Electron Microscopy and Multi‐Omics Reveal Mitochondrial Dysfunction and Structural Remodeling in the Hearts of Elderly Mice

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Aging is a key driver of cardiac dysfunction, promoting structural remodeling, metabolic alterations, and loss of cellular resilience. In aged hearts, extracellular matrix remodeling and collagen accumulation reduce ventricular compliance, impairing both diastolic function and stress adaptability. Cardiomyocytes exhibit diminished regenerative capacity and dysregulated stress responses, with mitochondrial dysfunction emerging as a central contributor to energy imbalance, oxidative stress, and fibrosis. Traditional single-omics approaches are insufficient to capture the complexity of these interconnected changes. To address this, we employed an integrative multi-omics strategy-combining spatial transcriptomics, proteomics, and metabo-lipidomics with electron microscopy-to investigate cardiac aging in mice at three life stages: adult (12 months), middle-aged (24 months), and elderly (30 months). Electron microscopy revealed enlarged, structurally compromised mitochondria. Spatial transcriptomics showed reduced expression of cardioprotective genes (MANF, CISH, and BNP) and increased expression of profibrotic markers like CTGF. Proteomics revealed widespread mitochondrial dysregulation and impaired ATP production. Metabolic and lipidomic profiling identified reduced antioxidant metabolites and accumulation of lipotoxic species, such as ceramides and diacylglycerols. This multiscale analysis highlights key molecular and metabolic alterations driving cardiac aging, identifying potential therapeutic targets to mitigate age-related functional decline. Overall, our findings highlight the value of integrated, system-level approaches for uncovering the complex mechanisms that drive organ aging. Although our study was conducted in mice, validation in human models will be crucial to establish the translational relevance of these results and to guide future research with potential impact across diverse biomedical fields.

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