Polymeric nanoparticles containing conjugated phospholipase A2 for nonviral gene delivery

Get out or die trying: Peptide- and protein-based endosomal escape of RNA therapeutics

RNA therapeutics offer great potential to transform the biomedical landscape, encompassing the treatment of hereditary conditions and the development of better vaccines. However, the delivery of RNAs into the cell is hampered, among others, by poor endosomal escape. This major hurdle is often tackled using special lipids, polymers, or protein-based delivery vectors. In this review, we will focus on the most prominent peptide- and protein-based endosomal escape strategies with focus on RNA drugs. We discuss cell penetrating peptides, which are still incorporated into novel transfection systems today to promote endosomal escape. However, direct evidence for enhanced endosomal escape by the action of such peptides is missing and their transfection efficiency, even in permissive cell culture conditions, is rather low. Endosomal escape by the help of pore forming proteins or phospholipases, on the other hand, allowed to generate more efficient transfection systems. These are, however, often hampered by considerable toxicity and immunogenicity. We conclude that the perfect enhancer of endosomal escape has yet to be devised. To increase the chances of success, any new transfection system should be tested under relevant conditions and guided by assays that allow direct quantification of endosomal escape.

Preparation of PEI-modified nanoparticles by dopamine self-polymerization for efficient DNA delivery

Achieving efficient and safe gene delivery is great of significance to promote the development of gene therapy. In this work, a polydopamine (PDA) layer was coated on the surface of Fe₃ O₄ nanoparticles (NPs) by dopamine (DA) self-polymerization, and then magnetic Fe₃ O₄ NPs were prepared by the Michael addition between amino groups in polyethyleneimine (PEI) and PDA. The prepared Fe₃ O₄ NPs (named Fe₃ O₄ @PDA@PEI) were characterized by FTIR, atomic force microscopy (AFM) and scanning electron microscope (SEM). As an efficient and safe gene carrier, the potential of Fe₃ O₄ @PDA@PEI was evaluated by agarose gel electrophoresis, MTT assay, fluorescence microscopy, flow cytometry. The results shows that the Fe₃ O₄ @PDA@PEI NPs is stable hydrophilic nanoparticles with a particle size of 50-150 nm. It can efficiently condense DNA at low N/P ratios and protect it from nuclease degradation. In addition, the Fe₃ O₄ @PDA@PEI NPs has higher safety than PEI. Further, the Fe₃ O₄ @PDA@PEI/DNA polyplexes could be effectively absorbed by cells and successfully transfected, and exhibit higher cellular uptake and gene transfection efficiency than PEI/DNA polyplexes. The findings indicate that the Fe₃ O₄ @PDA@PEI NPs has the potential to be developed into a novel gene vector. This article is protected by copyright. All rights reserved.

The TFAMoplex-Conversion of the Mitochondrial Transcription Factor A into a DNA Transfection Agent

Non-viral gene delivery agents, such as cationic lipids, polymers, and peptides, mainly rely on charge-based and hydrophobic interactions for the condensation of DNA molecules into nanoparticles. The human protein mitochondrial transcription factor A (TFAM), on the other hand, has evolved to form nanoparticles with DNA through highly specific protein-protein and protein-DNA interactions. Here, the properties of TFAM are repurposed to create a DNA transfection agent by means of protein engineering. TFAM is covalently fused to Listeria monocytogenes phospholipase C (PLC), an enzyme that lyses lipid membranes under acidic conditions, to enable endosomal escape and human vaccinia-related kinase 1 (VRK1), which is intended to protect the DNA from cytoplasmic defense mechanisms. The TFAM/DNA complexes (TFAMoplexes) are stabilized by cysteine point mutations introduced rationally in the TFAM homodimerization site, resulting in particles, which show maximal activity when formed in 80% serum and transfect HeLa cells in vitro after 30 min of incubation under challenging cell culture conditions. The herein developed TFAM-based DNA scaffolds combine interesting characteristics in an easy-to-use system and can be readily expanded with further protein factors. This makes the TFAMoplex a promising tool in protein-based gene delivery.