Fig. 8

Central illustration. Two doses of human umbilical cord mesenchymal stem cells alleviate cardiac dysfunction and inflammation in the dilated cardiomyopathy rat model by upregulating indoleamine 2,3-dioxygenase expression. Doxorubicin exposure led to cardiac dysfunction in the rat dilated cardiomyopathy model along with systemic and persistent low-grade inflammation in the heart, peripheral blood, lymph nodes, and spleen. Intravenous treatment with two doses of hUCMSCs alleviated cardiac dysfunction and modulated the imbalance of anti-inflammatory Treg and Th2 and pro-inflammatory Th1 and Th7 responses. Furthermore, IDO-OE hUCMSC treatment exerted more pronounced effects compared with the unmanipulated hUCMSC group in reducing cardiomyocyte apoptosis, and fibrosis, while treatment with IDO-KD hUCMSCs reduced their therapeutic effects. Therefore, we hypothesize that IDO and its metabolites may be important for hUCMSCs to regulate the immune-inflammatory responses in the DOX-induced heart failure