Microglia Turnover in the Human Brain

Researchers find that about a quarter of the immune cells are replaced every year.

Shawna Williams
Oct 1, 2017

THE BRAIN’S SENTINELS: Microglia (stained green in this rat brain culture) fight infection in the central nervous system. Neuronal processes stained in red.© GERRY SHAW/WIKIMEDIA COMMONS

The paper
P. Réu et al., “The lifespan and turnover of microglia in the human brain,” Cell Rep, 20:779-84, 2017.

A renewable resource?
Evidence has emerged that some of the brain’s cells can be renewed in adulthood, but it is difficult to study the turnover of cells in the human brain. When it comes to microglia, immune cells that ward off infection in the central nervous system, it’s been unclear how “the maintenance of their numbers is controlled and to what extent they are exchanged,” says stem cell researcher Jonas Frisén of the Karolinska Institute in Sweden.

Nuclear signature
Frisén and colleagues used brain tissue from autopsies, together with the known changes in concentrations of carbon-14 in the atmosphere over time, to...