Improving in Vivo Hepatic Transfection Activity by Controlling Intracellular Trafficking: The Function of GALA and Maltotriose

Lipid-nanoparticle-enabled nucleic acid therapeutics for liver disorders

Inherited genetic disorders of the liver pose a significant public health burden. Liver transplantation is often limited by the availability of donor livers and the exorbitant costs of immunosuppressive therapy. To overcome these limitations, nucleic acid therapy provides a hopeful alternative that enables gene repair, gene supplementation, and gene silencing with suitable vectors. Though viral vectors are the most efficient and preferred for gene therapy, pre-existing immunity debilitating immune responses limit their use. As a potential alternative, lipid nanoparticle-mediated vectors are being explored to deliver multiple nucleic acid forms, including pDNA, mRNA, siRNA, and proteins. Herein, we discuss the broader applications of lipid nanoparticles, from protein replacement therapy to restoring the disease mechanism through nucleic acid delivery and gene editing, as well as multiple preclinical and clinical studies as a potential alternative to liver transplantation.

A reversible cell penetrating peptide-cargo linkage allows dissection of cell penetrating peptide- and cargo-dependent effects on internalization and identifies new functionalities of putative endolytic peptides

Cell penetrating peptides (CPPs) are a promising technology for therapeutic delivery of macromolecular cargos. CPPs have generally used covalent linkages to cargo, ensuring a common fate as one molecule. Conversely, our CPP-adaptor, TAT-CaM, noncovalently binds calmodulin binding sequence (CBS)-containing cargos in calcium rich media then dissociates in the calcium-poor endosomal environment following internalization, enhancing endosomal escape relative to standard CPPs. In this study, we report cell entry of positively charged protein cargos that were not increased by TAT-CaM while cargos based on the negatively charged maltose binding protein (MBP) displayed little intrinsic internalization but were internalized by TAT-CaM. In addition, association of positively charged proteins with negatively charged nucleic acids reduced internalization. This evidence points to the dominant role cargo charge plays in apparent CPP effectiveness. There has been little systematic investigation as to how interaction between CPPs and cargos impacts internalization efficiency. Our adaptors provide a tool that allows combinatorial assays to detect emergent properties. Toward this end we added 4 endolytic peptide (EP) sequences between cargo CBS and MBP moieties to create 4 new cargos and between TAT and CaM to create 4 new adaptors. The new cargos were assayed for internalization alone and with a panel of CPP-adaptors to identify combinations that displayed increased internalization efficiency or other properties. Among the most important results, addition of the EP LAH4 improved adaptor performance and provided some CPP capability to cargos. MBP-LAH4-CBS was internalized more effectively by most adaptors, suggesting this sequence has general stimulatory ability. Two other EPs, Aurein 1.2 and HA2, also provided some CPP capability to their MBP cargos but were unexpectedly antagonistic to internalization by most adaptors due to retention of adaptor/cargo complexes on the cell surface. We thus identified LAH4 as stimulator of internalization in both adaptors and cargos and uncovered new functionality for Aurein 1.2 and HA2, which may be related to their identification as EPs. Future experiments will test new endolytic capabilities made possible with combinatorial approaches.

Robust delivery of RIG-I agonists using extracellular vesicles for anti-cancer immunotherapy

