Cardiac patients will soon be able to 'grow their own' heart valves and have them transplanted within weeks of seeing a doctor.
The groundbreaking treatment, developed by British surgeons, will create heart tissue from stem cells from the patient's body.
The technique offers hope to millions who suffer heart disease.
Scientists said the valves would not be rejected after a transplant because the tissue will have come from the patient and be genetically identical.
In April, a team led by heart surgeon Sir Magdi Yacoub of Harefield Hospital, in West London, revealed that they had used bone marrow stem cells to create a replacement heart valve for the first time.
As Sir Magdi's team publishes details of the experiment in the journal Philosophical Transaction of the Royal Society today, colleagues said the valves could be grown from scratch within weeks.
Dr Dorthe Schmidt, of the University of Zurich, said a valve could be implanted into a sick heart "after a time period of six to eight weeks".
Sir Magdi, professor of cardiac surgery at Imperial College London and one of the world's leading heart surgeons, said:
"Currently people suffering from heart valve disease can be treated with artificial replacement valves - they do the job and save lives but they are far from perfect.
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"Although there has been huge progress in developing mechanical replacements, they still work mechanically and not physiologically - they cannot match the elegant sophisticated functions of living tissues."
He added: "The ultimate goal is to produce an 'off the shelf' product which will not cause an immune response from patients. This should be possible in the next five to eight years."
Stem cells are the body's 'master cells' - undeveloped cells which have the ability to turn into any type of tissue, from brain cells to heart muscle.
Although the most potent form is found in newlycellsformed embryos, they are also present in the bodies of adults.
Sir Magdi's team harvested stem cells from a volunteer's bone marrow and used a cocktail of chemicals to coax them into becoming heart cells.
Placed on a scaffold made of biodegradable plastic, the grew and fused together to form discs of heart valve tissue just an inch wide. As the heart valves developed, the scaffold decayed, leaving behind solid tissue.
The researchers are due to begin testing the valves in animals this year and trials on people are expected to follow.
Professor Jeremy Pearson, of the British Heart Foundation, which funded the latest work, said: "Replacement human, animal and mechanical heart valves remain lifesaving for thousands every day in the UK.
"However, Professor Yacoub and his team are among the leaders in research to design better replacement heart valves using human stem cells and natural biological materials as the framework for these cells to grow in.
"We look forward to seeing the solutions to unresolved practical issues that will allow the promise of experimental research to become a reality for patients in the not too distant future."
Hearts have four valves which ensure blood flows in the right direction.
They have to be replaced if they leak or fail to open properly. Around 10,000 people a year need such surgery.
Adults are usually given artificial replacements, while children are given valves from human donors.
But donor valves are in short supply and tend to deteriorate over time, while patients given artificial valves must take drugs for the rest of their lives to stop blood clots forming.
Earlier this year, Israeli researchers said they had grown a tiny beating heart from stem cells from a newly-created embryo.