Department of Physical Pharmaceutics, School of Pharmaceutical Sciences, Wakayama Medical University.
Faculty of Pharmaceutical Sciences, Tokushima University.
Biol Pharm Bull. 2023;46(8):1098-1104. doi: 10.1248/bpb.b23-00135.
Since small extracellular vesicle (sEVs) are involved in cell-to-cell communication via transfer of certain bioactive molecules and have the capability to overcome biological barriers against drug transport, their use as a drug delivery system (DDS) has been demonstrated in treatment of a diverse range of diseases. However, some issues in drug encapsulation have been pointed out, including low encapsulation efficiency and poor reproducibility. It was previously reported that liposomes containing phosphatidylserine (PS) can fuse together in the presence of calcium ion, which allows for drug encapsulation into the resultant liposomes (i.e., calcium fusion method). On the other hand, PS is reportedly present in lipid membrane of sEVs as a distinct lipid composition. We therefore hypothesized that PS-mediated membrane fusion of sEVs with PS-liposomes encapsulating therapeutic agents via the calcium fusion method can be applied to convenient drug encapsulation into sEVs. Membrane fusion of PS-liposomes and sEVs derived from murine melanoma B16F1 cells (B16-sEVs) was firstly confirmed. The obtained nanoparticles, termed chimeric nanoparticles (CM-NP), showed comparable cellular uptake to B16-sEVs into B16F1 cells. Moreover, CM-NP encapsulating an anticancer drug doxorubicin (DOX) (CM-NP-DOX) could be prepared by membrane fusion of PS-liposomes encapsulating DOX (PS-Lipo-DOX) and B16-sEVs. CM-NP-DOX exhibited a superior anticancer effect on B16F1 cells in vitro compared with PS-Lipo-DOX. These findings suggest that the calcium fusion method could be applied for membrane fusion of sEVs and PS-liposomes, and that this approach would likely be useful for efficient drug encapsulation into sEVs, as well as increasing liposome functionality.
由于小细胞外囊泡（sEVs）通过转移某些生物活性分子参与细胞间通讯，并且具有克服药物运输生物屏障的能力，因此已将其作为药物递送系统（DDS）用于治疗多种疾病。然而，在药物包封方面存在一些问题，包括包封效率低和重现性差。先前有报道称，含有磷脂酰丝氨酸（PS）的脂质体在钙离子存在下可以融合在一起，这允许药物被包封到所得脂质体中（即钙融合方法）。另一方面，据报道 PS 存在于 sEVs 的脂质膜中，作为一种独特的脂质组成。因此，我们假设可以通过钙融合方法将含有治疗剂的 PS 脂质体与 sEVs 进行 PS 介导的膜融合，从而将药物方便地包封到 sEVs 中。首先证实了 PS 脂质体和源自鼠黑色素瘤 B16F1 细胞的 sEVs（B16-sEVs）之间的膜融合。获得的纳米颗粒，称为嵌合纳米颗粒（CM-NP），表现出与 B16-sEVs 相似的细胞摄取进入 B16F1 细胞的能力。此外，通过 PS 脂质体包封阿霉素（DOX）（PS-Lipo-DOX）和 B16-sEVs 的膜融合，可以制备包封抗癌药物 DOX 的 CM-NP-DOX。与 PS-Lipo-DOX 相比，CM-NP-DOX 在体外对 B16F1 细胞表现出更好的抗癌作用。这些发现表明，钙融合方法可用于 sEVs 和 PS 脂质体的膜融合，并且这种方法可能有助于高效地将药物包封到 sEVs 中，并提高脂质体的功能。