The RIG-I pathway can be activated by RNA containing 5' triphosphate, leading to type I interferon release and immune activation. Hence, RIG-I agonists have been used to induce immune responses against cancer as potential immunotherapy. However, delivery of 5' triphosphorylated RNA molecules as RIG-I agonists to tumour cells in vivo is challenging due to the susceptibility of these molecules to degradation. In this study, we demonstrate the use of extracellular vesicles (EVs) from red blood cells (RBCs), which are highly amenable for RNA loading and taken up robustly by cancer cells, for RIG-I agonist delivery. We evaluate the anti-cancer activity of two novel RIG-I agonists, the immunomodulatory RNA (immRNA) with a unique secondary structure for efficient RIG-I activation, and a 5' triphosphorylated antisense oligonucleotide with dual function of RIG-I activation and miR-125b inhibition (3p-125b-ASO). We find that RBCEV-delivered immRNA and 3p-125b-ASO trigger the RIG-I pathway, and induce cell death in both mouse and human breast cancer cells. Furthermore, we observe a significant suppression of tumour growth coupled with increased immune cell infiltration mediated by the activation of RIG-I cascade after multiple intratumoral injections of RBCEVs loaded with immRNA or 3p-125b-ASO. Targeted delivery of immRNA using RBCEVs with EGFR-binding nanobody administrated via intrapulmonary delivery facilitates the accumulation of RBCEVs in metastatic cancer cells, leading to potent tumour-specific CD8+ T cells immune response. This contributes to prominent suppression of breast cancer metastasis in the lung. Hence, this study provides a new strategy for efficient RIG-I agonist delivery using RBCEVs for immunotherapy against cancer and cancer metastasis.

Peptide-Assisted Nucleic Acid Delivery Systems on the Rise

Concerns associated with nanocarriers' therapeutic efficacy and side effects have led to the development of strategies to advance them into targeted and responsive delivery systems. Owing to their bioactivity and biocompatibility, peptides play a key role in these strategies and, thus, have been extensively studied in nanomedicine. Peptide-based nanocarriers, in particular, have burgeoned with advances in purely peptidic structures and in combinations of peptides, both native and modified, with polymers, lipids, and inorganic nanoparticles. In this review, we summarize advances on peptides promoting gene delivery systems. The efficacy of nucleic acid therapies largely depends on cell internalization and the delivery to subcellular organelles. Hence, the review focuses on nanocarriers where peptides are pivotal in ferrying nucleic acids to their site of action, with a special emphasis on peptides that assist anionic, water-soluble nucleic acids in crossing the membrane barriers they encounter on their way to efficient function. In a second part, we address how peptides advance nanoassembly delivery tools, such that they navigate delivery barriers and release their nucleic acid cargo at specific sites in a controlled fashion.

Development of lipid-like materials for RNA delivery based on intracellular environment-responsive membrane destabilization and spontaneous collapse

Messenger RNA and small interfering RNA are attractive modalities for curing diseases by complementation or knock-down of proteins. For success of these RNAs, a drug delivery system (DDS) is required to control a pharmacokinetics, to enhance cellular uptake, to overcome biological membranes, and to release the cargo into the cytoplasm. Based on past research, developing nanoparticles that are neutrally charged have been the mainstream of their development. Also, the materials are further mounted with pH- and/or reducing environment-responsive units. In this review, we summarize progress made in the molecular design of these materials. We also focus on the importance of the hydrophobic scaffold for tissue/cell targeting, intracellular trafficking, and immune responses. As a practical example, the design concept of the SS-cleavable and pH-activated lipid-like material (ssPalm) and subsequent molecular modification tailored to the RNA-based medical application is discussed.

Lipid nanoparticle technology for therapeutic gene regulation in the liver

Hereditary genetic disorders, cancer, and infectious diseases of the liver affect millions of people around the globe and are a major public health burden. Most contemporary treatments offer limited relief as they generally aim to alleviate disease symptoms. Targeting the root cause of diseases originating in the liver by regulating malfunctioning genes with nucleic acid-based drugs holds great promise as a therapeutic approach. However, employing nucleic acid therapeutics in vivo is challenging due to their unfavorable characteristics. Lipid nanoparticle (LNP) delivery technology is a revolutionary development that has enabled clinical translation of gene therapies. LNPs can deliver siRNA, mRNA, DNA, or gene-editing complexes, providing opportunities to treat hepatic diseases by silencing pathogenic genes, expressing therapeutic proteins, or correcting genetic defects. Here we discuss the state-of-the-art LNP technology for hepatic gene therapy including formulation design parameters, production methods, preclinical development and clinical translation.

