Growing organs tough to deliver

It's 1998 and science is taking big strides. The first cloned mammal, Dolly the sheep, has just had her first lamb; the first robotically assisted heart surgery has been completed.

In a bold announcement, biomedical engineer Professor Michael Sefton declared that within 10 years, scientists would have grown an entire heart, fit for transplant.

"We're shooting big," he said. "Our vision is that we'll be able to pop out a damaged heart and replace it as easily as you would replace a carburettor in a car."

Stem cells were a little-known area of research then. Here was a blank-template cell with the potential, given the know-how, to become any other type of cell in the body.

In 1997, the first regenerative cell-therapy had been given the go-ahead, where stem cells were used to regrow cartilage in the knee. Later in 1998, the first human embryonic stem cells were isolated.

Fifteen years on, however, we've had some liver cells, eye cells, even a lab-grown burger, but no whole human organs. We could be forgiven for asking: where's our heart?

Speaking last week about the 1998 vision he and his colleagues outlined, Sefton said they had been "hopelessly naive". As time plodded on and an understanding of the biological complexity increased, the task seemed bigger and bigger. Even now we are not much further ahead.

Chris Mason is a professor of regenerative medicine at University College London and believes that concentrating on organ regeneration is missing a trick. "These organs are immensely complex," he said.

"They've got nerves, blood vessels, in the case of the liver, a bile system - there are huge degrees of complexity. These things take a long time to grow in humans, let alone in the lab without all the natural cues that occur in the growing embryo.

"The research community is still going towards trying to produce major breakthroughs, but if you do the economics, you have to move forward things that are actually doable. There's no good in coming up with a therapy that can't be afforded."

The real progress, he thinks, is seen through the doors stem cell research has opened. In recent studies cells were taken from another part of the body, induced into a stem cell state, and then placed around damaged heart muscle.

Normally, the immune system responds to the heart attack so aggressively that it damages a lot of the muscle itself, but stem cells seem to dampen this response.

- Observer