An MRI-visible non-viral vector for targeted Bcl-2 siRNA delivery to neuroblastoma

Polyethylene glycol-grafted polyethylenimine (PEG-g-PEI) which was functionalized with a neuroblastoma cell-specific ligand, the GD2 single chain antibody (scAb(GD2)), was synthesized in order to effectively deliver Bcl-2 siRNA into neuroblastoma cells. This polymer was complexed first with superparamagnetic iron oxide nanoparticle (SPION) to get a MRI-visible targeted non-viral vector (scAb(GD2)-PEG-g-PEI-SPION) and then with Bcl-2 siRNA to form nanoparticles showing low cytotoxicity. The targeting capacity of scAb(GD2)-PEG-g-PEI-SPION was successfully verified in vivo and in vitro by magnetic resonance imaging. The single chain antibody encoded targeted polyplex was more effective in transferring Bcl-2 siRNA than the nontargeting one in SK-N-SH cells, a human neuroblastoma cell line, resulting in a 46.34% inhibition in the expression of Bcl-2 mRNA. Consequently, a high level of cell apoptosis up to 50.76% and a significant suppression of tumor growth were achieved, which indicates that scAb(GD2)-PEG-g-PEI-SPION is a promising magnetic resonance imaging-visible non-viral vector for targeted neuroblastoma siRNA therapy and diagnosis.