Graphic: top discoveries of 2008

A tissue reprogramming technique that promises an almost limitless source of stem cells without the need to destroy embryos has been named as the breakthrough of the year by the prestigious journal Science.

The method for turning back the clock on adult tissue, so it acquires the versatile properties of embryonic stem cells, heads a list of ten achievements that also includes the direct observation of planets orbiting distant stars, and cheaper and faster technologies for mapping the genetic code.

The stem-cell advance, made by separate teams in Japan and the United States, has excited scientists because it could lead to tissue therapies for diseases such as Parkinson’s and diabetes grown from a patient’s own skin.

It is also providing researchers with powerful laboratory models for investigating conditions such as motor neuron disease, Down’s syndrome and Huntington’s.

As so-called induced pluripotent stem cells (IPS cells) carry a patient’s DNA, they would not risk rejection by the immune system if transplanted.

They are also more ethically acceptable to some religious groups as their creation does not directly involve embryos, although embryonic stem-cells research was critical to the development of the technology.

Robert Coontz, deputy news editor of Science, said the great strides made by IPS cell technology in 2008 had made it an easy choice as the year’s most significant scientific landmark.

“When Science’s writers and editors set out to pick this year’s biggest advances, we looked for research that answers major questions about how the Universe works and that paves the way for future discoveries,” he said.

“Our top choice, cellular reprogramming, opened a new field of biology almost overnight and holds out hope of life-saving medical advances.”

The creation of IPS cells in mice was pioneered by a team led by Shinya Yamanaka, of the University of Kyoto. He and a team led by Jamie Thomson, of the University of Wisconsin, then repeated the feat with human tissue.

The cellular reprogamming involves wiping out a cell’s developmental “memory” by tweaking up to four genes, which causes it to revert to an embryo-like state from which it should be able to form any of the body’s 200 or so specialised cell types.

This year several groups around the world have created IPS cells that model real diseases. Other scientists have made progress in ironing out some of the safety problems – the first IPS cells were made by manipulating genes with viruses, in ways that could promote cancer. Science cautioned, however, that considerable work is still required before IPS cell technology is ready for clinical trials.

The runner-up on the breakthrough list was the direct observation of planets orbiting stars. While more than 300 of these “exoplanets” are now known, the vast majority were detected by measuring wobbles in the light from a star, or by other indirect means. This year, scientists have obtained direct images of several planets, such as three objects that orbit a star called HR8799, 128 light years from Earth. The achievement required sophisticated methods for blotting out the light from the planets’ parent stars, which normally makes them invisible.

The development of new genome sequencing technology, which promises to bring the cost of reading the human genetic code down to about $5,000 (£3,200), also made the list. These methods have also let scientists map the genomes of extinct animals, such as the woolly mammoth.

Other advances to be honoured include the most detailed video taken of a developing embryo, new calculations of the weight of the world, and the discovery of new genes that influence cancer. European big science was named as the phenomenon of the year, chiefly for the switch-on of the Large Hadron Collider at CERN in Switzerland, but also because of the start of construction work on the ITER experimental fusion reactor in France. The financial crisis was named as the “breakdown of the year”. Areas to watch in 2009 highlighted by the journal included insights into genes that split species in two and the Copenhagen climate change talks.

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