Epilepsy that does not respond to drug treatments has been stopped in adult mice, giving hope of a cure to human sufferers.
Researchers at the UC San Francisco have found a way to halt seizures in adult mice by transplanting medial ganglionic eminence (MGE) cells into the mice brains.
MGE cells inhibit signalling in overactive nerve circuits. They were inserted into the hippocampus, which is associated with seizures, as well as learning and memory.
During epileptic seizures, the brain abnormally fires many excitatory nerve cells at the same time. Seizures can cause sufferers to lose consciousness, fall and sometimes be seriously injured.
The cells that were transplanted into the mice brains prevented the "nerve-signalling firestorm" and stopped seizures in half of the mice. It also dramatically reduced the number of seizures in the other half.
The mice were given a form of epilepsy resembling mesial temporal lobe epilepsy, in which seizures are believed to arise from the hippocampus. This form of the disease often develops in human adolescence.
The mice model also shared other features of the human form of the disease, such as loss of cells in the hippocampus, impaired problem solving and behavioural changes.
Encouraging step forward
As well as having fewer seizures, the mice also became less agitated, less hyperactive and performed better in maze tests.
Study leader Scott Baraban explained that cell therapy is becoming increasingly prominent in epilepsy research because current medications only control symptoms and do not address the underlying causes.
He said many drugs have no value whatsoever, so researchers are working to find ways to stop the disease: "Our results are an encouraging step toward using inhibitory neurons for cell transplantation in adults with severe forms of epilepsy.
"This procedure offers the possibility of controlling seizures and rescuing cognitive deficits in these patients."
Malfunction or loss of inhibitory nerve cells plays a key role in many forms of epilepsy. The researchers found that the MGE cells from mice were able to replace the cells that fail in epilepsy, and were then integrated into existing neural circuits.
"These cells migrate widely and integrate into the adult brain as new inhibitory neurons," Baraban said. "This is the first report in a mouse model of adult epilepsy in which mice that already were having seizures stopped having seizures after treatment."