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.

A Novel Hybrid Silk Fibroin/Polyurethane Arteriovenous Graft for Hemodialysis: Proof‐of‐Concept Animal Study in an Ovine Model

“…According to several authors, graft‐vessel compliance mismatch represents a critical factor in determining the abnormal hemodynamic conditions (shear rate disturbances) leading to intimal hyperplasia. [ 30–32 ] Hence, we believe that the satisfactory patency results found in this study (i.e., 100% of subjects in the 90 days group with clinically relevant flow) might be ascribed to the similar values of radial dynamic compliance of Silkothane grafts as compared to native ovine vessels (4.8% per 100 mmHg for Silkothane grafts [ 8 ] versus 2.55–4.82% per 100 mm Hg for ovine carotid arteries [ 33,34 ] ). In contrast, ePTFE‐based grafts display lower radial compliance, ranging around 1.6% per 100 mm Hg.…”

Small-Diameter Blood Vessel Substitutes: Biomimetic Approaches to Improve Patency

“…Our team took a different biomimetic approach: approximate the design of the artery, more specifically the orientation of collagen fibrils around a tubular elastomeric construct. The first part of this approach was reported in 2020 [38]. This work served to identify the elastomeric biodegradable polymer as the main constituent of a cast tubular structure: this was a 70:30 copolymer of ε-Caprolactone and L-Lactide (PLC).…”

Bioresorbable Polymeric Scaffold in Cardiovascular Applications

“…The benefit of this technique allows pore sizes and porosity to be controlled. Behr et al [104] fabricated small diameter conduits produced through dip coating of poly (lactide-co-caprolactone) (PLCL) (matrix) in the presence of polyvinyl alcohol (PVA) and polyethylene glycol (PEG) (porogen). The structure is subsequently submerged in water to dissolve the PEG, forming pore sizes ranging from 2 to 9 µm.…”