Micropatterned Stent Coating for Anti-Migration and Removability
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Solution Overview
Problem
Esophageal stents face issues with migration, tissue ingrowth leading to reocclusion, and granulation tissue buildup, which complicates removal and impairs luminal flow, necessitating improved anchoring and removability.
Innovation Solution
A polymeric coating with micropatterned protrusions, such as micropillars, is applied to the stent surface to enhance interlocking with the vessel wall, reducing migration and promoting wound healing while allowing for retrievability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a coating is applied to the stent to prevent tissue ingrowth, then tissue ingrowth and reocclusion are reduced, but stent migration increases
Solution Approach 1:
The coating is applied selectively to specific regions of the stent rather than uniformly across the entire surface. The micropatterned protrusions are concentrated at the distal and proximal ends where anchoring is most critical, while maintaining a smoother coating in the mid-section to prevent tissue ingrowth. This localized differentiation resolves the contradiction by providing enhanced anchoring where needed without promoting tissue ingrowth elsewhere.
Solution Approach 2:
The coating structure is segmented into multiple functional zones: micropatterned protrusion regions for anchoring at the ends, and smoother coating regions for preventing tissue ingrowth in the middle section. This segmentation allows each zone to perform its specific function optimally, resolving the contradiction between preventing migration and preventing tissue ingrowth.
2Reliability
If bare metal portions are exposed to promote tissue ingrowth for anchoring, then stent migration is reduced, but reocclusion of the esophagus increases
Solution Approach 1:
Different surface properties are applied to different locations on the stent. The micropatterned protrusions at the ends create localized anchoring points that promote tissue ingrowth only where needed for stability, while the smoother coating areas prevent excessive tissue ingrowth that would cause reocclusion. This spatial differentiation of surface properties resolves the contradiction.
3Reliability
If a flared stent design is used to reduce migration, then anchoring is improved, but stent complexity and potential for migration increase
Solution Approach 1:
The mechanical flared structure is replaced with a micropatterned coating system that provides anchoring through micro-scale interlocking features. Instead of changing the overall stent geometry to achieve anchoring, the invention uses surface-level micropatterns that can be applied to various stent designs, reducing structural complexity while maintaining anchoring effectiveness.
4Adaptability or versatility
If the stent is made removable to avoid permanent implantation, then patient safety is improved, but stent migration increases
Solution Approach 1:
The micropatterned coating is designed to provide temporary anchoring strength during the critical early healing period, after which the attachment strength naturally decreases over time. This preliminary strong anchoring prevents migration during implantation and initial healing, while the gradual weakening of attachment allows for safe removal when needed, resolving the contradiction between removability and migration prevention.
Data Source
AI summary
An endoprosthesis has an expanded state and an unexpanded state, the endoprosthesis includes a stent, wherein the stent has a first end, a second end, an inner surface defining a lumen, an outer surface, and a thickness defined between the inner surface and the outer surface; and a stent end covering disposed at one of the first and second ends, the stent end covering including a polymeric coating that includes a base and a plurality of protrusions, the base including a first major surface facing the outer surface of the stent, the base further including a second major surface from which each of the plurality of protrusions extends outwardly, the first major surface opposing the second major surface, wherein the protrusions are arranged in a micropattern. Methods of making and using an endoprosthesis are provided.