Degradable Vascular Stent with Alkaline Microspheres for Late Restenosis

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Solution Overview

Problem

Degradable vascular stents made from polylactic acid-based polymers face issues with late restenosis due to inflammation caused by lactic acid release during degradation, leading to stent thrombosis and intimal hyperplasia.

Innovation Solution

A degradable vascular stent design featuring a polylactic acid-based polymer base region with a storage region containing an active agent, coated with a drug-sustained release layer, which releases the agent only after the polymer mass decreases by 10-20%, utilizing alkaline degradable polymers to neutralize lactic acid and prevent inflammation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polylactic acid based polymer is used for degradable stent, then biocompatibility is improved, but inflammation and late restenosis occur due to lactic acid release

Engineering Contradiction:

ImprovebiocompatibilityVSAvoidinflammation and late restenosis

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful lactic acid degradation products into a beneficial system by incorporating alkaline degradable polymer microspheres that release basic drugs (such as corticosteroids) to neutralize the inflammatory response caused by lactic acid accumulation, thereby transforming the harmful acidic environment into a controlled therapeutic opportunity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces alkaline degradable polymer microspheres as an intermediary substance between the polylactic acid base region and the surrounding tissue. These microspheres act as a buffer system that releases basic drugs to中和 the acidic lactic acid environment, mediating the interaction between the degradable stent and the biological environment to prevent inflammation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If drug is released early to prevent inflammation, then inflammation is reduced, but drug effectiveness is reduced at late stage when restenosis occurs

Engineering Contradiction:

ImproveinflammationVSAvoiddrug release timing

Core Design Contradiction:

Object-affected harmful factorsVSDuration of action of moving object

Solution Approach 1:

The patent segments the drug release function into two distinct components: the base region provides structural support and controlled early drug release, while the embedded alkaline degradable polymer microspheres provide delayed drug release. This segmentation allows different drug release profiles to address different stages of the healing process and prevent restenosis

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent incorporates alkaline degradable polymer microspheres containing basic drugs into the base region during manufacturing, preparing them in advance to be released at the appropriate time. The microspheres are pre-positioned to ensure delayed release of anti-inflammatory drugs precisely when lactic acid accumulation triggers inflammation, rather than releasing drugs immediately

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The stent effectively avoids late restenosis by controlled drug release, neutralizing acidic degradation products and inhibiting intimal inflammation, ensuring safe and reliable vascular patency without damage to the body.

Implementation Method 1

After the mass of the polymer of the base region is decreased by 10-20%, the alkaline degradable polymer is hydrolyzed to release alkaline monomers

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

an outer layer of a drug sustained release coating covered on the base region and/or the storage region

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11925728B2Degradable vascular stent capable of avoiding late restenosis

Publication Date: 2024.03.12 SHANDONG HUAAN BIOTECH CO LTD

AI summary

The present invention relates to a degradable vascular stent capable of avoiding late restenosis, comprising a base region formed by a polylactic acid based polymer; at least one storage region in which an active agent is stored; and an outer layer of a drug sustained release coating covered on the base region and/or the storage region. Before the mass of the polylactic acid based polymer is decreased by 10-20%, the active agent is retained in structural units of the polylactic acid based polymer. After the mass of the polylactic acid based polymer is decreased by 10-20%, the active agent is released from the storage region. The base region provides a supporting capacity for ensuring patency of blood vessels; the drug sustained release coating is used for drug release in an early stage; and the active agent only works in late degradation of the stent to avoid late restenosis.