Intravenous infusion of mesenchymal stem cells (MSCs) commonly leads to rapid cell entrapment and death in the microvasculature of the lung within 24 hours. however, within this short period, they manage to exhibit powerful immunomodulatory capabilities and therapeutic benefits.
Research done at Rotterdam detected dead MSCs within monocytic cells in the lung and liver and also disseminated throughout the body. It is suggested that the monocytes undergo change and exhibit multiple immunomodulatory characteristics such as increased expression of programmed death ligand-1 (suppresses the immune system) and interleukin-10 (an anti-inflammatory cytokine), reduced expression of TNF- α (an inflammatory cytokine), and the induced formation of Foxp3+ regulatory T cells (part of the adaptive immune system). The data suggests that monocytes play an important role in mediating, distributing and transferring the immunomodulatory effect of MSCs.