Seaweed molecules successful in synthetic vascular grafts

Research led by a team from the University of Waterloo has shown how a natural material derived from seaweed can help synthetic vascular grafts used in heart bypass surgery. Seaweed molecules were found to help to promote vascular cell growth, prevent blood clots and improve the performance of the grafts, especially for small artificial blood vessels where clots can develop into full blockages.

Bypass surgery can restore blood flow to the heart if vessels become blocked, and although such vessels are best taken from the patient, limited availability can mean the use of artificial vessels. Grafts are also used to combat vascular diseases and restore blood flow to organs and tissues. However, if synthetic grafts don’t allow vascular cells to grow on the inside of an artery or vessel, this often leads to clots or inflammation that restricts blood flow.

Here, the team looked to develop vascular grafts with flexible mechanical properties similar to native arteries in patients. Polyvinyl alcohol was tried but didn’t facilitate vascular cells to adhere and grow on the graft. A range of strategies was then attempted, with the difficult part being to encourage vascular cell to adhere but not promote the adhesion of blood clots to the graft.

As detailed in Bioactive Materials [Yao et al. Bioact. Mater. (2022) DOI: 10.1016/j.bioactmat.2022.10.011], a material called fucoidan was then assessed as a modification. Fucoidan, a molecule derived from seaweed with a similar structure as the commonly used anticoagulant drug heparin, was added to modify synthetic blood vessels, demonstrating improved growth of vascular cells around the inner surface of the graft to reduce the risk of clots.

Combined fucoidan and micropatterning showed significantly improved vascular cell coverage for the full length of the implanted vascular graft. As study leader Evelyn Yim told Materials Today, “The main significance is the identification that the application of using fucoidan with nanopatterning can enable the vascular cell coverage throughout the lumen of vascular graft”.

For patients, the breakthrough could mean fewer complications, enhanced quality of life and reduced risk of the recurrence of blockages needing further drug treatment or surgery. The team also managed to identify the mechanism of how vascular endothelial cells can attach to the fucoidan modified surface, and how the micropatterning of the lumen promoted cell migration into the graft. It is hoped the method can used for other synthetic vascular grafts or vascular devices, and to be expanded to large animal testing and then clinical trials.

“The main significance is the identification that the application of using fucoidan with nanopatterning can enable the vascular cell coverage throughout the lumen of vascular graft”Evelyn Yim