Japanese scientists have moved another step closer to creating usable stem cells which can morph into any cell in the body but have no ethical baggage.

Shinya Yamanaka, of Kyoto University, electrified the world of regenerative medicine late in 2007 when he showed that stem cells with all the versatility of embryonic stem cells could be created by reprogramming four genes in ordinary skin cells. His original method involved introducing a virus. But after his latest research on induced pluripotent stem (iPS) cells, outlined in an article in Science, these no longer seem to be needed.

Instead of using retroviruses, Yamanaka injected the cells with plasmids, which can be found around E.coli bacteria. Plasmids generally do not enter chromosomes, and it is believed that they do not pose a threat of causing gene abnormalities.

This latest development lays to rest concerns that reprogrammed cells might cause cancers. However, the new method’s drawback is that it is less efficient. "The iPS field and stem cell research in general is progressing rapidly," says one of Yamanaka’s colleagues. "But, as Shinya has shown, each step forward reveals a new set of challenges." ~ Mainichi Daily News, Oct 10; Science Daily, Oct 12