With Exceptional Performance, Outstanding Skills, and Meticulous Attention, Mediford Provides Patch-clamp Assay Tailored to Meet Our Clients’ needs.
The patch-clamp method, a technique for measuring cellular electrical activity, has been widely used in a variety of fields such as basic research and drug discovery. Mediford mainly provides study services for evaluating the effects of drugs on cardiac ion channels using cardiac ion channel-expressing cells and the accurately measurable manual patch-clamp platform. We offer evaluations from a wide range of implementation standards, from screening to GLP. Furthermore, we can also conduct studies under customized conditions and develop assay systems according to our clients’ needs.
Mediford always strives to improve the quality of our patch-clamp assay services and to ensure our services are tailored to meet our clients’ needs. Please feel free to contact us.
Exceptional performance
To date, mediford has consistently demonstrated exceptional performance in both quality and quantity of GLP hERG assays, earning high ratings from our valued clients. The hERG study, which is particularly important among in vitro cardiovascular studies, is a safety pharmacology core battery study conducted prior to the first-in-human dosing. In Jan. 2024, mediford launched a new study service, Best Practice hERG assay (GLP-compliant). From the perspective of proarrhythmic risk assessment based on the CiPA paradigm, there is a global trend towards integrating multiple ion channels assay—including Na channels (Nav1.5) and Ca channels (Cav1.2)—with in silico proarrhythmic models, moving beyond sole reliance on hERG channel. Thus, ion channel evaluation using the patch-clamp method in safety pharmacology studies is becoming increasingly diverse. Mediford is currently striving to establish Best Practice patch-clamp assays for Nav1.5 and Cav1.2.
Outstanding skills
Our highly-skilled staff performs measurements efficiently and submits flash reports expeditiously, eliminating concerns about the low throughput of the manual patch-clamp method. Taking into account the properties of drugs and target ion channels, we offer optimal study designs based on our accumulated expertise of more than 20 years of services in patch-clamp and cell culture methods.
Meticulous attention
Our greatest strength is the ability to provide the highest level of attention to detail. Our experienced study directors well-versed in the patch-clamp method and knowledgeable about relevant regulatory guidelines are adept at accommodating requests, swiftly addressing unforeseen situations, and ensuring the study meets our clients’ expectations. We specialize in assay development for pharmacological efficacy studies and/or novel studies on target molecules (ion channels) from the ground up, based on the properties of the drugs and ion channels. Please do not hesitate to contact us if you have any questions about patch-clamp assays.
Delivery and study schedule (hERG assay)
hERG screening assay (non-GLP, room temperature)
Standard study volume
3 compounds
Cumulative application of 2 concentrations (5 min/concentration)
N=2/compound (6 cell data in total)
Workflow
| Solubility test | 1 to 2 days (as necessary) | |
|---|---|---|
| Preparation of study protocol | ||
| Study implementation | Measurement | 1 day |
| Flash report | Approximately 1 week from study initiation | |
| Draft report | Approximately 1 month from study initiation (limited to summary and Table) |
|
GLP hERG assay (room temperature)
Standard study volume
Vehicle control, test substance (3 concentrations), positive control
N=5/group (25 cell data in total)
Workflow
| Solubility test | 0.5 days (conducted within analytical validation study) |
|
|---|---|---|
| Preparation of study protocol | ||
| Study implementation | Measurement | 1 to 2 weeks |
| Flash report | Approximately 1 month from study initiation (approximately 2 weeks after completion of measurement) |
|
| Draft report | 2 to 2.5 months from study initiation (1 to 1.5 months after completion of measurement) |
|
| Final report | 3 to 3.5 months from study initiation (2 to 2.5 months after completion of measurement) |
|
GLP hERG assay (Best Practice, near physiological temperature)
Standard study volum
Vehicle control, test substance (3 concentrations), positive control (4 concentrations, cumulative application of 2 concentrations)
N=4/group (24 cell data in total)
Workflow
| Solubility test | 0.5 days (conducted within analytical validation study) |
|
|---|---|---|
| Preparation of study protocol | ||
| Study implementation | Measurement | 3 to 4 weeks |
| Flash report | Approximately 1.5 months from study initiation (approximately 2 weeks after completion of measurement) |
|
| Draft report | 2.5 to 3 months from study initiation (1.5 to 2 months after completion of measurement) |
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| Final report | 3.5 to 4 months from study initiation (2.5 to 3 months after completion of measurement) |
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Glossary
Safety pharmacology core battery studies
Safety pharmacology studies are designed to investigate the potential undesirable pharmacodynamic effects of drugs on physiological functions. The studies to examine cardiovascular, central nervous, and respiratory systems, which are critical to supporting life, are designated as core battery studies and must be conducted under GLP-compliance prior to clinical trials.
