Fig. 7: IDO1 inhibitor (IDO1i) could reverse the tumor‑promoting effects of MSCs in vitro and in vivo.

Immunoblot showed that the expression of IDO1 decreased significantly in MSCs with the increased concentration of linrodostat (a). Colony formation assays (b) and wound-healing assays (c) confirmed that IDO1i can impede the pro-tumorigenic effects of MSCs in UMUC-3 cells. The growth rate of tumor volume was slow in IDO1i and MSC+IDO1i groups (d), and tumor weight also showed a significant decrease in IDO1i and MSC+IDO1i groups (e). No significant difference in body weight was observed in four groups (f). In the presence of linrodostat, MSCs failed to induce MMP hyperpolarization in UMUC-3 cells (g). TEM showed that MSCs improved mitochondrial morphology and increased mitochondrial numbers, which could be disrupted by linrodostat (h). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.