Researchers at the Stanford University School of Medicine have discovered a way to transplant new blood forming stem cells in the bone marrow of mice in the laboratory and the result was the mice developed a completely new immune system. This is the first step leading to the ultimate goal of being able to create a new immune system for human patients with many of the autoimmune or genetic blood diseases.
The mice are a poor imitation of the human immune system and they need to adapt many of the techniques that they used in the mice before they can begin to test it on humans, but once they have been able to accomplish it, the potential effects are huge.
Autoimmune diseases like multiple sclerosis cause the immune system to become defective and it then attacks the persons own body. To be able to transplant an immune system, like they are able to do with organs, would give the patients a system that might not go on the attack.
But you cannot do an immune system transplant the way you can an organ one. The way to do it is to transplant new blood forming stem cells in the bone marrow. It is here that they generate all of the blood cells. But you cannot transplant any new stem cells while the old ones are still there and until now the only way to remove them has been to use chemotherapy or radiation, which do a good job of removing the bone marrow cells, but unfortunately also damage healthy tissue and can cause lasting and devastating side effects like infertility or brain damage. They also put the patient at an increased risk of developing cancer.
The researchers set out to see if it was possible to just remove the blood forming stem cells without having to affect the bone marrow cells or any other tissues.
In experiments with mice, they injected them with molecules that attach themselves to specific proteins that are on the surface of the blood forming stem cells and this caused the death of just those cells. And there was no other damage done to the mice. When they then transplanted new blood forming stem cells in the mice, the cells set up in the bone marrow and were able to establish a completely new blood and immune system.
If they are eventually able to perform this procedure in humans with an autoimmune disease, it is more than likely that the new immune system would not attack the tissues like the defective one did. Also with people who have a genetic disorder such as sickle cell anemia, the new blood would not have the sickle cell mutation.
But there is much work to be done. They do not know if the same molecule on human blood is the right one to target. And the mice that were used in the tests did not have a functioning immune system. Before they can even think of doing tests in humans, they must first work with mice who have a normal immune system. Even though it will be some time before they
The lead researchers are Irving Weissman, MD, director of the Stanford Institute for Stem Cell Biology and Regenerative Medicine, Deepta Bhattacharya, PhD, a postdoctoral scholar in Weissman’s lab and Agnieszka Czechowicz, a first author and medical student.
Source: Stanford University Medical Center http://www.eurekalert.org/