Scientists pinpoint brain-swelling mechanism

By turning off a single gene, scientists from the Djavad Mowafaghian Centre for Brain Health (DMCBH), a partnership of UBC and Vancouver Coastal Health, were able to successfully stop swelling in rodent brains.

Brain swelling is a gradual process that becomes life-threatening within days of the injury, and is caused by sodium chloride drawing water into the nerve cells. This swelling--known as cytotoxic edema--eventually kills brain cells.

"We've known for years that sodium chloride accumulation in neurons is responsible for brain swelling, but now we know how it's getting into cells, and we have a target to stop it," explains brain researcher Brian MacVicar, co-director of DMCBH with the Vancouver Coastal Health Research Institute and the study's principal investigator.

The team, including Terrance Snutch, director of translational neuroscience at the DMCBH, developed several novel technological approaches to identify the cascade of events that took place within individual brain cells as they swelled.

They then switched off the expression of different genes and were able to pinpoint a single protein--SLC26A11--that acts as a channel for chloride to enter nerve cells. By turning off the chloride channel, the accumulation of fluid into the cells was halted, and nerve cells no longer died.

"It was quite a surprising result, because we had few indications as to what this protein did in the brain," says Ravi Rungta, then a graduate student in the MacVicar lab and the paper's lead author.

Though the technique used by the researchers to block swelling and cell death is unlikely to work quickly enough to mitigate swelling in the case of real head trauma, the discovery has provided a target for drug development.

"This discovery is significant because it gives us a specific target -- now that we know what we're shooting at, we just need the ammunition," says MacVicar. "That's what we're doing now: looking for drugs to inhibit the chloride channel."