High-Throughput Patch Clamping
Since patch clamping is the gold standard for screening ion channels, there is a distinct need for high-throughput systems for primary and secondary screening. As a result, three new high-throughput systems were introduced at the conference.
Fluxion Biosciences showed the IonFlux-HT, which looks like a traditional plate reader. Fluxion claims this system can deliver between 8,000 and 10,000 assays per day at a cost of $0.30 per data point, making it suitable for primary or secondary screening.
“The system uses a standard 384 microplate into which cells, compounds, and reagents are loaded,” Jeff Jensen, CEO, explained. “A polymer microfluidic channel network replaces the well plate bottom, with interconnected channels forming a fluidic network. By applying pressure, cells and compounds are introduced. By applying vacuum, the cells are trapped at channel junctions and their changes in currents can be measured by the system’s integrated electrodes,” Jensen added.
“We have tested the system with voltage-gated ion channels such as Kv2.1, hERG, and Nav1.7, and ligand-gated channels such as P2X3, TRPV1, and GABAA. We are providing the system with or without liquid-handling capability, and this means researchers can either manually pipette or integrate their own liquid handler in if they want, or purchase a fully integrated solution from Fluxion.”
Cellectricon has gone a different route to develop its high-throughput patch clamper. The company has teamed up with The Automation Partnership and AstraZeneca to produce Dynaflow®HT for a fully automated workflow. The system contains cell and compound storage, as well as robotic liquid and plate handling, all of which allow the cells to be prepared in one place. The cells are then sucked from 96 well plates into a silica microfluidic chip. Here the cell membrane breaks and it forms a seal with the chip where the current changes are monitored.
“This system has been custom built over the past three years, and the heart of it is the way the microfluidics work,” said Mattias Karlsson, Ph.D., CTO. “The system can currently achieve over 7,500 data points per day with competitive running costs and when we introduce our new chip later this year it will be able to generate 15,000 data points per day at a running cost of $0.10 per data point.”
The performance of this system was validated by Dr. Dekermendjian who presented data to show that the dose-response curves were comparable to a manual patch clamp of a GlyRa ligand-gated ion channel treated with a number of different compounds. According to Dr. Karlsson, Dynaflow HT has been used with cell lines including WSS, CHO, LTK, and HEK with voltage- and ligand-gated ion channels such as GABAA and hERG, and the system is now being further tested by BioFocus DPI to screen its SoftFocus® ion channel library of compounds.