Study shows stem cells could replace weakened immune system

• Injections of embryonic stem cells, versatile building blocks that can take on many functions, can reconstitute aging immune systems, according to a study of cows appearing today in the journal Cloning and Stem Cells.
• Using a technique similar to one South Korean researchers have experimented with in humans, Lanza cloned cow embryos by putting DNA from a cow's skin cell in the animal's egg cell to grow an embryo.
• The study demonstrates how tissues genetically matched to a DNA donor might be used to treat patients with immune disorders, said Piero Anversa, a stem-cell researcher and director of the Cardiovascular Research Institute at New York Medical College.
• People with injured immune systems, such as those with HIV, the virus that causes AIDS, are at high risk of infection with bacteria and viruses.
• ``We thought the cells might be competitive enough to make room in the immune system on their own,'' he said in a telephone interview.
• ACT shares fell 4 cents, or 1.5 percent to $2.70 yesterday in over-the-counter trading.
• The immune systems were successfully replaced in one cow that received low doses of immune-suppressing drugs and in a second cow that received no drugs, the study said.
• A third cow that received high doses of drugs that wiped out its immune system before the stem cell injection died from complications.
• In the successful injections, Lanza found large colonies of young immune cells in the cows' circulatory system that were similar to clusters of cells found in young animals and humans.
• South Korean stem cell researcher Hwang Woo Suk reported May 20 in Science that he had created patient-matched stem cells by transplanting DNA from skin cells into human eggs.