Application of mesenchymal stromal cells in bone marrow transplantation for sensitized recipients

Sensitized patients are at high risk for graft rejection during transplantation. It is of interest to investigate the effect of mesenchymal stromal cells (MSCs) in sensitized hematopoietic stem cell transplantation. MSCs were generated from bone marrow cells of BALB/c mice. The molecular markers of MSCs were detected by flow cytometry. MSCs labeled with green fluorescent dye were transplanted into nonsensitized and sensitized recipients, respectively. Homing of MSCs in vivo was monitored at different time points post-transplantation. Additionally, sensitized BALB/c mice under irradiation were transplanted with syngeneic MSCs and allogeneic bone marrow cells, and the rate of survival was monitored daily. The fourth passage of MSCs presented a typical spindle-shaped morphology and met the identification criteria of MSCs. Forty-eight hours post-transplantation, the homing of MSCs was found mainly in the bone morrow of nonsensitized recipients and the spleen of sensitized recipients, respectively. Moreover, all of the sensitized recipients died 12-16 days after receiving syngeneic MSCs and allogeneic bone marrow cells, with a median of 14 days. Our results suggest that the MSCs mainly homed to the spleen of sensitized recipients post-transplantation. MSCs could not enhance the engraftment of allogeneic bone marrow cells in sensitized recipients.