Senescence and extracellular vesicles: novel partners in vascular amyloidosis

Abstract

Amyloidosis is a prevalent age-associated pathology caused by the accumulation of fibrous, insoluble protein fibrils in tissues. The most common human amyloid is aortic medial amyloid (AMA), caused by aggregation of a 50-amino acid peptide called medin, which is cleaved by an unknown mechanism from its parent protein, milk fat globulin EGF-factor 8 (MFGE8). Medin is present in the vessel wall of 97% of Caucasians aged over 50-years, yet despite its prevalence in the ageing population there is a very limited understanding of the mechanisms driving AMA. The novel data presented in the paper by Whitehead et al. provides evidence that vascular smooth muscle cell (VSMC)-derived small extracellular vesicles (sEVs) are key mediators of medin accumulation in the vessel wall [1]. In addition, the authors identify, for the first time, a role for cellular senescence in triggering amyloidosis via changes in sEVs and extracellular matrix (ECM) composition. Thus, this study not only advances our understanding of how AMA is formed but uncovers potential therapeutic targets for mitigating the detrimental effects of amyloidosis on tissue function