American researchers have coaxed adult stem cells from adult mice to change into brain, nerve, heart and pancreatic cells -- a discovery that could put embryonic stem cells in the shade. A researcher at the University of Louisville, Dr Mariusz Ratajczak, said, "We have found a counterpart for embryonic stem cells in adult bone marrow. This could negate the ethical concerns." His next move will be to replicate the experiment with similar cells identified in adult humans.

"It's huge," said Ryan Reca, one of the researchers. "It's an amazing discovery." "If cells from adult humans behave the same, the discovery goes from 'very important' to 'incredibly important'," said Dr Stephen Emerson, of the University of Pennsylvania.

The cells are called "very small embryonic-like" cells, or VSELs, which exist in blood and help to repair damaged tissue after strokes. Ratajczak's discovery revolves around how to grow these in the laboratory, multiply them and change them into other cells with his patented growth factors. He has managed to get the VSELs to produce cardiac muscle cells, pancreatic cells, nerve cells and brain cells.