Gene delivery by peptide-assisted transport

The diverse amino acid chemistries and secondary structures in peptides provide 'minimalist' mimics of motifs in proteins and offer many ideal properties for targeted delivery approaches. Several non-viral vectors (polymers and lipids) have been studied for their potential applications in gene delivery. However, non-specific uptake, lack of targeting, inability to escape endosomes, and inefficient nuclear delivery limit their application. Peptide-assisted trafficking of non-viral vectors can potentially overcome these biological barriers to improve gene delivery through targeted uptake using key cell-surface receptors (e.g., integrins, growth factor receptors, and G-protein coupled receptors); membrane disruption for endosomal escape; and nuclear importation. Furthermore, the capacity of peptides to regulate spatio-temporal control over gene delivery opens multi-faceted avenues for effective gene delivery in a variety of complex applications. Rigorous on-going in vitro and in vivo studies utilizing peptides for targeted and microenvironment-sensitive gene delivery could promote their widespread clinical usage.

Membrane Active Peptides and Their Biophysical Characterization

In the last 20 years, an increasing number of studies have been reported on membrane active peptides. These peptides exert their biological activity by interacting with the cell membrane, either to disrupt it and lead to cell lysis or to translocate through it to deliver cargos into the cell and reach their target. Membrane active peptides are attractive alternatives to currently used pharmaceuticals and the number of antimicrobial peptides (AMPs) and peptides designed for drug and gene delivery in the drug pipeline is increasing. Here, we focus on two most prominent classes of membrane active peptides; AMPs and cell-penetrating peptides (CPPs). Antimicrobial peptides are a group of membrane active peptides that disrupt the membrane integrity or inhibit the cellular functions of bacteria, virus, and fungi. Cell penetrating peptides are another group of membrane active peptides that mainly function as cargo-carriers even though they may also show antimicrobial activity. Biophysical techniques shed light on peptide–membrane interactions at higher resolution due to the advances in optics, image processing, and computational resources. Structural investigation of membrane active peptides in the presence of the membrane provides important clues on the effect of the membrane environment on peptide conformations. Live imaging techniques allow examination of peptide action at a single cell or single molecule level. In addition to these experimental biophysical techniques, molecular dynamics simulations provide clues on the peptide–lipid interactions and dynamics of the cell entry process at atomic detail. In this review, we summarize the recent advances in experimental and computational investigation of membrane active peptides with particular emphasis on two amphipathic membrane active peptides, the AMP melittin and the CPP pVEC.

Cell Penetrating Peptides as Molecular Carriers for Anti-Cancer Agents

Cell membranes with their selective permeability play important functions in the tight control of molecular exchanges between the cytosol and the extracellular environment as the intracellular membranes do within the internal compartments. For this reason the plasma membranes often represent a challenging obstacle to the intracellular delivery of many anti-cancer molecules. The active transport of drugs through such barrier often requires specific carriers able to cross the lipid bilayer. Cell penetrating peptides (CPPs) are generally 5–30 amino acids long which, for their ability to cross cell membranes, are widely used to deliver proteins, plasmid DNA, RNA, oligonucleotides, liposomes and anti-cancer drugs inside the cells. In this review, we describe the several types of CPPs, the chemical modifications to improve their cellular uptake, the different mechanisms to cross cell membranes and their biological properties upon conjugation with specific molecules. Special emphasis has been given to those with promising application in cancer therapy.

