Maternal Cells Persist and Function in Human Brains Throughout Life, Study Finds

A groundbreaking study led by Sami Kanaan at the Fred Hutchinson Cancer Center reveals that maternal cells reside in the brains of children and adults for decades. Published on bioRxiv, the research shows these foreign cells, likely transferred from mother to fetus during pregnancy or breastfeeding, integrate into brain tissue and differentiate into various active brain cell types.

Using advanced single-nucleus RNA sequencing, researchers analyzed brain tissue from two groups: children undergoing surgery for severe epilepsy and adults up to age 90 who died without neurological diseases. Maternal cells were detected in 70% of children and 78% of adults examined. These cells differentiated into neurons, astrocytes (support cells), microglia (immune cells), vascular cells, and cells forming the protective neuronal sheath.

While maternal origin is the primary source, some cells may come from other relatives such as twins, older siblings, previous pregnancies, or maternal grandmothers. The study also found firstborn children were more likely to harbor maternal brain cells than their younger siblings. Over time, the maternal cells shift their differentiation pattern, favoring neurons in younger brains and microglia in older brains. Although their numbers decline with age, maternal cells remain present even into the ninth decade of life.

This phenomenon, known as microchimerism, was previously documented mainly in infant blood samples. The new research uses sophisticated techniques to detect these cells within complex brain tissue, suggesting they may play a vital role in healthy brain development. Understanding their function could deepen insights into human biology and brain health.