# Programmable Compliance in Small‐Diameter Vascular Grafts by Design of Melt‐Electrowritten Scaffold Architectures for In Situ Tissue Engineering

## TL;DR

Researchers created vascular grafts with adjustable stiffness to match human vessels, potentially reducing failure rates.

## Contribution

A novel design strategy for programmable compliance in vascular grafts using helical microfiber architectures via melt electrowriting.

## Key findings

- Controlling fiber winding angle enables tailored compliance matching arteries and veins.
- Gradient fiber architecture achieves arteriovenous graft compliance with smooth transitions.
- In vitro tests confirm mechanical properties suitable for clinical use.

## Abstract

In clinical practice, synthetic vascular grafts are advantageous due to their immediate availability but are burdened by high failure rates in small‐diameter settings because of thrombogenicity, infections, and intimal hyperplasia (IH). A mismatch in compliance between graft and host vessel has been identified as a major contributor to the development of IH. Here, we propose a design strategy to fabricate polymeric small‐diameter vascular graft scaffolds with programmable compliance based on a helical microfiber architecture via melt electrowriting (MEW). By controlling the fiber winding angle, this design strategy exploits, for the first time, the mechanical structure‐function relationship of MEW scaffolds to enable tailored compliance covering the physiological range of arteries and veins. This concept is complemented by an integrated microporous MEW graft wall, potentially enabling in situ tissue engineering to combine the advantages of synthetic (off‐the‐shelf) and autologous (living) grafts. Leveraging this, a gradient is introduced in the fiber architecture to achieve arteriovenous grafts matching the compliance of the target vessels at their ends (arterial vs. venous compliance) with a continuous smooth transitional region in between. The potential for clinical translation is demonstrated in vitro by assessing suture‐retention strength, anti‐kinking properties, burst pressure, and cannulation behavior.

Small‐diameter vascular grafts with compliance tunable by design are fabricated via melt electrowriting. By controlling the winding angle of intertwined helical fibers, grafts with compliances matching those of human vessels, from veins to arteries, are realized. This holds the potential of avoiding a compliance mismatch, which has been identified as a major driver for graft failure.