Microvesicles released from human embryonic stem cell derived-mesenchymal stem cells inhibit proliferation of leukemia cells.

Human embryonic stem cell derived-mesenchymal stem cells (hESC-MSCs) are able to inhibit proliferation of leukemia cells. Microvesicles released from human embryonic stem cell derived-mesenchymal stem cells (hESC-MSC-MVs) might play an important part in antitumor activity. Microvesicles were isolated by ultracentrifugation and identified under a scanning electron microscopy and transmission electron microscope separately. After 48-h cocultured with hESC-MSCs and hESC-MSC-MVs, the number of K562 and HL60 was counted and tumor cell viability was measured by CCK8 assay. The expression of proteins Bcl-2 and Bax were estimated by western blotting. Transmission electron microscope and western blot analysis were adopted to evaluate the autophagy level. Results showed that both hESC-MSCs and hESC-MSC-MVs inhibited proliferation of leukemia cells in a concentration-dependent manner. hESC-MSC-MVs reduced the ratio of Bc1/Bax, enhanced the protein level of Beclin-1 and LC3-II conversion, thus upregulating autophagy and apoptosis. In conclusion, microvesicles released from human embryonic stem cell derived-mesenchymal stem cells inhibited tumor growth and stimulated autophagy and excessive autophagy might induce apoptosis.