|Penn State researchers directly turned a brain support cell into a neuron in a living animal. This finding has therapeutic implications for the many causes of nerve loss|
This month’s report has some exciting advances in understanding how we can do a better job of generating specific tissues from stem cells. It details studies on lung, muscle and cartilage as well as the focus of this blog, neurons, the brain cells that let us think.
A research team at Pennsylvania State University went down a path many in the field believe to be one of the most promising for producing readily available therapies in the future. They got another type of tissue to directly turn into the desired tissue in living animals. They succeeded in using one growth factor to reprogram brain cells called glial cells into functional neurons in mouse brains. The team reported on their work in Cell Stem Cell online December 19.
Glial cells perform various protective and supportive roles for the neurons that carry out the work of the brain. They generally do a good job, but sometimes, after nerves are damaged by injury or disease, the glial cells get a little too zealous. They get summonsed to the damage in mass, sort of clogging the area, releasing factors that inhibit nerve growth and eventually form scar tissue. The team reasoned that those glial cells could be an abundant starting source for repair of the damage if they could be reprogrammed into neurons.
They began by working with a growth factor, NeruoD1 that is known to be active in new nerve growth in at least one part of the brain. They engineered a virus to carry the gene for the growth factor directly into glial cells in mice with brain injury and in mice that had a form of Alzheimer’s disease. In both models they saw glial cells converted to neurons. More important, two different types of glial cells converted into two different types of neurons, excitatory neurons and inhibitory neurons. Getting a balance of those on-switch and off-switch nerves is critical to normal brain function. They also verified that the new neurons were able to send and receive brain signals in a manner integrated with the animal’s existing neurons.
The team then sought to verify this was not a mouse-only phenomenon. They used the virus to insert the growth factor gene into human glial cells growing in the lab and found that again they were able to generate both excitatory and inhibitory nerves. The work seems to set up a framework for a potential therapeutic approach to many causes of nerve loss.
My full report is available online, along with links to my reports from previous months.