Seaweed molecules used to improve the results of bypass surgery

Photo of the synthetic grafts made by the researchers. Credit: University of Waterloo

Researchers are using a natural material derived from seaweed to promote vascular cell growth, prevent blood clots and improve the performance of synthetic vascular grafts used in heart bypass surgery.

The new approach, developed and tested at the University of Waterloo, is particularly important in cases involving small artificial blood vessels – those less than six millimeters in diameter – that are prone to clots that can develop into full-blown blockages.

“There is a critical need for the development of synthetic vascular graft materials that will increase the rate of long-term function,” said Dr. Evelyn Yim, a professor of chemical engineering and university research chair who is leading the project.

Researchers added a material called fucoidan, made from seaweed, to modify synthetic blood vessels. Fucoidan has a structure similar to heparin, a drug used as an anticoagulant.

When applied with a nanotechnology technique known as micropatterning, fucoidan promotes the growth of vascular cells around the inner surface of the graft, significantly reducing the chance of clots forming.

For patients, the potential benefits are fewer complications, better quality of life, and less risk of recurrence of blockages requiring additional drug treatment or surgery.

“A functional, ready-to-use, small-diameter vascular graft will help save lives,” said Yim, director of the Regenerative Nanomedicine Lab in Waterloo. “What’s important is that they last much longer and allow blood to flow freely.”

Bypass surgery is performed to restore blood flow to parts of the heart when blood vessels become clogged. Vessels harvested from the patient are the gold standard for grafts, but limited availability often requires the use of artificial vessels.

In addition to heart bypass surgery, grafts are used in medical procedures to treat vascular disease and restore blood flow to vital organs and tissues, including the brain and legs.

When synthetic graft material does not allow vascular cells to grow on the inside of an artery or vessel, there is a high risk of clots, which can develop into complete blockages or cause inflammation that restricts blood flow.

Yim has successfully tested the new technique using fucoidan and micropatterning on small animals and plans to expand into large animal trials before moving on to clinical trials.

Several researchers from the Department of Chemical Engineering at Waterloo and the Department of Biomedical Engineering at Oregon Health and Science University collaborated on this project.

A paper on the work, Fucoidan and topographical modification enhanced in situ endothelialization on acellular synthetic vascular grafts, appears in the journal Bioactive materials.

More information:
Yuan Yao et al, Fucoidan and topographic modification improved in situ endothelialization on acellular synthetic vascular grafts, Bioactive materials (2022). DOI: 10.1016/j.bioactmat.2022.10.011

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