Extracellular vesicles (EVs) are membrane-bilayered nanoparticles released by most cell types. Recently, an enormous number of studies have been published on the potential of EVs as carriers of therapeutic agents. In contrast to systems such as liposomes, EVs exhibit less immunogenicity and higher engineering potential. Here, we review the most relevant publications addressing the potential and use of EVs as a drug delivery system (DDS). The information is divided based on the key steps for designing an EV-mediated delivery strategy. We discuss possible sources and isolation methods of EVs. We address the administration routes that have been tested in vivo and the tissue distribution observed. We describe the current knowledge on EV clearance, a significant challenge towards enhancing bioavailability. Also, EV-engineering approaches are described as alternatives to improve tissue and cell-specificity. Finally, a summary of the ongoing clinical trials is performed. Although the application of EVs in the clinical practice is still at an early stage, a high number of studies in animals support their potential as DDS. Thus, better treatment options could be designed to precisely increase target specificity and therapeutic efficacy while reducing off-target effects and toxicity according to the individual requirements of each patient.

中文翻译：

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细胞外囊泡作为药物输送系统的最新进展及其在精密医学中的潜力

细胞外囊泡（EVs）是大多数细胞类型释放的膜双层纳米颗粒。最近，关于电动汽车作为治疗剂载体的潜力的大量研究已经发表。与诸如脂质体的系统相反，电动汽车显示出较低的免疫原性和较高的工程潜力。在这里，我们回顾了有关电动汽车作为药物输送系统（DDS）的潜力和用途的最相关出版物。该信息基于设计EV介导的交付策略的关键步骤进行划分。我们讨论了电动汽车的可能来源和隔离方法。我们介绍了已经在体内进行测试并观察到的组织分布的给药途径。我们描述了有关电动车清除的当前知识，这是提高生物利用度的重大挑战。也，EV工程方法被描述为改善组织和细胞特异性的替代方法。最后，对正在进行的临床试验进行了总结。尽管电动汽车在临床实践中的应用仍处于早期阶段，但大量的动物研究支持其作为DDS的潜力。因此，可以根据每个患者的具体需求设计更好的治疗方案，以精确地提高靶标特异性和治疗功效，同时降低脱靶效应和毒性。