Bypass surgery is performed to restore blood
flow to areas of the heart when vessels become blocked. 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 diseases and restore blood
flow to vital organs and tissues, including the brain and legs.
When synthetic graft material doesn’t allow
vascular cells to grow on the inside of an artery or vessel, there is a high
chance of clots, which can develop into full blockages or cause inflammation
that restricts blood flow.
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 especially important in cases involving small
artificial blood vessels – those less than six millimetres in diameter – which
are prone to clots that can develop into full blockages.
“There is a crucial need to develop synthetic
vascular graft materials that will increase the rate of long-term functions,”
said Dr. Evelyn Yim, a chemical engineering professor and University Research
Chair who leads the project.
Researchers added a material called fucoidan,
which is 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 chances of clots
forming.
For patients, the potential benefits include
fewer complications, better quality of life and less risk of the recurrence of
blockages requiring additional drug treatment or surgery.
“A functional, off-the-shelf, small-diameter
vascular graft will help save lives,” said Yim, director of the Regenerative
Nanomedicine Lab at Waterloo. “What’s important is that they will be much
longer-lasting and allow blood to flow freely.”
Yim has successfully tested the new technique
using fucoidan and micropatterning on small animals and plans to expand to
large animal testing before advancing to clinical trials.
Several researchers from the Department of
Chemical Engineering at Waterloo and the Department of Biomedical Engineering
at the Oregon Health and Science University have collaborated on this project.
Reference:
Dr. Evelyn Yim et al, JOURNAL Bioactive Materials