Evaluation of formation of granulation tissue caused by metallic stent placement in a rat urethral model.
OBJECTIVE
To evaluate the feasibility of metallic stent placement and the formation of granulation tissue caused by stent placement in a rat urethral model.


METHODS
A bare self-expanding metallic stent was inserted in the urethra under fluoroscopic guidance in 20 male Sprague-Dawley rats. Ten rats were euthanized at 4 weeks (group A), and the other 10 were euthanized at 8 weeks after stent placement (group B). Stenosis diameter, number of epithelial layers, degree of inflammatory cell infiltration, thickness of submucosal fibrosis, and percentage of granulation tissue area were assessed.


RESULTS
Stent placement was technically successful in all rats. Urethrograms showed perforation in three rats, partial migration in three, and stone formation in four. Granulation tissue formation was observed in all rats at the stent-implanted urethra, and the average percentage of granulation tissue area accounted for 41% and 45% of the original urethral lumen area in groups A and B, respectively. Urethrograms and urethral specimens showed significantly less stenosis diameter, less thickness of submucosal fibrosis, and lower percentage of granulation tissue area in the proximal urethra than in the distal urethra in both groups (P < .05). Histologic results demonstrated significantly fewer epithelial layers in group B compared with group A (P = .028).


CONCLUSIONS
Placement of a self-expandable metallic stent proved to be feasible in the rat urethra and an efficient approach to stimulate granulation tissue formation as a potential model for reproducing the mechanisms of restenosis.
Li
Yong-Dong
YD
Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Song
Ho-Young
HY
Kim
Jin Hyoung
JH
Woo
Cheol-Woong
CW
Park
Jung-Hoon
JH
Kim
Tae-Hyung
TH
Gong
Gyungyub
G
D000818:Animals; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005355:Fibrosis; D006097:Granulation Tissue / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008670:Metals; D011474:Prosthesis Design; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D015607:Stents / Q000009:adverse effects*; D013997:Time Factors; D014521:Urethra / Q000000981:diagnostic imaging / Q000473:pathology*; D014525:Urethral Stricture / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*
D008670:Metals