Changes in gene expression of hMSCs and NOD/scid mouse lung after IV infusion of hMSCs

Quantitative assays for human DNA and mRNA were used to examine the paradox that intravenously (IV) infused human multipotent stromal cells (hMSCs) can enhance tissue repair without significant engraftment. After 2 X 106 hMSCs were IV infused into mice, most of the cells were trapped as emboli in lung. The cells in lung disappeared with a half-life of about 24 hr but < 1,000 cells appeared in 6 other tissues. The hMSCs in lung up-regulated expression of multiple genes with a large increase in the anti-inflammatory protein TSG-6. After myocardial infarction, IV hMSCs but not hMSCs transduced with TSG-6 siRNA decreased inflammatory responses, reduced infarct size, and improved cardiac function. IV administration of recombinant TSG-6 also reduced inflammatory responses and reduced infarct size. The results suggest improvements in animal models and patients after IV infusions of MSCs are at least in part explained by activation of MSCs to secrete TSG-6. 3 samples containing either mouse lung and human cells or only mouse lung run on a 3 human and 3 mouse arrays. 1) control NOD/scid mouse lung 2) in vitro mix of NOD/scid mouse lung and hMSCs 3) NOD/scid mouse lung 10h after IV infusion of 2 million hMSCs