Cell Mechanical and Physiological Behavior in the Regime of Rapid Mechanical Compressions that Lead to Cell Volume Change

Abstract

Cells respond to mechanical forces by deforming in accordance with viscoelastic solid behavior. Studies of microscale cell deformation observed by high speed video microscopy have elucidated a new cell behavior in which sufficiently rapid mechanical compression of cells can lead to transient cell volume loss and then recovery. This work has discovered that the resulting volume exchange between the cell interior and the surrounding fluid can be utilized for efficient, convective delivery of large macromolecules (2000 kDa) to the cell interior. However, many fundamental questions remain about this cell behavior, including the range of deformation time scales that result in cell volume loss and the physiological effects experienced by the cell. In this study, a relationship is established between cell viscoelastic properties and the inertial forces imposed on the cell that serves as a predictor of cell volume loss across human cell types. It is determined that cells maintain nuclear envelope integrity and demonstrate low protein loss after the volume exchange process. These results define a highly controlled cell volume exchange mechanism for intracellular delivery of large macromolecules that maintains cell viability and function for invaluable downstream research and clinical applications.

Efficient and gentle delivery of molecules into cells with different elasticity via Progressive Mechanoporation

“…In the MDR-HDR cells undergo high mechanical compression that can enlarge and enrich pores. At the same time volume exchange under fast deformation 23,24 (<0.7 ms) can be favoured through the opened pores (Fig. 1b).…”

“…Methods based on shearinduced or contact-mediated cell deformation, employing different materials, device geometry and flow or pressure controller, have been developed in recent years to widen the applicability to different cell and cargo types. 1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][23][24][25][26][27]38 In previous mechanoporation methods, the flow inside the microfluidic chip has been controlled by either pressuredriven 10 (constant pressure) or a syringe-driven 21 (constant flow) system. Pressure-driven flow provides faster response and stabilization.…”

“…To enlarge cytosolic delivery by mechanoporation to a broad range of cargo molecules, Liu et al recently presented a novel method with molecular size-independent delivery efficiency, showing the importance of timescale deformation and cell mechanical properties in mechanoporation. 23,24 The molecules were loaded into cells by a phenomenon called cell volume exchange for convective transfer (cell VECT) enabled by rapidly passing cells through a microchannel, in which they undergo sudden deformations under several ridges. Cell VECT allowed delivery of different cargos with high efficiency regardless of molecule size and without impairing cell viability mostly in compliant cells.…”

“…Notably, even though molecular loading was independent of molecules' size, it remained dependent on cell size and velocity with delivery efficiency varying with number of ridges and gap size. Thus, VECT is dependent on timescale of deformation (compression time) and cell mechanical properties, 23,24 suggesting that the efficiency of the method might vary among different cells. Following the principle of volume exchange during fast deformation, Kizer et al introduced a new method called hydroporator, based on the rapid hydrodynamic cell shearing inside a microfluidic device under high Reynolds number (Re > 10 2 , ESI, † relevant parameters).…”

Tunable Harmonic Flow Patterns in Microfluidic Systems through Simple Tube Oscillation

“…The simplicity, controllability, versatility, and biocompatibility of the newly described technology make it highly suitable for multiple applications. These include important applications in physics (e.g., studying complex fluids and soft materials [5][6][7] and generation of droplets [58,59] ), chemistry (e.g., synthesis of various molecules and compounds [11,12] ), and biology (e.g., manipulation of cells, [60,61] performing multistep assays, [13] diagnostics, [62] and developing organ-on-a-chip platforms [63] for studying the mechanobiology of cells [64,65] and the human circulatory system [17,19,66] ). Notably, both customized harmonic and disturbed flow patterns can be created and studied using the newly described technology.…”