Biologically responsive carrier-mediated anti-angiogenesis shRNA delivery for tumor treatment

Small interfering RNA (siRNA) has increased the hope for highly-efficient treatment of gene-related diseases. However, the stable and efficient delivery of therapeutic nucleic acids is a prerequisite for the successful clinical translation of RNA interfering therapy. To achieve this, we condensed the low molecular weight polyethyleneimine (PEI, Mw < 2000) with 2,6-pyridinedicarboxaldehyde (PDA) to synthesize a biologically responsive and degradable cationic polymer (abbreviated to PDAPEI) which was utilized as a gene vector for the delivery of a VEGF-A shRNA expression plasmid DNA (pDNA). The resulting electrostatic interaction between PDAPEI and pDNA led to the self-assembly of nanoscale polyplexes with suitable particle size and stable zeta potential. The PDAPEI/pDNA polyplexes demonstrated an outstanding gene transfection and silencing efficiency at 30 w/w ratio, as well as negligible cytotoxicity. Also, the designed polymer showed no stimulation to the innate immune system. Moreover, compared with PEI 25 KDa, the polyplexes accomplished comparatively better anti-angiogenesis efficacy, which resulted in the inhibition of tumor growth in subcutaneous tumor mice models. In conclusion, PDAPEI has great potential to be a gene delivery vector for cancer therapy.