RX-021

Cytotoxicity assays are usually based on the assessment of cell membrane damage, which can also be indirectly detected by measuring cell viability. Detection methods include MTT assay, CKK-8 assay, LDH assay and ATP assay, etc.

Cardiovascular disease can be modeled as maladaptive cardiac remodeling, where ischemic injury or pressure overload activates inflammatory signaling, fibroblast activation, extracellular-matrix deposition, cardiomyocyte hypertrophy, vascular remodeling, and progressive ventricular dysfunction. The TGF-β/SMAD axis is a central profibrotic pathway after myocardial injury and pressure overload, while innate immune and cytokine pathways regulate leukocyte recruitment, scar formation, and adverse remodeling. Key unresolved questions include which inflammatory signals are reparative versus harmful, when fibrosis is protective versus maladaptive, and whether pathway inhibition improves function without weakening necessary infarct healing or compensatory remodeling.

Choosing the right model animal is a validity-driven decision in which the species, strain, sex, age, genetic background, disease-induction method, outcome measures, and welfare burden must match the scientific question rather than laboratory tradition or convenience. A model should be selected by judging face validity, construct validity, and predictive validity: whether it resembles the human phenotype, whether it reproduces relevant mechanisms, and whether results are likely to predict human biology or treatment response. Animal studies often fail to translate because of species differences, weak disease resemblance, poor experimental design, inadequate reporting, publication bias, and underuse of randomization, blinding, and sample-size justification. Unresolved questions include how to rank competing models objectively, how much human-disease complexity must be reproduced for a given objective, and when non-animal systems such as organoids, ex vivo tissue, or computational models