A comparison of the performance and application differences between manual and automated patch-clamp techniques

Abstract

The patch clamp technique is commonly used in electrophysiological experiments and offers direct insight into ion channel properties through the characterization of ion channel activity. This technique can be used to elucidate the interaction between a drug and a specific ion channel at different conformational states to understand the ion channel modulators' mechanisms. The patch clamp technique is regarded as a gold standard for ion channel research; however, it suffers from low throughput and high personnel costs. In the last decade, the development of several automated electrophysiology platforms has greatly increased the screen throughput of whole cell electrophysiological recordings. New advancements in the automated patch clamp systems have aimed to provide high data quality, high content, and high throughput. However, due to the limitations noted above, automated patch clamp systems are not capable of replacing manual patch clamp systems in ion channel research. While automated patch clamp systems are useful for screening large amounts of compounds in cell lines that stably express high levels of ion channels, the manual patch clamp technique is still necessary for studying ion channel properties in some research areas and for specific cell types, including primary cells that have mixed cell types and differentiated cells that derive from induced pluripotent stem cells (iPSCs) or embryonic stem cells (ESCs). Therefore, further improvements in flexibility with regard to cell types and data quality will broaden the applications of the automated patch clamp systems in both academia and industry.

Keywords: Automated patch clamp technique; Drug discovery; Drug safety; Induced pluripotent stem (iPS) cells; Ion channels; Patch clamp..

Fig. (1)

Schematic representations of four patch clamp configurations. (A) Cell-attached patch or on-cell patch. The electrode is tightly sealed to the patch of the membrane and the cell remains intact. (B) Whole cell patch. The tip of a micropipette is placed on a cell and suction is applied though the pipette to rupture the plasma membrane that directly accesses intracellular space. (C) Inside-out patch. After the gigaohm seal is formed, the micropipette is quickly withdrawn from the cell, leaving a patch of membrane attached to the micropipette and exposing the intracellular surface of the membrane to the medium. (D) Outside-out patch. After the whole-cell patch is formed, the electrode slowly withdraws from the cell, which allows the original outside of the membrane that faces outwards from the center of the electrode to form the patch.

Fig. (2)

Schematic representations of several automated pipette-based patch-clamp technologies. The pipette electrode moves to contact the surface of a randomly chosen cell that is suspended in a layer within a density gradient (A) or at the air/liquid interface (B). (C) A cell is positioned on the recording pipette electrode using negative pressure at the suction channel. (D) Cells are flushed into a pipette and are pushed into the inside tip of the pipette.

Fig. (3)

Schematic diagrams of the IonWorks single-hole (A) and population patch clamp (PPC) (B) planar array electrophysiology. The IonWorks Quattro System uses a Patch Plate PPC Substrate that contains multiple recording sites per well. Success rates with this substrate are nearly perfect (> 95%), and the recordings and subsequent IC₅₀ determinations are highly reproducible.