Figure 11. Chronic S1P₁R antagonism or HSP27 knockdown decreases endothelial cell viability.

MTT assay measured endothelial cell viability. A. Human umbilical vein endothelial cells were treated with vehicle (1% DMSO) with a selective S1P₁R antagonist (1 µM W146) for 3 days (N=4, top) or for 1 hr (N=4, bottom). Treatment with W146 for 3 days significantly reduced endothelial cell viability whereas 1 hr treatment had no effect. B. Representative gel images of RTPCR (top) and densitometric quantification of relative band intensities normalized to GAPDH (bottom) of HSP27 mRNA expression in human umbilical vein endothelial cells (N=4) treated with 20 nM control siRNA or with 20nM HSP27 siRNA for 48 hr (N=4). HSP27 siRNA treatment significantly attenuated HSP27 mRNA expression in endothelial cells. C. siRNA induced HSP27 knockdown significantly reduced endothelial cell viability in culture (N=4). *P<0.05 vs. vehicletreated cells.