DEPtech 3DEP Reader
The 3DEP system
Electrophysiology is everywhere.
Of course, we’ve known that for decades, even centuries. Ion fluxes and membrane potentials are the fundament of physiology. Electrophysiology doesn’t just underpin muscle contraction or nerve transmission, but all cells. And yet, if we’re looking to test new drugs, to understand cell differentiation, to examine physiology or even to detect cancer, we don’t usually turn to electrophysiology as a first tool to understand what’s going on. This can be attributed to the prohibitive costs which meant end users didn’t know that electrophysiology gave you a new way of looking at cell biology. Yes, we can use flow cytometry although, it is expensive and dye interactions can easily give artefactual results. On the other hand, to really determine the electrical properties of cells label-free we have to use patch-clamp which examines cells one at a time.
There is another way. Dielectrophoresis (DEP) is a technique that analyses the way in which cells move in electric fields at different frequencies. Think of it as being like electrophoresis for cells but with the added advantage of looking at AC behaviour – an additional dimension that unlocks the ability to determine not only the net electrical properties of the cells but the separate capacitance and resistance values for the cell membrane and cytoplasm.
Although the science underpinning DEP has been understood for decades, until now, no-one has ever been able to present it in a user-friendly, convenient and low cost package that enables any lab to take rapid, label-free cell measurements. Let’s take stem cells as an example. One of the keys to developing stem cell therapies is the rapid detection of differentiation potential, well in advance of differentiation taking place. Normal protocol involves looking for surface protein biomarkers however, by the time cells have expressed the biomarkers they have already differentiated. DEP can detect stem cell differentiation days in advance of conventional biomarkers by looking for changes in membrane capacitance.
It’s the same with cancer – the spectra below show DEP spectra for cancerous and healthy oral brush samples taken from the same patient. This is so accurate it’s being developed as a diagnostic technique. Moreover, recent research indicates that electrophysiological changes such as this could be a fundamental characteristic of all cancers.
It’s the same for other cell phenomena. Take apoptosis – unlike common tests like Annexin V, which require the cell to be so far down the apoptotic pathway that membrane lipids start to invert – DEP can identify early ion efflux events which changes the cytoplasm resistance, sometimes as little as 30 minutes after drug treatment – and all label free.