Patch-clamp Since it was first described by Neher and Sakmann in the 1970s, electrophysiology has remained an important tool in the study of ion channels. Ion channels are membrane proteins that allow ions to pass through the cell membrane. They're involved in practically every physiological process, and their dysfunction is at the root of many diseases, therefore they're prime pharmaceutical targets. Patch clamping is a very information-rich technique, but it requires competent workers to conduct studies, and only one experiment can normally be conducted at a time. The development of the automated patch-clamp (APC) technology changed ion-channel research in the late 1990s and early 2000s. The most successful method required substituting the patch-clamp pipette with a planar substrate (for a review, see [2]), which made the tests easier to carry out and allowed numerous cells to be recorded simultaneously. Much has happened in the field of ion-channel drug discovery and APC in the previous two decades, with improved throughput and increasing simplicity. We review the major changes over the last ten years and attempt to predict what will happen in the future.
If we go back about ten years, there were at least nine Automated Patch Clamp System available from six different companies, including Nanion Technologies' Port-a-Patch and Patchliner, Sophion Bioscience's QPatch, Molecular Devices' LonWorks HT, LonWorks Quattro, and PatchXpress, IonFlux (Fluxion Biosciences), CytoPatch (Cytocentrics), and Flyscreen 8500. (Flying). With GOhm seals, the throughput ranged from a single cell at a time (Port-a-Patch; CytoPatch), 2 or 4 cells (Flyscreen), 2, 4, or 8 wells (Patchliner), 16 or 48 wells (QPatch; PatchXpress; IonFlux), and up to 384 wells with loose (low MOhm) seals (QPatch; PatchXpress; IonFlux) (LonWorks HT). Many of these companies have risen and fallen throughout the years. Flyion's Flyscreen, with its Flip Tip technology and a more pipette-like approach, never caught on, and the company went out of business in 2014. Cytocentrics, the company that makes the CytoPatch, changed its name to CytoBioscience in 2016 to offer contract services and then to Inventa Biotech in 2019 after a series of acquisitions. The CytoPatch struggled to gain traction in the market, selling only a few devices throughout the years. Although Molecular Devices released the LonWorks Barracuda in 2013 with significant enhancements in liquid handling and software, the LonWorks and PatchXpress instruments were never upgraded and were eventually abandoned, leaving only two major participants in the market.
Instruments from the Automated Patch Clamp System are now used in a wide range of applications, from basic research into channelopathies to routine cardiac safety assessment. Over time, their application in cardiac safety screening has grown, and APC is now a widely used and acknowledged approach in most, if not all, safety testing laboratories. Only a few drugs have been withdrawn from the market due to pro-arrhythmic complications since the ICH S7B non-clinical guidance was introduced in November 2005, requiring all new drugs to be tested for activity on the IKr current carried by hERG expressed in recombinant cell lines using the patch-clamp technique.
Since its creation more than two decades ago, Automated Patch Clamp System has had a considerable impact on drug discovery, and it will continue to play a vital role in ion-channel drug discovery and safety testing in the years ahead. As the area of channelopathy grows, high-throughput APC will become increasingly important in determining the impact of various variations on channel kinetics and, eventually, disease phenotype. Patients' variations and mutations were detected and recombinantly expressed in cell lines or patient-derived stem cells. APC could be employed as a diagnostic tool or in the field of customized medicine to screen for substances that could benefit each particular patient. Because APC devices and consumables have become more affordable, patch-clamp data throughput and cost per data point have decreased dramatically in recent years, now being comparable to fluorescence-based assays like FLIPRTM, something that would have been unthinkable 20 years ago when patch-clamp experiments were performed on a conventional rig, recording a single cell at a time.
Automated Patch Clamp System Market as a complementary technique to manual patch clamp, not completely replacing conventional rigs, but rather being used at an earlier stage and in more aspects of drug discovery to simplify and increase the throughput of finding useful compounds, ensuring their safety, and, ultimately, driving effective and safer drugs to market.