Clustered versus Uniform Display of GALA-Peptides on Carrier Nanoparticles: Enhancing the Permeation of Noncharged Fluid Lipid Membranes

GALA-peptide is a random coil in neutral pH; in acidic pH, it becomes an amphipathic α-helix that aggregates in solution, possibly via its hydrophobic facet that runs along the helix's long axis. In the presence of fluid lipid membranes, the GALA-helix exhibits membrane-active properties that originate from the same hydrophobic facet; these properties make GALA a candidate for inclusion in drug delivery systems requiring permeation of the endosomal membrane to enable drug escape into the cytoplasm. Previous work has shown that the uniform functionalization of carrier nanoparticles with GALA-peptides improved their membrane activity and enhanced the endosomal escape of delivered therapeutics. The present study aims to evaluate the potential role of altering membrane activity via cluster-displayed GALA-peptides (for higher local valency) on the surface of carrier nanoparticles. The presentation of GALA-peptides on carrier nanoparticles was also designed to be pH-dependent. The peptide display on the surface of the carrier nanoparticles was uniform in neutral pH; in the acidic endosomal pH, the surface of nanocarriers formed domains (patches) with high local densities of GALA-peptides. The interactions between GALA-functionalized carrier nanoparticles and target lipid vesicles, utilized as endosome membrane surrogates that were used to primarily capture the fluid nature of these membranes, were studied as a function of pH. At endosomal pH values, ranging from 5.5 to 5.0, the greatest permeability of target membranes was induced by nanocarriers with clustered rather than uniformly displayed GALA. This enhancing effect had an optimum; at even more acidic pH values, too close an approximation of GALA-peptides residing within the same patches resulted in preferential intrapatch peptide interactions rather than interactions with the apposing target lipid membranes. This behavior could have the same physicochemical origin as the aforementioned GALA-peptide aggregation, observed in solution with decreasing pH at increasing peptide concentrations. The findings of this study support the potential of utilizing the clustered display of GALA-peptides on carrier nanoparticles to increase the permeation of fluid membranes used herein to capture this critical physical property of endosomal membranes and therefore to ultimately improve the endosomal escape of delivered therapeutics, enhancing therapeutic efficacy.

The ubiquitin-conjugating enzyme UBE2O modulates c-Maf stability and induces myeloma cell apoptosis

Background

UBE2O is proposed as a ubiquitin-conjugating enzyme, but its function was largely unknown.

Methods

Mass spectrometry was applied to identify c-Maf ubiquitination-associated proteins. Immunoprecipitation was applied for c-Maf and UBE2O interaction. Immunoblotting was used for Maf protein stability. Luciferase assay was used for c-Maf transcriptional activity. Lentiviral infections were applied for UBE2O function in multiple myeloma (MM) cells. Flow cytometry and nude mice xenografts were applied for MM cell apoptosis and tumor growth assay, respectively.

Results

UBE2O was found to interact with c-Maf, a critical transcription factor in MM, by the affinity purification/tandem mass spectrometry assay and co-immunoprecipitation assays. Subsequent studies showed that UBE2O mediated c-Maf polyubiquitination and degradation. Moreover, UBE2O downregulated the transcriptional activity of c-Maf and the expression of cyclin D2, a typical gene modulated by c-Maf. DNA microarray revealed that UBE2O was expressed in normal bone marrow cells but downregulated in MGUS, smoldering MM and MM cells, which was confirmed by RT-PCR in primary MM cells, suggesting its potential role in myeloma pathophysiology. When UBE2O was restored, c-Maf protein in MM cells was significantly decreased and MM cells underwent apoptosis. Furthermore, the human MM xenograft in nude mice showed that re-expression of UBE2O delayed the growth of myeloma xenografts in nude mice in association with c-Maf downregulation and activation of the apoptotic pathway.

Conclusions

UBE2O mediates c-Maf polyubiquitination and degradation, induces MM cell apoptosis, and suppresses myeloma tumor growth, which provides a novel insight in understanding myelomagenesis and UBE2O biology.

Peptides, polypeptides and peptide–polymer hybrids as nucleic acid carriers

Peptide, polypeptide and polymer–peptide hybrid based nucleic acid therapeutics (NAT).

