Maternal Cells Active in Human Brains for Life — SkimNews
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- Sami Kanaan and colleagues at the Fred Hutchinson Cancer Center identified maternal cells in 26 of 37 children's brain samples — averaging 2.2 maternal cells per 100,000 — using single-nucleus RNA sequencing paired with a custom tool called Cellector.
- The maternal cells were not just present but working: the team spotted them performing jobs as neurons, microglia (brain immune cells), astrocytes, oligodendrocytes, and endothelial cells lining blood vessels.
- Reanalysis of three prior RNA datasets covering individuals from a 22-week-old fetus to people in their 80s showed microchimeric cells persist across the lifespan, though counts decline with age, possibly through programmed cell death (apoptosis).
- Brain tissue came from 37 children aged newborn to 14 undergoing epilepsy surgery; Kanaan noted some maternal cells were likely missed when mother and child shared identical genetic variants at the markers tested.
- Hina Chaudhry of the Icahn School of Medicine at Mount Sinai, who was not involved in the study, called the methods "sophisticated" and said the findings show "every human brain is likely a genetic mosaic of more than one person."
- The rarity of the cells — roughly 1 in 100,000 — has historically made them nearly impossible to detect, which is why paired mother-child brain samples and computational tools like Cellector were needed, Kanaan said.
Why it matters: By showing maternal cells don't merely survive in the brain but actively differentiate into neurons, immune cells, and supporting cell types across a lifetime, the study reframes the human brain as a genetic mosaic from birth. For autoimmune and neurological disease research, it gives scientists a concrete cellular target — and a benchmark detection technique (Cellector) — to investigate how these foreign cells influence health, tissue repair, and aging.
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