USC researchers found a potential way to extend the clock on post-stroke treatment and enable better stroke recovery - an experimental stem cell therapy to help repair damaged brain tissue, co-developed by scientists at the Keck School of Medicine of USC, the University of Zurich and ETH Zurich in Switzerland. A study in the journal Nature Communications showed that a stem cell transplant performed one week after an ischemic stroke in mice led to recovery. Rust and his colleagues reprogrammed human blood cells into neural stem cells — which can mature into neurons — and transplanted them into the damaged brain tissue of mice that had strokes. After five weeks, the researchers compared their recovery to a group of mice from the same litter that had strokes but underwent surgery without transplantation. The brains of the mice that received transplanted neural stem cells showed more robust signs of recovery than those of untreated mice. The transplant recipients’ brains had less inflammation, more growth of neurons and blood vessels, and more connectivity among neurons than the brains of the mice that did not receive transplanted cells. The treated mice also had less leakage from the blood-brain barrier, which is important for normal brain function and acts as a filter to keep harmful substances out of the brain. To measure function, the researchers used artificial intelligence to closely track the movement of the animals’ limbs while walking and climbing up a ladder with irregular rungs. The team found that treated mice fully recovered the fine motor skills tested in the climbing task five weeks after the transplants. By the end of the study, their gait also improved significantly compared to mice that received a sham surgery.