June 30, 2006
Stem Cell Progress on Several Fronts Give Hope for ALS
[QUICK SUMMARY: New progress in stem cell research includes proof of principle that spinal cord injury can be repaired, as well as other important advances that could bring stem cells into the treatment arena for ALS.]
The ALS Association is featuring advances in stem cell research as part of this month’s journal news service. This month’s digest of noteworthy published findings marks the first full year of this new service that the research department is pleased to provide for the ALS community. In noting this anniversary, it is satisfying to see the progress many researchers are making in understanding stem cell biology, with an eye toward designing effective treatment for amyotrophic lateral sclerosis (ALS, also called Lou Gehrig’s disease).
A key finding that achieved wide press coverage was that motor neurons derived from embryonic stem cells could be placed into the spinal cords of rats that had lost motor neurons, with the rats regaining partial ability to walk. Yet several other publications in the stem cell field encourage those seeking to help treat motor neuron disorders.
In research funded by The ALS Association, Douglas Kerr, M.D., Ph.D., at Johns Hopkins University, showed that stem cell therapy can partially restore motor function in a report in the Annals of Neurology in July. The rats had been given a viral infection that specifically killed their own motor neurons and as a result were paralyzed. This is not the same type of rat that is often used to model ALS, the rat with a mutation to a protein changed in some inherited forms of ALS, namely, copper-zinc superoxide dismutase (SOD1). Since the rat in the Kerr report loses motor neurons, some similarities to ALS exist.
The important points of the Kerr team’s findings are that stem cell-derived motor neurons could make connections to muscle after implant. Yet this required a cocktail of treatments to overcome the inhibitory action of proteins made by myelin surrounding nerves. This cocktail approach had been discussed last September by participants at the workshop on stem cells at Banbury Center, Cold Spring Harbor, sponsored by The ALS Association. For more information on this workshop, click here.
The stem cells Kerr used were from mice, and the rats were given an anti-rejection drug. Indeed, another Hopkins team led by Vassilis Koliatsos, M.D., showed that stem cell transplants into SOD1 mutant mice survived longer—and the mice survived longer—with immune suppression, according to the report in Stem Cells.
Other routes toward stem cell therapy for ALS are quite possible. The adult brain has its own stores of stem cells, and these might be prompted to step into the breach left by motor neurons dying in ALS. Research published in Nature by Ronald D. McKay, Ph.D., and colleagues at the National Institute of Neurological Disorders and Stroke in Bethesda, Md., showed that providing certain signal molecules can boost the brain’s own stem cells to avert damage by a stroke in mice. This gives a hint of what might be accomplished if therapy could be devised to target the intrinsic stem cells in the body.
Even skin might serve as a stem cell source, as reported in the Journal of Neuroscience by Freda Miller, Ph.D., and collaborators at the Hospital for Sick Children Research Institute in Toronto, Canada. It is not clear yet if skin could generate sufficient stem cells for therapeutic purposes. The Canadian team demonstrated that stem cells derived from rat skin could produce support cells that make myelin, wrapping around nerves in mice that lack their own myelin insulation. The other support cells of the nervous system, called astrocytes, might serve as well as a stem cell therapy, according to findings by Stephen Davies, Ph.D., and colleagues at Baylor in Houston. They showed that astrocytes derived from stem cells can repair spinal injury in rats, as reported online in the Journal of Biology.
How will stem cell implants know where to go? The growth factor abbreviated as FGF may be a key signal that allows motor neurons to find the right muscle to connect to and to contract, according to a report in June in Neuron by Salk Institute researchers led by Samuel Pfaff, Ph.D., in La Jolla, California.
It is clear there are many possible routes to a stem cell therapy. What also became clear recently is that patients treated in China for spinal injury with a preparation of fetal cells have not shown any evidence that the treatment works. Instead many patients with spinal cord injury checked by other physicians had potentially harmful side effects in the days following the expensive procedure, as mentioned briefly in May’s monthly journal news. This issue was the focus of an article published in June by the Boston Globe which quoted Lucie Bruijn, Ph.D., science director and vice president of The ALS Association.
Many different routes are available for researchers to explore toward the goal of an effective stem cell therapy for ALS. The ALS Association will seek to fund any avenue that could show promise.
For further details and journal links, refer to the monthly journal news for June, 2006 and stem cells on The ALS Association web site.
