Automated Torque Microscopy to Investigate Cellular Left-Right Asymmetry with respect to Stem Cell Differentiation

Description

Left-right (LR) asymmetry in our body, e.g. the position of internal organs or theleft/right ventricles in a heart, is essential for many physiological functions such as theheart contraction and blood circulation. Errors of LR patterning may lead to birthdefects or even death. Yet, how LR asymmetry is formed remains largely unknown.Recently evidences showed that LR asymmetry may originate from single cell’s LRbiased motion including cell twisting, migration, and alignment. Cell differentiation mayplay a role that gives rise to the diverse forms of cellular LR biases, resulting thespecific cell-cell LR orientation essential for tissue formation. However, although therehave been many technologies to characterize cellular mechanical behaviors, for example,cell contractility, the appropriate platform to quantitatively measure the cell’s LR motionhas been lacking.In this proposal, we aim at providing an automated torque microscopy to quantitativelyinvestigate single cell’s LR asymmetry with respect to cell differentiation. Usingferromagnetic nanowire as the intracellular sensor, we recently discovered an unreportedmechanical force – torque – being exerted by cells. The cellular torque is eitherclockwise or counterclockwise depending on cell types. This nanowire magnetoscope isbelieved as the first technology to quantitatively measuring cellular LR biased motion. Inthis project, first, we will develop the automated torque microscopy integrating thenanowire magnetoscope, micropost array, time-lapse system, and program-controlledmagnetic field. Second, based on the developed platform, we will characterize the cellulartorque with respect to the differentiation of human mesenchymal stem cells. Adipogenic’(fat) and osteogenic (bone) differentiation will be the main focuses to reveal thedifference of cellular torque upon the commitment of specific lineages. Third, with theaid of the time-lapse system, we will continuously track single cells’ torque during thedifferentiation process. A program-controlled magnetic field by electromagnets will alsobe integrated to explore whether the externally applied magnetic torque would, from theother way around, enhance or suppress the cell differentiation. This combined analysison single cells will elucidate the time-dependence and the logic causality betweencellular torque and differentiation, i.e. whether differentiation affects torque or torqueaffects differentiation. Overall, we believe that our automated torque microscopy and theintegrated analysis of cellular torque vs. cell differentiation can provide a valuableunderstanding of how cells are enabled with varied types of LR biases, opening up a newdirection for cell mechanics, cell-cell communications, and tissue regeneration.?