Stem Cells Rebuild a Stroke-Damaged Brain in Mice: Neurons Form, Blood Vessels Heal, and Movement Returns
Researchers injected human stem cells into mice with stroke-induced brain damage. Over five weeks, the implanted cells largely stayed in place and matured into neurons capable of communicating with surrounding brain tissue. In parallel, blood vessels began to repair, inflammation decreased, and the blood-brain barrier grew stronger. The treated mice showed signs of improved movement and coordination, suggesting a potential path to restore lost functions in stroke patients.
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Cells Survive and Turn into Neurons
Using mice with stroke damage, scientists found that the human stem cells survived the full five-week analysis period. Most of them transformed into neurons and began to communicate with the existing brain cells. "We found that the stem cells survived for the full five weeks and that most of them transformed into neurons, which actually even communicated with the already existing brain cells," says Christian Tackenberg, neuroscientist at the University of Zurich.
Long-Term Integration: The Cells Connect
The team did not stop at cell survival. They investigated whether the transplanted cells formed functional connections with existing neural networks. "Our analysis goes far beyond the scope of other studies, which focused on the immediate effects right after transplantation," explains Tackenberg. The findings suggest transplanted neural stem cells can integrate into brain circuits rather than merely existing as isolated cells.
The Brain's Healing Environment
Beyond new neurons, the brain’s environment showed signs of repair. Blood vessels self-repaired, inflammation decreased, and the blood-brain barrier grew stronger. These changes point to a broader restoration of brain health following stem cell treatment in the stroke model.
From Mice to Humans: Opportunities and Hurdles
The study builds on earlier work about the timing of stem cell injections after a stroke, suggesting the brain must stabilize before transplantation is effective. While promising, translating these results to humans will require much longer observation and safety testing. Stroke damage is currently irreversible and affects about a quarter of the population, underscoring the high stakes. There are still many challenges ahead: any interference in the brain can go wrong, and researchers must prevent implanted cells from exceeding their intended remit. Still, researchers emphasize the potential of neural stem cells to not only form new neurons but also drive additional regeneration processes. The work was published in Nature Communications.
