Scientists have successfully transplanted human stem cells into brain-damaged mice and helped them recover their memory and learning skills.
The study was carried out by Dr. Su-Chun Zhang, a professor of neuroscience and neurology at the University of Wisconsin-Madison.
According to the study, the implanted human stem cells transformed into two common types of neurons, GABA and cholinergic neurons.
"These two neuron types are involved in many kinds of human behavior, emotions, learning, memory, addiction and many other psychiatric issues," said Zhang in a statement
For the experiment, Zhang treated the human stem cells with chemicals known to promote their development into nerve cells.
After receiving transplanted cells, the mice performed better in tests that measure learning and memory. One test in particular had the mice transverse a water maze, which challenged them to remember the location of a hidden platform in a pool.
Zhang said the damage to the mice brains was done in an area called the medial septum, which connects to the hippocampus by GABA and cholinergic neurons and is “fundamental to our ability to learn and remember.”
The transplanted cells were placed in the hippocampus.
Once implanted, the cells began to respond to chemical directions from the brain and began to specialize to connect to the appropriate cells in the hippocampus.
Zhang said the process is akin to removing a section of telephone cable. “If you can find the correct route, you could wire the replacement from either end,” he added.
While the study does provide some hope for future treatment to brain damaged humans, Zhang says the stem-cell therapy is unlikely to be the immediate benefit.
"For many psychiatric disorders, you don't know which part of the brain has gone wrong," he said.
The study was first published in the current issue of Nature Biotechnology