Controlled induction of immune tolerance by mesenchymal stem cells transferred by maternal microchimerism.

Feto-maternal immune tolerance is established during pregnancy; however, its mechanism and maintenance remain underexplored. Here, we investigated whether mesenchymal stem/stromal cells (MSCs) as non-inherited maternal antigens (NIMAs) transferred by maternal microchimerism could induce immune tolerance. We showed that MSCs had a potential equivalent to hematopoietic stem and progenitor cells (HSPCs) to induce immune tolerance and that MSCs were essential to induce tolerance to MSC-specific antigens. Furthermore, we demonstrated that MSCs as NIMAs transferred by maternal microchimerism could induce robust immune tolerance that can be further enhanced using a drug. Our data shed light on induction of immune tolerance and serve as a foundation to develop new therapies using maternally derived cells for autoimmune or genetic diseases.