Stretched Exponential Modeling Reveals Drug-Specific Kinetics in Human Engineered Skeletal Muscle

Understanding muscle tissue is key not only for advancing our knowledge of human biophysical function, but also for describing pathological states, improving treatment and providing insights for drug development. While using excised tissue is an excellent way to study muscular function, human tissue donation remains severely restricted, forcing reliance on non-human models. The past decade has seen a rise in 3D in-vitro models of human skeletal muscle. However, many current experimental approaches struggle with the high variability of primary cells or the limited translational relevance of murine lines. Furthermore, state-of-the-art functional analysis typically focuses on peak force, which overlooks critical kinetic information. In this study, we present a systematic approach to generate functional engineered skeletal muscle tissues (ESMs), measure their contraction force dynamics, and model these dynamics to extract the effects of standard pharmacological modulators. Within 14 days, ESMs based on the human immortalized LHCN-M2 cell line mature into aligned, multinucleated myofibers expressing key sarcomeric markers and exhibiting robust excitation-contraction coupling. To decode these dynamics, we introduce a novel mathematical model based on stretched exponential functions. This framework accurately captures heterogeneous contraction and relaxation phases across diverse phenotypes using only six interpretable parameters. We validated the platform's sensitivity using a library of pharmacological modulators. Our kinetic modeling revealed distinct parameter fingerprints for different drug classes, highlighting specific changes in contraction kinetics that peak force alone could not detect. Additionally, proteomic profiling confirmed the presence of necessary drug targets and established the maturation state of the tissue. Together, this study provides a scalable, high-fidelity human platform for high-content screening of contractile kinetics and muscle biophysics.