The use of mesenchymal stromal cells in solid organ transplantation

Organ transplantation is the only definitive treatment for many critical diseases of the liver, kidney, heart, pancreas, and lungs. Although it is the primary therapeutic option at present, transplanted patients have to deal with the numerous side effects of life-long dependence on immunosuppressive drugs, and these drugs still fail to prevent chronic rejection of the transplanted organ in many cases. The risk of developing cancer and opportunistic infections is also markedly increased in solid organ transplant (SOT) recipients receiving long-term immunosuppressive therapy. Cancer and opportunistic infections cannot be completely avoided since they result from the immunosuppressive drugs used posttransplant that affect not only the anti-graft response but also the entire immune response. Finding a way to establish donor-specific immunological tolerance without the need for nonspecific immunosuppression remains one of the major goals in transplantation medicine [1,2]. Another important aim is the improvement of graft survival and function. Overall, graft survival is about 15 years, but the increasing shortage of organs has led to the use of expanded criteria for donor organs often donated by older individuals, which are less robust organs than those donated by younger donors. Mesenchymal stromal cell (MSCs) are currently being evaluated in SOT with the hope of achieving more selective immunosuppression, better graft function, and longer graft survival.