Old blood can prematurely age the brains of young mice, and scientists may now be closer to understanding how. A protein located in the cells that form a barrier between the brain and blood could be partly to blame, experiments on mice suggest. As mice and humans age, levels of that protein circulating in the blood rise, Alzheimer researcher Tony Wyss-Coray at Stanford University and colleagues found.
After injecting young mice behind an eye with plasma from old mice, the team discovered that VCAM1 levels also rose in certain parts of the blood-brain barrier, a mesh of tightly woven cells that protect the brain from harmful factors in the blood.
The young mice showed signs of brain deterioration as well, including inflammation and decreased birthrates of new nerve cells. Plasma from old mice didn’t have a strong effect when injected into young mice genetically engineered to lack VCAM1 in certain blood-brain barrier cells.
Those antibodies also seemed to help the brains of older mice that had aged naturally, the team found.