For many years researchers at the University of Michigan have been injecting stem cells into mouse brains and coming up with remarkable discoveries. The experiments are among the first attempts to examine how stem cell therapies might alter the course of Alzheimer’s, a fatal disease that afflicts millions of people around the world. The research is being overseen by UM’s Dr. Eva Feldman, who pioneered America’s first clinical trial using stem cells in patients with amyotrophic lateral sclerosis.
In a new study, scientists have explained why we forget where exactly we left our car in a parking lot. They have done this by transplanting this rather common human experience permanently on mice and deriving clues from their behaviour about why strokes and Alzheimer’s disease can destroy a person’s sense of direction.
British-American and Norwegian scientists won this year’s Nobel Prize for Medicine for discovering grid and other specialized nerve cells known as ‘place cells,’ which make up the brain’s inner GPS. The San Diego scientists built upon this work and developed a micro-surgical procedure that enabled them to remove an area of the rat’s brain that contains the grid cells and show what happens to this hard-wired navigational system when these grid cells are wiped out.
Not surprisingly, one effect was that the rats internal map-making skills deteriorated rapidly. Senior co-author Robert Clark said that their loss of spatial memory formation was not a surprise, given the physiological characteristics of that area of the brain. But surprisingly one type of memory formation was not disrupted despite the removal of the grid cell area.
The scientists showed that even in the absence of grid cells the rats could mark spatial changes in their environment. By studying the signals being sent by the hippocampus in their brains, the scientists proved that the animals had developed place cells – cells that are believed to convey a sense of location – and that these cells were firing when an animal passed through a familiar place.
Clark said that while the removal of the grid-cell network deleted memory for places it left completely intact a whole host of other important memory abilities like recognition and memory of fearful events.
Although Feldman’s ALS trial is still incomplete she has begun an experiment to see how stem cells might fare in treating Alzheimer’s disease, another neurodegenerative disorder. In her experiment it was clear that the stem cells made the behaviour of mice with Alzheimer’s disease indistinguishable from that of the healthy mice.
“When you work in science, many experiments don’t work,” Feldman said. “When you get something that works so beautifully (like this experiment), you can quickly see its translational potential. I am looking at a mouse but someday I could be looking at a man. As a clinician scientist, those are the moments you live for.”