CELL SWITCH


Scientists succeed in cell switch
By Malcolm Ritter, The Associated Press Article Last Updated: 08/27/2008

NEW YORK - Talk about an extreme makeover: Scientists have transformed one type of cell into another in living mice, a big step toward the goal of growing replacement tissues to treat a variety of diseases.

The switch turned ordinary pancreas cells into the rarer type that churns out insulin, essential for preventing diabetes. But its implications go beyond diabetes to many other possibilities, scientists said.
It's the second advance in about a year suggesting that someday doctors might be able to use a patient's own cells to treat disease or injury without turning to stem cells taken from embryos.
The work is "a major leap" in reprogramming cells from one kind to another, said one expert not involved in the research, John Gearhart of the University of Pennsylvania.
That's because the feat was performed in living mice rather than a lab dish, the process was efficient, and it was achieved directly without "middlemen" like embryonic stem cells, he said.
The newly created cells made insulin in diabetic mice, though they were not cured. But if the experiment's approach proves viable, it might lead to treatments such as growing new heart cells after a heart attack, growing nerve cells to treat disorders such as ALS, also known as Lou Gehrig's disease.
Douglas Melton, a Harvard Stem Cell Institute co-director and Howard Hughes Medical Institute researcher, cautioned that the approach is not ready for people.

Basically, the identity switch comes about by a reprogramming process that changes the pattern of which genes are active and which are shut off.
Scientists have long hoped to find a way to reprogram a patient's cells to produce new ones. Research with stem cells - and similar entities called induced pluripotent stem cells or iPS cells, announced last year - has aimed to achieve this in a two-step process.
The first step results in a primitive and highly versatile cell. This intermediary is then guided to mature into whatever cell type scientists want. That guiding process is difficult to do efficiently, especially for creating insulin-producing cells, Gearhart noted. But the new method holds promise of going directly from one mature cell type to another - like making a scientist a lawyer with no need for another childhood, Melton says. So, he says, someday scientists may be able to replace dead nerve or heart cells in people by converting some neighboring cells. At the same time, he stressed, it's still important to study embryonic stem cells and iPS cells