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.
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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.