Mini-hearts created from stem cells could help put new drugs to the test

I'm looking at a human mini-heart. Well, a model of a mini-heart. A person can give 2.5ml of blood to Professor Ronald Li Tang-wai and his team; within six months, they can create the stem cells, which in turn can build a blood-ejecting mini "cloned" human heart. The potential is huge. And it's a world first.

Li's mini-heart is created by using "pluripotent" stem cells, which can also be turned into other types of cells and tissues in the body.

"As soon as I get your blood," he says, "I can turn it into pluripotent stem cells. So first we get the raw material, then we tell these stem cells to become ventricular heart muscle cells, followed by assembling them into the desired three-dimensional forms, such as a patch, a fibre or a heart for different purposes."

The human heart has a billion cells, says Li. The heart his team has created is the same size as that of a fetus - but even with a partial adult heart, he says, it could be used to revolutionise drug discovery immediately.

Drugs could be tested on bio-artificial human hearts to see their impact, levels of toxicity, and side-effects. Many people, he says, who take hard-hitting cancer drugs end up with cardiovascular issues, or even die from heart failure because the drugs are so toxic. Doctors cannot tell who are more susceptible to drug-induced heart problems.

This would provide a safe environment for patients and drug companies to try out drugs.

"Cardiac toxicity is a common serious effect of numerous new as well as marketed drugs, not just those for the heart," says Li, 44, whose company has signed a strategic partnership with a major pharmaceutical firm.