Action potential-based MEA platform for in vitro screening of drug-induced cardiotoxicity using human iPSCs and rat neonatal myocytes.

Drug-induced cardiotoxicity poses a negative impact on public health and drug development. Cardiac safety pharmacology issues urged for the preclinical assessment of drug-induced ventricular arrhythmia leading to the design of several in vitro electrophysiological screening assays. In general, patch clamp systems allow for intracellular recordings, while multi-electrode array (MEA) technology detect extracellular activity.

Primary culture of embryonic rat olfactory receptor neurons.

Embryonic cells are very robust in surviving dissection and culturing protocols and easily adapt to their in vitro environment. Despite these advantages, research in the olfactory field on cultured embryonic olfactory neurons is sparse. In this study, two primary rat olfactory explant cultures of different embryonic d (E17 and E20) were established, comprising epithelium and bulb.

Open-cell recording of action potentials using active electrode arrays.

The investigation of complex communication in cellular networks requires superior measurement tools than those available to date. Electrode arrays integrated onto silicon electronics are increasingly used to measure the electrical activity of cells in an automated and highly parallelized fashion, but they are restricted to recording extracellular potentials. Here, we report on an array of TiN electrodes built using standard silicon electronics for intracellular action potential recording.

Single-cell recording and stimulation with a 16k micro-nail electrode array integrated on a 0.18 μm CMOS chip.

To cope with the growing needs in research towards the understanding of cellular function and network dynamics, advanced micro-electrode arrays (MEAs) based on integrated complementary metal oxide semiconductor (CMOS) circuits have been increasingly reported. Although such arrays contain a large number of sensors for recording and/or stimulation, the size of the electrodes on these chips are often larger than a typical mammalian cell. Therefore, true single-cell recording and stimulation remains challenging.

Micro-sized syringes for single-cell fluidic access integrated on a micro-electrode array CMOS chip.

Very-large scale integration and micro-machining have enabled the development of novel platforms for advanced and automated examination of cells and tissues in vitro. In this paper, we present a CMOS chip designed in a commercial 0.18 μm technology with integrated micro-syringes combined with micro-nail shaped electrodes and readout electronics.

Local electrical stimulation of single adherent cells using three-dimensional electrode arrays with small interelectrode distances.

In this paper, we describe the localized and selective electrical stimulation of single cells using a three-dimensional electrode array. The chip consisted of 84 nail-like electrodes with a stimulation surface of 0.8 microm(2) and interelectrode distances as small as 3 microm.

Local electrical stimulation of cultured embryonic cardiomyocytes with sub-micrometer nail structures.

In this paper, we demonstrate the feasibility of selective extracellular electrical stimulation at the (sub)cellular level in dissociated cultured cells. Using a CMOS-compatible process, we have fabricated an electrode array with sub-micrometer nail probes. Due to their particular configuration, the nails are strongly engulfed by the cellular membrane.

On-chip chemical stimulation of neurons by local and controlled release of neurotransmitter.

This paper describes the fabrication and in vitro testing of a device capable of chemically stimulating individual neurons. Electrophoretic actuation is used to locally induce the release of the neurotransmitter L-glutamate in a network of hippocampal neurons cultured on top of the device. Cell activation by the neurotransmitter is visualized using calcium imaging.

Swelling-activated K+ efflux and regulatory volume decrease efficiency in human bronchial epithelial cells.

This study describes the correlation between cell swelling-induced K+ efflux and volume regulation efficiency evaluated with agents known to modulate ion channel activity and/or intracellular signaling processes in a human bronchial epithelial cell line, 16HBE14o(-1). Cells on permeable filter supports, differentiated into polarized monolayers, were monitored continuously at room temperature for changes in cell height (T(c)), as an index of cell volume, whereas (86)Rb efflux was assessed for K+ channel activity. The sudden reduction in osmolality of both the apical and basolateral perfusates (from 290 to 170 mosmol/kg H(2)O) evoked a rapid increase in cell volume by 35%.

Membrane cholesterol extraction decreases Na+ transport in A6 renal epithelia.

In this study, we have investigated the dependence of Na+ transport regulation on membrane cholesterol content in A6 renal epithelia. We continuously monitored short-circuit current (Isc), transepithelial conductance (GT), and transepithelial capacitance (CT) to evaluate the effects of cholesterol extraction from the apical and basolateral membranes in steady-state conditions and during activation with hyposmotic shock, oxytocin, and adenosine. Cholesterol extraction was achieved by perfusing the epithelia with methyl-beta-cyclodextrin (mbetaCD) for 1 h.

Extracellular Ca2+ regulates the stimulation of Na+ transport in A6 renal epithelia.

We investigated the involvement of intracellular and extracellular Ca2+ in the stimulation of Na+ transport during hyposmotic treatment of A6 renal epithelia. A sudden osmotic decrease elicits a biphasic stimulation of Na+ transport, recorded as increase in amiloride-sensitive short-circuit current (Isc) from 3.4 +/- 0.

The transoocyte voltage clamp: a non-invasive technique for electrophysiological experiments with Xenopus laevis oocytes.

We developed a non-invasive technique for electrophysiological investigations of ion transport proteins endogenously or heterologously expressed in Xenopus laevis oocytes. We named this technique the transoocyte voltage clamp (TOVC). Whereas in the classical two-microelectrode voltage-clamp (TEVC) technique, the oocyte is impaled with two glass microelectrodes, we mount the egg in a modified Ussing chamber as used for transepithelial electrophysiological studies.

Measurement of rapid changes in cell volume by forward light scattering.

Light scattering is an empirical technique employed to measure rapid changes in cell volume. This study describes a new configuration for the method of light scattering and its corroboration by measurements of cell height (as a measure of cell volume). Corneal endothelial cells cultured on glass cover-slips were mounted in a perfusion chamber on the stage of an inverted microscope.

Hypotonic treatment evokes biphasic ATP release across the basolateral membrane of cultured renal epithelia (A6).

In renal A6 epithelia, an acute hypotonic shock evokes a transient increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)) through a mechanism that is sensitive to the P2 receptor antagonist suramin, applied to the basolateral border only. This finding has been further characterized by examining ATP release across the basolateral membrane with luciferin-luciferase (LL) luminescence. Polarized epithelial monolayers, cultured on permeable supports were mounted in an Ussing-type chamber.

Mg(2+)-sensitive non-capacitative basolateral Ca(2+) entry secondary to cell swelling in the polarized renal A6 epithelium.

Polarized renal A6 epithelia respond to hyposmotic shock with an increase in transepithelial capacitance (C(T)) that is inhibited by extracellular Mg(2+). Elevation of free cytosolic [Ca(2+)] ([Ca(2+)](i)) is known to increase C(T). Therefore, we examined [Ca(2+)](i) dynamics and their sensitivity to extracellular Mg(2+) during hyposmotic conditions.