Single exosome study reveals subpopulations distributed among cell lines with variability related to membrane content.
Single exosome study reveals subpopulations distributed among cell lines with variability related to membrane content.
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DOI：
10.3402/jev.v4.28533
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发表时间：
2015
影响因子：
16
通讯作者：
Wachsmann-Hogiu S
中科院分区：
文献类型：
--
作者：
Smith ZJ;Lee C;Rojalin T;Carney RP;Hazari S;Knudson A;Lam K;Saari H;Ibañez EL;Viitala T;Laaksonen T;Yliperttula M;Wachsmann-Hogiu S
目前对外切体的分析主要集中在批量分析上，无法评估外切体到外切体的可变性。在本研究中，我们利用拉曼光谱研究了单个外切体的化学组成。我们测量了8个细胞系的单个外切体的光谱。细胞系平均光谱差异很大，反映了外体总蛋白、脂类、遗传和胞浆含量的变化。出乎意料的是，从同一细胞类型分离出来的单个外切体也表现出很高的光谱变异性。随后的光谱分析显示，单个外切体聚集成4个不同的组，这些组不是细胞系特有的。每组都含有来自多个细胞系的外切体，大多数细胞系都有多个组的外切体。这些组之间的差异与化学差异有关，主要是由于膜成分的不同。通过主成分分析，我们确定了外切体之间光谱差异的主要来源是胆固醇含量、磷脂对胆固醇的相对表达以及表面蛋白的表达。例如，来自癌症和非癌症细胞系的外切体可以根据它们对胆固醇和磷脂的相对表达而在很大程度上被分离。我们首次指出外体亚群在不同的细胞类型之间是共享的，这表明外体的功能是分布的。这些差异的起源可能与细胞外小泡亚群在正常细胞功能和癌变过程中的特殊作用有关，它们可能在单个外切体水平上提供诊断潜力。
Current analysis of exosomes focuses primarily on bulk analysis, where exosome-to-exosome variability cannot be assessed. In this study, we used Raman spectroscopy to study the chemical composition of single exosomes. We measured spectra of individual exosomes from 8 cell lines. Cell-line-averaged spectra varied considerably, reflecting the variation in total exosomal protein, lipid, genetic, and cytosolic content. Unexpectedly, single exosomes isolated from the same cell type also exhibited high spectral variability. Subsequent spectral analysis revealed clustering of single exosomes into 4 distinct groups that were not cell-line specific. Each group contained exosomes from multiple cell lines, and most cell lines had exosomes in multiple groups. The differences between these groups are related to chemical differences primarily due to differing membrane composition. Through a principal components analysis, we identified that the major sources of spectral variation among the exosomes were in cholesterol content, relative expression of phospholipids to cholesterol, and surface protein expression. For example, exosomes derived from cancerous versus non-cancerous cell lines can be largely separated based on their relative expression of cholesterol and phospholipids. We are the first to indicate that exosome subpopulations are shared among cell types, suggesting distributed exosome functionality. The origins of these differences are likely related to the specific role of extracellular vesicle subpopulations in both normal cell function and carcinogenesis, and they may provide diagnostic potential at the single exosome level.