Noncoding DNA in lipofection of HeLa cells-a few insights

At the Intersection of Biomaterials and Gene Therapy: Progress in Non-viral Delivery of Nucleic Acids

Biomaterials play a critical role in technologies intended to deliver therapeutic agents in clinical settings. Recent explosion of our understanding of how cells utilize nucleic acids has garnered excitement to develop a range of older (e.g., antisense oligonucleotides, plasmid DNA and transposons) and emerging (e.g., short interfering RNA, messenger RNA and non-coding RNAs) nucleic acid agents for therapy of a wide range of diseases. This review will summarize biomaterials-centered advances to undertake effective utilization of nucleic acids for therapeutic purposes. We first review various types of nucleic acids and their unique abilities to deliver a range of clinical outcomes. Using recent advances in T-cell based therapy as a case in point, we summarize various possibilities for utilizing biomaterials to make an impact in this exciting therapeutic intervention technology, with the belief that this modality will serve as a therapeutic paradigm for other types of cellular therapies in the near future. We subsequently focus on contributions of biomaterials in emerging nucleic acid technologies, specifically focusing on the design of intelligent nanoparticles, deployment of mRNA as an alternative to plasmid DNA, long-acting (integrating) expression systems, and in vitro/in vivo expansion of engineered T-cells. We articulate the role of biomaterials in these emerging nucleic acid technologies in order to enhance the clinical impact of nucleic acids in the near future.

Direct interrogation of DNA content distribution in nanoparticles by a novel microfluidics-based single-particle analysis

Nonviral gene delivery holds great promise not just as a safer alternative to viral vectors in traditional gene therapy applications, but also for regenerative medicine, induction of pluripotency in somatic cells, and RNA interference for gene silencing. Although it continues to be an active area of research, there remain many challenges to the rational design of vectors. Among these, the inability to characterize the composition of nanoparticles and its distribution has made it difficult to probe the mechanism of gene transfection process, since differences in the nanoparticle-mediated transfection exist even when the same vector is used. There is a lack of sensitive methods that allow for full characterization of DNA content in single nanoparticles and its distribution among particles in the same preparation. Here we report a novel spectroscopic approach that is capable of interrogating nanoparticles on a particle-by-particle basis. Using PEI/DNA and PEI-g-PEG/DNA nanoparticles as examples, we have shown that the distribution of DNA content among these nanoparticles was relatively narrow, with the average numbers of DNA of 4.8 and 6.7 per particle, respectively, in PEI/DNA and PEI-g-PEG/DNA nanoparticles. This analysis enables a more accurate description of DNA content in polycation/DNA nanoparticles. It paves the way toward comparative assessments of various types of gene carriers and provides insights into bridging the efficiency gap between viral and nonviral vehicles.

Cell division responsive peptides for optimized plasmid DNA delivery: the mitotic window of opportunity?

The delivery of plasmid DNA remains hard to achieve, especially due to the presence of the nuclear membrane barrier. During cell division, however, the nuclear membrane is temporarily disassembled. We evaluated two different strategies to optimize plasmid DNA delivery in dividing cells: 1) phosphorylation responsive peptides that release plasmid DNA preferentially during mitosis and 2) chromatin targeting peptides to anchor plasmid DNA in newly formed nuclei upon cell division. Peptide/DNA particles alone were not efficient in penetrating cells. Upon co-delivery with lipid-based carriers, however, transfection efficiency drastically improved when compared to controls. For the phosphorylation responsive peptides, the presence of the phosphorylation sequence slightly increased transfection efficiency. For the chromatin targeting peptides, however, the chromatin targeting sequence did not seem to be the main reason for the improvement of transfection efficiency when applied in living cells. In conclusion, the pre-condensation of plasmid DNA with peptides improves lipid based delivery, but the nature of the peptides (cell responsive or not) does not seem to be the main reason for the improvement. It seems that the nuclear entry of foreign plasmid DNA is still under tight control, even during the mitotic window of opportunity.