Exogenous Nitric Oxide Increases the Expression of Oct-4 and May Modify Bone Marrow Stem Cell Differentiation into Endothelial Cells in vitro.

This study was designed to explore the role of exogenous nitric oxide (NO) in the biological behavior of bone marrow stem cells and their differentiation into endothelial cells in vitro. Adult mouse bone marrow multipotent progenitor cells were used as the source of stem cells. The biological behavior of the stem cells was evaluated by assessing the cell proliferation and expression of Oct-4 with real-time PCR with or without NO donor DETA-NONOate. The cells were induced to differentiate into endothelial cells with or without DETA-NONOate. The stages of differentiation were monitored with morphology and endothelial cell marker von Willebrand factor (vWF). It was found that Oct-4 expression was significantly increased by 57.5% (n=5, p<0.05) in stem cells exposed to DETA-NONOate in a concentration-dependant manner. However, the ceil proliferation was significantly decreased when treated with DETA-NONOate for 48 hrs (1,680+/-26 cells/cm2 for control, 1,221+/-29 cells/era2 for 50 uM, and 543+/-77 cells/cm2 for 100 uM, n=6, p<0.05). When the stem cells were exposed to DETA-NONOate (100uM) for the first 48 hrs during differentiation, vWF expression was increased by 17.7% at day 14 in the differentiating cells. However, vWF expression was decreased in the cells at day 14 or cell death occurred if the cells exposed to DETA-NONOate over 72 hrs during differentiation. To demonstrate dependence of DETA-NONOate on cyclic GMP, experiments were repeated in the presence of guanylyl cyclase inhibitor ODQ or cGMP analog 8-Br-cGMP. The effect of DETA-NONOate on cell proliferation and Oct-4 expression of the stem cells was not affected by ODQ or 8-Br-cGMP, suggesting a cGMP-independent mechanism. These data indicate that exogenous NO plays an important role in the biological behavior and differentiation of bone marrow stem cells through a mechanism independent of cGMP. [ABSTRACT FROM AUTHOR]