Micropatterned Biliary Stent Coating for Anchoring Without Flaps
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Solution Overview
Problem
Existing biliary and gastrointestinal stents face issues such as rapid fouling, migration, tissue irritation, and the need for anchoring mechanisms that compromise the gastrointestinal system, requiring frequent replacements and potentially causing duodenal biliary reflux.
Innovation Solution
A polymeric coating with hierarchical micropatterns of protrusions and textures is applied to the stent, providing anchoring while reducing fouling and migration, and promoting controlled tissue ingrowth for stable implantation without damaging the gastrointestinal system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stents use flaps or curled ends for anchoring, then stent retention is improved, but tissue irritation and inflammation increase
Solution Approach 1:
The stent incorporates a porous coating layer with controlled porosity that allows tissue ingrowth through the stent wall, creating a biological anchor rather than relying on mechanical flaps or curls. This porous structure enables cells to penetrate and adhere, securing the stent while avoiding irritation from protruding elements.
Solution Approach 2:
The invention changes the anchoring mechanism from mechanical (flaps, curls) to biological (tissue ingrowth through porous structure). By controlling parameters such as pore size, porosity percentage, and coating thickness, the stent achieves reliable retention through biological integration rather than mechanical interference with tissue.
2Ease of operation
If plastic stents are used with small gauge for delivery, then ease of insertion is improved, but stent diameter is limited and clogging occurs rapidly
Solution Approach 1:
The stent employs a dynamic structure that transitions from a compressed low-profile state during delivery to an expanded high-diameter state at the implantation site. The self-expanding or balloon-expandable mechanism allows the stent to overcome the delivery catheter diameter constraint while achieving a sufficiently large final diameter to prevent clogging.
Solution Approach 2:
The stent is designed to be nested within the delivery catheter in a compressed state, similar to a nested doll structure. The stent framework can be collapsed into a small profile that fits through the catheter working channel, then expands at the target site to provide adequate lumen diameter for sustained patency.
3Adaptability or versatility
If metal wire stents are used for expandability, then stent diameter flexibility is improved, but migration occurs due to insufficient anchoring
Solution Approach 1:
The stent combines metal wire framework with a porous polymeric coating layer to create a composite structure. The metal provides structural integrity and expandability, while the porous coating provides biological anchoring through tissue ingrowth, thereby preventing migration while maintaining diameter flexibility.
Solution Approach 2:
The invention merges two different anchoring approaches: the mechanical expandability of metal wire stents and the biological anchoring of porous coatings. By combining these features into a single integrated device, the stent achieves both diameter flexibility and migration resistance.
4Reliability
If retention flaps are added to secure stent, then migration is reduced, but cellular material accumulates in flap openings and causes obstruction
Solution Approach 1:
The invention extracts the anchoring function from the stent body and places it in the porous coating layer instead. By removing the retention flaps structure and relying on tissue ingrowth through the porous coating, the device maintains retention while eliminating the flap openings that trap cellular material and cause obstructions.
Data Source
AI summary
The present disclosure provides an endoprosthesis where a preferably polymeric coating has a number of surface features such as protrusions or textures that are arranged in a micropattern. The endoprosthesis optionally has an expanded state and a contracted state, and in some cases includes a stent with a polymeric coating attached to an outer surface of the stent. The stent may have an inner surface defining a lumen, an outer surface, and a stent thickness defined between the inner surface and outer surface. The stent may comprise a plurality of surface textures extending from the stent surfaces, wherein the textures are arranged in a macropattern.