Polymeric Biodegradable Stent Insertion in the Esophagus

Comprehensive review of materials, applications, and future innovations in biodegradable esophageal stents

Esophageal stricture (ES) results from benign and malignant conditions, such as uncontrolled gastroesophageal reflux disease (GERD) and esophageal neoplasms. Upper gastrointestinal endoscopy is the preferred diagnostic approach for ES and its underlying causes. Stent insertion using an endoscope is a prevalent method for alleviating or treating ES. Nevertheless, the widely used self-expandable metal stents (SEMS) and self-expandable plastic stents (SEPS) can result in complications such as migration and restenosis. Furthermore, they necessitate secondary extraction in cases of benign esophageal stricture (BES), rendering them unsatisfactory for clinical requirements. Over the past 3 decades, significant attention has been devoted to biodegradable materials, including synthetic polyester polymers and magnesium-based alloys, owing to their exceptional biocompatibility and biodegradability while addressing the challenges associated with recurring procedures after BES resolves. Novel esophageal stents have been developed and are undergoing experimental and clinical trials. Drug-eluting stents (DES) with drug-loading and drug-releasing capabilities are currently a research focal point, offering more efficient and precise ES treatments. Functional innovations have been investigated to optimize stent performance, including unidirectional drug-release and anti-migration features. Emerging manufacturing technologies such as three-dimensional (3D) printing and new biodegradable materials such as hydrogels have also contributed to the innovation of esophageal stents. The ultimate objective of the research and development of these materials is their clinical application in the treatment of ES and other benign conditions and the palliative treatment of malignant esophageal stricture (MES). This review aimed to offer a comprehensive overview of current biodegradable esophageal stent materials and their applications, highlight current research limitations and innovations, and offer insights into future development priorities and directions.

Biodegradable Stents in the Management of Refractory Esophageal Strictures in Children

Background: Management of refractory esophageal strictures in children is challenging and mostly involves frequent and prolonged dilatations that are associated with significant physical and psychological complications. Biodegradable stents (BDS) have recently been used and it is particularly attractive in children as stent removal is avoided due to their dissolution. Report of Cases: We report our experience with BDS use in 3 children with severe refractory esophageal strictures. Two of the patients had strictures as a result of caustic ingestion and 1 after long-gap esophageal atresia repair. Median number of dilatations prestent is 5 per year. Custom-made uncovered BDS were inserted under general anesthesia. Median follow-up period was 23 months. Results: Minor postprocedure complications occurred in 1 patient. Stent insertion led to temporary improvement in swallowing in all cases. However, all of the patients developed recurrent symptoms as severe as before stenting and need for dilatations remained unchanged. They also experienced mucosal hyperplasia that contributed to their recurrent symptoms. Conclusion: All of the cases in our series did not have a favorable outcome with BDS use. BDS is yet to be proven as an effective management option for refractory esophageal strictures in children from our experience as well as most other published reports.

Biodegradable esophageal stents for the treatment of refractory benign esophageal strictures

This review attempts to present the available evidence regarding the use of biodegradable stents in refractory benign esophageal strictures, especially highlighting their impact on clinical success and complications. A comprehensive literature search was conducted in PubMed, using the terms "biodegradable" and "benign"; evidence from cohort and comparative studies, as well as data from one pooled analysis and one meta-analysis are presented. In summary, the results from these studies indicate that the effectiveness of biodegradable stents ranges from more than one third to a quarter of cases, fairly similar to other types of stents used for the same indication. However, their implementation may reduce the need for re-intervention during follow up. Biodegradable stents also seem to reduce the need for additional types of endoscopic therapeutic modalities, mostly balloon or bougie dilations. Results from pooled data are consistent, showing moderate efficacy along with a higher complication rate. Nonetheless, the validity of these results is questionable, given the heterogeneity of the studies included. Finally, adverse events may occur at a higher rate but are most often minor. The lack of high-quality studies with sufficient patient numbers mandates further studies, preferably randomized, to elucidate the exact role of biodegradable stents in the treatment of refractory benign esophageal strictures.

Silicone-covered biodegradable magnesium stent for treating benign esophageal stricture in a rabbit model

BACKGROUND

Stent insertion can effective alleviate the symptoms of benign esophageal strictures (BES). Magnesium alloy stents are a good candidate because of biological safety, but show a poor corrosion resistance and a quick loss of mechanical support in vivo.

AIM

To test the therapeutic and adverse effects of a silicone-covered magnesium alloy biodegradable esophageal stent.

METHODS

Fifteen rabbits underwent silicone-covered biodegradable magnesium stent insertion into the benign esophageal stricture under fluoroscopic guidance (stent group). The wall reconstruction and tissue reaction of stenotic esophagus in the stent group were compared with those of six esophageal stricture models (control group). Esophagography was performed at 1, 2, and 3 weeks. Four, six, and five rabbits in the stent group and two rabbits in the control groups were euthanized, respectively, at each time point for histological examination.

RESULTS

All stent insertions were well tolerated. The esophageal diameters at immediately, 1, 2 and 3 wk were 9.8 ± 0.3 mm, 9.7 ± 0.7 mm, 9.4 ± 0.8 mm, and 9.2 ± 0.5 mm, respectively (vs 4.9 ± 0.3 mm before stent insertion; P < 0.05). Magnesium stents migrated in eight rabbits [one at 1 wk (1/15), three at 2 wk (3/11), and four at 3 wk (4/5)]. Esophageal wall remodeling (thinner epithelial and smooth muscle layers) was found significantly thinner in the stent group than in the control group (P < 0.05). Esophageal injury and collagen deposition following stent insertion were similar and did not differ compared to rabbits with esophageal stricture and normal rabbits (P > 0.05).

CONCLUSION

Esophageal silicone-covered biodegradable magnesium stent insertion is feasible for BES without causing severe injury or tissue reaction. Our study suggests that insertion of silicone-covered magnesium esophageal stent is a promising approach for treating BES.

A Review of Self-Expanding Esophageal Stents for the Palliation Therapy of Inoperable Esophageal Malignancies

Esophageal cancer is a very deadly disease, killing more than 15,000 people in the United States annually. Almost 400,000 new cases happen in the worldwide every year. More than 50% esophageal cancer patients are diagnosed at an advanced stage when they need an esophageal stent to open the blocked esophagus for feeding and drinking. Esophageal stents have evolved in stages over the years. Current clinically used stents commonly include stainless steel or nitinol self-expandable metallic stent (SEMS) and self-expandable plastic stent (SEPS). There are many choices of different types of stents and sizes, with fierce competition among manufacturers. However, current stent technology, whether uncovered, partially covered, fully covered SEMS or SEPS, has their own advantages to solve the dysphagia, stricture, and fistula problems, but they also cause some clinical complications. The ideal stent remains elusive. New 3D printing technique may bring new promising potential to manufacturing personalized esophageal stents. Drug-eluting stents could be the new avenue to do more than just pry open a stricture or cover a defect in the esophageal lumen, a possibility of proving local anticancer therapy simultaneously. Additionally, the lack of esophageal cancer animal models also hinders the progress of stent development. This paper reviews these topics for a comprehensive understanding of this field. In a conclusion, the ultimate goal of the future esophageal stent would have multifunction to treat the underlying conditions and restore esophageal function to near normal.