Intracellular Delivery of Proteins with Cell-Penetrating Peptides for Therapeutic Uses in Human Disease

Protein therapy exhibits several advantages over small molecule drugs and is increasingly being developed for the treatment of disorders ranging from single enzyme deficiencies to cancer. Cell-penetrating peptides (CPPs), a group of small peptides capable of promoting transport of molecular cargo across the plasma membrane, have become important tools in promoting the cellular uptake of exogenously delivered proteins. Although the molecular mechanisms of uptake are not firmly established, CPPs have been empirically shown to promote uptake of various molecules, including large proteins over 100 kiloDaltons (kDa). Recombinant proteins that include a CPP tag to promote intracellular delivery show promise as therapeutic agents with encouraging success rates in both animal and human trials. This review highlights recent advances in protein-CPP therapy and discusses optimization strategies and potential detrimental effects.

Multifunctional enveloped nanodevices (MENDs)

It is anticipated that nucleic acid medicines will be in widespread use in the future, since they have the potential to cure diseases based on molecular mechanisms at the level of gene expression. However, intelligent delivery systems are required to achieve nucleic acid therapy, since they can perform their function only when they reach the intracellular site of action. We have been developing a multifunctional envelope-type nanodevice abbreviated as MEND, which consists of functional nucleic acids as a core and lipid envelope, and can control not only biodistribution but also the intracellular trafficking of nucleic acids. In this chapter, we review the development and evolution of the MEND by providing several successful examples, including the R8-MEND, the KALA-MEND, the MITO-Porter, the YSK-MEND, and the PALM.

Surface modification of nonviral nanocarriers for enhanced gene delivery

Biomedical nanotechnology has given a new lease of life to gene therapy with the ever-developing and ever-diversifying nonviral gene delivery nanocarriers. These are designed to pass a series of barriers in order to bring their nucleic acid cargo to the right subcellular location of particular cells. For a given application, each barrier has its dedicated strategy, which translates into a physicochemical, biological and temporal identity of the nanocarrier surface. Different strategies have thus been explored to implement adequate surface identities on nanocarriers over time for systemic delivery. In that context, this review will mainly focus on organic nanocarriers, for which these strategies will be described and discussed.

Intracellular co-delivery of zinc ions and plasmid DNA for enhancing gene transfection activity

Zinc ions, methylated poly(1-vinylimidazole) (PVIm-Me) and plasmid DNA (pDNA) have formed ternary complexes for gene delivery. The resulting Zn-PVIm-Me-pDNA complexes have delivered both Zn(2+) ions and pDNA inside cells, leading to the nuclear translocation of the pDNA. By use of the pDNA containing a nuclear protein, NF-κB, binding sequence, the intracellular co-delivery of Zn(2+) ions and pDNA has enhanced gene expression. These results suggest that the intracellular Zn(2+) ions delivered by Zn-PVIm-Me-pDNA complexes activated the NF-κB, enhancing the nuclear translocation of the pDNA. In conclusion, it has been demonstrated that the Zn-PVIm-Me-pDNA complex is capable of enhancing the gene transfection activity by a synergic effect of the PVIm-Me and the co-delivered intracellular Zn(2+) ions.

Ion permeability of the nuclear pore complex and ion-induced macromolecular permeation as studied by scanning electrochemical and fluorescence microscopy

Efficient delivery of therapeutic macromolecules and nanomaterials into the nucleus is imperative for gene therapy and nanomedicine. Nucleocytoplasmic molecular transport, however, is tightly regulated by the nuclear pore complex (NPC) with the hydrophobic transport barriers based on phenylalanine and glycine repeats. Herein, we apply scanning electrochemical microscopy (SECM) to quantitatively study the permeability of the NPCs to small probe ions with a wide range of hydrophobicity as a measure of their hydrophobic interactions with the transport barriers. Amperometric detection of the redox-inactive probe ions is enabled by using the ion-selective SECM tips based on the micropipet- or nanopipet-supported interfaces between two immiscible electrolyte solutions. The remarkably high ion permeability of the NPCs is successfully measured by SECM and theoretically analyzed. This analysis demonstrates that the ion permeability of the NPCs is determined by the dimensions and density of the nanopores without a significant effect of the transport barriers on the transported ions. Importantly, the weak ion-barrier interactions become significant at sufficiently high concentrations of extremely hydrophobic ions, i.e., tetraphenylarsonium and perfluorobutylsulfonate, to permeabilize the NPCs to naturally impermeable macromolecules. Dependence of ion-induced permeabilization of the NPC on the pathway and mode of macromolecular transport is studied by using fluorescence microscopy to obtain deeper insights into the gating mechanism of the NPC as the basis of a new transport model.

