Kooijmans S A A, Fliervoet L A L, van der Meel R, Fens M H A M, Heijnen H F G, van Bergen En Henegouwen P M P, Vader P, Schiffelers R M
Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands.
Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, The Netherlands.
J Control Release. 2016 Feb 28;224:77-85. doi: 10.1016/j.jconrel.2016.01.009. Epub 2016 Jan 7.
Extracellular vesicles (EVs) are increasingly being recognized as candidate drug delivery systems due to their ability to functionally transfer biological cargo between cells. However, the therapeutic applicability of EVs may be limited due to a lack of cell-targeting specificity and rapid clearance of exogenous EVs from the circulation. In order to improve EV characteristics for drug delivery to tumor cells, we have developed a novel method for decorating EVs with targeting ligands conjugated to polyethylene glycol (PEG). Nanobodies specific for the epidermal growth factor receptor (EGFR) were conjugated to phospholipid (DMPE)-PEG derivatives to prepare nanobody-PEG-micelles. When micelles were mixed with EVs derived from Neuro2A cells or platelets, a temperature-dependent transfer of nanobody-PEG-lipids to the EV membranes was observed, indicative of a 'post-insertion' mechanism. This process did not affect EV morphology, size distribution, or protein composition. After introduction of PEG-conjugated control nanobodies to EVs, cellular binding was compromised due to the shielding properties of PEG. However, specific binding to EGFR-overexpressing tumor cells was dramatically increased when EGFR-specific nanobodies were employed. Moreover, whereas unmodified EVs were rapidly cleared from the circulation within 10min after intravenous injection in mice, EVs modified with nanobody-PEG-lipids were still detectable in plasma for longer than 60min post-injection. In conclusion, we propose post-insertion as a novel technique to confer targeting capacity to isolated EVs, circumventing the requirement to modify EV-secreting cells. Importantly, insertion of ligand-conjugated PEG-derivatized phospholipids in EV membranes equips EVs with improved cell specificity and prolonged circulation times, potentially increasing EV accumulation in targeted tissues and improving cargo delivery.
细胞外囊泡(EVs)因其能够在细胞间功能性转移生物货物,越来越被视为候选药物递送系统。然而,由于缺乏细胞靶向特异性以及外源性EVs在循环中快速清除,EVs的治疗适用性可能受到限制。为了改善EVs向肿瘤细胞递送药物的特性,我们开发了一种用与聚乙二醇(PEG)偶联的靶向配体修饰EVs的新方法。将表皮生长因子受体(EGFR)特异性纳米抗体与磷脂(DMPE)-PEG衍生物偶联,制备纳米抗体-PEG-胶束。当胶束与源自Neuro2A细胞或血小板的EVs混合时,观察到纳米抗体-PEG-脂质向EV膜的温度依赖性转移,这表明存在一种“后插入”机制。该过程不影响EV的形态、大小分布或蛋白质组成。将PEG偶联的对照纳米抗体引入EVs后,由于PEG的屏蔽特性,细胞结合受到损害。然而,当使用EGFR特异性纳米抗体时,与EGFR过表达肿瘤细胞的特异性结合显著增加。此外,未修饰的EVs在小鼠静脉注射后10分钟内迅速从循环中清除,而用纳米抗体-PEG-脂质修饰的EVs在注射后60分钟以上仍可在血浆中检测到。总之,我们提出后插入是一种赋予分离的EVs靶向能力的新技术,无需修饰分泌EVs的细胞。重要的是,在EV膜中插入配体偶联的PEG衍生化磷脂可使EVs具有更好的细胞特异性和更长的循环时间,可能增加EVs在靶向组织中的积累并改善货物递送。