Development of Improved Assays for Cell Adhesion through Local Application of Force to Cells

In this project, we are developing new methods to investigate if and how cell adhesion strength changes in diseased cells. In neurons, cell adhesion is particularly important, as cell-cell contacts at the synapse are required for electrical signal transmission. In Alzheimer’s and other neurological diseases, neuron signaling networks fail by cell retraction, but it is not known if retraction arises from loss of adhesion, or by another pathway. To test this, we are developing improved methods to apply forces directly to cells using optical traps or magnetic tweezers, custom-built  tools that manipulate small dielectric or magnetic particles that are coupled to the cell surface. In our preliminary work we are using both a synthetic system of engineered hydrogels to test adhesion strength of known cellular proteins, and to optimize our binding and pulling protocols, as well as living cells. Our cellular work, we will start with a non-neuronal cell line (Cos 7 cells), which has the advantage of fast proliferation, ease of transfection with proteins of interest, and ease of imaging with microscopy. By applying forces directly to the cells we can measure detachment forces, and in the future will also visualize cell deformation under loading. In addition to investigating the role of adhesion in neurological disease, the ability to apply forces to neurons would also allow us to investigate the effects of blunt force trauma, with importance to understanding traumatic brain injury.