Human veins have been grown in a laboratory in a breakthrough that could revolutionise heart bypass surgery for tens of thousands of Britons each year.
The home-grown blood vessels, which were mass-produced from donated human muscle tissue, could also help kidney patients dependent on dialysis.
The scientists behind the DIY vessels say surgeons will soon be able to ‘grab them off the shelf’ during an operation instead of using veins from the patient’s own body.
Scientists created this 6mm-thick vein by culturing smooth muscle cells from a donor on a tube-like 'scaffold'
The veins are completely sterile and will not be rejected by the patient’s immune system.
It is the first time researchers have been able to create human blood vessels that last for a year or more in cold storage.
Dr Alan Kypson, of the Brody School of Medicine at East Carolina University who was involved in the experiment, said: ‘This new type of bioengineered vein allows them to be easily stored in hospitals so they are readily available to surgeons at time of need.
‘Currently, grafting using the patient’s own veins remains the gold standard. But harvesting a vein from the patient’s leg can lead to complications, and for patients who don’t have suitable veins the bioengineered veins could serve as an important new way to provide a coronary bypass.’
However, not all patients have suitable spare veins. Some may already have been used in previous bypass operations. Others may be badly damaged or furred up.
Removing a vein from the leg also increases the risk of a patient suffering from complications such as infection.
Experts say 'bio-engineered veins could serve as an important new way to provide a coronary by-pass'
Professor Jeremy Pearson, associate medical director at the British Heart Foundation, said: ‘Not everyone is well enough to have a vein taken from another part of their body during heart surgery, so using synthetic veins can become an important part of a patient’s treatment. However, sometimes even synthetic veins aren’t suitable.
‘This study shows bioengineering can be used to create a novel type of vascular graft that has the potential to improve outcomes for patients. We look forward to the results of clinical trials.’
In the past, scientists have grown replacement veins from a patient’s own cells. However, the process takes at least nine months and most people cannot wait that long for surgery. The American researchers created 37 blood vessels by culturing smooth muscle cells from a donor on a tube-like ‘scaffold’ made from biodegradable material.
The cells were bathed in nutrients so they spread over the circular frame in nine months, producing collagen and other substances that meshed into a tube.
By the time the scaffold had dissolved, a fully formed blood vessel was left behind, the researchers reported yesterday in the journal Science Translational Medicine.
The researchers then washed away the donor muscle cells with detergent, creating a sterile human vein capable of carrying blood. The researchers say veins were strong and elastic even after being stored in a fridge in salt water for a year.
When they were grafted onto the blood vessels of a baboon and dog for six months they remained ‘open and strong’.
Around 26,000 Britons have a coronary bypass operation every year. The veins could also be used for some of the 15,000 kidney patients who need regular dialysis to filter their blood.
Many of these patients lack the healthy veins necessary to get access to their blood and rely on an arteriovenous graft connecting an artery and vein in one arm. Most of these grafts are synthetic tubes which are at risk of infection or blockage.
Dr Jeffrey Lawson, another author of the paper at Duke University, North Carolina, said each dialysis graft needed to be repaired an average of 2.8 times over its lifetime just to keep it working.
‘There is a huge need for a functionally superior, off-the-shelf, graft that suffers fewer complications than current materials,’ he said.
Because the veins can be mass produced they will be relatively cheap, the researchers say. However, they are unlikely to be available to patients for several years.
Dr Shannon, who led the study, said: ‘While there is still considerable research to be done before a product is available, we are highly encouraged by the results.’
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