Cells to boost the human immune system may one day be grown in "piglet banks," it has been claimed.
Scientists have succeeded in growing stem cells from human umbilical cord blood and bone marrow in developing pig fetuses.
When the pigs were born the cells were found to have matured into a wide range of human T-cells - essential components of the immune system.
Mixed with ordinary cells from the donor who provided the stem cells, they did not mount an immune attack. However they did react to cells from other people, showing that they were functional.
Researcher leader Dr. Jeffrey Platt (pictured), from the University of Michigan at Ann Arbor, believes piglets could be used to provide "factories" for immune cells that fight specific diseases.
When some of his animals were vaccinated against a virus and a bacterium, human T-cells extracted from the animals staged immune responses against both.
"If I had HIV, I could put my stem cells in pigs and immunize them with an HIV vaccine," Dr. Platt told New Scientist magazine. "You would get immunity in the pig that you would never get in my body."
Adult immune systems were often too mature to react to such vaccines, he pointed out. The same could be done to encourage cells to attack cancer.
One option would be to use "mini-pigs" which are much smaller than farmyard pigs and easier to rear, said Dr. Platt.
A potential worry was that dormant viruses embedded in pig DNA might be spread to humans through the immune cells. But according to Dr. Platt this has never been shown to happen outside highly artificial laboratory conditions.
Illustration: University of Michigan.
University of Michigan Surgery Department, Transplantation Biology Program