Stem cell transplants helped regenerate stroke-damaged brain tissue in mice, producing new neurons and restoring lost motor function. The treatment also improved blood vessels, inflammation, and the blood-brain barrier, raising hopes that a similar approach could eventually help repair the human brain after stroke.
Not universal, for example we use zebrafish for spine defect models since mouse spine has an odd curve/hunch that doesn’t line up as well. But for general metabolism/pathology/embryonic development they do a great job of mimicking human disease under the microscope. Its not always 1:1 but we learn a lot from these little guys.