Photothermal-mediated Local Heating Using a Nano-Functionalized Stent to Suppress Stent-induced Tissue Hyperplasia in the Rat Gastric Outlet

Abstract

Background and Purpose: Despite advances in various stent technologies used to suppress stent-induced tissue hyperplasia, the current therapeutic strategies are insufficient. The purpose of this study is to investigate the effects of photothermal (PT)-mediated local heating on suppressing stent-induced tissue hyperplasia in the rat gastric outlet.

Materials and Methods: A branched gold nanoparticles (BGNPs)-coated, self-expandable metallic stent (SEMS) was produced through a two-step synthesis process in order to create a stent capable of PT-mediated local heating under near infrared (NIR) laser irradiation. Forty-five rats subjected to SEMS placement in the rat gastric outlet were randomly divided into three groups of 15 rats each. Group A received non-coated SEMS. Group B received BGNP-coated SEMS with local heating at 55 °C after SEMS placement. Group C received BGNP-coated SEMS without local heating. The therapeutic effectiveness of local heating was assessed by comparing the results of western blot analysis and histopathological analysis among the three groups. All groups of five each were immediately sacrificed after local heating for western blot analysis. HSP70 expression was assessed by western blot analysis. In addition, all groups of 10 each were sacrificed by administrating inhalable pure dioxide at four weeks after stent placement for histopathological analysis.

Results: BGNP-coated SEMSs were successfully fabricated using a two-step synthesis process. Stent placement and local heating were successful in all rats. Stent-induced tissue hyperplasia-related variables were significantly lower in group B than in groups A and C (all p <0.001). The mean degrees of CD31-positive-deposition were significantly lower in group B than in groups A and C (p < 0.001). However, the mean degrees of TUNEL-positive-deposition were significantly higher in group B than in groups A and C (p < 0.001). The Ki67-positive mesothelial monolayers were more prominent in groups A and C than in group B.

Conclusion: PT-mediated local heating suppresses tissue hyperplasia after stent placement in the rat gastric outlet.