# Analysing calcium signalling of cells under high shear flows using discontinuous dielectrophoresis

## TL;DR

A new method uses dielectrophoresis to immobilize cells and study their calcium signaling under high shear stress without damaging them.

## Contribution

A quick, label-free cell immobilization technique that enables calcium signaling analysis under high shear flows with minimal cell damage.

## Key findings

- At least 90% of cells remained immobilized under 63 dyn/cm2 shear stress.
- The method enables analysis of calcium signaling in HEK-293 cells expressing TRPV4 under physiological shear stress.
- Electric field activation was limited to 120 s to preserve cell integrity.

## Abstract

Immobilisation of cells is an important feature of many cellular assays, as it enables the physical/chemical stimulation of cells; whilst, monitoring cellular processes using microscopic techniques. Current approaches for immobilising cells, however, are hampered by time-consuming processes, the need for specific antibodies or coatings, and adverse effects on cell integrity. Here, we present a dielectrophoresis-based approach for the robust immobilisation of cells, and analysis of their responses under high shear flows. This approach is quick and label-free, and more importantly, minimises the adverse effects of electric field on the cell integrity, by activating the field for a short duration of 120 s, just long enough to immobilise the cells, after which cell culture media (such as HEPES) is flushed through the platform. In optimal conditions, at least 90% of the cells remained stably immobilised, when exposed to a shear stress of 63 dyn/cm2. This approach was used to examine the shear-induced calcium signalling of HEK-293 cells expressing a mechanosensitive ion channel, transient receptor potential vaniloid type 4 (TRPV4), when exposed to the full physiological range of shear stress.