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PurposeTo evaluate an EW-7197-eluting nanofiber-covered stent (NFCS) for suppressing granulation tissue formation after stent placement in a canine urethral model.Materials and methodsAll experiments were approved by the committee of animal research. A total of 12 NFCSs were placed in the proximal and distal urethras of six dogs. Dogs were divided into two groups with 3 dogs each. The control stent (CS) group received NFCSs and the drug stent (DS) group received EW-7197 (1000 μg)-eluting NFCSs. All dogs were sacrificed 8 weeks after stent placement Histologic findings of the stented urethra were compared using the Mann-Whitney U test.ResultsStent placement was technically successful in all dogs without procedure-related complications. On urethrographic analysis, the mean luminal diameter was significantly larger in the DS group than in the CS group at 4 and 8 weeks after stent placement (all p < 0.001). On histological examination, mean thicknesses of the papillary projection, thickness of submucosal fibrosis, number of epithelial layers, and degree of collagen deposition were significantly lower in the DS group than in the CS group (all p < 0.001), whereas the mean degree of inflammatory cell infiltration was not significantly different (p > 0.05).ConclusionThe EW-7197-eluting NFCS is effective and safe for suppressing granulation tissue formation after stent placement in a canine urethral model.

Self-expanding non-vascular metal stents (SEMS) is now a choice of treatment for tumor-induced obstructive symptoms of gastrointestinal tract. But in-growing tumor causes re-stenosis. Here, we studied a paclitaxel-eluting nanofiber-covered stent for palliative chemotherapy of gastrointestinal cancer and its related stenosis. In vivo and in vitro feasibility of nanofiber-covered nonvascular stent was evaluated in this study. Nanofiber-covered stent released paclitaxel (PTX) in controlled manner for 30 days. PTX-NFM significantly inhibited the growth of CT-26 colon cancer in comparison with PTX injection. PTX maintained higher tumor concentrations over 1.0 μg/ml for more than 14 days without systemic exposure. TUNEL and H&E staining proved locally concentrated PTX induced the higher apoptosis than PTX injection. In this way, PTX-eluting nanofiber-covered stent possibly inhibits in-growth of cancer and extends patency of stent. Clinical feasibility of PTX-eluting nanofiber nonvascular stent for cholangiocarcinoma and gastrointestinal cancers will be investigated in further studies.