How can stem cell research benefit people suffering from multiple sclerosis?
-An undergraduate from California
March 2, 2007
As with many other diseases, stem cells hold great promise for treating multiple sclerosis (MS). One way to use them is to completely replace someone's immune system. Another is to use stem cells to fix damaged nerves.
To understand these uses of stem cells, we need to understand MS better. MS can be a really serious illness. It mostly affects women aged 20-50 years old.
It is a disease where our own bodies attack the protective covering of our nerves. And as the disease gets worse, more and more areas of damage appear.
These damaged areas affect the nerves which are under the covering or myelin sheath. This causes a person with MS to have weakness and sometimes be paralyzed.
Many doctors think our immune system causes this. Usually our immune system is the good guy -- it helps us fight infections. In MS, though, it gets confused. Instead of attacking foreign cells, the immune cells attack the cells covering our nerves.
What makes MS even worse is our bodies are not very good at replacing these lost cells. So the disease just keeps getting worse.
So what can you do to treat something like this? One approach is to deal with the immune system that is causing the problem.
This is how some current treatments work. They weaken, or suppress, the immune system so that an MS patient's nerves are not attacked as strongly.
A more radical approach is to replace the patient's immune system using stem cells. This can happen if a person gets a bone marrow transplant.
Our bone marrow has blood stem cells. These stem cells make new blood cells as the old ones wear out.
Our immune system is in our blood cells. By replacing our blood, we are establishing a new immune system. One that hopefully won't attack our myelin sheath.
Over the world, 70 people had a bone marrow transplant to treat MS (click here for more details). Because the procedure is such a big deal, it is usually used as a last resort to help patients with the most severe MS symptoms. Out of the 70 patients, 40 did well. This treatment shows promise for patients with advanced cases of MS.
Of course this only stops more damage from happening. It doesn't do anything to fix what was broken. But stem cells may be able to help us here too.
As I said before, the body is terrible at growing new nerve tissue. But it wasn't always this way.
Our bodies used to be able to make new nerves. Like when we were growing in the womb and developing from a single cell. So maybe we could use these types of cells to make new nerve tissue.
The idea would be to inject these cells into a person, and those cells could find their way to the damaged nerves. When they got there, they could repair them by making new layers of the myelin sheath.
Scientists call this "endogenous repair" because you would use your own body to repair what was lost. The cells we're talking about here are stem cells.
And they aren't any stem cells. They're those controversial embryonic ones. But they may not be the only ones that can make nerve tissue.
Stem cells are also in the umbilical cord, and in adults. These cells, called "progenitor cells" can develop into the nerve cells which can replace the ones which were destroyed in MS.
Well, like in many areas of stem cell research, there's a lot of controversy here. Some scientists have injected stem cells into mice which had a disease very similar to MS. They found that the mice which were paralyzed got better after these treatments.
Some doctors in the Netherlands have been working on MS. They used umbilical cord stem cells in adults and say the patients improved. Unfortunately, other scientists aren't convinced of these findings.
More importantly, some scientists and doctors aren't sure these therapies are safe yet. Most specialists think that more research is needed in this area before we can use stem cells for therapy.
The good news is that stem cells already seem to be helpful. Many who received bone marrow transplants did well. And, in lab experiments, mice did well with other types of stem cells. Future research may improve these techniques. And, it might be more available to really help people with MS.
by Dr. Devasena Gnanashanmugam, Stanford University