Research could lead to new hearts made to order.
British doctors have successfully grown a heart valve using stem cells. The medical team predicts that the breakthrough technique could allow a complete heart to be "built to order" within a decade.
The researchers, including physicists, pharmacologists, clinicians and cellular scientists, have spent 10 years analysing the form of the human heart to allow it to be grown.
The complexity of the heart makes it difficult to build but, as heart disease is the number one killer in the Western world, the work is being hailed as a major breakthrough.
The team, led by heart surgeon Sir Magdi Yacoub, took stem cells from bone marrow and put them into collagen moulds to grow the 3cm heart valves. The tissues will now be implanted into animals and monitored for side effects.
Stem cell organs have a huge advantage over transplanted organs since they can be grown from the body in which they will be implanted. This overcomes the rejection of donor organs that makes current heart replacement so risky.
The team estimates that it could be 10 years before a full human heart is grown, but said that this is a long estimate and that research could go a lot faster.
Simple body parts like tendons, cartilages and bladders can already be grown from stem cells.