Fabrication of a Delaying Biodegradable Magnesium Alloy-Based Esophageal Stent via Coating Elastic Polymer

Esophageal stent implantation can relieve esophageal stenosis and obstructions in benign esophageal strictures, and magnesium alloy stents are a good candidate because of biodegradation and biological safety. However, biodegradable esophageal stents show a poor corrosion resistance and a quick loss of mechanical support in vivo. In this study, we chose the elastic and biodegradable mixed polymer of Poly(ε-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) as the coated membrane on magnesium alloy stents for fabricating a fully biodegradable esophageal stent, which showed an ability to delay the degradation time and maintain mechanical performance in the long term. After 48 repeated compressions, the mechanical testing demonstrated that the PCL-PTMC-coated magnesium stents possess good flexibility and elasticity, and could provide enough support against lesion compression when used in vivo. According to the in vitro degradation evaluation, the PCL-PTMC membrane coated on magnesium was a good material combination for biodegradable stents. During the in vivo evaluation, the proliferation of the smooth muscle cells showed no signs of cell toxicity. Histological examination revealed the inflammation scores at four weeks in the magnesium-(PCL-PTMC) stent group were similar to those in the control group (p > 0.05). The α-smooth muscle actin layer in the media was thinner in the magnesium-(PCL-PTMC) stent group than in the control group (p < 0.05). Both the epithelial and smooth muscle cell layers were significantly thinner in the magnesium-(PCL-PTMC) stent group than in the control group. The stent insertion was feasible and provided reliable support for at least four weeks, without causing severe injury or collagen deposition. Thus, this stent provides a new stent for the treatment of benign esophageal stricture and a novel research path in the development of temporary stents in other cases of benign stricture.

Fabrication and evaluation of polymer-based esophageal stents for benign esophagus stricture insertion

In benign esophageal strictures, polymeric lines and membranes were chosen to knit an esophageal stent for relieving esophageal lesions caused by esophageal stenosis and obstruction.

A highly flexible paclitaxel-loaded poly(ε-caprolactone) electrospun fibrous-membrane-covered stent for benign cardia stricture

In benign esophageal strictures, inflammation reaction and tissue hyperplasia after stent placement greatly limit the stent retention time and affect subsequent scar formation, which is one of the main influences on long-term recurrence rate. A newly developed biodegradable electrospun drug-fiber-coated stent (DFCS) was fabricated to inhibit inflammation and scar formation. The electrospun paclitaxel/poly(ε-caprolactone) (PCL) fibers integrally covered the bare stent using the rotating collection method. The paclitaxel entrapment did not significantly affect the physical properties of electrospun PCL fibrous membranes. The mechanical results demonstrated that electrospun fibers containing paclitaxel covering the stent maintained the original mechanical characteristics of the stent, and no membrane tearing or ablation was observed after hundreds of repeated compressions. Paclitaxel release profiles were controlled mainly via diffusion of drug through the drug content, and stable release of paclitaxel continued up to 32 days at pH 4.0. Higher inhibition of smooth muscle cell proliferation rates was observed on fibrous membranes with higher paclitaxel content. DFCS showed a significant decrease in tissue inflammation and collagen fiber proliferation, and was easily removed from the esophageal part, which had almost no damage to the tissues in the dog model. Therefore, DFCSs may have great potential to markedly attenuate stent-induced inflammation and scar formation in esophageal stenosis therapy.