Scientists Discover a Mother and Child Reunion (of Cells)
For the first time, male DNA has been found to be widely distributed in the female brain.
-- by Suzanne Boothby
The maternal bond usually begins during pregnancy, but researchers have found more evidence of the strong connection between mother and child.
A new study conducted at the Fred Hutchinson Cancer Research Center in Seattle found mothers’ brains contain cells from their children. While all of us may save some cells from our mothers during gestation, and moms are known to retain cells from their children, this study marks the first time male DNA was found widely distributed in the human female brain.
“Trafficking of fetal cells into the maternal circulation begins very early in pregnancy, and the effects of this cell traffic are longlasting,” said Keelin O’Donoghue, Ph.D. in his 2008 study published in the journal Obstetric Medicine. “All types of fetal cells, including stem cells, cross the placenta during normal pregnancy to enter maternal blood, from where they may be recovered in pregnancy for the purpose of genetic prenatal diagnosis.”
The process is known as fetal microchimerism, and is characterized by genetically distinct cells originating from one body found in another. Fetal cells can persist and multiply in the mother for several decades, and studies have already reported the phenomenon in mouse brains. The cells can establish residence inside tissues too, becoming an essential part of the body's organs. Study authors also say these cells linger in the blood, bone, and bone marrow for decades.
This current research looked at DNA in the human female brain as a marker for microchimerism of fetal origin—from a woman bearing a male child and even from women who have miscarried. Scientists targeted the “Y” chromosome, looking at autopsied brains from women without clinical or pathologic evidence of neurologic disease, as well as the autopsied brains of women who had Alzheimer's disease.
More than 60 percent of the females tested harbored male microchimerism in the brain. Because these cells were less common in the brains of women with Alzheimer's, the reason they stay could be related to brain health.
“Male microchimerism was present in multiple brain regions and results also suggested lower prevalence and concentration of male microchimerism in the brains of women with Alzheimer's disease than the brains of women without neurologic disease,” the study authors wrote.
The chimeric state of women could have far-reaching implications, according to O’Donoghue. It can influence recovery after injury or surgery, aging, graft survival after transplantation, survival after cancer, and could even help explain women’s tendency to live longer than men.
The new findings further the unity women experience with their offspring. Michochermism of fetal origin could impact both maternal health and have larger evolutionary significance. While some women might feel strange with this newfound lack of genetic autonomy, it will certainly open new doors for research.
“At present, the biological significance of harboring microchimerism in the human brain requires further investigation,” the authors wrote.