*Review* **An Update on Isolation Methods for Proteomic Studies of Extracellular Vesicles in Biofluids**

#### **Jing Li 1, Xianqing He 1, Yuanyuan Deng 2 and Chenxi Yang 2,\***


Academic Editors: Marcello Locatelli, Angela Tartaglia, Dora Melucci, Abuzar Kabir, Halil Ibrahim Ulusoy and Victoria Samanidou

Received: 10 September 2019; Accepted: 26 September 2019; Published: 27 September 2019

**Abstract:** Extracellular vesicles (EVs) are lipid bilayer enclosed particles which present in almost all types of biofluids and contain specific proteins, lipids, and RNA. Increasing evidence has demonstrated the tremendous clinical potential of EVs as diagnostic and therapeutic tools, especially in biofluids, since they can be detected without invasive surgery. With the advanced mass spectrometry (MS), it is possible to decipher the protein content of EVs under di fferent physiological and pathological conditions. Therefore, MS-based EV proteomic studies have grown rapidly in the past decade for biomarker discovery. This review focuses on the studies that isolate EVs from di fferent biofluids and contain MS-based proteomic analysis. Literature published in the past decade (2009.1–2019.7) were selected and summarized with emphasis on isolation methods of EVs and MS analysis strategies, with the aim to give an overview of MS-based EV proteomic studies and provide a reference for future research.

**Keywords:** extracellular vesicles; isolation methods; biofluid; proteomics; mass spectrometry
