TI - Results Laminar SS accelerates endothelial cell death in the presence of Bleomycin . AB - HUVEC were exposed to a SS of 12 dyne/cm2 for 16 hours (h) in the presence or absence of a sub-lethal concentration of Bleo ( 10 ug/ml ) . In this experimental condition the endothelial cell treatment with Bleo alone promoted the chromatin incorporation of the PHOSphorylated isoform of histone H2AX ( gammaH2AX ) ( Figure 1a ) . Figure 1b , left and right panels , shows the results of experiments in which cell death and apoptosis were evaluated by propidium-iodide staining/FACS analysis ( left ) and free nucleosomes release ( right ) respectively . Both were found significantly increased in endothelial cells exposed to SS and Bleo . The evidence of a proapoptotic program activation was further supported by the presence of caspase 3 cleavage ( Figure 1c , left panel ) which reached the highest level , two fold above static control and about seven fold above SS alone , ( Figure 1c , right panel ) in the presence of Bleo and SS .