Assessing Contractility of 3D iPSC-derived Muscle Models for Safety and Discovery Using a Novel, High-throughput, and Label-free Instrumentation Platform.

Stem cell models hold great promise for improving the predictive power of preclinical in vitro assays for new therapies, drug discovery, basic scientific research, and disease modeling. Complex 3D platforms, such as Engineered Muscle Tissues (EMTs) fabricated from primary or iPSC-derived cells, can directly measure tissue contractility, which is challenging in conventional 2D platforms where cells are rigidly attached to a surface. However, traditional methods to fabricate EMTs demand extensive bioengineering expertise, and measuring contractility often involves laborious, serial, and low-throughput optical measurements. Here, we report on the design, fabrication, and validation of a novel 3D EMT platform that uses 1) facile and scalable bioengineering approaches to generate tissues from a variety of cell sources, and 2) a label-free parallel measurement technique. Our tissue casting approach has a success rate of >96% (n > 100) and produces consistently-sized constructs with a standard deviation of +/- 9% across 6 experiments. Tissue casting, media changes, and drug dosing are also highly amenable to automation. The substrate features an embedded magnet; as tissues contract, the magnet's displacement is quantitatively detected in a highly-parallel manner using specialized sensors. We detected 24 contractions simultaneously with a measurement rate of 100Hz, which is suitable for measuring various aspects of contractility such as upstroke velocity, decay time, and fatigability. We demonstrated that the signal voltage changes are linear with respect to EMT contraction. We will present data showing acute effects of drugs measured minutes after EMT dosing and chronic effects of structural cardiotoxicants like doxorubicin, sunitinib, and BMS-986094 on EMTs. All chronically-dosed tissues showed statistically significant dose-dependent reduction in twitch frequency over a multi-day time course (p <0.05). We will also show that our platform can be used to generate physiologically-relevant skeletal muscle constructs and achieve tetanic responses upon stimulation. In addition to modeling healthy tissues, our platform can also be used to study disease models. We are currently developing patient-specific Duchenne Muscular Dystrophy models for the development of personalized gene therapies. EMTs can be made from cells sourced from patients and used to test whether a new therapy will improve or recover functional contraction. We have designed a novel system that can leverage the complexity of 3D cellular models in a scalable format and can be tailored for specific applications, including personalized medicine or disease modeling. The Mantarray platform will provide a stand-alone tool capable of screening significant numbers of compounds for the rapid safety evaluation of drug candidates thereby accelerating drug discovery and development.