Influence of short-chain cell-penetrating peptides on transport of doxorubicin encapsulating receptor-targeted liposomes across brain endothelial barrier.

PURPOSE: To investigate the influence of different cell penetrating peptides (CPPs-TAT, Penetratin and Mastoparan), on the transport of doxorubicin encapsulating transferrin (Tf)-liposomes across brain endothelial barrier, in vitro and in vivo.
METHODS: The cellular uptake of dual-functionalized, (Tf-CPP), liposomes into various tumor cells was assessed using HPLC. The transport of liposomes was also measured across a robust 3D brain tumor model constructed using chitosan-PLGA scaffolds. The growth of tumor cells was monitored using H&E staining and the fully grown tumor scaffolds were visualized using SEM. The tumor scaffolds were combined with the culture inserts carrying tightly packed brain endothelial cells. The in vitro and in vivo transport of drug (using Tf-CPP-liposomes) across the brain endothelial barrier was determined by extraction of the drug from cells and tissues followed by analysis using HPLC.
RESULTS: The results demonstrated improved delivery of doxorubicin using dual-functionalized liposomes versus the single ligand or unmodified liposomes. Among different Tf-CPP-liposomes, the Tf-Penetratin liposomes showed efficient cellular transport of the encapsulated drug (approximately 90-98%) and maximum translocation of the drug across the brain endothelial barrier (approximately 15% across in vitro and 4% across in vivo BBB). The Tf-Penetratin and Tf-TAT liposomes demonstrated excellent cellular biocompatibility and no hemolytic activity upto 200nM phospholipid concentration.
CONCLUSIONS: The Tf-CPP liposomes showed efficient translocation of the anticancer drug across the brain endothelial barrier. In addition, an absolute and robust in vitro brain tumor model was successfully constructed to overcome the practical intricacies of developing a successful in vivo orthotopic brain tumor model.