Probing Cell Structure Responses Through a Shear and Stretching Mechanical Stimulation Technique

Abstract

Cells are complex, dynamic systems that respond to various in vivo stimuli including chemical, mechanical, and scaffolding alterations. The influence of mechanics on cells is especially important in physiological areas that dictate what modes of mechanics exist. Complex, multivariate physiological responses can result from multi-factorial, multi-mode mechanics, including tension, compression, or shear stresses. In this study, we present a novel device based on elastomeric materials that allowed us to stimulate NIH 3T3 fibroblasts through uniaxial strip stretching or shear fluid flow. Cell shape and structural response was observed using conventional approaches such as fluorescent microscopy. Cell orientation and actin cytoskeleton alignment along the direction of applied force were observed to occur after an initial 3 h time period for shear fluid flow and static uniaxial strip stretching experiments although these two directions of alignment were oriented orthogonal relative to each other. This response was then followed by an increasingly pronounced cell and actin cytoskeleton alignment parallel to the direction of force after 6, 12, and 24 h, with 85% of the cells aligned along the direction of force after 24 h. These results indicate that our novel device could be implemented to study the effects of multiple modes of mechanical stimulation on living cells while probing their structural response especially with respect to competing directions of alignment and orientation under these different modes of mechanical stimulation. We believe that this will be important in a diversity of fields including cell mechanotransduction, cell-material interactions, biophysics, and tissue engineering.

Quantitative characterization of endothelial cell morphologies depending on shear stress in different blood vessels of domestic pigs using a focused ion beam and high resolution scanning electron microscopy (FIB-SEM)

“…In consequence, the ECs elongate their shape with increasing length and decreasing width and height due to higher shear stress. This confirms the resulted already published in other studies (Malek and Izumo, 1996;Steward et al, 2010).…”

Cellular force signal integration through vector logic gates

“…Fig. 1) is described in the supplementary materials section and the perpendicular shearstretch device has been described by us previously (Steward et al, 2010).…”

“…Cells were stretched by applying compressed air to the bottom of a PDMS substrate constrained in either the perpendicular shear-stretch device or parallel shear-stretch device, as described previously (Steward et al, 2010;Kubicek et. al., 2004).…”

“…3). Independent experiments conducted for the perpendicular shear-stretch device have been described previously (Steward et al, 2010). Therefore in this paper we call this stretch "uniaxial" due to the significant stretch being in one direction.…”

“…A flow pump exerted cell culture media across the top surface of cells coated on a PDMS membrane at magnitudes ranging between 0.1 and 0.6 Pa (1-6 dynes/cm 2 ), as described previously (Steward et al, 2010). ANSYS was used to model the fluid flow properties of cell culture media flowing through our perpendicular shear stretch device and parallel shear-stretch device.…”