Several investigators have reported that MSC have a remarkable ability to modulate the immune system, including the function and response of dendritic cells, T and B cells, and neutrophils, in part through the release of proinflammatory and antiinflammatory cytokines and lipid mediators, such as prostaglandin E2 (PGE2).1,4 MSC also produce angiopoietin-1, a molecule that improves endothelial barri