Researchers at Columbia University have determined that in most cases of amyotrophic lateral sclerosis (ALS), a toxin released by cells that typically nurture neurons in the brain and spinal cord can trigger loss of the nerve cells affected in the disease. The research was reported in the online edition of the journal Neuron. The toxin is produced by astrocytes and kills nearby motor neurons. In ALS, the death of motor neurons causes a loss of control over muscles required for movement, breathing, and swallowing.
The research team removed astrocytes from the brain and spinal cords of six ALS patients shortly after death and placed the cells in petri dishes next to healthy motor neurons. The results of the study show that within 2 weeks, many of the motor neurons had shrunk and their cell membranes had disintegrated, while about half of the motor neurons in the dish had died. Also, astrocytes removed from people who died from causes other than ALS had no effect on the motor neurons, nor did other types of cells taken from ALS patients.
As indicated on the Columbia University Medical Center news release, the researchers confirmed that the cause of the motor neurons’ death was a toxin release into the environment by immersing healthy motor neurons in the astrocytes’ culture media. The presence of the media, even without astrocytes, killed the motor neurons. The findings of the study are notable because they apply to the most common form of ALS.
Serge Przedborski, MD, PhD, senior author of the study, says, “I think this is probably the best evidence we can get that what we see in mouse models of the disease is also happening in human patients.” Przedborski adds, “Now that we know that the toxin is common to most patients, it gives us an impetus to track down this factor and learn how it kills the motor neurons.”
Przedborski states, “Its identification has the potential to reveal new ways to slow down or stop the destruction of the motor neurons.”
Photo Appears Courtesy of Diane Re
Photo Caption: The culture system shows that patient astrocytes (shown above with a blue-stained nucleus) release a toxin that kills motor neurons via a recently discovered process described as a “controlled cellular explosion.”
Source: Columbia University Medical Center