A Penn State research team recently completed a study that may make medical science one step closer toward actual neuron repair following a traumatic brain injury (TBI). Gong Chen, a Penn State professor of biology and the Verne M. Willaman Chair in Life Sciences lead the study – which was published in Cell Stem Cell journal on December 19th. Chen said:
“This technology may be developed into a new therapeutic treatment for traumatic brain and spinal cord injuries, stroke, Alzheimer’s disease, Parkinson’s disease, and other neurological disorders.”
Study Focuses on Glial Cell Formation to Heal Neurons Instead of Blocking Them
Whenever a brain is harmed by traumatic injury or illness, many neurons often die or degenerate. In the process, glial cells become more numerous. Glial cell formation is a part of the body’s defense mechanism to prevent bacteria and toxins from infiltrating healthy nerve tissues. However, this process eventually forms glial scars over axons, effectively inhibiting the growth and function of still-healthy neurons. Chen further explained:
“A brain-injury site is like a car-crash site. Reactive glial cells are like police vehicles, ambulances, and fire trucks immediately rushing in to help — but these rescue vehicles can cause problems if too many of them get stuck at the scene. The problem with reactive glial cells is that they often stay at the injury site, forming a glial scar and preventing neurons from growing back into the injured areas.”
Chen’s research team began focusing on how reactive glial cells respond to a specific protein, NeuroD1, which is known in Neurology to be a key element in the formation of nerve cells in the hippocampus area of adult brains. Chen’s team hypothesized that introducing NeuroD1 protein into the reactive glial cells at the injury site could help to generate new neurons – mimicking the role in the hippocampus. To test this hypothesis, his team began by first infecting reactive glial cells with a retrovirus that specifies the genetic code for the NeuroD1 protein.
Research Results Show Promise, Science May Be One Step Closer to Cell Repair in Damaged Brains
In a first test, the team at Penn State investigated whether the reactive glial cells could be converted into functional neurons after injecting NeuroD1 retrovirus into the cortex of adult mice. The scientists found that two types of reactive glial cells — star-shaped astroglial cells (astrocytes) and NG2 glial cells – had in fact been reprogrammed into neurons within one week after being infected with the NeuroD1 retrovirus.
In their next test phase, Chen’s team utilized a transgenic-mouse model for Alzheimer’s disease. They had previously demonstrated that reactive glial cells in the mouse’s diseased brain also can be converted into functional neurons, establishing a model approach for a brain with traumatic injury.
To be sure the glial cell-to-neuron conversion method was not limited to only rodent mammals, the team further then tested the method on cultured human glial cells. Chen said:
“Within 3 weeks after expression of the NeuroD1 protein, we saw in the microscope that human glial cells were reinventing themselves: they changed their shape from flat sheet-like glial cells into normal-looking neurons with axon and dendritic branches.”
As a final step, Chen and his group examined the function of these newly converted human neurons and confirmed they were capable of both releasing and responding to neurotransmitters. With confidence that these tests may be the basis for the next major step toward brain cell repair after either an injury or a condition such as Alzheimer’s disease, Chen explained:
“Our dream is to develop this in vivo conversion method into a useful therapy to treat people suffering from neural injury or neurological disorders. Our passionate motivation for this research is the idea that an Alzheimer’s patient, who for a long time was not able to remember things, could start to have new memories after regenerating new neurons as a result of our in vivo conversion method, and that a stroke victim who could not even move his legs might start to walk again.”
References:
Cell Stem Cell Journal
