By David Prentice

Editor’s note. This appeared on Dr. Prentice’s blog in a slightly different form yesterday--http://www.frcblog.com/2010/11/blood-cells-from-skin/

Canadian scientists have shown that they can turn human skin cells into blood cells,, without going through an intermediate stem cell stage (www.nature.com/news/2010/101107/full/news.2010.588.html).

The technique, generally called “direct reprogramming,” adds specific genes to normal cells, transforming them directly into a different cell type, but without creating a stem cell.

The Canadian group used only one (called Oct-4) of the original four genes used by Dr. Shinya Yamanaka of Japan to reprogram skin cells into iPS cells. (IPS cells--“induced pluripotent stem cells”--are stem cells that behave like embryonic stem cells but are created without use of embryos or eggs.) The direct reprogramming created a blood cell precursor, and further treatment with specific blood-induced factors led to various types of specialized blood cells.

Direct reprogramming from one cell type to another avoids the problems inherent in pluripotent stem cells, including the problems of tumor formation, as well as the ethical problems of embryonic stem cells (www.physorg.com/news/201011-scientists-skin-blood.html). The cells that were directly reprogrammed did not produce any tumors in mice.

The study was published online in Nature. Previous studies have shown success of direct reprogramming in mice, producing neurons, heart muscle precursors, and insulin-secreting cells. But the McMaster University team is the first to show that direct reprogramming can work with human cells.