Exosomes are a heterogeneous group of nano-sized natural membrane vesicles released from various cells and exist in body fluids. Different from the previous understanding of the function of exosomes as "garbage bins", exosomes act as carriers with many kinds of bioactive molecules (e.g., proteins, lipids, and nucleic acids) to play an important role in cell-cell communication. Growing evidence in recent years has suggested that exosomes also play some roles in the pathogenesis, diagnosis, and treatment modalities of some brain diseases, including ischemic stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, and brain cancers. Exosomes as therapeutic drug carriers for brain drug delivery have received extensive attention as well as exosomes can overcome the blood-brain barrier (BBB). However, the low targeting ability and size-dependent cellular uptake of native exosomes could profoundly affect the delivery performance of exosomes. Recent studies have indicated that engineered exosomes can increase the drug uptake efficiency and the subsequent drug efficacy. In the present paper, we will briefly introduce the engineering methods and applications of engineered exosomes in the treatment of brain diseases, and then focus on discussing the advantages and challenges of exosome- based drug delivery platforms to further enrich and boost the development of exosomes as a promising drug delivery strategy for brain diseases.

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工程外泌体：一种有前途的脑疾病药物输送策略。

外泌体是一组异质的纳米级天然膜囊泡，从各种细胞中释放出来，存在于体液中。与以往将外泌体功能理解为“垃圾箱”不同，外泌体作为携带多种生物活性分子（如蛋白质、脂质和核酸）的载体，在细胞间通讯中发挥重要作用。近年来越来越多的证据表明，外泌体在一些脑部疾病的发病机制、诊断和治疗方式中也发挥着一定的作用，包括缺血性中风、阿尔茨海默病、帕金森病、多发性硬化症和脑癌。外泌体作为脑药物递送的治疗药物载体受到广泛关注，外泌体可以克服血脑屏障（BBB）。然而，天然外泌体的低靶向能力和大小依赖性细胞摄取可能会深刻影响外泌体的递送性能。最近的研究表明，工程外泌体可以提高药物吸收效率和随后的药物功效。在本文中，我们将简要介绍工程化外泌体在治疗脑疾病中的工程方法和应用，然后重点讨论基于外泌体的药物递送平台的优势和挑战，以进一步丰富和促进外泌体作为外泌体的发展。一种有前途的脑部疾病药物输送策略。最近的研究表明，工程外泌体可以提高药物吸收效率和随后的药物功效。在本文中，我们将简要介绍工程化外泌体在治疗脑疾病中的工程方法和应用，然后重点讨论基于外泌体的药物递送平台的优势和挑战，以进一步丰富和促进外泌体作为外泌体的发展。一种有前途的脑部疾病药物输送策略。最近的研究表明，工程外泌体可以提高药物吸收效率和随后的药物功效。在本文中，我们将简要介绍工程化外泌体在治疗脑疾病中的工程方法和应用，然后重点讨论基于外泌体的药物递送平台的优势和挑战，以进一步丰富和促进外泌体作为外泌体的发展。一种有前途的脑部疾病药物输送策略。