APP and Alzheimer disease: To investigate if angiogenesis is halted by a failure in differentiation between tip and stalk cells (NPA) in AD mouse models (Fig. 3a), we separated CD31+ (an endothelial/innate immune cell marker) and CD11b-negative (an innate immune marker) cells using fluorescence-activated cell sorting (Supplementary Fig. 2a–c) from aged (18-month-old) APP-PSEN1/+ and WT mice.