Bidirectional passage of cells through the placenta and the persistence of this cells postnatally (feto-maternal microchimerism) is a well described phenomenon^1-4, as well as the potential for this to translate in a long-lasting tollerance allowing the transplant of stem cells form mother to offspring and viceversa^5-9. In this setting a GvM effect has also been observed^10-12.

The use of the mother as stem cell donor has the potential advantage of not requiring costly cell purification procedures that are generally employed in the context of partially matched family donor transplantation (e.g. T-cell depletion through magnetic cell-sorting). Moreover, this type of study may extend this life-saving procedure to countries with ethnic groups less represented in international donor registries and/or stringent economical limitations.