Recent announcements regarding the outcome of stem cell studies in MS have aroused excitement and hope that we may finally have an answer to the problems caused by MS. Over the last several decades, research teams all over the world have worked extensively to try and unlock the mystery of why MS occurs and how to arrest the characteristic damage to the brain and spinal cord that causes the multiplicity of symptoms experienced in MS.
Basically, we understand MS to be a disease in which the immune system turns against specific structures in the body and damages them rather than protecting them. In the case of MS, the structure most involved in damage is myelin. Myelin is the fatty sheath that surrounds nerve axons, the nerve processes that connect one group of nerve cells to other nerve cells in an organised and complex way so that communication between different parts of the brain and spinal cord can work in concert to bring about organised actions (controlled movement for example) or to inform us about the world around us- touch, sensation, vision etc. When you consider that we believe there are many more of these interconnections between nerves in different parts of the nervous system than there are stars in the Milky Way it becomes evident that we are dealing with a very complex and well-ordered system that once damaged will not be easy to put back together.
For many years, it has been thought that the key to addressing MS is to try and prevent episodes of damage (relapses) or other ongoing events that we do not fully understand (progressive phases of MS) by understanding the role of the immune system in the development and continuation of nerve damage and to target these events. Extending our understanding of these very complex events has led to the development of several very powerful drugs that suppress the damaging events in MS and reduce the rate of change in early relapse/remitting MS (see our information on drugs used in MS). The one thing these drugs do not appear to do is to help repair the damage already caused. Long term disability still occurs and while it is undoubtedly helpful to slow down the progress of MS the real goal must include some elements of restoring the normal function of the nervous system.
Stem cell studies take many different forms. One concept is to try and “rebuild” the damaged nerve tissues or restore the myelin protective coating to nerve axons. This type of stem cell work is still a very long way from restoring function in people who have MS. Never the less many laboratories are concentrating on understanding the ways in which this is achieved in normal brain development and applying this information to attempts at nerve and myelin repair. The capability to do this is a goal for many neurological conditions as well as traumatic damage to the brain and spinal cord and at the basic science level this wealth of world-wide studies could provide vital information that will help towards repairing MS related damage in time.
More often reported is the concept of using stem cells to rebuild the immune system to rid the body of cells that will continue to cause damage even when they have been suppressed by the type of drugs discussed above. All blood cells originate in specialist tissues inside bone-the bone marrow- that continuously makes new cells (via a stage now recognised as “stem cells”) to replenish the immune cells, red blood cells, and other cells normally carried throughout the body in the blood. In MS, the focus is mostly on lymphocytes, the white blood cells that help fight infections and protect us from a range of disease causing agents such as viruses. To do this cells must first recognise “self” and “not self” so that in normal situations damage is only caused to invading “foreign” agents and not the person’s own body. In MS, we believe that in some way as yet unexplained, lymphocytes mistakenly become sensitised to some element of normal myelin and start to attack the body’s own myelin.
The procedure known as autologous bone marrow stem cell transplantation is now recognised as one that for numerous reasons is thought to be relatively safe for human studies and offers many advantages. Autologous means that the person being treated receives only their own cells avoiding rejection. Stem cells can be harvested directly from the bone marrow or by inducing the release of high numbers of stem cells into the blood stream and harvesting them from blood. Stem cells destined to become immune cells can be separated and protected from being exposed to the activating agent in the blood of MS patients that may cause them to attack myelin. Different procedures for transplantation are being investigated, the most published methods being those in the HALT-MS series of studies. However, several other studies are underway and all such studies carry some element of risk.
We expect the next few years to deliver some of the most exciting research in MS and longer term studies will determine the most effective methodology, the best way to limit risks associated with stem cell transplantation and the means to enable such procedures to be carried out in specialist centres around the world with minimum risk and maximum advantage. MS Research will contribute to such studies to help define the most effective and safest way forward.