Migration of microchimeric fetal cells into maternal circulation before placenta formation.

Fetal cell microchimerism is defined as the persistence of pluripotent fetal cells in the maternal body long after delivery. The exact process by which fetal cells cross the placental barrier and enter maternal circulation is still being investigated. We reported that fetal cells persist only in the maternal bone marrow and may give rise to subpopulations with the ability to differentiate into the tissue-specific mature cells within injured maternal organs.

Fetal cell microchimerism develops through the migration of fetus-derived cells to the maternal organs early after implantation.

Fetus-derived cells are present in the blood and tissues of the maternal body over a long period of time, even after delivery, resulting in fetal cell microchimerism. The exact process by which fetal cells cross the placental barrier to enter the maternal circulation is unclear. The objective of this paper was to determine the time during pregnancy that fetal cells with multilineage potential migrate to the maternal organs.