Thiazine Red + platelet inclusions in Cerebral Blood Vessels are first signs in an Alzheimer's Disease mouse model

Abstract

Strong evidence shows an association between cerebral vascular diseases and Alzheimeŕs disease (AD). In order to study the interaction of beta-Amyloid (Aβ) plaques with brain vessels, we crossbred an AD mouse model (overexpressing amyloid precursor protein with the Swedish-Dutch-Iowa mutations, APP-SweDI) with mice expressing green fluorescent protein (GFP) under the flt-1/VEGFR1 promoter in vessels (GFP-FLT1). Our data show, that only very few Aβ plaques were seen in 4-months old mice, focused in the mammillary body and in the lateral septal nucleus. The number of plaques markedly increased with age being most prominent in 12-months old mice. Thiazine Red was used to verify the plaques. Several Thiazine Red + inclusions were found in GFP + vessels, but only in non-perfused 4-months old mice. These inclusions were verified by Resorufin stainings possibly representing cerebral amyloid angiopathy. The inclusions were also seen in non-crossbred APP-SweDI but not in wildtype and GFP-FLT1 mice. In order to characterize these inclusions Flow Cytometry (FACS) analysis demonstrated that platelets were specifically stained by Thiazine Red +, more pronounced when aggregated. In conclusion, our data show that Thiazine Red + inclusions representing aggregated platelets are a first pathological sign in AD before plaque development and may become important therapeutic targets in early AD.