Researchers To Observe Fetal Cells In Blood Of Mothers After Donor Egg Pregnancies

Suppression of the immune system's surveillance response could prevent transplant rejection and fetal cells may be an easier source of stem cells than banking.

For the first time, researchers have observed that fetal cells remain in the blood of mothers who had pregnancies with donor eggs for years after delivery, without being destroyed by her immune system. This mechanism could prevent transplant rejection and these cells may be an easier source of stem cells. These findings were presented by lead author Zev Williams, MD, PhD, of Brigham and Women's Hospital (BWH) at the Society of Gynecological Investigators conference in San Diego on March 26, 2008, and will be published this week on-line in Fertility and Sterility, the journal of the American Society for Reproductive Medicine.

"These findings may impact how we think about using stem cells in regenerative medicine because the 'foreign' fetal cells are not rejected by the mother's immune system, even in donor egg pregnancies," said Williams, a chief resident in the Department of Obstetrics and Gynecology at BWH. "Not only do we want to understand the novel mechanism that suppresses the immune system's surveillance response, but we want to know if these fetal cells can be a source of stem cells later in life for the mother and even for unmatched patients, which could eliminate the need for stem cell banking."

Williams and colleagues studied the blood of 11 healthy women 18 to 60 years of age who had delivered a male infant using a donor egg, and were able to detect male cells in the blood of these women up to nine years after delivery. The unmatched and foreign fetal cells' ability to evade detection and destruction by the mother's immune system's surveillance response may also be beneficial in transplant medicine, where powerful immunosuppressant medications are required to prevent rejection, even of matched organs.

"It is also interesting to note, that after a donor egg pregnancy the mother and child do, in fact, share DNA, albeit at a very low level and therefore do have a biological connection," added Williams.