HUMAN HIPPOCAMPAL ORGANOID MODEL OF EARLY ALZHEIMER’S DISEASE REVEALS MITOCHONDRIAL HYPERMETABOLISM

Alzheimer’s disease (AD) is the leading cause of dementia worldwide, a pathological condition whose prevalence has increased 1.6 times in the last 30 years. Despite extensive efforts, the limited ability of current AD animal models to fully recapitulate key aspects of human disease and to resolve early cell-type–specific pathological mechanisms has hindered the development of efficient treatments. For this reason, it is indispensable to establish human AD models that enable the characterization of early disease stages and the elucidation of mitochondrial and cellular dysfunction. Here, we developed an early-stage AD human hippocampal organoid (hhO) model to investigate mitochondrial pathophysiology. AD hhOs were generated from iPSCs carrying two familial AD mutations in the APP and PSEN1 genes. A refined differentiation protocol integrating recently developed strategies and established brain organoid methods was used to generate mature hhOs at 120 days in vitro (DIV). At this stage, control hhOs show mature functional hippocampal neurons, astrocytes, and oligodendrocytes. Compared to controls, AD hhOs show significant differences in size and morphology, particularly during early development (0–30 DIV), and at 120 DIV show astrogliosis and altered firing properties. Mitochondrial analysis revealed increased mitochondrial mass and a hypermetabolic state in AD hhOs. To further characterize this phenotype, we also examined mitochondrial network organization and dynamic remodeling. In conclusion, our protocol generates mature functional hhOs and reveals a hypermetabolic mitochondrial signature in AD.