The role of mesenchymal stromal cells in chronic transplant rejection after solid organ transplantation

Purpose of review Despite impressive improvements in short-term survival after solid organ transplantation (SOT), the long-term outcome remains an important challenge. In recent years, it has become evident that ongoing alloreactivity, cellular and/or humoral, may play a critical role in the premature loss of kidney allografts. Clinical trials with mesenchymal stromal cells (MSCs) are currently underway for the treatment of various inflammatory disorders. Due to their immunosuppressive and reparative properties MSC immunotherapy constitutes an attractive intervention for chronic rejection, while avoiding the undesired adverse effects associated with excessive use of immunosuppressive drugs. Recent findings The immunoregulatory properties of MSCs in both cellular and antibody-mediated inflammatory models and diseases have highlighted their potential to treat chronic rejection after SOT. Moreover, MSCs can also induce tissue regeneration and repair due to their antifibrotic and angiogeneic properties. Studies in experimental animals after SOT support the potential for MSCs to treat or prevent ongoing alloreactivity and the first clinical trials in transplant recipients are underway. Summary MSCs are arising as promising cellular immunotherapy in transplant recipients and carry the potential to prevent or reduce the consequences of chronic or ongoing alloimmune injury.