No abstract

The applications of polyamidoamine (PAMAM) dendrimers have attracted much attention in biomedicine specially non-viral gene delivery because of thier unique characteristics including hyperbranching, multivalency, and well-defined uniform globular three-dimensional structures. In the current study, in order to enhance the transfection efficiency and reduce the cytotoxicity of PAMAMs, bromoalkylcarboxylates with different chain length (2-bromoacetic, 6-bromohexanoic, 10-bromodecanoic and 16-bromohexadecanoic acids) were covalently conjugated with 10% and 30% of primary amines of generation 4 and 5 (G4 and G5) of PAMAM dendrimers to increase the hydrophobicity of the carrier. At the next stage, the alkylcarboxylate-PAMAMs were pegylaed to further modify the PAMAM structures for biological applications. Obtained results demonstrated that the prepared PAMAM derivatives had particle size around 140 nm with net-positive surface charge. None of the prepared PAMAM-based non-viral vactors exhibited significant hemolytic activity and also cytotoxicity. Meanwhile decahexanoate-PAMAM G4 [G4(16C-10%)] and decanoate-PAMAM G4 conjugated to polyethylene glycol (PEG) (G4[(10C-30%)(10C-PEG)]) showed highest transfection efficiency in murine neuroblastoma (Neuro-2a) cell line, interestingly only the latter had improved transfection efficiency in mesenchymal stem cells (MSCs). This study proved the potential utility of alkylcarboxylate-grafted PAMAM dendrimers (G4 and G5) with or without PEG modification for efficient gene transfer into cancerous cells as well as MSCs.

One of the major limitations of effective nonviral gene carriers is their potential high cytotoxicity. Conjugation of polyethylene glycol (PEG) to polymers is a common approach to decrease toxicity and improve biodistribution. The aim of this study was to evaluate the effect of PEGylation on generation 5 polypropylenimine (PPI) dendrimer by using PEG moieties or alkyl-PEG groups. Polymers were synthesized by grafting of 5 and 10 % primary amines of PPI to NH2-PEG-COOH or Br-(CH2)9-CO-NH-PEG-COOH through Amide bond formation or nucleophilic substitution, respectively. Transfection efficiency and cytotoxicity were analyzed after 4 and 24 h exposure of neuroblastoma cell line (Neuro-2a) with synthesized vectors. Among all of the PEG-PPI derivatives, 5 % PEG-conjugated G5 PPI with alkyl chain (PPI-alkyl-PEG 5 %) resulted in the most efficient gene expression. This vector also significantly decreased the in vitro cytotoxicity and sub-G1 peak in flow cytometry histogram after 24 h incubation. Our results indicate that modification of 5 % primary amines of G5 PPI with PEG using alkyl chain as linker produces a promising vector combining low cytotoxicity, appropriate biodegradability, and high gene transfection efficiency.

No abstract

Specific and effective delivery of drugs and genes to cancer cells are the major issues in successful cancer treatment. Recently, targeted cancer gene therapy has been emerged as a main technology for the treatment of different types of cancers. Among various synthetic carriers, polyethylenimine is one of the most well-known polymers for gene delivery. In this study, we conjugated phage-derived peptide (DMPGTVLP) to polyethylenimine (10 kDa) via disulfide bonds for targeted gene delivery into breast adenocarcinoma cells (MCF-7). As negative-control cells, we used non-related hepatocellular carcinoma cells (HepG2). Peptide-conjugated polyplex exhibited low cytotoxicity and significantly increased the transfection efficiency in comparison with unmodified polyethylenimine. Therefore, the peptide-modified vector can be used as a good targeting agent for gene or drug delivery into breast adenocarcinoma cells.