Stem cell transplant can grow new immune system in certain mice, Stanford resear...( STANFORD Calif. - Researchers at the...),Health

STANFORD, Calif. - Researchers at the Stanford University School of Medicine have taken a small but significant step, in mouse studies, toward the goal of transplanting adult stem cells to create a new immune system for people with autoimmune or genetic blood diseases.

The researchers found a way to transplant new blood-forming stem cells into the bone marrow of mice, effectively replacing their immune systems. Many aspects of the technique would need to be adapted before it can be tested in humans, said Irving Weissman, MD, a co-senior author of the study and director of the Stanford Institute for Stem Cell Biology and Regenerative Medicine. The work was done on a particular group of mice that are a poor mimic for the human immune system. Still, Weissman suggested the remaining hurdles could eventually be overcome.

When those barriers are surmounted, the benefits are potentially big. The study will be published in the Nov. 23 issue of Science.

A person with an autoimmune disease such as multiple sclerosis has a defective immune system in which immune cells attack the person's own body. An immune system transplant, much like a liver or heart transplant, would give the person a new system that might not attack the body.

The way to get a new immune system is to transplant new blood-forming stem cells into the bone marrow, where they generate all the cells of the blood. But before transplanting new stem cells, the old ones first must be removed, which is currently done by intensive chemotherapy or radiation. Those processes eliminate the cells of the bone marrow, but also damage other tissue and can cause lasting effects including infertility, brain damage and an increased risk of cancer. A treatment for M.S. at the expense of brain function is hardly an ideal therapy.

Weissman and co-first author Deepta Bhattacharya, PhD, a postdoctoral scholar in Weissman's lab, thought one way around this problem would be to elimi
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