Regulating the Membrane Transport Activity and Death of Cells via Electroosmotic Manipulation

Abstract

Although the volume of living cells has been known to heavily influence their behavior and fate, a method allowing us to control the cell size in a programmable manner is still lacking. Here, we develop a technique in which precise changes in the cellular volume can be conveniently introduced by varying the voltage applied across a Nafion membrane that separates the culture medium from a reservoir. It is found that, unlike sudden osmotic shocks, active ion transport across the membrane of leukemia K562 cells will not be triggered by a gradual change in the extracellular osmolarity. Furthermore, when subjected to the same applied voltage, different lung and nasopharyngeal epithelial cancer cells will undergo larger volumetric changes and have a 5-10% higher death rate compared to their normal counterparts. We show that such distinct response is largely caused by the overexpression of aquaporin-4 in tumor cells, with knockout of this water channel protein resulting in a markedly reduced change in the cellular volume. Finally, by taking into account the exchange of water/ion molecules across the Nafion film and the cell membrane, a theoretical model is also proposed to describe the voltage-induced size changes of cells, which explain our experimental observations very well.

Quantitative screening of the effects of hyper-osmotic stress on cancer cells cultured in 2- or 3-dimensional settings

“…Moreover, extracellular osmolarity or modification of specific ion concentrations strongly impacts the mechanical properties of the cell through cell volume changes that may affect various cellular processes (e.g. mitosis, mitochondrial functions and DNA repair) 15–19 .…”

Detection of the mesenchymal-to-epithelial transition of invasive non-small cell lung cancer cells by their membrane undulation spectra

“…38,39 This suggests that the observed surface undulation of tumor cells may be caused by associated cytoskeleton and adhesion dynamics inside. [40][41][42] On the other hand, recent evidence has also demonstrated that slow changes in the cellular volume can be triggered by active cross-membrane transport of water and ion molecules, 19,[43][44][45][46] which could also lead to the surface undulation of cells. Further investigations are certainly Fig.…”

“…17,18 Interestingly, recent evidence has indicated that the invasiveness of tumor cells is intimately related to their physical characteristics. For example, it was found that invasive epithelial cells are generally soer, as well as more capable to undergo shape changes, than those with low metastatic potential [19][20][21] both in cell lines and clinical samples from non-small cell carcinoma of the lung, breast ductal adenocarcinoma, and pancreatic adenocarcinoma. 22,23 Along this direction, the use of deep learning method to relate the physical response of cells to different cancer biomarkers [11][12][13] has received increasing attention, with the vision of achieving precision oncology eventually.…”

Role of Aquaporins in the Physiological Functions of Mesenchymal Stem Cells

“…It has been reported that AQP3 affects the Wnt/GSK-3β/β-catenin pathway in liver CSCs (LCSCs), and modulates their stemness, differentiation, and apoptosis [ 135 ]. Other studies have identified AQP4 as the most abundant AQP in nasopharyngeal and lung CSCs and have shown its involvement in the regulation of large volumetric changes related to an increase in death rate [ 155 ]. Using a novel electro-osmotic microfluidic system that controls cell osmolarity gradients, AQP4 expression has been shown to be directly correlated with the speed of cell migration [ 137 ] ( Table 3 ).…”