Silk Composite Vascular Graft for Thrombogenicity Reduction
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Solution Overview
Problem
Current synthetic vascular grafts for small caliber arteries and arteriovenous fistulae have high thrombogenicity, poor patency rates, and are unsuitable for long-term use due to mismatched mechanical properties and limited endothelial growth, particularly in haemodialysis applications where frequent punctures and infection resistance are required.
Innovation Solution
A medical device comprising a multilayered silk composite tube with a porous silk fibroin matrix and knitted silk fibres, where the silk fibres include RGD motifs for enhanced endothelial compatibility and thrombogenicity resistance, providing a strong and flexible graft suitable for vascular applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If synthetic grafts (PET, PTFE) are used for small caliber arteries, then the graft provides structural strength and durability, but the graft exhibits high thrombogenicity and poor endothelial growth
Solution Approach 1:
The invention uses a composite structure combining Dacron ® polyester knitted fabric for structural strength with a silane-modified gelatin coating layer for reduced thrombogenicity. The gelatin coating contains cross-linked gelatin polymers that provide a thromboresistant surface while the underlying Dacron ® layer maintains mechanical integrity and durability
Solution Approach 2:
The gelatin coating undergoes sol-gel transition and cross-linking parameter changes to form a stable, thromboresistant surface layer. The silane modification enables controlled cross-linking that transforms the gelatin from a soluble state to an insoluble, mechanically stable coating that resists thrombus formation
2Duration of action of stationary object
If Dacron ® polyester grafts are used for arteriovenous fistulae, then the graft provides mechanical durability, but the graft is prone to infections and has high thrombogenicity
Solution Approach 1:
The invention creates a composite graft structure where the Dacron ® polyester knitted fabric provides mechanical durability and structural support, while the silane-modified gelatin coating layer provides infection resistance and reduced thrombogenicity. The coating acts as a protective barrier that maintains the mechanical properties of the underlying polyester structure
Solution Approach 2:
The gelatin coating is applied specifically to the luminal surface of the graft where blood contact occurs, providing localized thromboresistance and infection protection. The coating thickness and cross-linking density can be varied to optimize local properties at the blood-graft interface while maintaining the bulk mechanical properties of the Dacron ® structure
3Object-affected harmful factors
If autologous veins are used for bypass grafting, then the graft has good biocompatibility and low thrombogenicity, but adequate veins are not available in 20% of patients and harvesting involves additional surgery
Solution Approach 1:
The invention creates a synthetic graft that replicates the biocompatibility properties of autologous tissue without requiring harvesting from the patient. The silane-modified gelatin coating provides a biocompatible surface that mimics natural endothelium, eliminating the need for additional vein harvesting surgery while maintaining good biocompatibility and low thrombogenicity
Data Source
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AI summary
The present invention relates to a medical device, particularly a vascular graft or an arteriovenous (AV) graft for haemodialysis. The medical device comprises a layer of porous silk fibroin matrix and a layer of knitted silk fibres. The invention further relates to processes of manufacture of such medical devices and methods of use of such devices.