Abstract
BackgroundThe successful gene delivery into the brain is a major challenge due to the presence of the blood–brain barrier (BBB). In order to transport plasmid DNA across the BBB and target the brain glioma, the PEGylated liposomes (PLs) modified with OX26 and chlorotoxin (CTX) were developed as a dual-targeting gene delivery system, and the therapeutic efficacy of OX26/CTX-PL/pC27 against glioma was evaluated using in vitro and in vivo experimental models.MethodsThe PEGylated liposome complexes were prepared by the reverse phase evaporation method, and their physicochemical properties were examined. The transfection efficiency, intracellular distribution, in vitro effects of OX26/CTX-PL/pC27 were determined on C6, F98 and HEK293T cell lines. The dual-targeting therapeutic efficacy of OX26/CTX-PL/pC27 against glioma were assessed using the BMVECs/C6 cells co-culture model and the rat orthotopic glioma model.ResultsThe OX26/CTX-PL/pDNA complexes exhibited a subglobose shape, and possessed notably low toxicities to HEK293T and C6 cells post 4 h incubation. In the in vitro transfection experiment, gene expressions of hTERTC27 from C6 and F98 cells were significantly improved by OX26 and CTX modification. Our in vitro results also showed that OX26 endowed the PLs with the transport ability across the BBB. Using the BMVECs/C6 cells co-culture model, the viability of C6 cells was decreased to 46.0% after OX26/CTX-PL/pC27 transfection. The OX26/CTX-PL/pC27 complexes exhibited enhanced therapeutic effects on C6 cells. Moreover, the dual-targeting therapeutic effects were further conformed with diminished tumor volumes (18.81 ± 6.15 mm3) and extended median survival time (46 days) in C6 glioma-bearing rats. Immunohistochemical analysis revealed the therapeutic effects derived from enhanced hTERTC27 expression in the tumor site.ConclusionsThe PEGylated liposomes modified with OX26 and CTX are able to significantly promote cell transfection, increase the transport of plasmid DNA across the BBB and afterwards target the brain glioma cells in vitro and in vivo, exhibit the most significant therapeutic efficacy. The ligand OX26 plays a critical role in transporting the lipoplexes across the BBB, and CTX acts as a major role in targeting brain glioma cells. The results would encourage further developments for non-invasive targeting therapy of brain gliomas by intravenous injection.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-4598-13-191) contains supplementary material, which is available to authorized users.
Highlights
The successful gene delivery into the brain is a major challenge due to the presence of the blood–brain barrier (BBB)
We employed the PEGylated liposomes as the delivery vector of plasmid DNA and constructed the dual-targeting gene delivery system
OX26-PEGylated liposomes (PLs)/pDNA, OX26/CTX-PL/pDNA complexes were prepared through the outer maleimide groups of PLs reacting with the thiol groups of OX26-SH and CTXSH (Figure 1)
Summary
The successful gene delivery into the brain is a major challenge due to the presence of the blood–brain barrier (BBB). The high-grade glioma, glioblastoma multiforme (GBM), almost invariably infiltrates the surrounding normal brain tissue, which makes it impossible for a complete surgical tumor removal, and is typically associated with rapid progression and a fatal outcome [2]. Another obstacle for the treatment of GBM is the presence of the blood–brain barrier (BBB), which prevents most large-molecule drugs and more than 98% of smallmolecule pharmaceuticals entering the brain tissue [3]. To obtain a better therapeutic effect, a gene delivery system is urgent for clinic employ to transport genes across the BBB and target the brain glioma
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