rate was 100%,the bladder and skin were sutured well,and there were no surgery-related deaths.The body weight of beagle dogs in each group decreased slightly one week after operation,and the white blood cells of the 0.8mc group increased slightly in the first week(p<0.05).2.The diameter of ureter and the score of radiation damage in each group increased with the increase of radiation dose(p<0.05).Histopathological analysis showed that there was mild inflammation in the 0.8mci group at the second week,the granulation tissue proliferated at the fourth week and the muscle layer thickened at the eighth week.Masson staining further revealed that the early ureter was collagen fiber proliferation and the late muscle fiber proliferation.3.The up-regulation of Caspase-3 molecule at the level of mRNA and protein with the increase of particle activity showed that the increase of radiation dose aggravated cell apoptosis(p<0.05).4.The up-regulation of Collagen I and α-SMA molecules at the level of mRNA and protein with increasing dose and time indicated that the degree of ureteral fibrosis was gradually increasing(p<0.05).5.PCNA decreased with the increase of particle activity and the extension of observation time,showing that the increase of radiation dose can effectively inhibit the proliferation of the wall after ureteral stent placement(p<0.05).6.The absorbed dose of 5mm and 10mm tissues beside the particle chain were evaluated.With the extension of time,the absorbed dose of both gradually increased,and the 5mm was higher than 10mm at each time point;the organs at risk(OAR)in group B and group C were under safe radiation dose.Conclusions:Placement of the newly designed 125I BUS was safe and feasible in dogs,it should be emphasized that the BUS implantation or replacement time is less than 8 weeks,and 0.8 mCi 125I can be used to increase the radiation dose,resulting in mild damage to the normal ureter.Clinical studies are required to test its use in humans. |
