Exosome-membrane and polymer-based hybrid-complex for systemic delivery of plasmid DNA into brains for the treatment of glioblastoma

Herpes simplex virus thymidine kinase (HSVtk) gene therapy is a promising strategy for glioblastoma therapy. However, delivery of plasmid DNA (pDNA) encoding HSVtk into the brain by systemic administration is a challenge since pDNA can hardly penetrate the blood-brain barrier. In this study, an exosome-membrane (EM) and polymer-based hybrid complex was developed for systemic delivery of pDNA into the brain. Histidine/arginine-linked polyamidoamine (PHR) was used as a carrier. PHR binds to pDNA by electrostatic interaction. The pDNA/PHR complex was mixed with EM and subjected to extrusion to produce pDNA/PHR-EM hybrid complex. For glioblastoma targeting, T7 peptide was attached to the pDNA/PHR-EM complex. Both pDNA/PHR-EM and T7-decorated pDNA/PHR-EM (pDNA/PHR-EM-T7) had a surface charge of -5 mV and a size of 280 nm. Transfection assays indicated that pDNA/PHR-EM-T7 enhanced the transfection to C6 cells compared with pDNA/PHR-EM. Intravenous administration of pHSVtk/PHR-EM-T7 showed that pHSVtk/PHR-EM and pHSVtk/PHR-EM-T7 delivered pHSVtk more efficiently than pHSVtk/lipofectamine and pHSVtk/PHR into glioblastoma <i>in vivo</i>. pHSVtk/PHR-EM-T7 had higher delivery efficiency than pHSVtk/PHR-EM. As a result, the HSVtk expression and apoptosis levels in the tumors of the pHSVtk/PHR-EM-T7 group were higher than those of the other control groups. Therefore, the pDNA/PHR-EM-T7 hybrid complex is a useful carrier for systemic delivery of pHSVtk to glioblastoma.