Cell therapy approaches aiming at minimization of immunosuppression in solid organ transplantation

Purpose of review Cell transplantation or administration of cellular products has escaped preclinical experimental status and will be integrated as a substantial component of future individualized treatment modalities for a broad scope of medical fields, including transplantation tolerance, cancer immunotherapies and auto-immune diseases. Recent findings Renal allograft tolerance has been successfully demonstrated using bone marrow transplantation with nonmyeloablative conditioning to induce transient hematopoietic chimerism, hereby exemplifying the immunomodulatory potential of living cells to reprogram an existing immune system to recognize and accept nonself major histocompatibility antigens expressed on the allogeneic donor organ. Strong efforts are currently undertaken to circumvent the necessity of hematopoietic chimerism induction by harnessing peripheral regulatory mechanisms. Potential candidate cell populations that bear immunomodulating and regulatory properties comprise regulatory T cells, dendritic cells and deactivated macrophages as well as stem cells of various origins, currently tested in different clinical transplantation tolerance trials. Summary Although transplantation tolerance is still on its way to be reliably accomplished in clinical settings, use of well specified and functionally characterized cellular therapeutics with regulatory properties is now entering the field of personalized medicine for transplanted patients to benefit from minimization protocols and less severe side affects related to conventional immunosuppressive drug treatment.