Effects of silencing the RET/PTC1 oncogene in papillary thyroid carcinoma by siRNA-squalene nanoparticles with and without fusogenic companion GALA-cholesterol

BACKGROUND

RET/PTC1 is the most prevalent type of gene rearrangement found in papillary thyroid carcinoma (PTC). Previously, we introduced a new noncationic nanosystem for targeted RET/PTC1 silencing by efficient delivery of small interfering RNA (siRNA) using the "squalenoylation" approach. With the aim of improving these results further, we designed new squalenoyl nanostructures consisting of the fusogenic peptide GALA-cholesterol (GALA-Chol) and squalene (SQ) nanoparticles (NPs) of siRNA RET/PTC1.

METHODS

The siRNA RET/PTC1-SQ bioconjugate was synthesized. The corresponding NPs were prepared with or without GALA-Chol by nanoprecipitation and then characterized for their size and zeta potential. The effects of NPs on BHP 10-3 SCmice and TPC-1 cell viability (MTT assay), gene and protein silencing (reverse transcription-quantitative polymerase chain reaction [rt-qPCR], Western blot), and cellular uptake (fluorescent microscopy) were studied. In vivo gene silencing efficiency of siRNA RET/PTC1-SQ NPs was assessed by administration in nude mice via either intratumoral (i.t.) or intravenous (i.v.) routes. Tumor growth was followed for 19 days. Tumors were then collected, and RET/PTC1 gene and protein inhibitions were assessed by RT-qPCR and Western blot.

RESULTS

The combination of siRNA RET/PTC1-SQ bioconjugate and GALA-Chol leads to stable NPs of ∼200 nm diameter. In vitro, the results revealed that combining GALA-Chol with siRNA RET/PTC1-SQ NPs decreased cell viability, enhanced cellular internalization, and induced gene silencing efficiency in both human PTC (BHP 10-3 SCmice and TPC-1) cell lines. On the contrary, in vivo, the siRNA RET/PTC1-SQ GALA-Chol NPs were not found to be efficient either in gene silencing or in tumor growth inhibition, compared to siRNA RET/PTC1-SQ NPs both via i.t. and i.v. routes (p<0.001).

CONCLUSIONS

Conversely to siRNA RET/PTC1-SQ NPs, the siRNA RET/PTC1-SQ GALA-Chol NPs are efficient in vitro but not in vivo. Finally, NPs of siRNA RET/PTC1-SQ were found to be efficient silencers of the RET/PTC1 fusion oncogene in in vivo applications even at a concentration lower than used in a previously published study.

Efficient protection and transfection of small interfering RNA by cationic shell-crosslinked knedel-like nanoparticles

