Recent progress in allogeneic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (ASCT) is a well-established treatment for patients with malignant and non-malignant immunohematopoietic diseases. Matched unrelated donors are increasingly used and improved HLA matching has led to increased survival. In addition, stem cells derived from peripheral blood and cord blood are being utilized to a greater extent. During the last decade, reduced-intensity conditioning, which is preferentially used in older patients or those with organ dysfunction, was introduced as an alternative to standard myeloablative regimens. In addition, the isolation of patients after transplant has been challenged by allowing patients to be treated at home after ASCT. Analysis of mutations in caspase recruitment domain containing protein 15 and levels of regulatory T-cells may be important in identifying patients at risk for acute graft-versus-host disease (GVHD). Mesenchymal stem cells that have immunomodulatory effects home in to injured tissues and may be used in the treatment of patients with steroid-refractory GVHD. In addition, the graft-versus-tumor (GVT) or graft-versus-leukemia (GVL) effect (ie, the attack of the transplanted immune system against the tumor or leukemia), is of major importance for the success of ASCT in patients with malignant disease. GVT and GVL effects may be improved by utilizing differences in minor histocompatibility antigens between the patients and the donor or by using natural killer cell alloreactivity. ASCT has shown GVT effects in patients with solid tumors. New developments in clinical ASCT have been highlighted in this review.