Scientists have known for several years that the brain liquefies after a stroke. If cut off from blood and oxygen for a long enough period, a portion of the brain will die, slowly morphing from a hard, rubbery substance into liquid.
Now, researchers at the University of Arizona College of Medicine - Tucson have discovered that this liquefied brain tissue is toxic and can slowly leak into the healthy portion of the brain, causing harm.
Researchers are now optimistic that the discoveries may help develop new treatments to prevent dementia after stroke.
Dr. Kristian Doyle, an assistant professor in the UA Department of Immunobiology and his laboratory team, studied mice that had experienced strokes.
To begin the study, the researchers extracted fluid from the area of liquefaction and tested its toxicity by placing it in a petri dish with living neurons. After a little over four hours, more than half of the neurons in the dish had died, compared to neurons that were placed in a dish with regular, healthy brain fluid.
The group of researchers later evaluated how well this toxic fluid was sealed off from the surviving brain.
Normally, a scar forms around dying brain tissue after a stroke and creates a barrier around the injured area to protect the remaining brain; it's formation is critical to the healing process.
Using a high-powered microscope, the researchers imaged this barrier between the healthy and injured portions of the mouse brain. Up close, the glial scar looked like "a fence made of branches twisted tightly together," Dr. Doyle said.
After that, they injected a dye into the injured portion of the brain. At seven weeks post-stroke, the dye was able to spread past the glial scar and into the healthy brain region. According to the researchers, this suggested that toxic substances present in the liquefied tissue also leak into the brain after a stroke, possibly killing healthy neurons.
Researchers at the University of Arizona believe the leaking fluid may be a cause of dementia after stroke. They hope to prove its results in the future and develop a drug.