TTR and metabolic dysfunction-associated steatotic liver disease: Therapeutic extracellular vesicles (EVs) predominantly accumulate in the diabetic liver, delivering miR‐31‐5p to suppress macrophage platelet‐derived growth factor B (PDGFB), thereby impeding non‐alcoholic fatty liver disease (NAFLD) progression and enhancing neurovascular health by promoting pericyte recovery and transthyretin (TTR)‐mediated hippocampal homeostasis through cross‐organ (liver‐brain axis) repair.