2020 - Automated Patch Clamp System Introducing Simulated Ik1 Into stem cell derived Cardiomycoytes Using Dynamic Clamp
Patchliner poster, 64th Annual Meeting of the Biophysical Society (1.0 MB)
Dynamic clamp is a powerful tool involving injection of real-time simulated currents into patch clamped cells. It has been successfully employed in conventional patch clamp electrophysiology to inject IK1 current into human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). hiPSC-CMs are attractive cell types because of their unlimited availability and human origin. However, IK1 is expressed at low levels in those cells, hence they display a more depolarized resting membrane potential (RMP) than adult cardiomyocytes (CMs). Introducing simulated IK1 into hiPSC-CMs improves their resting potential and makes them a viable alternative to the scarcely available adult human CMs. Furthermore, small cell capacitance and low potassium conductance can result in higher membrane resistance, which can influence the measured RMP. To measure reliable RMP values with the patch clamp technique it is crucial to have a very high RSeal or high K+-conductance carried out by IK1. Hence, we developed an automated dynamic clamp system combining the injection of simulated IK1 currents with automatic RSeal compensation. Our results show that virtual IK1 can be successfully injected into hiPSC-CMs in up to 8 cells simultaneously and that RSeal is adequately compensated. Our approach results in stable RMP and improved action potential shape. Increased IK1 shortened the action potential duration (APD) and accelerated the upstroke velocity. We measured native, but small, Ba2+-sensitive IK1 in voltage clamp in approximately 50% of these cells. Adding a Ca2+channel activator (BayK 8644), or blocker (Nifedipine) caused an increase and decrease of the APD, respectively. In conclusion, combining dynamic clamp and RSeal compensation with APC resulted in an enhanced, medium-throughput new platform for safety pharmacology, the Patchliner Dynamite8.