Cyclic RGD-polyethylene glycol-polyethylenimine for intracranial glioblastoma-targeted gene delivery

Even though the blood-brain barrier (BBB) is compromised for angiogenesis, therapeutic agents for glioblastoma multiforme (GBM) are particularly inefficient due to the existence of a blood-tumor barrier (BTB), which hampers tumor accumulation and uptake. Integrin α(v)β(3) is overexpressed on glioblastoma U87 cells and neovasculture, thus making its ligands such as the RGD motif target glioblastoma in vitro and in vivo. In the present work, we have designed a modified polyethylene glycol-polyethylenimine (PEG-PEI) gene carrier by conjugating it with a cyclic RGD sequence, c(RGDyK) (cyclic arginine-glycine-aspartic acid-D-tyrosine-lysine). When complexed with plasmid DNA, this gene carrier, termed RGD-PEG-PEI, formed homogenous nanoparticles with a mean diameter of 73 nm. These nanoparticles had a high binding affinity with U87 cells and facilitated targeted gene delivery against intracranial glioblastoma in vivo, thereby leading to a higher gene transfer efficiency compared to the PEG-PEI gene carrier without RGD decoration. This intracranial glioblastoma-targeted gene carrier also enhanced the therapeutic efficacy of pORF-hTRAIL, as evidenced by a significantly prolonged survival of intracranial glioblastoma-bearing nude mice. Considering the contribution of glioblastoma neovasculature to the BBB under angiogenic conditions, our results demonstrated the therapeutic feasibility of treating a brain tumor through mediation of integrin α(v)β(3), as well as the potential of using RGD-PEG-PEI as a targeted gene carrier in the treatment of intracranial glioblastoma.