Analysis: Reprogrammed cells open new medical window

LONDON (Reuters) - The Nobel Prize-winning discovery of how to reprogram ordinary cells to behave like embryonic stem cells offers a way to skirt around ethical problems with human embryos, but safety concerns make their future use in treating disease uncertain.

While researchers have already applied the scientific breakthroughs of Britain's John Gurdon and Japan's Shinya Yamanaka to study how diseases develop, making such cells into new treatments will involve a lot more checks.

Stem cells act as the body's master cells, providing the source material for all other cells. They could transform medicine by regenerating tissue for diseases ranging from blindness to Parkinson's disease.

Creating embryo-like stem cells without destroying embryos gets round a key controversy by avoiding the need to process embryos left over at fertility clinics - a system that has led to political objections in the United States and elsewhere.

Reprogrammed cells - known as induced pluripotent stem cells, or iPS cells - offer an ethically neutral alternative. They have been a source of intense research since Yamanaka discovered their potential in 2006, building on work that Gurdon did in frogs and tadpoles 40 years earlier.

SAFETY CONCERNS

Recently, however, different research groups have noticed problems with iPS cells, suggesting they may not be as good as embryonic ones. In one study, iPS cells died more quickly and another found multiple genetic mutations, raising concerns that they could cause tumors.

Despite this, Japanese researchers hope to test iPS cells in clinical trials for a form of blindness as early as next year - catching up with recent successful eye trials using embryonic stem cells.

Researchers in the West are generally more wary.

"There is a bit of a divergence between Japan and the rest of the world on this," Chris Mason, professor of regenerative medicine at University College London, told Reuters.

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Analysis: Reprogrammed cells open new medical window