Frictional Behavior of Individual Vascular Smooth Muscle Cells Assessed By Lateral Force Microscopy

Abstract

With the advancement of the field of biotribology, considerable interest has arisen in the study of cell and tissue frictional properties. From the perspective of medical device development, the frictional properties between a rigid surface and underlying cells and tissues are of a particular clinical interest. As with many bearing surfaces, it is likely that contact asperities exist at the size scale of single cells and below. Thus, a technique to measure cellular frictional properties directly would be beneficial from both a clinical and a basic science perspective. In the current study, an atomic force microscope (AFM) with a 5 μm diameter borosilicate spherical probe simulating endovascular metallic stent asperities was used to characterize the surface frictional properties of vascular smooth muscle cells (VSMCs) in contact with a metallic endovascular stent. Various treatments were used to alter cell structure, in order to better understand the cellular components and mechanisms responsible for governing frictional properties. The frictional coefficient of the probe on VSMCs was found to be approximately 0.06. This frictional coefficient was significantly affected by cellular crosslinking and cytoskeletal depolymerization agents. These results demonstrate that AFM-based lateral force microscopy is a valuable technique to assess the friction properties of individual single cells on the micro-scale.

Morphological and nanomechanical changes in mechanosensitive endothelial cells induced by colloidal AFM probes

“…This value is very close to a value measured with a spherical AFM probe using similar scan conditions but on different kind of cells, i.e. vascular smooth muscle cells, that was found to be approximately 0.06 (Dean et al ., ). Taking μ = 0.06, one obtains the value of shear stress at the level of τ = 13 Pa.…”

The endothelial glycocalyx anchors von Willebrand factor fibers to the vascular endothelium

“…This imaging technique has been established by material scientists to detect, for example, charge distributions on nonbiological surfaces. 48 Although the physicochemical characterization of biological samples by AFM is less frequently reported, [49][50][51] we selected this method because the direct detection of cell-bound COSs by fluorescence microscopy failed (data not shown). AFM enabled us to measure an increased friction between the scanning probe and the endothelial cell surface after treatment with COSs (Figure 2A lateral deflection image).…”

Probing the frictional properties of soft materials at the nanoscale

“…32,42,68, On the right side of the figure are shown the FFM studies using a colloidal probe made from: collagen; 96 latex; 97 polyethylene (PE); 25,28,45,98 polyethylene glycol (PEG); 99 poly(methyl methacrylate) PMMA; 26,27,95,100 polystyrene (PS); 33,71,101 cellulose; 31,[102][103][104][105][106][107][108][109] and silica. 35,36,98,[110][111][112][113][114][115][116][117] The volume of the symbol corresponds to the number of studies using the specific system of materials. Colloidal probes of the same material are in groups, while the green-shaded area represents the knowledge gap on friction between soft surfaces that requires future research attention.…”

“…For instance, FFM employing a borosilicate colloidal probe was used to study the frictional behaviour of individual vascular smooth cells. 110 It revealed that µ was increased with increasing cellular crosslinking and decreased by cytoskeletal polymerization, which could be used to improve the design in applications of intravenous devices such as stents and heart valves. Furthermore, by directly measuring friction on cells, one could better understand the disorder related to stresses in cells, such as diagnosis of heart diseases.…”