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Dr. Geoffrey Gurtner from Stanford University explains.(www.hXen.com)
"We have developed a way to overcome one of the big problems in tissue engineering which is how do you get blood vessels into big blocks of tissue so that you can potentially make things like hearts or livers or very solid organs, and we've done it in a somewhat unique way."
An important step in the new technique is the use of microcirculatory beds, using the main vein and artery.
The tissue is kept alive on a bio-reactor, which pumps a blood-like liquid through it.
The tissue would die quickly without this life-support system.
But the bio-reactor keeps it alive and healthy for up to 24 hours, long enough to embed the stem cells, which can become any type of cell in the body.
Dr. David Schaffer from the Stem Cell Center of the University of California Berkeley, says Gurtner's innovation is important.
"This study, by taking pre-existing mature vasculature (arrangement of blood cells in an organ) actually circumvents the need to build your own vasculature within a tissue-engineered equivalent and as a result it promises to greatly enhance the survival of the resulting tissue once it's implanted inside the body."
But he also urges extreme caution until the technique has been proven in humans.
So far, all the experiments have been restricted to rats.
The scientists also admit they're nowhere near being able to generate whole organs.
They even agree that other more effective methods might be developed more quickly.