Abstract
Treatment of several complications remains as important issues after stem cell transplantation. Potent immunosuppressive drugs or T-cell depletion of the graft can eliminate graft-versus-host disease (GVHD) but this strategy leads to an increased risk of tumor relapse as well as fatal viral infections. Mortality remains high when conventional treatment fails. Because the underlying mechanism of cellular immunity has been elucidated and an innovative cell isolation and culture system developed recently, alternative strategies have been developed; to enhance the engraftment, decrease relapse rate, and prevent/treat GVHD and viral infections. Ex vivo expanded mesenchymal stem cells or viral specific cytotoxic T cells have been shown to efficiently inhibit lethal GVHD or fatal viral infections, respectively. Preclinical data has provided encouraging evidence that regulatory T cells lessened the incidence of GVHD and facilitated engraftment. However, few reports with a limited number of patients are available on the safety and efficacy of these novel cell therapies. The optimal dose and frequency of cell administration should be evaluated in phase II clinical trials. High scientific and ethical standards are required according to Good Clinical Practice guidelines in the clinical trials. Furthermore, the manufacturing of clinical trial materials mandate current good manufacturing practices grade cell processing to assure the safety and quality of manipulated cell products. This review presents an overview of the current progress and remainine issues in the cell therapies.
