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

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.