外泌体被各种细胞分泌，其主要功能包括细胞间通讯、免疫反应、人体生殖和突触可塑性。它们分子集装箱反映了其细胞来源正在经历的生理过程。因此，许多研究表明，外泌体可能是许多疾病的有前途的生物标志物工具，主要是由于它们的生物相关性和易于接近的广泛的体液。此外，由于它们的生物组成使它们可以双向穿过血脑屏障，越来越多的证据指出外泌体作为大脑疾病过程的新兴镜像。在这方面，本综述探讨了外泌体的生物发生和生物功能，它们在不同生理和病理过程中的作用，它们在临床实践中的潜力，以及关于外泌体在主要人类脑疾病（如阿尔茨海默氏病（AD）、帕金森病（PD）、多发性硬化（MS）、肌萎缩侧索硬化（ALS）或脑肿瘤等）中作用的最新研究。©作者。

Extracellular vesicles are secreted by a wide variety of cells, and their primary functions include intercellular communication, immune responses, human reproduction, and synaptic plasticity. Their molecular cargo reflects the physiological processes that their cells of origin are undergoing. Thus, many studies have suggested that extracellular vesicles could be a promising biomarker tool for many diseases, mainly due to their biological relevance and easy accessibility to a broad range of body fluids. Moreover, since their biological composition leads them to cross the blood-brain barrier bidirectionally, growing evidence points to extracellular vesicles as emerging mirrors of brain diseases processes. In this regard, this review explores the biogenesis and biological functions of extracellular vesicles, their role in different physiological and pathological processes, their potential in clinical practice, and the recent outstanding studies about the role of exosomes in major human brain diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), or brain tumors.© The author(s).