Scientists reported Thursday they had developed a technique that can quickly create safe alternatives to human embryonic stem cells, a major advance toward developing a less controversial approach for treating for a host of medical problems. The researchers published a series of experiments showing they can use laboratory-made versions of naturally occurring biological signals to quickly convert ordinary skin cells into cells that appear virtually identical to embryonic stem cells. Moreover, the same strategy can then coax those cells to morph into specific tissues that would be a perfect match for transplantation into patients. The work, by a team led by Derrick Rossi of the Children's Hospital Boston, was praised by other researchers as a breakthrough. 'This paper is a major paper, in my view, in the field of regenerative medicine,' said Douglas Melton, who co-directs the Harvard Stem Cell Institute. Opponents of human embryonic stem cell research, meanwhile, seized on the advance as the most convincing evidence yet that alternatives were sufficient, rendering the morally questionable cells unnecessary. Rossi and other researchers, however, said that embryonic stem cell research was still crucial because, among other things, embryonic stem cells are irreplaceable for validating alternatives. Nevertheless, the announcement, described in a paper published in the journal Cell Stem Cell, could mark a pivotal moment in the long, contentious history of embryonic stem cell research. The advance comes as the future of federal funding for embryonic stem cell research hangs in doubt. A federal judge stunned the field Aug. 23 by ruling that the Obama administration's new more permissive policy for funding the research violated a federal law barring taxpayer dollars from being used for studies that involve destroying human embryos. The National Institutes of Health said that it supports research only on cells that have been obtained by privately funded scientists. An appeals court Tuesday let the NIH continue the funding as the case winds through the legal system. Scientists hope embryonic stem cells will lead to cures for diabetes, Alzheimer's disease, Parkinson's disease, spinal cord injuries and a host of other ailments because they can turn into almost any tissue in the body. But they can be obtained only by destroying days-old embryos, which some consider equivalent to killing human life. In 2006, researchers discovered that they could coax adult cells into a state that appeared identical to embryonic stem cells, dubbed induced pluripotent stem cells (iPS cells), by activating four genes. Those cells could morph into various tissues in the same way that embryonic stem cells can. But the process involved inserting genes into cells using retroviruses, which raised the risk the cells could cause cancer. Since then, scientists have been racing to develop alternative methods. Several approaches, using chemicals or other types of viruses, have shown promise. But none has completely eliminated the safety concerns, and most have been slow and inefficient. The new approach involves molecules known as 'messenger RNA,' or mRNA, which the DNA inside cells use to create proteins they need carry out various vital functions. The researchers created mRNA molecules carrying the instructions for the cell's machinery to produce the four key proteins needed to reprogram themselves into iPS cells. After tinkering with the mRNA molecules in the laboratory to make signals that the cells would not destroy as dangerous invaders, the researchers found that a daily cocktail of their creations were surprisingly fast and efficient at reprogramming the cells. The approach converted the cells in about half the time of previous methods - only about 17 days - with surprising economy - up to 100 times more efficient than the standard approach. Moreover, detailed tests indicated the cells had not experienced any disturbing changes in their DNA caused by previous methods and were virtually identical to embryonic stem cells. In addition, the researchers went one step further and showed that they could use the approach to then coax the iPS cells they created into a specific type of cell, in this case muscle cells. t 