Mesenchymal stem cells as therapy for graft versus host disease: What have we learned?

Mesenchymal stem cells (MSC) are a population of phenotypically heterogeneous cells that are one component of the supportive, stromal micro-environment. They can be isolated from many readily accessible tissues including bone marrow, umbilical cord, placenta, and adipose tissue, and extensive ex vivo and pre-clinical data suggest that subpopulations within MSC contribute to the immunomodulation of the host, without provoking an allo-reactive T cell response. Furthermore, largely through paracrine effects, they contribute to tissue repair. These unique properties make MSC an ideal agent to investigate for the therapy of graft host disease (GVHD). Therapeutic trials with varied MSC dosing schedules and clinical endpoints have shown mixed results. In this chapter, we will review recent preclinical data, and summarize the results of clinical trials utilizing MSC for the treatment of acute and chronic GVHD.