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British team grows human heart valve from stem cells
Tissue for transplants could be available within three years if trials are successful
Alok Jha, science correspondent Monday April 2, 2007 The Guardian
A British research team led by the world's leading heart surgeon has grown part of a human heart from stem cells for the first time. If animal trials scheduled for later this year prove successful, replacement tissue could be used in transplants for the hundreds of thousands of people suffering from heart disease within three years. Sir Magdi Yacoub, a professor of cardiac surgery at Imperial College London, has worked on ways to tackle the shortage of donated hearts for transplant for more than a decade. His team at the heart science centre at Harefield hospital have grown tissue that works in the same way as the valves in human hearts, a significant step towards the goal of growing whole replacement hearts from stem cells.
To crack the problem, Prof Yacoub assembled a team of physicists, biologists, engineers, pharmacologists, cellular scientists and clinicians. Their task - to characterise how every bit of the heart works - has so far taken 10 years. The progress of his team and that of colleagues around the world will be published in August in a special edition of the journal Philosophical Transactions of the Royal Society.
Prof Yacoub said his team's latest work had brought the goal of growing a whole, beating human heart closer. "It is an ambitious project but not impossible. If you want me to guess I'd say 10 years. But experience has shown that the progress that is happening nowadays makes it possible to achieve milestones in a shorter time. I wouldn't be surprised if it was some day sooner than we think."
Currently, many people suffering from heart valve disease have artificial replacement valves. Though they save lives, the artificial valves are far from perfect. They perform none of the more sophisticated functions of living tissue, children need their valves replaced as they grow, and patients need a lifetime of drugs to prevent complications after surgery.
"The way a living valve functions, it anticipates haemodynamic events and responds and changes its shape and size. It's completely different from an artificial valve which will just open and shut. The heart muscle itself will appreciate something which will make it free to contract properly," said Prof Yacoub.
Adrian Chester, one of the lead scientists at the Harefield centre, has focused on characterising the valves in the heart. "You have mediators in blood or released locally in the valve that can make parts of the valve contract and relax. That work has then extended into looking at the incidence of nerves in the valve - these can cause the types of contractions and relaxations in a very specific way."
By using chemical and physical nudges, the scientists first coaxed stem cells extracted from bone marrow to grow into heart valve cells. By placing these cells into scaffolds made of collagen, Dr Chester and his colleague Patricia Taylor then grew small 3cm-wide discs of heart valve tissue. Later this year, that tissue will be implanted into animals - probably sheep or pigs - and monitored to see how well it works as part of a circulatory system.
If that trial works well, Prof Yacoub is optimistic that the replacement heart tissue, which can be grown into the shape of a human heart valve using specially-designed collagen scaffolds, could be used in patients within three to five years.
Growing a suitably-sized piece of tissue from a patient's own stem cells would take around a month but he said that most people would not need such individualised treatment. A store of ready-grown tissue made from a wide variety of stem cells could provide good matches for the majority of the population.
Prof Yacoub's inspiration has come not only from other scientists but also from an unexpected source - the celebrated British artist, Antony Gormley, who has donated a sculpture to the heart science centre. "We need a lot of experts from different fields but we also need a lot of imagination and a lot of understanding of how form interacts with function," said Prof Yacoub. "Art gives a lot of inspiration and beauty. And beauty is part of science."
Mr Gormley, who has also contributed to the upcoming special issue of the Philosophical Transactions of the Royal Society with an article on the relationship between form and function in sculpture, said he admired the universalism with which Prof Yacoub approached his work. "He manages to do the Robin Hood job in a very important way for the benefit of all humanity. I found in him a fellow traveller in terms of trying to do things at the fringes of the possible with the highest levels of input in terms of technology and intelligence. Everybody breathes air, everybody pumps blood."
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Stem cell research does not have to be taken from embryonic stem cells. Much has also been done with adult stem cells and with umbilical stems cells as well. There are quite a few companies working on these as well. It is quite admirable to take on these issues instead of assuming that one must destroy one life to assist in another one. That seems quite a contradiction it itself.
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Not really. Organ donation falls under the same category.
Someone dies, the viable organs are harvested so that someone else can live.
I am not against restricting stem cell procurement...that just makes too much sense. But the... what is it...6 viable stem cell lines we have left here in America limit us so much!
I'd say a one time dispensation for parents who have frozen embryos and want to advance stem cell research can donate an embryo to science.
1 time only, 1 embryo per family. Given the hundreds of thousands who have frozen embryo's left over from when they were having trouble getting pregnant but have since achieved their goal that should give us plenty. And I don't see much of a moral issue as these will be donations from stock that will otherwise stay frozen forever.
-------------------- No longer eligible for government service due to lack of tax issues.
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I wonder if they can put the cells in the heart valve area and have them grow? It appears by the article that the valve will have to grow outside the heart then be inserted. It would be nice to see them eliminate that major surgery. I guess time will tell.
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