Stem cell therapy will not cure Alzheimer’s disease
Researchers from the University of California at San Diego have been able to isolate stem cells from Alzheimer’s disease patients and made them behave like neurons.
This is a great scientific feat that will help the research community understand better the mechanisms by which the Alzheimer’s brain deteriorates. It has also generated some media buzz about how stem cell therapy may one day cure this devastating condition. Unfortunately, that is extremely unlikely to happen, and here’s why:
Stem cell therapy involves replacing damaged or injured cells with new ones, called stem cells, which have the ability to become identical to the cells they are replacing. The supply of stem cells is unlimited and, because they originate from the person suffering the injury or the disease, there are no concerns about immune rejection. This sort of therapy can lead to a dream scenario where people can tap into their own stem cell reservoir any time a major disease or an injury strike and replace damaged or dead cells with new ones.
Stem cell therapy is in fact already working in many cases and is likely to be successful in many more, but it simply cannot work with Alzheimer’s disease, because of the unique properties of the cells that are injured and that die in this condition. Perhaps this will be best understood if we compare it with Parkinson’s disease, in which stem cell therapy is likely to succeed. What happens in Parkinson’s is similar to Alzheimer’s disease in that there is massive death of neurons, but in the Parkinson’s case those neurons are in charge of one thing: coordinating movement skills. This is a relatively simple task, more or less mechanical in nature, and it is not difficult to see how one could replace dead or injured neurons with new ones that will do the same job and will help sufferers recover their movement skills.
Now compare this with what happens to Alzheimer’s disease sufferers. Their problem is not a loss of movement skills or any other relatively basic function. What they lose is cognitive function, mental sharpness, intelligence, senses of irony, sadness, happiness…In short, they lose the essence of who they are, and that essence is defined mostly by the unique connections and interactions amongst brain cells, not by the actual cells themselves. Because those connections are created and evolve as a consequence of life experiences that are obviously unique to each of us, once the cells die and the connections are lost, we cannot get them back, unless we could live the same life all over again with the newly replaced cells. Obviously, that does not make sense, and therefore neither does attempting to use stem cell therapy to cure Alzheimer’s disease.
All of this is not to say that stem cell research is not a good thing. It is in fact a great research tool, which, together with many others already in place, will help us understand how the brain deteriorates in Alzheimer’s disease. But it will not cure Alzheimer’s disease. If we want to do that, we need to understand what happens in the brain BEFORE it begins to deteriorate, so we can have intervention strategies at that stage. Unfortunately, and as we wrote in our previous post here, that is unlikely to happen any time soon and Alzheimer’s disease is well on its way to becoming the plague of the XXI century.