Effects of Fluid Flow on Murine Embryonic Stem Cells

Abstract

Embryonic stem cells are cells with the ability to make more of themselves (selfrenew)and to produce all the cells of the body (pluripotency). These abilities giveembryonic stem cells much value to study for medical applications, such as regenerativemedicine for treating damaged tissues. However, a large number of specific types ofcells are required for tissue therapy. Thus embryonic stem cells must be expandedand differentiated in a controlled manner. In order to better control embryonic stemcells, the cell signalling pathways responsible for cell behaviour must be understood.Cell signalling is the molecular chain of events that occurs due to a stimulus in theenvironment. From previous studies examining embryonic stem cell behaviour underfluid flow conditions in spinner flask bioreactors, it was found that pluripotencymarkers were maintained even in media that should lead to cell differentiation intoother cell types. We hypothesized that several key signalling pathways triggeredby shear stress were responsible for this behaviour. To test this hypothesis, mouseembryonic stem cells were placed in parallel plate flow chambers and exposed touniform fluid shear stress. These embryonic stem cells were previously transfectedwith a reporter construct that detects b-catenin activity, which is related to pluripotencyof stem cells. Furthermore, these flow exposed cells were stained for L-pSmad2, asignalling protein found to increase with shear stress in another cell type. Underconfocal microscopy, it was determined that exposure to fluid shear stress influencedboth b-catenin activity and L-pSmad2 protein expression in embryonic stem cells.Overall, this study provides a better understanding of the cell signalling responsiblefor controlling the pluripotency of embryonic stem cells.