Grow your own heart cells

Patches of human heart tissue that could eventually lead to a "puncture repair kit" for cardiac disease or injury have been grown artificially in the United States, writes Geraint Smith.

The patches, a few millimetres across, were grown inside a Nasadesigned device called "the bioreactor". According to scientists Lisa E Freed and Gordana Vunjak-Novakovic, who grew the heart tissue, the cells contract exactly like a beating heart. "The possibilities are breathtaking," said Nasa today. "One day, perhaps, biomedical engineers will simply grow new hearts for people who need them."

Nasa developed the bioreactor for cell studies in space. Scientists discovered that on Earth, the bioreactor mimics some aspects of weightlessness, making new cells stick together more easily.

As yet, there are no blood vessels in bioreactor-grown tissue. "More work is needed," the scientists say.