A novel robotic system capable of microinjecting individual heart cells between beats shows promise in identifying potential treatments for cardiac arrhythmias. Developed by researchers at the University of Toronto, the system assesses the function of gap junctions, which are critical channels that facilitate electrical communication between heart cells, enabling coordinated beating.
The robotic cell manipulator was utilized to screen for drugs that could treat arrhythmogenic cardiomyopathy (ACM), a leading cause of sudden cardiac death among young adults. ACM is often associated with gene mutations encoding proteins in desmosomes, intercellular junctions that help cells adhere to one another. Specifically, mutations in the desmosomal protein plakophilin-2 (PKP2) have been linked to faulty gap junctions.
High-Throughput Screening of Cardiomyocytes
Traditional methods for assessing gap junction activity have been laborious and manual. To address this, the researchers developed a robotic cell manipulation system incorporating visual feedback from digital holographic microscopy. This allowed for the creation of three-dimensional and label-free images of human induced pluripotent stem cell-derived cardiomyocytes.
The system can measure cell height and microinject dye at a consistent depth across cardiomyocytes in their resting phase. Microinjection in beating cardiomyocytes was achieved at a rate of approximately 20 cells per minute, with a dye deposition success rate of 95.2%, demonstrating high reproducibility and post-injection cell viability.
Identification of PCO 400 (Pinacidil) as a Potential Therapeutic
Using the robotic system, researchers studied the permeability of healthy and diseased cells and identified five compounds that could improve gap junction permeability in cardiomyocytes affected by PKP2 mutations. One of these compounds, PCO 400 (pinacidil), demonstrated the ability to reduce beating irregularities in a mouse model of ACM.
Wenkun Dou, PhD, from the University of Toronto, noted in the journal Science Robotics, "Although gap junction dysfunction has long been recognized as a contributing factor in many human diseases, the notion of modulating gap junction function is a relatively new and emerging treatment paradigm."
Implications for Gap Junction-Focused Therapies
The researchers emphasize that gap junctions play a pivotal role in mediating cell-to-cell communication and are implicated in a broad spectrum of human conditions, including skin and joint disorders, as well as inflammatory, neurodegenerative, and heart diseases. The robotic system offers a rapid and reliable method for assessing gap junction permeability in vitro, facilitating therapeutic development for diseases characterized by aberrant gap junction activity, such as ACM.
"Our robotic microinjection assay provides a suitable platform for future screening of drugs across different cardiomyocytes and disease models to identify innovative gap junction–focused therapies," Dou added.
