Human embryonic stem cells have been turned into nerve cells that actually helped restore memory and the ability to learn in mice.
This marks the first time that human stem cells have shown the capability to heal neurological problems after implanting themselves in the brain.
The study took place at the University of Wisconsin-Madison where human embryonic stem cells were altered with chemicals to transform them into nerve cells. To be used on mice, researchers had to use a particular strain that was transferable to other species.
Inside the brain of the mouse, the stem cells created two important types of neurons.
"These two neuron types are involved in many kinds of human behavior, emotions, learning, memory, addiction and many other psychiatric issues," Professor of Neuroscience and Neurology and Senior Author of the experiment Su-Chun Zhang said.
Following the stem cells being planted in the mouse brains, the subjects were tested in a water maze that had the mice trying to remember the location of a platform hidden in a pool. The mice scored significantly better after the transplant.
Zhang says that precise location, timing and purity were necessary for the completion of this study.
"Developing brain cells get their signals from the tissue that they reside in, and the location in the brain we chose directed these cells to form both GABA and cholinergic neurons,” Zhang said.
For the study, the mice had to receive a controlled sort of brain damage. The medial septum was the target, which Zhang describes as “fundamental to our ability to learn and remember.”
The cells were put in the hippocampus, an important memory center at one end of the memory circuitry. Zhang compares the process to rewiring a telephone cable, as you can wire the replacement from the other end and make it work.
The real trick of the study, Zhang said, was making sure that the transplanted cells did not form a tumor in the brains of the mice.
“We need to be sure we do not inject the seeds of cancer,” he said.
Zhang said that the results of the study will possibly allow for applications in creating models for drug screening.