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Life Sciences & Medicine Active Updated Aug 9, 2026

Blood stem cells replenish the aging human brain's immune cells

Stanford researchers found that as people age, bone marrow sends a large wave of immune cells into the human brain that become microglia, overturning the assumption that microglia renew only from within the brain. The finding appears in humans but not mice, and builds on an earlier discovery that certain blood stem cell mutations lower Alzheimer's risk, raising the possibility of engineering blood-derived cells to clear amyloid or tau before symptoms start.

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  1. Aug 9, 2026 Latest

    Stanford researchers led by postdoctoral scholar Julia Belk traced shared DNA mutations between blood stem cells and brain tissue to show that bone marrow sends a large wave of immune cells into the aging human brain that become microglia, a process not seen in mice or other lab primates, published July 30 in Nature.

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