Sirolimus-eluting cobalt–chrome alloy stent suppresses stent-induced tissue hyperplasia in a porcine Eustachian tube model

Abstract

Various preclinical studies with developed Eustachian tube (ET) stents are in progress but have not yet been clinically applied. ET stent is limited by stent-induced tissue hyperplasia in preclinical studies. The effectiveness of sirolimus-eluting cobalt–chrome alloy stent (SES) in suppressing stent-induced tissue hyperplasia after stent placement in the porcine ET model was investigated. Six pigs were divided into two groups (i.e., the control and the SES groups) with three pigs for each group. The control group received an uncoated cobalt–chrome alloy stent (n = 6), and the SES group received a sirolimus-eluting cobalt–chrome alloy stent (n = 6). All groups were sacrificed 4 weeks after stent placement. Stent placement was successful in all ETs without procedure-related complications. None of the stents was able to keep its round shape as original, and mucus accumulation was observed inside and around the stent in both groups. On histologic analysis, the tissue hyperplasia area and the thickness of submucosal fibrosis were significantly lower in the SES group than in the control group. SES seems to be effective in suppressing stent-induced tissue hyperplasia in porcine ET. However, further investigation was required to verify the optimal stent materials and antiproliferative drugs.

Tapered self-expandable metallic stent optimized for Eustachian tube morphology in a porcine ET model

“…The shape of the stent can also be altered by movements surrounding the ET in a living animal, such as swallowing and chewing 4 , 5 . Previous studies reported that the distal end of the stent collapsed because of the insertion of a cobalt–chrome stent 13 , 14 , 17 . Therefore, the T-SEMS and C-SEMS were fabricated with nitinol, a self-expandable metal.…”

“…In a human cadaver study, stents with different diameters were inserted and evaluated; however, all stents were not fully dilated at the distal cartilaginous portion 18 . Additionally, a commercially available coronary cobalt–chrome stent was implanted in the ET of sheep and pigs and subsequently evaluated 13 , 14 , 17 . In this study, a T-SEMS made of self-expanding nitinol wire was optimized for the ET.…”

“…A histological examination was conducted on the basis of previous ET stent studies 14 , 15 . The stented ET tissues were extracted.…”

Preliminary results of absorbable magnesium stent for treating eustachian tube dysfunction in a porcine model

“…The technical feasibility and safety of cobalt-chrome alloy stent placement via a minimally invasive approach under endoscopic guidance have been reported. However, stent-induced tissue hyperplasia caused by mechanical injuries remains a significant obstacle to a successful stent placement [ 10 , 11 ]. Drug-eluting stents loaded with antiproliferative agents have been investigated to overcome these limitations.…”

“…Drug-eluting stents loaded with antiproliferative agents have been investigated to overcome these limitations. Recently, a sirolimus-eluting stent successfully prevented stent-induced tissue hyperplasia in the porcine ET model [ 11 , 14 ].…”