Stem Cells Restore Memory in Mice
Wednesday, October 31, 2007; 12:00 AM
WEDNESDAY, Oct. 31 (HealthDay News) -- A new U.S. study involving mice suggests the brain's own stem cells may have the ability to restore memory after an injury.
These neural stem cells work by protecting existing cells and promoting neuronal connections.
In their experiments, a team at the University of California, Irvine, were able to bring the rodents' memory back to healthy levels up to three months after treatment.
The finding could open new doors for treatment of brain injury, stroke and dementia, experts say.
"This is one of the first reports that you can take a stem cell transplantation approach and restore memory," said lead researcher Mathew Blurton-Jones, a postdoctorate fellow at the university. "There is a lot of awareness that stem cells might be useful in treating diseases that cause loss of motor function, but this study shows that they might benefit memory in stroke or traumatic brain injury, and potentially Alzheimer's disease."
In the study, published in the Oct. 31 issue of theJournal of Neuroscience, Blurton-Jones and his colleagues used genetically engineered mice that naturally develop brain lesions. The researchers destroyed cells in a brain area called the hippocampus. These cells are known to be vital to memory formation and it is in this region that neurons often die after injury, the researchers explained.
To test the mice's memory, Blurton-Jones's group conducted place and object recognition tests with both healthy mice and brain-injured mice.
Healthy mice remembered their surroundings about 70 percent of the time, while brain-injured mice remembered it only 40 percent of the time. For objects, healthy mice recalled objects about 80 percent of the time, but injured mice remembered them only 65 percent of the time.
The researchers then injected each mouse with about 200,000 neural stem cells.
They found that mice with brain injuries that received the stem cells now remembered their surroundings about 70 percent of the time -- the same as healthy mice. However, mice that didn't receive stem cells still had memory deficits.
The researchers also found that in healthy mice injected with stem cells, the stem cells traveled throughout the brain. In contrast, stem cells given to injured mice lingered in the hippocampus. Only about 4 percent of those stem cells became neurons, indicating that the stem cells were repairing existing cells to improve memory, rather than replacing the dead brain cells, Blurton-Jones's team noted.
The researchers are presently doing another study with mice stricken with Alzheimer's. "The initial results are promising," Blurton-Jones said. "This has a huge potential, but we have to be cautious about not rushing into the clinic too early."
One expert is optimistic about the findings.
"Putting in these stem cells could eventually help in age-related memory decline," said Dr. Paul R. Sanberg, director of the Center of Excellence for Aging and Brain Repair at the University of South Florida College of Medicine. "There is clearly a therapeutic potential to this."
Sanberg noted that for the process to work with Alzheimer's it has to work with older brains. "There is clearly therapeutic potential in humans, but there are a lot of hurdles to overcome," he said. "This is another demonstration of the potential for neural stem cells in brain disorders."
For more information on memory, visit the U.S. National Library of Medicine.
SOURCES: Mathew Blurton-Jones, Ph.D., postdoctorate fellow, University of California, Irvine; Paul R. Sanberg, M.D., director, Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, Tampa; Oct. 31, 2007,Journal of Neuroscience.