Identification of extracellular vesicle (EV) subpopulations remains an open challenge. To date, the common strategy is based on searching and probing set of molecular components and physical properties intended to be univocally characteristics of the target subpopulation. Pitfalls include the risk to opt for an unsuitable marker set - which may either not represent the subpopulation or also cover other unintended subpopulations - and the need to use different characterization techniques and equipment. This approach focused on specific markers may result inadequate to routinely deal with EV subpopulations that have an intrinsic high level of heterogeneity. In this paper, we show that Fourier-transform Infrared (FT-IR) spectroscopy can provide a collective fingerprint of EV subpopulations in one single experiment. FT-IR measurements were performed on large (LEVs, ~600 nm), medium (MEVs, ~200 nm) and small (SEVs ~60 nm) EVs enriched from two different cell lines medium: murine prostate cancer (TRAMP-C2) and skin melanoma (B16). Spectral regions between 3100-2800 cm-1 and 1880-900 cm-1, corresponding to functional groups mainly ascribed to lipid and protein contributions, were acquired and processed by Principal Component Analysis (PCA). LEVs, MEVs and SEVs were separately grouped for both the considered cell lines. Moreover, subpopulations of the same size but from different sources were assigned (with different degrees of accuracy) to two different groups. These findings demonstrate that FT-IR has the potential to quickly fingerprint EV subpopulations as a whole, suggesting an appealing complement/alternative for their characterization and grading, extendable to healthy and pathological EVs and fully artificial nanovesicles.

中文翻译：

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傅立叶变换红外（FT-IR）光谱技术可识别不同大小和细胞来源的细胞外囊泡的亚群。

胞外囊泡（EV）亚群的鉴定仍然是一个开放的挑战。迄今为止，通用策略是基于搜索和探测分子组成和物理特性的集合，这些分子组成和物理特性旨在成为目标亚群的唯一特征。陷阱包括选择不合适的标记集的风险-可能不代表亚群，也可能涵盖其他意外亚群-以及需要使用不同的表征技术和设备。这种针对特定标记物的方法可能导致常规内含物高度异质性的电动车亚群无法正常处理。在本文中，我们表明傅立叶变换红外（FT-IR）光谱可以在一个实验中提供EV亚群的集体指纹。FT-IR测量是在富含两种不同细胞系培养基的大型（LEVs，〜600 nm），中等（MEVs，〜200 nm）和小型（SEVs〜60 nm）EV上进行的：鼠前列腺癌（TRAMP-C2）和皮肤黑色素瘤（B16）。通过主成分分析（PCA）获得并处理了3100-2800 cm-1和1880-900 cm-1之间的光谱区域，这些区域对应于主要归因于脂质和蛋白质作用的官能团。对于两种考虑的细胞系，将LEV，MEV和SEV分别分组。此外，将大小相同但来自不同来源的亚种群（具有不同的准确度）分配给两个不同的组。这些发现表明，傅立叶变换红外（FT-IR）可以快速对整个EV亚种群进行指纹识别，这表明它们的特征和等级具有吸引力，可以作为替代品/替代品，