Exosomal delivery of rapamycin modulates blood-brain barrier penetration and VEGF axis in glioblastoma

Abstract

Exosomes (Exos), nanosized membranous vesicles (30–160 nm), have been validated as an effective drug delivery system capable of traversing biological barriers. Mesenchymal stem cells (MSCs), due to their near-limitless self-renewal capabilities, provide a plentiful source of exosomes for clinical applications. In this study, we utilized an exosome-encapsulated rapamycin (Exo-Rapa) delivery strategy, which permits the use of smaller drug dosages to achieve effects typically seen with higher dosages, thus enhancing drug efficacy. Moreover, Exos can transport pharmaceuticals across the blood-brain barrier (BBB) to the brain, and further penetrate GL261 cells to exert their effects. Within the tumor microenvironment, Exo-Rapa is released more rapidly and efficiently at the tumor site. The acidic conditions in tumors accelerate the release of Exo-Rapa, a characteristic that may make it a promising targeted therapeutic in future cancer research. Additionally, a series of in vivo experiments have further demonstrated the permeability of Exo-Rapa across the BBB, enabling it to accumulate at tumor sites; it also ameliorates inflammatory responses in Glioblastoma multiforme (GBM) mouse models and enhances anti-tumor activity through the regulation of angiogenesis via the VEGF/VEGFRs axis. Our results indicate that MSC-derived exosomes are a potent therapeutic carrier for GBM, offering an effective strategy for enhancing drug delivery across the BBB and providing a scientific foundation for the use of exosomes in the treatment of GBM and other diseases.