APP and Alzheimer disease: More recently, early plaque formation in the cortex and hippocampus in a APP/PS1 mouse model was related to elevated iron content [29] and was associated with hemoglobin (Hb) binding to Aβ localized within the plaque and vascular amyloid deposits in post-mortem AD brains [30]; namely, the formation of an envelope-like structure composed of Aβ surrounding the Hb droplets was observed in APP/PS1 transgenic mice [30].