A new gel created by UCLA researchers helped regrow neurons and blood vessels in mice whose brains had been damaged by strokes, suggesting that such an approach might eventually be used to treat human patients, according to findings reported Monday.
The brain has a limited capacity for recovery after stroke. Unlike the liver, skin and some other organs, the brain does not regenerate new connections, blood vessels or tissue structures after it is damaged. Instead, dead brain tissue is absorbed, which leaves a cavity devoid of blood vessels, neurons or axons — the thin nerve fibers that project from neurons.
“We tested this in laboratory mice to determine if it would repair the brain and lead to recovery in a model of stroke,” said Dr. S. Thomas Carmichael, a professor of neurology at the David Geffen School of Medicine at UCLA. “The study indicated that new brain tissue can be regenerated in what was previously just an inactive brain scar after stroke.”
To see if healthy tissue surrounding the cavity could be coaxed into healing the stroke injury, Dr. Tatiana Segura, a former professor of chemical and biomolecular engineering at UCLA who collaborated on the research, engineered a hydrogel that, when injected into the cavity, thickens to create a scaffolding into which blood vessels and neurons can grow, according to the university.
The gel is infused with medications that stimulate blood vessel growth and suppress inflammation, since inflammation results in scars and impedes functional tissue from regrowing.
After 16 weeks, the stroke cavities contained regenerated brain tissue, including new neuronal connections — a result that had not been seen before, according to the UCLA researchers. The mice’s ability to reach for food improved, a sign of improved motor behavior, although the exact mechanism for the improvement wasn’t clear, according to the study published in the scientific journal Nature Materials.
“The new axons could actually be working,” said Segura, now a professor at Duke University. “Or the new tissue could be improving the performance of the surrounding, unharmed brain tissue.”
The gel was eventually absorbed by the body, leaving behind only new tissue, she said.