Augmented loading efficiency of doxorubicin into glioma-derived exosomes by an integrated microfluidic device

Glioma is a lethal brain cancer in the central nervous system (CNS). The therapeutic usage of potent anticancer drugs for glioma is restricted by their poor penetration across the blood-brain barrier (BBB). Current reports have revealed that cell-derived exosomes can cross the BBB, suggesting their prospective use as drug delivery vehicles for targeting glioma as well as neurological disorders. However, conventional isolation of intact, specific, and optimal exosomes for drug delivery from various donor cells is laborious and time-consuming. Particularly, increasing loading efficiency of non-hydrophobic anticancer drugs, such as doxorubicin, into exosomes has been challenged. Therefore, a single integrated microfluidic device has been developed, based on the principles of immunocapture and density-gradient-free centrifugation, using soft lithography for efficient exosome isolation and drug loading consecutively. The isolated glioma-exosomes were characterized by transmission electron microscopy (TEM), immunogold-EM, and nano tracking analyzer. The loading efficiency of doxorubicin into glioma-exosomes was evaluated by UV-visible spectrophotometer as well high performance liquid chromatography (HPLC). Furthermore, the doxorubicin loaded glioma-exosomes were treated to autologous and heterologous glioma cells, followed by evaluation with confocal microscopy. The present study has shown that our integrated microfluidic device isolates pure exosomes from glioma cells, and it dramatically increases loading efficiency of doxorubicin into the exosomes, supporting its usefulness to study the exosome-mediated drug delivery for glioma therapy.