Patch-clamp method
Patch-clamp, a laboratory technique in electrophysiology, was developed by Erwin Neher and Bert Sakmann (Nobel laureates in Physiology or Medicine, 1991). This method allows for precise measurement of electrical activity across biological membranes by achieving an extremely high seal resistance of >1 GΩ between a glass pipette electrode filled with buffer solution and the cell membrane to minimize leakage current. The cell can be clamped, keeping the cell membrane potential constant while recording ionic currents (voltage clamp). Alternatively, the cell membrane potential can be recorded while a constant current is being injected into the cell (current clamp). This technique is widely used to investigate the electrical properties of cells in detail.
hERG (human ether-a-go-go-related gene)
hERG channels are selectively permeable to potassium ions and play an important role in repolarizing the action potential of cardiomyocytes (Figure 1). It is known that QT prolongation due to delayed repolarization of cardiac action potentials can increase the risk of drug-induced lethal polymorphic ventricular tachycardia (TdP) (Figure 2). Therefore, the drug candidates with hERG inhibition often are rejected from further development due to safety concerns, which are regarded as missed opportunities for new drug discovery.
Figure 1：Cardiac action potential and ionic currents
| Ionic current | Ion channels | Physiology |
|---|---|---|
| INa | Nav1.5 | Phase 0 (overshoot) |
| Ito | Kv4.2/4.3 | Phase 1 |
| ICa | Cav1.2 | Phase 2 (plateau), contraction |
| IKr | hERG | Phase 3 (repolarization) |
| IKs | KvLQT1/minK | Phase 3 (repolarization) |
| IK1 | Kir2.1 | Phase 4 (resting potential), relaxation |
- Overshoot: For membrane potential to depolarize beyond 0 mV.
- Inward current: Ionic currents that flow into the cell and depolarize membrane potential.
- Outward current: Ionic currents that flow out of the cell and repolarize/hyperpolarize membrane potential.
Figure 2：QT interval prolongation associated with hERG block
- QT interval: Time from the start of the Q wave to the end of the T wave. QT interval prolongation is attributed to delayed repolarization (Phase 3) and prolonged plateau (Phase 2).
- Polymorphic ventricular tachycardia：Arrhythmia induced by consecutive ectopic impulses within the ventricles. Torsades de Pointes (TdP) is a form of polymorphic ventricular tachycardia in the setting manifested by QT interval prolongation.
GLP
A set of rules and criteria for a quality system to ensure the reliability when conducting non-clinical safety studies.
ICH S7B Guideline
Describes a non-clinical testing strategy for assessing the potential of a test substance to delay ventricular repolarization. In 2022, the associated Q&As and Training Materials were adopted.
Best Practice
The ICH S7B Guideline Q&As 2.1 provides Best Practice recommendations for patch-clamp assays including those involving hERG channel. To date, each facility has conducted hERG assays using its own methods. However, the adoption of Best Practice is expected to harmonize procedures and reduce data variability across facilities. Non-clinical data recorded under Best Practice will be used for integrated risk assessment alongside clinical findings.
CiPA（Comprehensive in vitro Proarrythmia Assay）
An innovative paradigm for better predicting proarrhythmic risk of drugs in combination with assays of multiple cardiac ion channels assay including hERG channel, simulation of in silico proarrhythmic models using the patch-clamp assay results, and human iPS cell-derived cardiomyocytes. This is based on proarrhythmogenicity and expected to serve as a new paradigm to replace the original guideline strategy (S7B) that focuses on delayed ventricular repolarization, or QT prolongation.
