Characterization of Partially Covered Self-Expandable Metallic Stents for Esophageal Cancer Treatment: In Vivo Degradation

Abstract

Partially covered self-expandable metallic esophageal stent (SEMS) placement is the most frequently applied palliative treatment in esophageal cancer. Structural characterization of explanted 16 nitinol-polyurethane SEMS (the group of 6 females, 10 males, age 40–80) was performed after their removal due to dysfunction. The adverse bulk changes in the polymer structure were identified using differential scanning calorimetry (DSC), differential mechanical thermal analysis (DMTA), and attenuated total reflectance infrared spectroscopy (ATR-IR) and discussed in terms of melting point shift (9 °C), glass-transition shift (4 °C), differences in viscoelastic behavior, and systematic decrease of peaks intensities corresponding to C–H, C=O, and C–N polyurethane structural bonds. The scanning electron and confocal microscopic observations revealed all major types of surface degradation, i.e., surface cracks, peeling off of the polymer material, and surface etching. The changes in the hydrophobic polyurethane surfaces were also revealed by a significant decrease in wettability (74°) and the corresponding increase of the surface free energy (31 mJ/m 2 ). To understand the in vivo degradation, the in vitro tests in simulated salivary and gastric fluids were performed, which mimic the environments of proximal and distal ends, respectively. It was concluded that the differences in the degradation of the proximal and distal ends of prostheses strongly depend on the physiological environment, in particular stomach content. Finally, the necessity of the in vivo tests for SEMS degradation is pointed out.

Sonochemical Formation of Fluorouracil Nanoparticles: Toward Controlled Drug Delivery from Polymeric Surfaces

“…Thus, it seems of particular importance to investigate other drug-polymer systems where the drug elution from the polymeric surface is advantageous, e.g., in anticancer therapy. One such system involves the improvement of polyurethane-based esophageal stents used in cancer palliative treatment . For this application, fluorouracil is suggested as a systemic first-line drug.…”

“…One such system involves the improvement of polyurethane-based esophageal stents used in cancer palliative treatment. 24 For this application, fluorouracil is suggested as a systemic first-line drug. To limit its dose, fluorouracil nanoparticles can be sonochemically formed and immobilized at the polyurethane cover of the stent and by prolonged elution act directly in the vicinity of the tumor.…”

Recent advances in 3D-printed polylactide and polycaprolactone-based biomaterials for tissue engineering applications

“…The material takes two years for complete degradation [102]. However, the porosity, molecular and other mechanical properties [114]- [116]. Figure 5 also depicts different grafting sites using 395 various kinds of implanting materials including non-biodegradable polymers, biodegradable 396 polymers, metals, and ceramics [117].…”