Human neural stem cells repair stroke damage and restore movement in mice

In a series of experiments, scientists from the University of Zurich transplanted human neural stem cells—derived from reprogrammed somatic cells—into mice that had suffered permanent strokes resembling human cases. The mice were genetically modified to accept human cells without rejection, and the transplants were performed one week after stroke onset. Over a five-week observation period, the stem cells persisted, largely matured into neurons that integrated into existing neural circuits, and triggered broader repair mechanisms, including new blood-vessel formation, dampened inflammation, and restoration of the blood-brain barrier.

Motor deficits caused by the strokes were reversed, as shown by AI-driven analysis of walking patterns. The researchers also developed an animal-free production protocol with Kyoto University’s CiRA and noted that delayed transplantation improved outcomes, easing potential clinical implementation. Ongoing work focuses on safety switches to prevent uncontrolled cell growth and on less invasive delivery methods such as endovascular injection, aiming toward human trials.