Endothelial extracellular vesicles in aging

Project Summary The aging population is rapidly growing. Aging is associated with impaired organ function and repair and increased susceptibility to various chronic diseases. Angiogenesis – the formation of new blood capillaries- plays a key role in organ development and regeneration. Angiogenesis is impaired in aging animals and

contributes to age-related pathologies. In order to develop more efficient therapies for aging-associated diseases, we need to understand the mechanisms by which aging impairs angiogenesis. Senescent cells promote aging and exacerbate age-related pathologies. The levels of endothelial cell (EC) senescence are

higher in aged ECs compared to young ECs, mediating age-dependent impairment of angiogenesis. Extracellular vesicles (EVs) serve as a messenger of signals, maintaining tissue homeostasis and function in physiology and contributing to age-related diseases. EVs collected from lung ECs under regeneration stimulate

angiogenesis, while senescence-associated secretory phenotype factors are enriched in EVs from senescent ECs, highlighting EC-derived EVs (EC-EVs) as a critical contributor to age-dependent decline in angiogenesis. EVs contain and transfer a diverse cargo of proteins, lipids, and various types of nucleic acid to target cells and

control cell-cell communications. Among EV-enclosed RNAs, Y-RNAs are one of the most abundant non- coding RNAs in EVs, and the levels of Y-RNAs correlate with age-related cardiovascular diseases, in which angiogenesis is deregulated. The role of EV-enclosed Y-RNAs in EC senescence and age-related decline in

angiogenesis remains unclear. The overall goal of this proposal is to determine whether EV-enclosed Y-RNAs mediate age-dependent impairment of angiogenesis. Among four human Y-RNAs (Y1, 3, 4, 5), Y5-RNA is the most abundant Y-RNAs in EC-EVs. Our preliminary data demonstrate that: (1) conditioned media (CM) that

contains EVs, from aged human ECs induces senescence in young ECs; (2) the levels of Y5-RNA are lower in EVs collected from CM of aged ECs; (3) overexpression of Y5-RNA 5’ fragment suppresses senescence and restores migration in aged ECs; (4) Y5-RNA knocked down EC-EVs inhibit DNA synthesis in young ECs; and

(5) young EC-EVs restore blood vessel formation of aged ECs in the subcutaneously implanted hydrogel, while Y5-RNA knocked down EC-EVs inhibit the effects. We hypothesize that age-dependent decreases in Y5-RNA in EC-EVs mediate EC senescence and impairment of angiogenesis in aged ECs. In Aim 1, we will examine

whether Y5-RNA in EC-EVs mediates age-dependent induction of EC senescence. In Aim 2, we will determine whether Y5-RNA in EC-EVs mediates age-dependent decline in angiogenesis in vitro and in the gel implanted on mice. Our focus to investigate the effects of Y5-RNA in EC-EVs on EC senescence and age-dependent

impairment of angiogenesis is unique and conceptually innovative. If this study proves that manipulation of Y5- RNA in aged EC-EVs reverses the age-related decline in angiogenesis, this work will lead to the development of new and efficient EV-based strategies for age-related diseases.