Human Stem Cells Improve Mouse Neurodegenerative Disease
By Ann Carroll*

A California research team reported in the journal Nature Medicine that the injection of either human embryonic stem cells or fetal neural stem cells into the brains of mice with an inherited neurodegenerative disease resulted in delayed disease onset and prolonged lifespan.

The mice used in the study had a disease that resembles Sandhoff disease, an inherited neurodegenerative disorder that is marked by impaired control of body movement, mental retardation, and death in infancy. The mice are not able to produce an enzyme that is critical for breaking down fatty substances called lipids. This causes a build up of the fatty substances in the brain and spine, resulting in progressive impairment of normal body movement. The mice die by about 4 months, rather than the normal two-year lifespan.

The team first observed that injection of normal mouse neural stem cells into newborn diseased mice greatly slowed down the progression of the disease. The treated mice retained control of body movement for longer periods than untreated mice, and they lived for one third longer. When the stem cell therapy was combined with a drug that enhances the action of lipid breakdown, a further improvement was seen.

Next, the researchers turned to human neural stem cells, taken from either fetal neural tissue or derived from human embryonic stem cells, and again transplanted these into the sick mice. Similar improvements were seen in both cases.

How do the neural stem cells work? The neural stem cells appear to work by replacing lost neurons and also by providing ‘supporting’ cells that surround the neurons and help their function. In addition, inflammation, that can cause further damage to the tissue, is decreased. With the new cells present, the response to a previously known drug improves.

This research shows that injected neural stem cells may work in several ways to help restore and protect neural function and that together with other treatments neural stem cell therapy may give better results than either treatment alone.

Notes
Lee, J. P., Jeyakumar, M., Gonzalez, R., Takahashi, H., Lee, P. J., Baek, R. C., Clark, D., Rose, H., Fu, G., Clarke, J., et al. (2007). Stem cells act through multiple mechanisms to benefit mice with neurodegenerative metabolic disease. Nat Med. DOI: 10.1038/nm1548

*Author affiliation
Ann Carroll, PhD
Freelance Consultant
acarrollfr@aol.com

Posted April 6, 2007