Canadian scientists have shown that they can turn human skin cells into blood cells, without going through an intermediate stem cell stage. The technique, called "direct reprogramming", used only one (Oct 4) of the four "Yamanaka factors" used previously to reprogram skin cells into iPS cells (pluripotent stem cells that behave like embryonic stem cells). Further treatment with specific cytokines induced various types of blood cells to form. 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.

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