Adhesion and viscoelasticity of living tissues: the Live Cell Monolayer Rheometer (LCMR)

Speaker： Gerald Fuller Academician

Time：14:00, 2018.4.2

Place：Room 709,Computer Experimental Building, Guangzhou University

Organization：Chemical Engineering, Stanford University, Stanford, CA 94305

During the last decades several techniques have been developed to investigate the mechanical properties of living tissues. At the cellular level, the experimental methods include atomic force microscopy, magnetic twisting and pulling cytometry, micropipette aspiration, optical particle trapping and optical tweezers, the two micro-plates method, and traction force microscopy. While these methods offer great insight, for a complete understanding of cells as a physical system, multiple cell approaches must also be considered.

In this work, we present rheological measurements using a purpose-built Live Cell Monolayer Rheometer (LCMR) that can characterize averaged cell mechanics and cell adhesion. The LCMR enables the investigation of biologically active, confluent layers of cells in contact with extracellular membrane components or other surfaces. Upon shearing the layer of cells, direct determination of the viscoelastic response of the cells and their adhesive strength to bounding surfaces can be determined.

In this presentation, the LCMR is applied to two problems: i) the adhesion of human bladder cells to bacteria with a particular attention paid to the role of biofilms and ii) the role of inflammation on the endothelial cell membrane stiffening. We find that the presence of curli significantly enhance adhesion of bacteria against bladder cells and this elevation in adhesive strength can be quantified. In the case of inflammation response, the instrument reports a 60% increase in the shear moduli of endothelial cells upon exposure to the signaling protein tnf-alpha.