Two million Americans are afflicted by traumatic brain injuries every year. The causing effect is cell death and inflammation in the brain. As a result, those who suffer from a head injury are typically inflicted by permanent memory loss and can even develop epilepsy. There has been no remedy to date that can stop this from happening.
Now, a breakthrough cell therapy to improve memory and prevent seizures in mice following traumatic brain injury (TBI) has been developed by a team of researchers from the University of California, Irvine. The study involved the team transplanting embryonic progenitor interneurons into the hippocampus of mouse models of TBI. Those neurons then migrated to the injury site and made new connections. Soon after, the animal’s memory improved, and there was a reduction in seizures. The study has been published in the journal Nature Communications.
The Study
- Embryonic progenitor cells capable of generating inhibitory interneurons were transplanted into the brains of mice with traumatic brain injury. (Embryonic progenitor cells are a specific type of nerve cell that controls the activity of brain circuits).
- The researchers targeted the brain region responsible for memory and learning – the hippocampus.
The Results
- The transplanted neurons migrated into the injury site.
- Once there, they formed new connections with the damaged brain cells and were able to thrive long term.
- After only one month following treatment, there was a noticeable improvement in the memory of the mice. They were able to tell the difference between a box where they experienced an unpleasant moment, to one where they hadn’t.
- Furthermore, the mice that received the cell transplant did not develop epilepsy. More than half of the mice with brain injuries that did not receive the treatment did suffer from epilepsy.
Robert Hunt, Ph.D., assistant professor of anatomy and neurobiology at UCI School of Medicine who led the study, said:
Inhibitory neurons are critically involved in many aspects of memory, and they are extremely vulnerable to dying after a brain injury. While we cannot stop interneurons from dying, it was exciting to find that we can replace them and rebuild their circuits.
The idea to regrow neurons that die off after a brain injury is something that neuroscientists have been trying to do for a long time. But often, the transplanted cells don’t survive, or they aren’t able to migrate or develop into functional neurons.
Double-Check
To double-check their findings, the team silenced the transplanted neurons with a drug. As a result, memory problems returned.
Bingyao Zhu, a junior specialist and first author of the study, said:
It was exciting to see the animals’ memory problems come back after we silenced the transplanted cells because it showed that the new neurons really were the reason for memory improvement.
The next phase of their research is to create interneurons from human stem cells. Hunt said:
So far, nobody has been able to convincingly create the same types of interneurons from human pluripotent stem cells. But I think we’re close to being able to do this.
The team is hopeful that the results in mice can someday be replicated in humans as it would have a tremendous impact on patients.
