A Case Study on Resmetirom and Zebrafish Models in MASH Drug Discovery

Metabolic dysfunction–associated steatohepatitis (MASH) has a long history of therapeutic challenge due hepatic fat accumulation, inflammation and progressive fibrosis. Traditional drug candidates introduced many new problems such as hypoglycemia, LDL elevation and complex drug–drug interactions lead to limiting long term safety use. Resmetirom, a selective thyroid hormone receptor beta (THR-β) agonist has directly enhanced liver specific lipid metabolism without causing any thyroid hormone effects.

In preclinical and clinical trials, a set of assays demonstrated resmetirom’s mechanism and its safety profile. Oil Red O staining procedure quantified lipid reduction in hepatocytes while other biomarkers such as ALT, AST, TG, TC, LDL, and fibrosis markers showed metabolic and inflammatory improvements. ELISA assays in HepG2 and NCTC 1469 cells validated the pathway activation and MTT viability assay ensured reduction in cytotoxicity. Molecular profiling through qPCR and RNA sequencing validated downstream activation of THR-β involved in lipid oxidation and mitochondrial function. Therefore, FDA approval secured by significant MASH resolution, fibrosis improvement and safety profile in targeting liver selective receptor rather than systemic hormonal stimulation.

Graphs illustrating ALT and AST levels in Zebrafish MASH disease model across all experimental groups.

Zebrafish models ensure rapid evaluation of MASH pathology. High-fat diet and chemically induced steatosis models show hepatic lipid accumulation suitable for drug testing. Nile Red lipid staining visualizes live fat droplets while Oil Red O staining quantifies tissue steatosis. Imaging of hepatocyte morphology and oxidative stress assays measure ROS reduction. qPCR in zebrafish livers along with locomotor and metabolic assays further reveal how THR-β activation restores lipid homeostasis.