Wang Jie, Ma Peng, Kim Daniel H, Liu Bi-Feng, Demirci Utkan
Canary Center at Stanford for Cancer Early Detection, Bio-Acoustic MEMS in Medicine (BAMM) Laboratory, Department of Radiology, School of Medicine Stanford University, Palo Alto, California 94304-5427, USA.
Canary Center at Stanford for Cancer Early Detection, Department of Radiology, Stanford University School of Medicine, Palo Alto, California 94305, USA.
Nano Today. 2021 Apr;37. doi: 10.1016/j.nantod.2020.101066. Epub 2021 Jan 13.
Exosomes are a class of cell-secreted, nano-sized extracellular vesicles with a bilayer membrane structure of 30-150 nm in diameter. Their discovery and application have brought breakthroughs in numerous areas, such as liquid biopsies, cancer biology, drug delivery, immunotherapy, tissue repair, and cardiovascular diseases. Isolation of exosomes is the first step in exosome-related research and its applications. Standard benchtop exosome separation and sensing techniques are tedious and challenging, as they require large sample volumes, multi-step operations that are complex and time-consuming, requiring cumbersome and expensive instruments. In contrast, microfluidic platforms have the potential to overcome some of these limitations, owing to their high-precision processing, ability to handle liquids at a microscale, and integrability with various functional units, such as mixers, actuators, reactors, separators, and sensors. These platforms can optimize the detection process on a single device, representing a robust and versatile technique for exosome separation and sensing to attain high purity and high recovery rates with a short processing time. Herein, we overview microfluidic strategies for exosome isolation based on their hydrodynamic properties, size filtration, acoustic fields, immunoaffinity, and dielectrophoretic properties. We focus especially on advances in label-free isolation of exosomes with active biological properties and intact morphological structures. Further, we introduce microfluidic techniques for the detection of exosomal proteins and RNAs with high sensitivity, high specificity, and low detection limits. We summarize the biomedical applications of exosome-mediated therapeutic delivery targeting cancer cells. To highlight the advantages of microfluidic platforms, conventional techniques are included for comparison. Future challenges and prospects of microfluidics towards exosome isolation applications are also discussed. Although the use of exosomes in clinical applications still faces biological, technical, regulatory, and market challenges, in the foreseeable future, recent developments in microfluidic technologies are expected to pave the way for tailoring exosome-related applications in precision medicine.
外泌体是一类细胞分泌的纳米级细胞外囊泡，具有直径为30 - 150 nm的双层膜结构。它们的发现和应用在众多领域带来了突破，如液体活检、癌症生物学、药物递送、免疫治疗、组织修复和心血管疾病等。外泌体的分离是外泌体相关研究及其应用的第一步。标准的台式外泌体分离和传感技术既繁琐又具有挑战性，因为它们需要大量样本体积、多步骤操作，这些操作复杂且耗时，还需要笨重且昂贵的仪器。相比之下，微流控平台有潜力克服其中一些限制，这得益于其高精度处理能力、在微尺度上处理液体的能力以及与各种功能单元（如混合器、致动器、反应器、分离器和传感器）的可集成性。这些平台可以在单个设备上优化检测过程，代表了一种强大且通用的外泌体分离和传感技术，能够在短处理时间内实现高纯度和高回收率。在此，我们概述基于外泌体流体动力学特性、尺寸过滤、声场、免疫亲和性和介电泳特性的外泌体分离微流控策略。我们特别关注具有活性生物学特性和完整形态结构的外泌体无标记分离方面的进展。此外，我们介绍用于高灵敏度、高特异性和低检测限检测外泌体蛋白质和RNA的微流控技术。我们总结了外泌体介导的靶向癌细胞治疗递送的生物医学应用。为突出微流控平台的优势，还纳入了传统技术进行比较。还讨论了微流控技术在外泌体分离应用方面未来面临的挑战和前景。尽管外泌体在临床应用中的使用仍面临生物学、技术、监管和市场方面的挑战，但在可预见的未来，微流控技术的最新进展有望为在精准医学中定制外泌体相关应用铺平道路。
