Star Shaped Poly(ethylene glycols) Yield Biocompatible Gene Delivery Systems

Brain Gene Silencing with Cationic Amino-Capped Poly(ethylene glycol) Polyplexes

“…This low level of derivatisation was deliberately chosen in order to engineer a biocompatible vector. We know from previous work that limiting the level of tertiary amines in particular was associated with less cytotoxicity of a polymer siRNA vector [ 15 ] and that 4APEG-NH2 is a suitable synthetic scaffold from which to construct gene delivery vectors [ 23 ] and here we show that a low level of amine moieties on 4APPA is associated with good cell biocompatibility ( Table 1 ).…”

“…We observed a similar biocompatibility advantage with tetra-O,O,O,O-[poly(ethyleneglycol-O-2-ethyleneimine)-graft-N-(2-ethylamine)-]-pentaerythritol (4-arm-PEG-ethylamine—4APEA), a 4APEG-NH 2 derivative synthesised for intravenous gene delivery [ 23 ]. 4APEA had an IC50 of 4.76 ± 0.27 mg in the A431 cell line.…”

“…We have previously reported the synthesis of a relatively biocompatible gene delivery polymer—4APEA (IC50 in the A431 cell line = 4.76 ± 0.27 mg mL −1 ) that successfully delivered genes to tumours on intravenous administration [ 23 ]. Here, we show, for the first time, that a relatively biocompatible nucleic acid transfer molecule: 4APPA (IC50 = 13.97 ± 6 mg mL −1 in the A431 cell line— Table 1 ) that is 3–4 orders of magnitude less cytotoxic than both Lipofectamine ( Table 1 ) and 25 kDa poly(ethylenimine) [ 16 ], is able to complex with siRNA to form 150 nm positively charged complexes at an siRNA to 4APPA weight ratio of ~1:40, with the siRNA complexes being taken up by cells in culture and effecting gene silencing of the demonstrator ITCH gene ( Figure 2 and Figure 3 ).…”

Limiting the level of tertiary amines on polyamines leads to biocompatible nucleic acid vectors

“…The stability of the complexes in the presence of biological polyanions was thus examined by incubation with heparin (Figure 6). Heparin is known to displace nucleic acids from polyplexes (Iemsam-Arng et al, 2014). At the lower heparin concentration (0.1 mg mL -1 ) the stability of the complexes followed the trend: EAGC29 > EAGC21 > EAGC17, whereas at the higher heparin concentration (1 mg mL -1 ) the stability of the complexes followed the trend: EAGC29 > EAGC21 = EAGC17.…”

“…We then set out to examine the effect of proteins on the transfection efficiency of the polymers, using EAGC21 as a representative polymer. Serum proteins are known to destabilise polyplexes (Iemsam-Arng et al, 2014).…”