Polyethylene terephthalate textile heart valve: How poly(ethylene glycol) grafting limits fibrosis

Transcatheter aortic valve replacement (TAVR) is an alternative technique to surgical valve replacement for over 300,000 patients worldwide. The valve material used in the TAVR is made of biological tissues, whose durability remains unknown. The success of the TAVR favors the research toward synthetic valve leaflet materials as an alternative to biological tissues. In particular, polyethylene terephthalate (PET) textile valves have recently proven durability over a 6-month period in animal sheep models. Excessive fibrotic tissue formation remains, however, a critical issue to be addressed. The aim of this work was therefore to investigate the potential of PET textiles covalently conjugated with polyethylene glycol (PEG), known for its antifouling properties, to modulate the fibrosis formation both in vitro and in vivo. For this purpose, the surfaces of heart valves made of PET textiles were functionalized with an atmospheric pressure plasma, leading to the formation of carboxylic acid (COOH) groups, further used for PEG-NH₂ conjugation. Surface modification efficiency was assessed by X-ray photoelectron spectroscopy and water contact angle measurements. The biological behavior of the as-modified surfaces was evaluated by in vitro assays, using rat cardiac fibroblast cells. The results show that PEG treated substrates restrained the fibroblasts adhesion and proliferation. The PEG treated valve, implanted in a juvenile sheep model, showed a significant fibrosis reduction. The explant also revealed calcification issues that need to be addressed.