MSC sacrifice for immunosuppression

Transplantation Transfer of mesenchymal stromal cells (MSCs) induces immunosuppression, even though the cells are undetectable shortly after transfer. The immunosuppressive mechanism of MSCs has been something of a mystery. Galleu et al. now suggest that MSC apoptosis is crucial. In a mouse model of graft versus host disease, cytotoxic cells rendered the MSCs apoptotic shortly after transfer. Moreover, cells from patients that responded to MSC therapy had more cytotoxic activity against MSCs. These findings suggest that patients could be screened for likely responsiveness to MSC therapy before transfer. Sci. Transl. Med. 9 , eaam7828 (2017).