Chen, C., Sun, M., Wang, J., Su, L., Lin, J., & Yan, X. (2021). Active cargo loading into extracellular vesicles: Highlights the heterogeneous encapsulation behaviour. Journal of Extracellular Vesicles, 10,e12163. https://doi.org/10.1002/jev2.12163

Active cargo loading into extracellular vesicles: Highlights the heterogeneous encapsulation behaviour

Chaoxiang Chen,Mengdi Sun,Jialin Wang,Liyun Su,Junjie Lin,Xiaomei Yan
First published: 31 October 2021 https://doi.org/10.1002/jev2.12163 

Abstract

Extracellular vesicles (EVs) have demonstrated unique advantages in serving as nanocarriers for drug delivery, yet the cargo encapsulation efficiency is far from expectation, especially for hydrophilic chemotherapeutic drugs. Besides, the intrinsic heterogeneity of EVs renders it difficult to evaluate drug encapsulation behaviour. Inspired by the active drug loading strategy of liposomal nanomedicines, here we report the development of a method, named “Sonication and Extrusion-assisted Active Loading” (SEAL), for effective and stable drug encapsulation of EVs. Using doxorubicin-loaded milk-derived EVs (Dox-mEVs) as the model system, sonication was applied to temporarily permeabilize the membrane, facilitating the influx of ammonium sulfate solution into the lumen to establish the transmembrane ion gradient essential for active loading. Along with extrusion to downsize large mEVs, homogenize particle size and reshape the nonspherical or multilamellar vesicles, SEAL showed around 10-fold enhancement of drug encapsulation efficiency compared with passive loading. Single-particle analysis by nano-flow cytometry was further employed to reveal the heterogeneous encapsulation behaviour of Dox-mEVs which would otherwise be overlooked by bulk-based approaches. Correlation analysis between doxorubicin auto-fluorescence and the fluorescence of a lipophilic dye DiD suggested that only the lipid-enclosed particles were actively loadable. Meanwhile, immunofluorescence analysis revealed that more than 85% of the casein positive particles was doxorubicin free. These findings further inspired the development of the lipid-probe- and immuno-mediated magnetic isolation techniques to selectively remove the contaminants of non-lipid enclosed particles and casein assemblies, respectively. Finally, the intracellular assessments confirmed the superior performance of SEAL-prepared mEV formulations, and demonstrated the impact of encapsulation heterogeneity on therapeutic outcome. The as-developed cargo-loading approach and nano-flow cytometry-based characterization method will provide an instructive insight in the development of EV-based delivery systems.

细胞外囊泡（EVs）在作为药物递送纳米载体方面表现出独特的优势，但货物包封效率远未达到预期，特别是对于亲水性化疗药物。此外，电动汽车的内在异质性使得评估药物封装行为变得困难。受脂质体纳米药物的主动载药策略的启发，我们在此报告了一种名为“超声和挤出辅助主动加载”(SEAL) 的方法的开发，该方法用于对 EV 进行有效和稳定的药物封装。使用载有阿霉素的牛奶衍生 EVs (Dox-mEVs) 作为模型系统，应用超声处理暂时透化膜，促进硫酸铵溶液流入管腔，从而建立主动加载所必需的跨膜离子梯度。除了通过挤压来缩小大型 mEV、使粒径均匀化和重塑非球形或多层囊泡外，与被动加载相比，SEAL 的药物封装效率提高了约 10 倍。通过纳米流式细胞术进行的单粒子分析被进一步用于揭示 Dox-mEV 的异质封装行为，否则这些行为会被基于体积的方法所忽视。多柔比星自发荧光与亲脂性染料 DiD 荧光之间的相关性分析表明，只有脂质包裹的颗粒是可主动加载的。同时，免疫荧光分析显示，85% 以上的酪蛋白阳性颗粒不含阿霉素。这些发现进一步激发了脂质探针和免疫介导的磁分离技术的发展，以分别选择性地去除非脂质封闭颗粒和酪蛋白组件的污染物。最后，细胞内评估证实了 SEAL 制备的 mEV 制剂的卓越性能，并证明了封装异质性对治疗结果的影响。所开发的货物装载方法和基于纳米流式细胞仪的表征方法将为基于 EV 的递送系统的开发提供有益的见解。

客户在该研究中使用我司生产的巯基磁珠偶联抗体。

巯基磁珠产品http://www.purimagbead.com/Product/2410795519.html