Survivors of traumatic brain injury (TBI) often suffer from debilitating, life changing symptoms like memory decline and epileptic seizures. Researchers had observed that following TBI, a stem cell-rich area of the brain provides a spike in new nerve cell growth, presumably to help replace damaged or destroyed brain cells. But, like a lot of things in biology, more is not always better. And a new report in Stem Cell Reports provides evidence that this spark of brain cell growth shortly after TBI may actually be responsible for post-injury seizures as well as long-term memory problems for people with this condition.The Rutgers University research team behind the study came to this counterintuitive conclusion by examining brain injury in laboratory rats. They showed that brain cells at the injury site that are known to play a role in memory had doubled in number within three days after injury. But a month later, these brain cells had decreased by more than half the amount seen in rats without injury. Neural stem cells, which develop into the mature cells found in the brain, showed this same up and down pattern, suggesting they were responsible for the loss of the brain cells. Lead scientist, professor Viji Santhakumar, described how these changes in brain cell growth lead to brain injury symptoms:
“There is an initial increase in birth of new neurons after a brain injury but within weeks, there is a dramatic decrease in the normal rate at which neurons are born, depleting brain cells that under normal circumstances should be there to replace damaged cells and repair the brain’s network,” she said in a press release. “The excess new neurons lead to epileptic seizures and could contribute to cognitive decline. It is normal for the birth of new neurons to decline as we age. But what we found in our study was that after a head injury the decline seems to be more rapid.”
The researchers next aimed to slow down this increase in nerve cell growth after injury. To accomplish this goal, they used an anti-cancer drug currently in clinical trials which has been known to block the growth and survival of new nerve cells. Sure enough, the drug blocked this initial, rapid burst in nerve cells in the rats, which prevented the long-term decline in the brain cells that are involved in memory decline. The team also reported that the rats were less vulnerable to seizures when this drug was administered.
“That’s why we believe that limiting this process might be beneficial to stopping seizures after brain injury,” Dr. Santhakumar commented.
Hopefully, these findings will one day help lessen these short- and long-term, life-altering symptoms seen after brain injury.