Experimental Models of Ischaemia-Reperfusion Injury: Animal Species, Organ-Specific Approaches, Molecular Biomarkers and Therapeutic Targets

Ischaemia and reperfusion (I/R) injury results from the combined effects of restricted tissue perfusion and potentially damaging consequences of blood flow restoration. Experimental animal models are essential for investigating the cellular and molecular events underlying I/R injury; however, their outcomes are strongly influenced by the species, target organ, method and duration of vascular occlusion/ligation/clamping, reperfusion interval, anaesthetic protocol, sampling time, and analytical approach. This narrative review examines commonly used cardiac, cerebral, hepatic, renal, intestinal, pulmonary, spinal cord, and skeletal-muscle I/R models, with emphasis on their methodological characteristics and translational limitations. It also critically evaluates biomarkers and mechanistic endpoints associated with oxidative and nitrosative stress, inflammation, mitochondrial dysfunction, ionic dysregulation, autophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis. Conventional measures—including malondialdehyde, antioxidant-enzyme activities, cytokines, caspases, and histopathological scores—remain widely used but often lack organ specificity and are highly dependent on sampling time and assay methodology. Emerging approaches based on microRNAs, metabolomics, proteomics, lipidomics, and mitochondrial functional measurements may improve mechanistic resolution, although most candidate markers require independent and cross-species validation. Reliable interpretation therefore requires the integration of molecular, biochemical, functional, and histological outcomes rather than reliance on a single marker. Greater standardisation of experimental design, transparent reporting, and incorporation of animal welfare and bias-reduction measures are necessary to improve reproducibility and clinical translation.