Matching Static and Dynamic Compliance of Small-Diameter Arteries, with Poly(lactide-co-caprolactone) Copolymers: In Vitro and In Vivo Studies

Abstract

Mechanical mismatch between vascular grafts and blood vessels is a major cause of smaller diameter vascular graft failure. To minimize this mismatch, several poly-l-lactide-co-ε-caprolactone (PLC) copolymers are evaluated as candidate materials to fabricate a small diameter graft. Using these materials, tubular prostheses of 4 mm inner diameter are fabricated by dip-coating. In vitro static and dynamic compliance tests are conducted, using custom-built apparatus featuring a closed flow system with water at 37 °C. Grafts of PLC monomer ratio of 50:50 are the most compliant (1.56% ± 0.31∙mm Hg^-2 ), close to that of porcine aortic branch arteries (1.56% ± 0.43∙mm Hg^-2 ), but underwent high continuous dilatation (87 µm min^-1 ). Better matching is achieved by optimizing the thickness of a tubular conduit made from 70:30 PLC grafts. In vivo implantation and function of a PLC 70:30 conduit of 150 µm wall-thickness (WT) are tested as a rabbit aorta bypass. An implanted 150 µm WT PLC 70:30 prosthesis is observed over 3 h. The recorded angiogram shows continuous blood flow, no aneurysmal dilatation, leaks, or acute thrombosis during the in vivo test, indicating the potential for clinical applications.

Keywords: compliance matching; dip-coating; mechanical testing; poly( l-lactide-co-ε-caprolactone); vascular prosthesis.