A New Determination of the Shear Modulus of the Human Erythrocyte Membrane Using Optical Tweezers

Hong

Animal Cells and Systems

et al. 2013

Although cancerous cells and normal cells are known to have different elasticity values, there have been inconsistent reports in terms of the actual and relative values for these two cell types depending on the experimental conditions. This paper investigated the mechanical characterization of normal hepatocytes (THLE-2) and hepatocellular carcinoma cells (HepG2) using atomic force microscopy indentation experiments and the HertzÁSneddon model, and the results were confirmed by an independent de-adhesion assay. To improve the reliability of the data, we considered the effects of tip geometry and indentation depth on the measured elasticity of the cells. This study demonstrated that THLE-2 cells had a higher elastic modulus compared with the HepG2 cells and that this difference was more significant when a conical tip was used. The inhibitor study indicated that this difference in the mechanical properties of THLE-2 and HepG2 cells was mainly attributed to differential arrangements in the cytoskeletal networks of actin filaments. An independent de-adhesion assay also confirmed that THLE-2 cells had a higher elastic modulus compared with the HepG2 cells, which resulted in a shorter time constant for cellular contractility.

Section: Afm Indentation Experimentsmentioning

confidence: 99%

Comparative study on the differential mechanical properties of human liver cancer and normal cells

Hong

Animal Cells and Systems

et al. 2013

“…1 For the analysis of single cells, optical stretchers, micropipette aspiration, magnetic tweezers, and microcantilevers are some of the approaches that have been explored. [2][3][4][5] Other groups have been successful in implementing high sensitivity electrical techniques for cell counting. [6][7][8] The present work describes an electrical approach to the mechanical analysis of cells that uses a combination of electromanipulation for stimulus and capacitance for sensing.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic electromanipulation with capacitive detection for the mechanical analysis of cells

et al. 2008

The mechanical behavior of cells offers insight into many aspects of their properties. We propose an approach to the mechanical analysis of cells that uses a combination of electromanipulation for stimulus and capacitance for sensing. To demonstrate this approach, polystyrene spheres and yeast cells flowing in a 25 m ϫ 100 m microfluidic channel were detected by a perpendicular pair of gold thin film electrodes in the channel, spaced 25 m apart. The presence of cells was detected by capacitance changes between the gold electrodes. The capacitance sensor was a resonant coaxial radio frequency cavity ͑2.3 GHz͒ coupled to the electrodes. The presence of yeast cells ͑Saccharomyces cerevisiae͒ and polystyrene spheres resulted in capacitance changes of approximately 10 and 100 attoFarad ͑aF͒, respectively, with an achieved capacitance resolution of less than 2 aF in a 30 Hz bandwidth. The resolution is better than previously reported in the literature, and the capacitance changes are in agreement with values estimated by finite element simulations. Yeast cells were trapped using dielectrophoretic forces by applying a 3 V signal at 1 MHz between the electrodes. After trapping, the cells were displaced using amplitude and frequency modulated voltages to produce modulated dielectrophoretic forces. Repetitive displacement and relaxation of these cells was observed using both capacitance and video microscopy.

Experimental Cell Research

“…The mechanical properties of the cellular cortex have been measured by several techniques such as cell poking [12,13], micropipette aspiration [14,15], optical tweezers [16][17][18] and magnetic beads twisting [19][20][21]. However, the temporal and/or spatial resolutions of these techniques do not suffice for a thorough understanding of the variations in mechanical properties caused by cellular functions.…”

Section: Introductionmentioning

confidence: 99%

Contribution of cellular contractility to spatial and temporal variations in cellular stiffness

Nagayama

Haga

Takahashi

et al. 2004

Scanning probe microscopy and immunofluorescence observations indicated that cellular stiffness was attributed to a contractile network structure consisting of stress fibers. We measured temporal variations in cellular stiffness when cellular contractility was regulated by dosing with lysophosphatidic acid or Y-27632. This experiment reveals a clear relation between cellular stiffness and contractility: Increases in contractility cause cells to stiffen. On the other hand, decreases in contractility reduce cellular stiffness. In both cases, not only the stiffness of the stress fibers but also that of the whole of the cell varies. Immunofluorescence observations of myosin II and vinculin indicated that the stiffness variations induced by the regulation of cellular contractility were mainly due to rearrangements of the contractile actin network on the dorsal surface. Taken together, our findings provide evidence that the actin cytoskeletal network and its contractility features provide and modulate the mechanical stability of adherent cells.