(W1098) AUTOMATING HIGH-THROUGHPUT SCREENING OF CARDIAC CONTRACTILITY BY ROBOTICALLY CONTROLLED FUNCTIONAL TESTING OF STEM CELL-DERIVED MICRO-TISSUES IN A 96-WELL PLATE FORMAT

Abstract: Human engineered cardiac tissues, which typically comprise a thin strip of cells and supporting matrix suspended between polymeric force sensors, offer a stem cell-based alternative to experimental animals for compound testing and disease modeling, aligned with FDA Modernization Act 2.0. However, a large cell count and time-consuming data acquisition protocols often limit the throughput and efficiency of cardiac contractility screening. To overcome these challenges, our team developed a miniaturized version of our human ventricular Cardiac Tissue Strip (hvCTS), configured in a standard 96-well plate format. Cells suspended in a liquid hydrogel are constrained by surface tension to a hydrophobic channel in each well, allowing tissue self-assembly onto two flexible end-posts with curved anchor points optimized by finite element analysis. The resulting micro Cardiac Tissue Strips (µCTS) are 3-mm long and require only 150,000 cells per tissue, an 85% reduction of cell number from its predecessor. Optical tracking and twitch force measurement is achieved by a custom lid featuring intensity-regulated lighting and carbon electrode pairs to stimulate the tissues for controlling beat rate and promoting cardiomyocyte maturation. The µCTS exhibit > 90% viability, a coefficient of variation < 20%, and a strong signal-to-noise ratio. Validation using six different drug classes (adrenergic agonist, cardiac glycoside, cardiac myosin activator, Ca2+ sensitizer, Ca2+ channel blocker, hERG K+ channel blocker) demonstrated dose-dependent functional responses as expected for human heart muscle. Our robotic cardiac tissue screening system localizes the electrical stimulation and captures data from 16 tissues simultaneously, automatically translating the plate through up to 6 regions and conducting user-defined experimental protocols, thus reducing the screening time to less than 10% of that required for single-tissue readouts. Our next-generation 96-well µCTS system offers increased sample number, fewer cells per tissue, low variability across tissues, decreased overall measurement time, and compatibility with automated liquid handling systems, enabling efficient high-throughput human stem cell-based preclinical screening of cardiac contractility, satisfying the latest regulatory guidelines.

Funding Source: Hong Kong Innovation and Technology Commission (Enterprise Support Scheme #B/E008/22)

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