Unstoppable growth

Scientists keep running into the same brick wall blocking the path to curing diseases with embryonic stem cells. In late October, American scientists published a study whose results were both hopeful and heart-rending for patients with Parkinson's disease.

The study tested the theory that scientists could turn embryonic stem cells-the progenitors of almost all human tissue-into dopamine-producing nerve cells that would repair the damaged brains of Parkinson's patients. The stem cells used in the experiment were taken from embryos, which died in the cell-harvesting process. Scientists then got the stem cells to form dopamine-producing cells by growing them with special substances that mimic the environment in the brain. When implanted in rats with Parkinson's disease, the nerve cells reversed some of the disease's symptoms. But they also turned into other types of cells that would have eventually formed tumors in the animals' brains.

Scientists have long struggled to prevent tumors from forming when experimenting with fetal and embryonic tissue. The young cells have too much potential for growth; they do not know when to stop and do not always retain the "programming" that tells them what kind of cell to become. At least one patient has died from a tumor after doctors implanted fetal tissue in his brain, though no one has reported trying the same experiment on humans with embryonic stem cells.

But the battle against tumors in embryonic stem-cell research has had small victories. Studies have shown that embryonic stem cells might be able to control themselves if scientists give them more time to grow and develop in the lab before implantation. And in a study in Japan that was published in 2005, monkeys that underwent embryonic stem-cell treatment for Parkinson's had no signs of tumor development when scientists dissected their brains more than 14 weeks after the transplant.

Making the Rounds

AIDS: U2 lead singer Bono's latest humanitarian effort last month inspired Americans to start shopping for a cause. On Oct. 13, the rocker appeared on The Oprah Winfrey Show to introduce (PRODUCT) RED, a partnership between the Global Fund and popular consumer labels such as Motorola, Apple, Emporio Armani, and the Gap. The companies have agreed to produce special (PRODUCT) RED merchandise-only some of it is actually red-and give profits to the Global Fund, an organization that uses the RED money for grants to African governments fighting AIDS.

HEALTH: Investigators have identified a wild pig on a California ranch as a possible contaminator in the spinach-borne E. coli outbreak that infected more than 200 people. The pig tested positive for the same strain of the disease found in spinach distributed by Natural Selection Foods LLC in San Juan Bautista, Calif. The California Department of Health Services wants to examine test results from other spinach fields before declaring the pig guilty, but investigators suspect that wild pigs broke into spinach fields and either contaminated the crop firsthand or tracked infected feces from cattle into the field.

FLU: European vaccine maker sanofi pasteur says clinical trials show its pandemic bird flu vaccine protecting against more variants of the H5N1 strain of influenza than expected. The company has a $150 million contract to mass-produce the vaccine in the United States. The U.S. government ordered the vaccine in fear that H5N1 bird flu would mutate into a form that could pass between humans.