Article from Wall-Street Journal:
Stem-Cell Study Treats
Sickle-Cell Anemia in Mice
By GAUTAM NAIK
December 6, 2007 2:06 p.m.
In the latest of a string of stem-cell breakthroughs, scientists have derived embryonic-like stem cells from mature tissue of mice, then used the fresh cells to successfully treat a version of sickle-cell anemia in the animals.
The experiment is an encouraging sign that similar transplant therapies may one day work in humans. It builds on recent advances in which embryonic-like stem cells have been created by reprogramming mature cells in mice and humans -- a promising approach that doesn't require the use of eggs or destruction of embryos, which can be ethically contentious when applied to humans.
People with sickle-cell anemia, which often is fatal, inherit two defective genes for the disease, one from each parent. As a result, there aren't enough healthy red blood cells to carry oxygen throughout the body. Symptoms can include episodes of pain in organs or joints, fatigue and shortness of breath. There are treatments but no cures.
In the latest advance, published Thursday in the online version of the journal Science, researchers used stem cells to treat specially engineered mice that had the same defective genes as someone with sickle-cell anemia. The treatment required several steps.
The scientists first introduced four specific genes into mature skin cells taken from mice. These genes "reprogrammed" the cells and returned them to a more primitive, embryonic-like state. In a lab dish, the cells were then chemically turned into a type of tissue that can generate blood cells in the body.
Next, a normal gene was substituted for the defective "sickle cell" gene in the freshly derived tissue. This step corrected the tissue, which was injected back into the ill mice, where they formed healthy blood cells free from disease.
The mice had previously suffered from rapid breathing, low body weight and low blood counts. After treatment, their condition improved. "It was striking," says Rudolph Jaenisch, whose lab at the Whitehead Institute for Biomedical Research in Cambridge, Mass., did the experiment. "Once you repair it, all the symptoms go away." The paper's lead author is Jacob Hanna, also from Whitehead.
There are limitations to the approach similar to those faced by other recent stem-cell innovations. As part of the reprogramming step, the Whitehead scientists had to use potentially dangerous viruses to introduce the four genes into the mouse's cells. Researchers are now trying to find a benign virus that can do the same trick. While sickle-cell disease is a fairly well-understood malady -- especially the genetic underpinnings -- complex ailments such as Parkinson's will probably be far harder to treat, even in mice.
Nonetheless, the latest piece of science adds to several big advances in recent months in the field of cell reprogramming. Several scientists have shown it is possible to return mature skin cells to an embryonic-like state in both mice and humans. But it will take years -- and a lot more research -- before the transplantation technique can be tried in people.
Write to Gautam Naik at gautam.naik@wsj.com