In vitro and in vivo gene transfection using biodegradable and low cytotoxic nanomicelles based on dendritic block copolymers

Abstract

Dendritic block copolymers with different chain length of poly(ε-caprolactone) (PCL) and poly(2-(dimethyl-amino)ethylmethacrylate) (PDMAEMA) were prepared and investigated as non-viral vectors for gene transfection in vitro and in vivo. Gel retardation analysis showed that all these dendritic copolymers could completely retard the mobility of DNA at and above an N/P ratio of 2.5/1. Dynamic light scattering analysis revealed that, at and above an N/P ratio of 5/1, these dendritic copolymers strongly condensed DNA into nanoscale polyplexes with average sizes ranging from about 50–160 nm and positive surface charges ranging from +13.4 to +30.3 mV. In vitro transfection tests using the plasmid encoding green fluorescence protein as gene reporter indicated that dendritic PCL-b-PDMAEMA copolymers were capable of transfecting MCF-7 and SKOV-3 cells, yielding comparable or higher transfection efficiencies in the absence or presence of serum when compared to 25 kDa branched polyethylenimine (bPEI) or 50 kDa PDMAEMA homopolymer as positive controls. Moreover, by intravenous injection of the polyplexes of these dendritic copolymers into SKOV-3 tumor-bearing nude mice, detectable transgene expression was observed in the tumor and other organs. These dendritic copolymers exhibited low in vitro cytotoxicity against MCF-7 and SKOV-3 cells with >80% viable cells at the tested polymer concentration below 25 μg mL⁻¹ and also caused no death of the mice in vivo at a dose of 0.75 mg kg⁻¹. The results manifested that dendritic PCL-b-PDMAEMA copolymers have high potential as safe and efficient gene delivery vectors.