Marked increase in tumor transfection with a truncated branched polymer

Delivery of mRNA with Histidine-Lysine Peptides

Transfection with mRNA has been considered superior to that with plasmids since the mRNA can be translated to a protein in the cytosol without entering the nucleus. One disadvantage of using mRNA is its susceptibility to enzymatic biodegradability, and consequently, significant research has occurred to determine nonviral carriers that will sufficiently stabilize this nucleic acid for cellular transport. Histidine-lysine peptides (HK) are one such class of mRNA carriers, which we think serves as a model for other peptides and polymeric carrier systems. When the HK peptide and mRNA are mixed and interact through ionic and nonionic bonds, mRNA polyplexes are formed, which can transfect cells. In contrast to linear HK peptides, branched HK peptides protected and efficiently transfected mRNA into cells. After describing the preparation and biophysical characterization of these polyplexes, we will provide protocols for in vitro and in vivo transfection for these mRNA polyplexes.

Peptide-Based Nanoparticles for Systemic Extrahepatic Delivery of Therapeutic Nucleotides

Peptide-based nanoparticles (PBN) for nucleotide complexation and targeting of extrahepatic diseases are gaining recognition as potent pharmaceutical vehicles for fine-tuned control of protein production (up- and/or down-regulation) and for gene delivery. Herein, we review the principles and mechanisms underpinning self-assembled formation of PBN, cellular uptake, endosomal release, and delivery to extrahepatic disease sites after systemic administration. Selected examples of PBN that have demonstrated recent proof of concept in disease models in vivo are summarized to offer the reader a comparative view of the field and the possibilities for clinical application.

Novel branched amphiphilic peptides for nucleic acids delivery

Highly efficient and safe non-viral vectors for nucleic acids delivery have attracted much attention due to their potential applications in gene therapy, gene editing and vaccination against infectious diseases, and various materials have been investigated and designed as delivery vectors. Herein, we designed a series of branched amphiphilic peptides (BAPs) and tested their applications as pDNA/mRNA delivery vectors. The BAP structure was inspired by the phospholipids, in which lysine oligomers were used as the "polar head", segments containing phenylalanine, histidine and leucine were used as the "hydrophobic tails", and a lysine residue was used as the branching point. By comparing the gel retardation, particle sizes and zeta potentials of the BAP/pDNA complexes of the short-branch BAPs (BAP-V1 ∼ BAP-V4), we determined the optimal lysine oligomer was K₆. However, their cell transfection efficiencies were not satisfactory, and thus three long-branch BAPs (BAP-V5 ∼ BAP-V7) were further designed. In these long-branch BAPs, more hydrophobic residues were added and the overall amphiphilicity increased accordingly. The results showed that these three BAPs could effectively compact the nucleic acids, including both pDNA and mRNA, and all could transfect nucleic acids into HEK 293 cells, with low cytotoxicity. Among the three long-branch BAPs, BAP-V7 (bis(FFLFFHHH)-K-K₆) showed the best transfection efficiency at N/P = 10, which was better than the commercial transfection reagent PEI-25 K. These results indicate that increased amphiphilicity would also benefit for BAP mediated nucleic acid delivery. The designed BAPs provide more documents of such novel type of nucleic acids delivery vectors, which is worth of further investigation as a new gene theranostic platforms.