Mon Apr 2, 1:17 PM
LONDON (AFP) - British researchers said Monday they have grown human heart tissue from stem cells, raising hopes for the transplant of replacement valve tissue within a few years.
Researchers told AFP the advance could eventually lead to the production of "off-the-shelf hearts," perhaps within a decade, though this would require a sophisticated international effort.
Researchers led by Magdi Yacoub, Egyptian-born professor of cardiac surgery at Imperial College London, said they have grown tissue from stem cells in bone marrow that works in the same way as the valves in human hearts.
Stem cells are immature cells that grow into various tissues.
"We have a sort of rudimentary new valve tissue," Adrian Chester, one of the lead researchers, told AFP.
"We have been using various mechanical stimulae to cause this change in the cell function. We are still a matter of (three) years away before being able to test this in an animal."
Animal tests would allow scientists to determine how the tissue holds up under pressure of blood flows before experiments on human beings, he added.
"We need to know the durability and the strength of the tissue we would want to implant into a human," Chester said.
There is a global shortage of replacement organs, and though some of the functions can be reproduced by artificial systems, not all can.
"The way a living valve functions, it anticipates haemodynamic events and responds and changes its shape and size," Yacoub told The Guardian newspaper.
"It's completely different from an artificial valve that will just open and shut."
If a damaged part of the body can be replaced by tissue that is genetically matched to the patient, it cannot be rejected.
Scientists until now have grown tendons, cartilage and bladders but none of these has the complexity of organs.
The Guardian said that many people suffering from heart valve disease have artificial replacement valves, but such valves work less well than the real thing, even if they do save lives.
Chester told AFP that there was now hope for growing whole hearts, though the problem is complex.
"The long-term goal of engineering a whole heart would achieve the answer to the shortage of donors, if we were able to have an off-the-shelf heart," he said.
"It is very much more in its infancy because the whole heart is a much more complex organ with very specialised cells and vascular supply. That's why that's going to take at least 10 years probably," he said.
Professor Colin McGuckin, a Newcastle University researcher who has grown a miniature artificial human liver, said he believed German researcher Christof Stamm produced heart valve tissue from stem cells last year.
"It's a first in this country. In itself for even two groups to achieve this so early on in stem cells (research) is really astounding," he said.
McGuckin said replacement tissue for heart valves in animals may be achievable within years, but it was "a long way off" for humans. Whole hearts may be 50 years away, he added.
World Health Organisation figures show that there were 15 million deaths from heart disease in 2005, the Guardian said. By 2010, it is estimated that 600,000 people around the world will need replacement heart valves.
The heart valve research will be published in August in a special edition of the journal Philosophical Transactions of the Royal Society, the paper added. _________________ kyranŠ
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