Silver nanoparticle-coated self-expandable metallic stent suppresses tissue hyperplasia in a rat esophageal model

Background To evaluate the efficacy of a silver nanoparticle (AgNP)-coated self-expandable metallic stent (SEMS) for suppressing tissue hyperplasia in a rat esophageal model. Methods Twenty-four male Sprague-Dawley rats were randomly assigned to four groups. Animals in group A underwent uncoated SEMS placement, whereas animals in groups B, C, and D underwent 6, 12, and 24 mg/mL AgNP-coated SEMS placement, respectively. All animals were euthanized 4 weeks after SEMS placement, and a gross examination and histological analyses were performed. Results All rats achieved technical success and survived until the end of the study. The gross examination showed moderate to severe tissue hyperplasia in 5 rats in group A and 2 rats in group B. In contrast, no animals in groups C and D had moderate or severe tissue hyperplasia. The gross examination revealed no complications. The percentage of granulation tissue area, number of epithelial layers, thickness of submucosal fibrosis, percentage of connective tissue area, inflammatory cell infiltration grade, degree of collagen deposition, and degrees of Ki67, TUNEL, and α-SMA-positive deposition were significantly lower in groups C and D than in group A (all p