In a variety of situations in living organisms, cells interact with their environment by generating traction forces. For example, muscle contractility (cardiac, skeletal and smooth muscles), ECs and permeability, stem cell differentiation might correlate with contractility (maybe…Engler). There are currently few methods by which one can measure the traction forces in a quantitative way, especially on the single-cell level; the most common method by which to study cells in vitro has been to use a polystyrene dish. However, the rigidity of the substrates makes it impossible to visualize cell traction forces. Thus, it has been difficult to quantitatively study the underlying mechanisms by which a cell generates traction forces, and how traction forces can be modulated to promote normal development or halt disease progression. Our lab has developed a technique to overcome these limitations. The method is based on a vertical array of flexible cantilevers, the stiffness and size scale of which are such that individual cells spread across many cantilevers and deflect them in the process. We can measure the deflections under a microscope and calculate the magnitude and direction of traction forces required to produce the observed deflections. We call these substrates microfabricated post-array-detectors, or mPADs. Here, we will show you how we fabricate and use the mPADs to asses modulations of cellular contractility.
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