Stem cell transplant can grow new immune system in certain mice

Nov 22, 2007

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 eliminate only the blood-forming stem cells without affecting bone marrow cells or other tissues. They worked with Agnieszka Czechowicz, first author and medical student, to accomplish that feat by injecting the mice with molecules that latch on to specific proteins on the surface of the blood-forming stem cells, effectively destroying the cells. That technique eliminated the blood-forming stem cells without otherwise harming the mice.

"It is essentially a surgical strike against the blood-forming stem cells," said Weissman, the Virginia & D.K. Ludwig Professor for Clinical Investigation in Cancer Research. When they transplanted new blood-forming stem cells into the mice, those cells took up residence in the bone marrow and established a new blood and immune system.

In a person with autoimmune disease, that new immune system would likely no longer attack tissues of the body. Likewise, in people with a genetic disorder such as sickle cell anemia, the new blood system would not have the sickle-cell mutation, eliminating the cause of disease. However, the barriers are still significant.

First, the researchers don't know whether the same molecule on human blood-forming stem cells would be the right one to target with a therapy. Also, the mice they used in the study lack a functioning immune system. They'll need to get the therapy working in mice with a normal immune system before they can begin testing the technique in humans.

Although these steps will take time to overcome, Weissman said he considered this work to be the beginning of research that could lead to human studies.

Source: Stanford University

Explore further: Recombinant peptide for transplantation of pancreatic islets in mice models of diabetes

add to favorites email to friend print save as pdf

Related Stories

A single-cell breakthrough

Mar 18, 2015

The human gut is a remarkable thing. Every week the intestines regenerate a new lining, sloughing off the equivalent surface area of a studio apartment and refurbishing it with new cells. For decades, researchers ...

Vaccines from a reactor

Mar 02, 2015

In the event of an impending global flu pandemic, vaccine production could quickly reach its limits, as flu vaccines are still largely produced in embryonated chicken eggs. Udo Reichl, Director at the Max ...

Nano-antioxidants prove their potential

Feb 09, 2015

Injectable nanoparticles that could protect an injured person from further damage due to oxidative stress have proven to be astoundingly effective in tests to study their mechanism.

Recommended for you

Novel nanoparticle therapy promotes wound healing

Mar 26, 2015

An experimental therapy developed by researchers at Albert Einstein College of Medicine of Yeshiva University cut in half the time it takes to heal wounds compared to no treatment at all. Details of the therapy, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.