1608-P: MyoScreen—A High-Content–Based Discovery Platform to Model Key Metabolic Processes in Human Skeletal Muscle

Introduction & Objective: Loss of muscle mass and function are now recognized as early and common abnormalities in a wide range of chronic diseases especially obesity, diabetes and cardiomyopathies. However, relevant in-vitro screening models mimicking human physiological processes in muscles are still lacking.

Method: Using MyoScreen, a high-throughput and robust skeletal muscle drug discovery platform derived from human primary myoblasts, we have developed a panel of predictive in-vitro image-based functional assays combined with newly developed image analysis scripts, that recapitulate key metabolic disease hallmarks such as autophagy, lipid accumulation, muscle atrophy and mitochondrial health. 

Results: Dose dependent accumulation of LC3b spots (puncta) (EC₅₀= 20.77 μM for CQ, Chloroquine, EC₅₀= 3.9 nM for BafA1, Bafilomycin) and area of vesicles positive for LC3b (EC₅₀= 25.97 μM for CQ, EC₅₀= 6.1 nM for BafA1) can be monitored in fixed starved (8h) cells following inhibition of autophagy flux. Co-labeling of LAMP1-LC3b (EC₅₀= 23.17 μM for CQ, EC₅₀= 2.7 nM for BafA1) follows the autophagic flux and autophagolysosome formation. Oversupply of FAs (fatty acids) increases mitochondrial fragmentation and the relative area of LDs (lipid droplets) in myotubes by 13-23%: this accumulation can be modulated by siRNAs treatment. MyoScreen demonstrated the ability to distinguish phenotypic properties related to stimulatory or inhibitory effects of hypertrophic (IGF-1 EC₅₀=95.5 pM for fusion index) or atrophic (TNF-α IC₅₀=15.9 pM for fusion index) signaling compounds. 

Conclusion: The MyoScreen platform brings new prospects for drug discovery in metabolic disorders facilitating a predictive research strategy for identifying and validating novel targets, understanding mechanism of action, and supporting preclinical development to select innovative drug candidates targeting key aspects of muscle metabolic function.