Non-Viral in Vitro Gene Delivery: It is Now Time to Set the Bar!

The cell-penetrating YopM protein-functionalized quantum dot-plasmid DNA conjugate as a novel gene delivery vector

Non-viral gene delivery systems have great potential for safe and efficient gene therapy, while inefficient cellular and nuclear uptake remain as the major hurdles. Novel approaches are needed to enhance the transfection efficiency of non-viral vectors. In accordance with this need, the objective of this study was to construct a non-viral vector that could achieve gene delivery without using additional lipid-based transfection agent. We aimed to impart self-delivery property to a non-viral vector by using the cell and nucleus penetrating properties of YopM proteins from the three Yersinia spp. (Y. pestis, Y. enterocolotica and Y. pseudotuberculosis). Plasmid DNA (pDNA) encoding green fluorescent protein (GFP) was labeled with quantum dots (QDs) via peptide-nucleic acid (PNA) recognition site. Recombinant YopM protein was then attached to the conjugate via a second PNA recognition site. The YopM ̶ QDs ̶ pDNA conjugate was transfected into HeLa cells without using additional transfection reagent. All three conjugates produced GFP fluorescence, indicating that the plasmid was successfully delivered to the nucleus. As control, naked pDNA was transfected into the cells by using a commercial transfection reagent. The Y. pseudotuberculosis YopM-functionalized conjugate achieved the highest GFP expression, compared to other two YopM proteins and the transfection reagent. To the best of our knowledge, YopM protein was used for the first time in a non-viral gene delivery vector.

Nanoparticle-Mediated Gene Silencing for Sensitization of Lung Cancer to Cisplatin Therapy

Platinum-based chemotherapy remains a mainstay treatment for the management of advanced non-small cell lung cancer. A key cellular factor that contributes to sensitivity to platinums is the 5'-3' structure-specific endonuclease excision repair cross-complementation group 1 (ERCC1)/ xeroderma pigmentosum group F (XPF). ERCC1/XPF is critical for the repair of platinum-induced DNA damage and has been the subject of intense research efforts to identify small molecule inhibitors of its nuclease activity for the purpose of enhancing patient response to platinum-based chemotherapy. As an alternative to small molecule inhibitors, small interfering RNA (siRNA) has often been described to be more efficient in interrupting protein-protein interactions. The goal of this study was therefore to determine whether biocompatible nanoparticles consisting of an amphiphilic triblock copolymer (polyethylenimine-polycaprolactone-polyethylene glycol (PEI-PCL-PEG)) and carrying siRNA targeted to ERCC1 and XPF made by microfluidic assembly are capable of efficient gene silencing and able to sensitize lung cancer cells to cisplatin. First, we show that our PEI-PCL-PEG micelleplexes carrying ERCC1 and XPF siRNA efficiently knocked down ERCC1/XPF protein expression to the same extent as the standard siRNA transfection reagent, Lipofectamine. Second, we show that our siRNA-carrying nanoparticles enhanced platinum sensitivity in a p53 wildtype model of non-small cell lung cancer in vitro. Our results suggest that nanoparticle-mediated targeting of ERCC1/XPF is feasible and could represent a novel therapeutic strategy for targeting ERCC1/XPF in vivo.

Interaction of Lipoplex with Albumin Enhances Gene Expression in Hepatitis Mice

Understanding the in vivo fate of lipoplex, which is composed of cationic liposomes and DNA, is an important issue toward gene therapy. In disease conditions, the fate of lipoplex might change compared with the normal condition. Here, we examined the contribution of interaction with serum components to in vivo transfection using lipoplex in hepatitis mice. Prior to administration, lipoplex was incubated with serum or albumin. In the liver, the interaction with albumin enhanced gene expression in hepatitis mice, while in the lung, the interaction with serum or albumin enhanced it. In normal mice, the interaction with albumin did not enhance hepatic and pulmonary gene expression. Furthermore, hepatic and pulmonary gene expression levels of albumin-interacted lipoplex were correlated with serum transaminases in hepatitis mice. The albumin interaction increased the hepatic accumulation of lipoplex and serum tumor necrosis factor-α level. We suggest that the interaction with albumin enhanced the inflammation level after the administration of lipoplex in hepatitis mice. Consequently, the enhancement of the inflammation level might enhance the gene expression level. Information obtained in the current study will be valuable toward future clinical application of the lipoplex.