Engineering the Future Vessel: Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Scaffolds for Small-Diameter Vascular Grafts in Bypass Surgery

Oana Dobre

Centre for the Cellular Microenvironment, Advanced Research Centre, University of Glasgow, United Kingdom.

Small-diameter vascular grafts (<6 mm) remain one of the most persistent unsolved challenges in cardiovascular surgery. Existing synthetic conduits continue to fail through mechanisms of thrombosis, compliance mismatch, and inability to remodel — and to date, no tissue-engineered vascular graft has demonstrated consistent clinical success. Biodegradable, piezoelectric biomaterials such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) offer a promising alternative, combining favourable degradation kinetics with mechano-electrical cues that may support vascular cell behaviour.

This presentation reports on the design and characterisation of electrospun PHBV scaffolds fabricated as multilayer tubular constructs of increasing wall thickness. Fibre morphology was assessed by scanning electron microscopy, and mechanical performance was evaluated through uniaxial tensile and burst pressure testing. A non-piezoelectric poly(ε-caprolactone) (PCL) scaffold with matched fibre diameter served as a negative control. Endothelial compatibility was assessed using human umbilical vein endothelial cells (HUVECs), with cell adhesion and viability evaluated at defined time points.

Increasing scaffold wall thickness produced reproducible gains in tensile stiffness and ultimate tensile strength that exceeded minimum clinical benchmarks, and substantially improved pressure-bearing capacity. However, burst pressures remained below native arterial values, constrained by leakage at layer interfaces rather than structural failure of the fibrous network — a finding that points toward opportunities for interfacial refinement in future multilayer architectures. While PHBV supported HUVEC adhesion and survival, a confluent endothelial monolayer was not achieved under the conditions tested, underscoring the need for targeted surface functionalisation strategies.

Together, these findings establish electrospun PHBV as a promising platform for small-diameter vascular graft development, demonstrate the central role of multilayer scaffold design in achieving clinically relevant mechanical properties, and delineate the mechanical and biological challenges that must be resolved on the path to a functional, implantable construct. Future work will focus on optimising layer bonding to improve burst performance, and on bio-functionalisation strategies to promote endothelialisation and long-term patency.