In response to yesterday’s blog entry, SLC asked:

“In the current controversy over embryonic stem cell research, some of the advocates have pointed to ALS as one of the conditions that might be amenable to treatments derived from such research. Given Dr. Novella’s neurological specialty, could he comment on this issue?”

I’d be glad to.

ALS and other motor neuron diseases are ones for which stem cell therapy holds some hope and promise. Since these diseases result from the death of cells (motor neuron) the idea is that stem cells could be transplanted into the brains or spinal cords of patient and then coaxed into becoming neurons to replace the ones that are lost. It is further hoped that these new neurons will be healthy and not suffer the same fate as the neurons they are replacing.

Today, treatments (both proven and experimental) for ALS are designed to reduce one or more of the sources of metabolic stress on the neurons – making a friendlier environment for the, – so that they survive longer. At best such therapy would stop the death of surviving neurons, but would do nothing to restore those already lost. In practice, these therapies only slow down the death of neurons, not stop it. So patients do not get better, in fact they continue to get worse, only slower.

But stem cells have the potential to actually make patients better by replacing lost neurons.

Unfortunately, we are still far from perfecting this technology. We are still working on the basics: getting the stem cells to survive in the host where they are transplanted, getting them to become the right kind of cells, and keeping them from turning into tumors or cancer. With neurons there is also the further complexity of getting the neurons to make the proper connections. That is a real challenge.

However, there is also another potential use for stem cells – not as replacement cells but as drug delivery systems. For example, stem cells could be turned not into neurons but glia. Glia are cells of the nervous system whose primary (although not only) function are as support cells. They keep the neurons alive and happy. Some researchers are exploring the possibility of engineering stem cells into specialized glial cells that can be transplanted around the surviving motor neurons in patient with ALS. These special glia will then manufacture and excrete trophic factors and other chemicals to keep the neurons alive and perhaps even improve their function. This is a far easier goal to achieve, because the glial cells do not have to make any precise neuronal connections; they can do their job by just dumping their products into the local environment.

As I blogged about here stem cells are not ready to use in people at this time. Any clinics or doctors claiming they have an effective stem cell therapy for ALS or any other disease are either mistaken or con artists. But stem cells are an extremely promising avenue of research, and I have reasonable hope that I will see them used during my career.