The role of membrane lipid rafts in osteoblastic sensing and propagation of mechanical forces: A microfluidicbased single cell analysis study

With the advent of microfluidic devices it has become possible to control on-demand the properties of fluidic environments at the microscale. This has opened the way to the development of microfluidic systems capable of analysing the response of individual cells under exposure to a range of different physical and chemical stimuli. This methodology, which has been defined by many as single-cell analysis (SCA), has permitted to gain a deeper understanding of the mechanisms with which cells transduce extracellular stimuli into intracellular biophysical and biochemical activities. However, it still remains unclear how this transduction process develops in osteoblast cells and which are the key governing parameters. In the present study we report a microfluidic-based SCA technique for investigating the mechanisms of osteoblast mechanotransduction under exposure to fluid shear stress (FSS). With the developed method we quantified local cellular adaptations under exposure to FSS, and we found that membrane cholesterol-rich domains (lipid rafts, LRs) acted as one of the main regulators of cellular adaptation. LRs content was found to be correlated with the extent of cell membrane deformation, stress fiber formation and change of traction force at the increased number of focal adhesion points (FAPs).