Background Although the mechanisms of action are not fully understood, extracellular vesicles (EVs) have emerged as key indicators and effectors of immune function. Characterizing circulating EVs associated with stem and immune cells across the lifespan of healthy individuals could aid an understanding of immunosenescence, a process of age-related decline of cells in both adaptive and innate immune systems. Results Using high resolution multicolor flow cytometry, we identified three major subsets of EVs of varying sizes in healthy control (HC) plasma. Multiple plasma EVs associated with immune cells declined with ageing in HCs. In addition, we observed age-associated declines of respiring mitochondria cargo in EVs of several types of immune cells, suggesting that these parent cells may experience a decline in mitophagy or a mitochondrial dysfunction-induced immunosenescence. By contrast, the number of CD34+ hematopoietic stem cell-associated EVs were high and carried respiring mitochondria, which did not decline with age. Conclusion As demonstrated here, multicolor flow cytometry simultaneously measures plasma EV size, surface markers and cargo that reflect biological processes of specific cell types. The distinct surface markers and cytokine cargo of plasma EVs suggest that they may carry different bio-messages and originate by different biogenesis pathways.

中文翻译：

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免疫细胞胞外囊泡及其线粒体含量随年龄增长而下降。

背景尽管作用机制尚不完全清楚，但细胞外囊泡 (EV) 已成为免疫功能的关键指标和效应物。在健康个体的整个生命周期中表征与干细胞和免疫细胞相关的循环 EV 有助于理解免疫衰老，这是适应性和先天免疫系统中与年龄相关的细胞衰退过程。结果 使用高分辨率多色流式细胞仪，我们确定了健康对照 (HC) 血浆中不同大小的 EV 的三个主要子集。与免疫细胞相关的多个血浆 EV 随着 HC 的老化而下降。此外，我们观察到几种免疫细胞的电动汽车中呼吸线粒体货物与年龄相关的下降，表明这些亲代细胞可能经历线粒体自噬下降或线粒体功能障碍诱导的免疫衰老。相比之下，与 CD34+ 造血干细胞相关的 EV 的数量很高，并且携带有呼吸功能的线粒体，并且不会随着年龄的增长而下降。结论 如本文所示，多色流式细胞仪同时测量血浆 EV 大小、表面标志物和反映特定细胞类型生物过程的货物。血浆 EV 的不同表面标志物和细胞因子货物表明它们可能携带不同的生物信息并起源于不同的生物发生途径。多色流式细胞仪同时测量血浆 EV 大小、表面标志物和反映特定细胞类型生物过程的货物。血浆 EV 的不同表面标志物和细胞因子货物表明它们可能携带不同的生物信息并起源于不同的生物发生途径。多色流式细胞仪同时测量血浆 EV 大小、表面标志物和反映特定细胞类型生物过程的货物。血浆 EV 的不同表面标志物和细胞因子货物表明它们可能携带不同的生物信息并起源于不同的生物发生途径。