Despite the great potential of small interfering RNA (siRNA) as a therapeutic agent, progress in this area has been hampered by a lack of efficient biocompatible transfection agents. Recently, cationic shell-crosslinked knedel-like nanoparticles (cSCKs) were found to possess lower cytotoxicity and better transfection ability for phosphorothioate ODNs and plasmid DNA than the commonly used cationic lipid-based agent Lipofectamine. To determine the usefulness of cSCKs for siRNA transfection, a small library of cSCKs with varying percentage of primary and tertiary amines was assessed for its ability to bind to siRNA, inhibit siRNA degradation in human serum, and to transfect HeLa and mouse macrophage cell lines. The silencing efficiency in HeLa cells was greatest with the cSCK with 100% primary amines (pa100) as determined by their viability following transfection with cytotoxic and non-cytotoxic siRNAs. cSCK-pa100 showed greater silencing efficiency than Lipofectamine 2000 in the HeLa cells, as well in 293T and human bronchial epithelial (HEK) cells, but was comparable in human bronchial epithelial (BEAS-2B) cells and human mammary epithelial (MCF10a) cells. cSCK-pa100 also showed greater silencing of iNOS expression than Lipofectamine 2000 in a mouse macrophage cell line, and provided greater protection from serum degradation, demonstrating its potential usefulness as an siRNA transfection agent. The siRNA silencing of iNOS at lower concentrations of siRNA could be enhanced by complexation with the fusogenic GALA peptide, which was shown to enhance endosomal escape following uptake.

Enhanced cellular transfection by ternary non-viral gene vectors coupled with adeno-associated virus-derived peptides

The establishment of efficient and safe gene delivery systems is crucial for biomedical applications. To address this objective, novel, ternary hybrid gene vectors are designed with viral capsid peptides in non-viral gene carriers. The viral peptide, TQVGQKT, is coupled with a membrane active peptide, LK15. Which acts as a linker to tag peptide with plasmid DNA. Additionally, polyethylenimine (PEI) is employed to condense the complexes further, thereby forming ternary DNA/TQVGQKT-LK15/PEI complexes. The ternary complexes result in rapid internalization leading to significantly enhanced cellular transfection. The new moiety, TQVGQKT, as well as enhanced cellular transfection, will certainly provide crucial insights for the design of novel non-viral gene carriers with efficient and safe properties.

Improving the endosomal escape of cell-penetrating peptides and their cargos: strategies and challenges

Cell penetrating peptides (CPPs) can deliver cell-impermeable therapeutic cargos into cells. In particular, CPP-cargo conjugates tend to accumulate inside cells by endocytosis. However, they often remain trapped inside endocytic organelles and fail to reach the cytosolic space of cells efficiently. In this review, the evidence for CPP-mediated endosomal escape is discussed. In addition, several strategies that have been utilized to enhance the endosomal escape of CPP-cargos are described. The recent development of branched systems that display multiple copies of a CPP is presented. The use of viral or synthetic peptides that can disrupt the endosomal membrane upon activation by the low pH of endosomes is also discussed. Finally, we survey how CPPs labeled with chromophores can be used in combination with light to stimulate endosomal lysis. The mechanisms and challenges associated with these intracellular delivery methodologies are discussed.

Pretreatment of hepatocyte growth factor gene transfer mediated by octaarginine peptide-modified nanoparticles ameliorates LPS/D-galactosamine-induced hepatitis

We previously reported that an octaarginine- and pH-sensitive fusogenic peptide-modified multifunctional envelope-type nano device (R8-GALA-MEND) produces a high level of gene expression in the liver. In this study, we report on an examination of whether this gene delivery system exerts potent hepatoprotective effects against lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced acute liver injury. In vivo-jetPEI(™)-Gal, a commercially available in vivo transfection reagent, was used as a reference. The systemic administration of the R8-GALA-MEND or in vivo-jetPEI(™)-Gal showed that the latter was more toxic than the R8-GALA-MEND, indicating that R8-GALA-MEND is a safer system than in vivo-jetPEI(™)-Gal. Pretreatment with R8-GALA-MEND or in vivo-jetPEI(™)-Gal loaded with hepatocyte growth factor (HGF) pDNA inhibited serum GPT and GOT levels from becoming elevated. However, the survival rate of the mice was significantly enhanced in the case of R8-GALA-MEND, but not for the in vivo-jetPEI(™)-Gal treatment. These results demonstrate that R8-GALA-MEND has the potential for use in the pretreatment of an acute liver injury.