Pathologic high shear stress induces apoptosis events in human platelets.

Recently, it has been discovered that apoptosis of anucleate platelets can be induced by chemical agonists. Other studies demonstrated that mechanical forces (shear stresses) stimulate platelet activation and signaling in the absence of exogenous chemical stimuli. We analyzed whether shear stresses can trigger platelet apoptosis, a question that has not yet been studied.

Smooth muscle cell growth in monolayer and aortic organ culture is promoted by a nonheparin binding endothelial cell-derived soluble factor/s.

Objective: To characterize endothelial derived soluble factor(s) that regulate neointimal formation in porcine aortic organ cultures.

Methods And Results: Endothelial cell (EC) conditioned medium, collected in preconfluent EC cultures at 4 days after plating, stimulates vascular smooth muscle cell (SMC) growth in cell culture and in the intima of porcine aortic organ cultures. EC conditioned medium was fractionated consecutively by salt precipitation, ion exchange chromatography and affinity chromatography on a heparin column.