Alkaline loading of extracellular vesicles produced from human neural stem cell-derived neurospheres enables CNS drug delivery.

The blood brain barrier and blood tumor barrier (BBB and BTB, respectively) represent significant obstacles for the delivery of drugs to treat diseases of the central nervous system, such as brain cancers and neurodegenerative diseases. Extracellular vesicles (EVs) or exosomes have emerged as a new drug delivery vehicle for CNS diseases as they may penetrate the BBB/BTB and are less immunogenic than liposomal carriers. EVs derived from human neural stem cells (hNSC) provide additional benefits over other EV sources due to their increased homing capability to neural cells and demonstrated efficacy for treating stroke and traumatic brain injury in rodent models. However, the utilization of EVs from hNSC for drug delivery remains largely unexplored, due in part to difficulties in manufacturing capacity compared to traditional cell lines. Here, we report the development of a hNSC suspension neurosphere system for EV production and drug delivery. As proof of concept, doxorubicin was loaded into hNSC-EV, using a novel, high-efficiency alkaline passive loading method, and shown to be effective at inducing cytotoxicity in glioma cells in vitro and exhibiting higher BBB penetrance than doxorubicin-alone in vivo. These studies demonstrate the potential for hNSC-EV loaded doxorubicin as a therapeutic treatment for brain cancers such as glioblastoma, while also establishing hNSC-EVs as a drug-delivery vehicle for CNS diseases.