Doctors have launched a trial to test whether heart disease can be treated using a patient's own stem cells.
Different therapies will be tested
The study, at Barts and the London NHS Trust, is funded by a charity set up by a man who underwent stem cell treatment for his heart condition in Germany.
The aim will be to determine whether adult stem cells taken from bone marrow can repair damaged heart muscle.
In total, 700 patients will take part in the study, which will test three different forms of stem cell therapy.
Gerry Sherrick, 71, a retired taxi driver from Essex has had two heart attacks and two triple bypass operations.
He said: "My heart has become steadily weaker over the years. I now struggle to do many of the things I could do before. Mundane tasks like getting washed, eating and even lifting up a newspaper can leave me feeling completely exhausted.
"I have my good days but on others it can be a struggle just to get out of bed."
The first part of the study will involve 300 patients whose hearts are failing because of heart disease or a previous heart attack.
A second arm will involve 200 patients whose hearts are failing specifically because of dilated cardiomyopathy - a heart muscle disorder.
And a final element will involve 200 patients who have just had a heart attack.
Some patients will have stem cells extracted from bone marrow in their hip and injected into their major coronary arteries or directly into their heart.
Others will receive injections of growth factor drugs to try to cause stem cells to spill out of their bone marrow and into their blood without the need for the operation.
Lead researcher Dr Anthony Mathur said: "This is one of the biggest and most comprehensive trials of its kind in the world.
Ian Rosenberg has benefitted from stem cell therapy
"Our studies will tell us if adult stem cells in bone marrow can repair damaged hearts and if so how these cells should be administered to patients.
"There is growing evidence to suggest that stem cells may benefit people with serious heart conditions, such as heart failure or those who have had heart attacks."
Stem cells are the body's master cells, with the ability to turn into almost any type of cell in the body.
Dr Mathur said harnessing the cell's potential to repair damaged heart muscle good be good news for the 2.7m people with heart disease in the UK.
He said: "If proven to work, these cells could revolutionise the way we treat heart disease and could transform the lives of millions of people not only in the UK but around the world."
The work is being funded by a new charity, the Heart Cells Foundation, set up by Ian Rosenberg.
Two years ago doctors told Mr Rosenberg his heart disease was so severe that he had just a couple of months to live.
He travelled to Germany, were stem cells were injected into his heart.
"Within a matter of months, I was able to do things I could only dream of doing before, such as walking up and down stairs or playing golf," he said.
"Stem cell therapy has given me years I never thought I would have.
"I set up the Heart Cells Foundation so that others may benefit from this new and exciting science."
So far the charity has raised £1m to fund the Barts' research. However, another £5m will be needed over the next four years.
Peter Weissberg, of the British Heart Foundation, said stem cell therapy had the potential to revolutionise the treatment of heart disease.
However, he said much work was needed to determine whether the therapy was safe as well as effective.
People interested in taking part in the clinical trial can get more information by calling 020 8983 2216, or by emailing email@example.com.