How Stem Cells Might Help ALS Patients

Understanding how amyotrophic lateral sclerosis affects patients is key to developing stem cell treatments for the condition. In Lou Gehrig’s disease the motor neurons degenerate and die, affecting nerve signal transmission controlling movements. Motor neurons also relay information back to the central nervous system in order to allow processing before instructions for movement are sent back. Glands and organs are also affected as messages are not properly delivered to and from the CNS to allow their proper function. Motor neurons can measure a meter long and are protected by a myelin sheath that also helps insulate the nerve signals, just like the insulation on an electrical wire. Damage along any area of that neuron can affect the nerve signal transmission and produce the symptoms of ALS and it is likely that the myelin insulation would be the target of any stem cell therapy to treat ALS.

Stem Cells for ALS Using Nerve Scaffolding

Other discoveries have prompted scientists to wonder about transplanting neural stem cells onto existing nerve pathways to promote regeneration of nerves in ALS patients. This is based on the revelation that after a nerve dies there remains, for an indefinite period, a scaffolding of sorts which connects to the muscles and organs. Such a scaffolding may allow for stem cell transplantation and a reversal of ALS symptoms.

Stem Cells and Demyelinating Disease

Diseases that affect the myelin sheaths around nerves, such as multiple sclerosis and amyotrophic lateral sclerosis, are hard to treat due to the current inability of medicine to repair the lost myelin. In most cases the best hope is to try to slow down the degeneration of the insulation by controlling inflammation in the body, and then offering palliative care for the patients’ existing symptoms. Scientists at Harvard University however have found that the inability of the body to repair lost myelin is largely age-related, offering an opportunity to reverse the damage by transplanting younger stem cells into the central nervous system.

Immune Cells and Stem Cells in ALS

Working alongside researchers at the University of Cambridge, and publishing the resulting work in the journal Cell Stem Cell, the Harvard scientists demonstrated proof-of-principle of defect reparation when older mice with an induced CNS lesion were exposed to the circulatory system of a younger mouse. The apparent repair of the myelin around the nerves was thought due to an influx of macrophages, immune system cells, from the younger mouse’s bloodstream that then prompted the stem cells in the older mouse’s spinal cord to restore the myelin.

Removing Damaged Myelin to Restore It

The research carried out by the Cambridge and Harvard scientists provides an example of how damaged myelin can impede regeneration. The young immune system cells effectively cleared away the damaged myelin thus allowing the older mouse’s own stem cells to commence repair. As most patients with ALS are older it may be that autologous stem cell transplants will prove inefficient at treating the damaged neurons and that donor blood would be more efficient. It is also possible that further research allow scientists to develop drugs that mimic the action of these younger immune system cells and provide signals to the resident stem cells to begin restoring the myelin lost through ALS. Such developments are more likely to be of use in other demyelinating diseases however, such as multiple sclerosis, as they typically continue over many years of life and involve a gradual demyelination that may be more easily reversed if caught early enough. Such treatments for ALS and MS would work without stem cell transplantation then, using instead the body’s own stem cells to repair itself.

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