A scorpion venom peptide that blocks a critical heart potassium channel reproduced drug-induced long QT syndrome features in human stem cell-derived heart cells, establishing a new tool for cardiac safety testing.
External hERG blockerBeKm-1 blocks hERG channels from the outside — a unique mechanism compared to most cardiac drugs — while reproducing all key LQTS features
What the researchers found
BeKm-1, a scorpion venom peptide that selectively blocks hERG potassium channels from the outside of the cell, successfully reproduced key features of drug-induced long QT syndrome in human stem cell-derived cardiomyocytes. The peptide delayed heart cell repolarization, induced early afterdepolarizations (abnormal electrical events), and reduced spontaneous beating rate, calcium transients, and contraction frequency — all hallmarks of arrhythmia risk.
Because BeKm-1 blocks hERG from the extracellular face (unlike most drugs that block from inside), it serves as a unique reference compound for cardiac safety testing and as a modifiable molecular platform for designing new hERG-targeting therapeutics.
Why it matters
Many drugs are withdrawn from market because they accidentally block hERG channels and cause fatal heart rhythm disorders. This study validates a scorpion venom peptide as a tool for testing cardiac drug safety in human stem cell-derived heart cells, and establishes it as a starting point for engineering new hERG modulators with therapeutic potential.
The numbers in context
BeKm-1 high-affinity hERG blocker · hiPS-CMs model · Induced early afterdepolarizations · Reduced beating frequency · External face binding (unique mechanism)
How the study worked
Laboratory study using human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs). BeKm-1 affinity for hERG channels was compared to reference compounds using automated patch-clamp electrophysiology. Comprehensive assessment included action potential properties, calcium handling, and beating/contraction measurements.
Who was studied
Not applicable (in vitro study using human induced pluripotent stem cell-derived cardiomyocytes)
What this study cannot tell us
This is an in vitro study using stem cell-derived cardiomyocytes, which may not fully replicate mature human heart cell physiology. hiPS-CMs are known to have immature electrophysiological properties. The study does not assess in vivo safety or therapeutic applications of BeKm-1 or its derivatives.
How to read the evidence
This is an in vitro laboratory study using stem cell-derived cardiomyocytes. While technically rigorous with comprehensive electrophysiological characterization, it is a proof-of-concept study without in vivo validation.
When this study was published
Published in 2020, this study reflects ongoing efforts to improve cardiac safety testing using human stem cell-derived models and venom-derived peptide tools.
The bigger picture
Cardiac safety testing is a critical bottleneck in drug development — hERG channel blockade is the most common reason drugs are withdrawn post-approval. This study advances the field by validating a venom-derived peptide as a reference compound in human stem cell heart models, and by demonstrating that peptides blocking hERG from the outside may offer new approaches to modulating cardiac electrical activity.
Questions still open
- Can BeKm-1 derivatives be engineered to selectively modulate hERG without causing arrhythmia?
- How does BeKm-1's external hERG blocking mechanism differ functionally from drugs that block from the intracellular side?
- Could modified versions of BeKm-1 have therapeutic applications for cardiac arrhythmias?
Common questions
What is the hERG channel and why does it matter for drug safety?
How can scorpion venom help with heart research?
Read the original research
Functional Impact of BeKm-1, a High-Affinity hERG Blocker, on Cardiomyocytes Derived from Human-Induced Pluripotent Stem Cells.
International journal of molecular sciences, 21(19)
Citation
De Waard, Stephan; Montnach, Jérôme; Ribeiro, Barbara; Nicolas, Sébastien; Forest, Virginie; Charpentier, Flavien; Mangoni, Matteo Elia; Gaborit, Nathalie; Ronjat, Michel; Loussouarn, Gildas; Lemarchand, Patricia; De Waard, Michel. (2020). Functional Impact of BeKm-1, a High-Affinity hERG Blocker, on Cardiomyocytes Derived from Human-Induced Pluripotent Stem Cells.. International journal of molecular sciences, 21(19). https://doi.org/10.3390/ijms21197167