Enhanced blood–brain barrier penetration and glioma therapy mediated by a new peptide modified gene delivery system

Successful glioma gene therapy lays on two important factors, the therapeutic genes and efficient delivery vehicles to cross the blood–brain barrier (BBB) and reach gliomas. In this work, a new gene vector was constructed based on dendrigraft poly-l-lysines (DGL) and polyethyleneglycol (PEG), conjugated with a cell-penetrating peptide, the nucleolar translocation signal (NoLS) sequence of the LIM Kinase 2 (LIMK2) protein (LIMK2 NoLS peptide, LNP), yielding DGL-PEG-LNP. Plasmid DNA encoding inhibitor of growth 4 (ING4) was applied as the therapeutic gene. DGL-PEG-LNP/DNA nanoparticles (NPs) were monodispersed, with a mean diameter of 90.6 ± 8.9 nm. The conjugation of LNP significantly enhanced the BBB-crossing efficiency, cellular uptake and gene expression within tumor cells. Mechanism studies suggested the involvement of energy, caveolae-mediated endocytosis and macropinocytosis in cellular uptake of LNP-modified NPs. MTT results showed that no apparent cytotoxicity was observed when cells were treated with synthesized vectors. Furthermore, LNP-modified NPs mediated strongest and most intensive apoptosis on the tumor site, and the longest median survival time of glioma-bearing mice. All the results demonstrated that LNP is a kind of efficient CPPs especially for BBB-crossing application, and DGL-PEG-LNP/DNA is a potential non-viral platform for glioma gene therapy via intravenous administration.