Application of sequential cyclic compression on cancer cells in a flexible microdevice

Abstract

Mechanical forces shape physiological structure and function within cell and tissue microenvironments, during which cells strive to restore their shape or develop an adaptive mechanism to maintain cell integrity depending on strength and type of the mechanical loading. While some cells are shown to experience permanent plastic deformation after a repetitive mechanical tensile loading and unloading, the impact of such repetitive compression on plastic deformation of cells is yet to be discovered. As such, the ability to apply cyclic compression is crucial for any experimental setup aimed at the study of mechanical compression taking place in cell and tissue microenvironments. Here, the capability of our microfluidic compression platform to aid in the observation of the sequential cyclic compression of live cell actin is illustrated using SKOV-3 ovarian cancer cells. Live imaging of the actin cytoskeleton dynamics of the compressed cells was performed for the applied varying pressures in ascending order during cell compression. Additionally, recovery of the compressed cells was investigated by capturing actin cytoskeleton and nuclei profiles of the cells at zero time and 24 h-recovery after compression in end point assays. This was performed for a range of mild pressures within the physiological range. The extent of recovery of the compressed cells can give insights into the plasticity of the cancer cells by imaging cell membrane bulges and actin cytoskeleton and measuring the shape descriptors of cell nuclei. As demonstrated in this work, the developed platform can control the strength and duration of cyclic compression, while enabling the observation of morphological and cytoskeletal and nuclear changes in cells, thus providing a powerful new tool for the study of mechanobiological processes in cancer and cell biology.

Microdevice-based mechanical compression on living cells

“… 52 , 53 In contrast, microfluidics-based platforms have shown to be able to easily apply global compression to cells cultured in various platforms and at various scale, including single cells, monolayers, hydrogel-based 3D culture models, as well as spheroids. It is expected that the development and integration of force sensors on-chip and/or computational modeling to measure forces generated inside chips 22 , 24 , 28 , 29 will further close any functional gaps between AFM and microdevices. As discussed in the following, the latter already incorporate advanced capabilities of controlled compressive force application in both static and dynamic manner, portability, and ease of use with different microscopes.…”

“…Furthermore, cell shape deformation and recovery post compression, which is an important phenomenon in cell mechanics, can be investigated after the position recovery of the respective compressing unit within flexible microdevices. 27 , 29 …”

“…Based on the strength and mode of the mechanical loading, cells either strive to restore their shape or develop an adaptive mechanism to maintain cell integrity and prevent mechanical damage. 29 , 60 The degree of cell deformation and recovery of the compressed cells to their previous state, and whether they show plastic response in form of permanent deformation and develop into a partially or completely damaged state, have been among the phenomena studied using cell compression microdevices. 23 , 27 , 29 …”

“… 29 , 60 The degree of cell deformation and recovery of the compressed cells to their previous state, and whether they show plastic response in form of permanent deformation and develop into a partially or completely damaged state, have been among the phenomena studied using cell compression microdevices. 23 , 27 , 29 …”

“… 24 , 25 , 27 , 61 Subcellular structures, such as cell nuclei and actin cytoskeleton supporting the cell body, are highly mechanoresponsive to applied forces and tend to distinctly change their morphology under the impact of compression. 21 , 28 , 29 , 62 For instance, Ho et al. performed volumetric scanning of single adherent cells being flattened and observed a decrease in cell height, mainly contributed to by a change in volume of the nuclei region and cytoskeleton when increasing pressures were applied in their aforementioned microfluidic device.…”