Department of Molecular and Translational Medicine, Università degli Studi di Brescia, Viale Europa 11, 25123 Brescia, Italy; Center for Colloid and Surface Science (CSGI), Viale della Lastruccia 3, 50019 Sesto Fiorentino, Italy.
Department of Surgery, Division of Cancer Biology and Therapeutics, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
Colloids Surf B Biointerfaces. 2022 Oct;218:112728. doi: 10.1016/j.colsurfb.2022.112728. Epub 2022 Jul 25.
Nanomaterials are characterized by an extremely large surface-to-volume ratio. Extracellular Vesicles (EVs) - which have been recently recognized as the universal agent of intercellular communication, being involved in many physiological and pathological processes and interkingdom biochemical communication - are nanoparticles, but this key aspect has never been rationally addressed. Here we report the first attempt to quantify the membrane-to-lumen partition of proteins in EVs. A semi-quantitative model based on available well-established compositional and microstructural data is formulated. The model allows for the estimation of the overall protein content of an EV as well as of the partition between membrane (surface) associated and lumen (bulk) contained proteins as a function of the EV size and shape. It further identifies 180 nm as a switch diameter, below which EVs result composed of more membrane than luminal proteins. At larger diameters the partition is reversed, reaching predominance of luminal proteins (> 80 %) in large EVs (diameter > 800 nm). The model is successfully tested to analyze and describe a real preparation composed of subpopulations of small EVs (diameter < 200 nm), including exosomes and ectosomes, and large EVs including large oncosomes (diameter > 1000 nm) from human prostate cancer cells. These findings provide the basis for a better colloidal description of EV samples, might help to understand the stoichiometry of proteins in distinct EV sub-populations, and will improve the design and interpretation of experiments, including EV engineering and dosing in-vitro and in-vivo.
纳米材料的特点是具有极大的表面积与体积比。细胞外囊泡（EVs）——最近被认为是细胞间通讯的通用介质，参与许多生理和病理过程以及生物化学的种间通讯——是纳米颗粒，但这一关键方面从未得到合理的解决。在这里，我们首次尝试定量 EVs 中蛋白质的膜-腔分配。基于现有的成熟的组成和微观结构数据，建立了一个半定量模型。该模型可以估计 EV 的总蛋白含量以及膜（表面）相关蛋白和腔（体）内蛋白的分配，作为 EV 大小和形状的函数。它进一步确定 180nm 为一个开关直径，小于该直径的 EV 由比腔蛋白更多的膜组成。在更大的直径下，分配发生逆转，大 EV（直径 > 800nm）中腔蛋白占主导地位（>80%）。该模型成功地用于分析和描述由人类前列腺癌细胞的小 EV（直径<200nm），包括外泌体和ectosomes，和大 EV（直径>1000nm）组成的真实制剂。这些发现为更好地胶体描述 EV 样本提供了基础，可能有助于理解不同 EV 亚群中蛋白质的化学计量，并且将改进实验的设计和解释，包括 EV 的工程和体外和体内给药。
