Gene transfection efficiency of tracheal epithelial cells by DC-chol-DOPE/DNA complexes

mRNA delivery via non-viral carriers for biomedical applications

As an emerging new class of nucleic acid drugs, messenger RNA (mRNA) has huge potential in immunotherapy, regenerative medicine, vaccine, and gene editing. Comparing with siRNA and pDNA, mRNA is more vulnerable to nucleases in vivo. However, the lack of effective and safe delivery methods impedes the broad application of mRNA-based therapeutics. Up to now, the delivery of mRNA remains largely unexplored, and therefore, is a hot topic in the field of gene therapy. In this review, we will summarize the ongoing challenges in mRNA-based therapeutics and unmet requirements for delivery vehicles in terms of the unique structure of mRNA. We then highlight the advancement in mRNA delivery in both fundamental research and clinical applications. Finally, a prospective will be proposed upon reviewing the current progress in mRNA delivery.

Anti- c-myc cholesterol based lipoplexes as onco-nanotherapeutic agents in vitro

Background: Strategies aimed at inhibiting the expression of the c-myc oncogene could provide the basis for alternative cancer treatment. In this regard, silencing c-myc expression using small interfering RNA (siRNA) is an attractive option. However, the development of a clinically viable, siRNA-based, c-myc silencing system is largely dependent upon the design of an appropriate siRNA carrier that can be easily prepared. Nanostructures formed by the electrostatic association of siRNA and cationic lipid vesicles represent uncomplicated siRNA delivery systems. Methods: This study has focused on cationic liposomes prepared with equimolar quantities of the cytofectin, N,N-dimethylaminopropylamido-succinylcholesteryl-formylhydrazide (MS09), and cholesterol (Chol) for the development of a simple, but effective anti- c-myc onco-nanotherapeutic agent. Liposomes formulated with dioleoylphosphatidylethanolamine (DOPE) in place of Chol as the co-lipid were included for comparative purposes. Results: Liposomes successfully bound siRNA forming lipoplexes of less than 150 nm in size, which assumed bilamellar aggregrates. The liposome formulations were well tolerated in the human breast adenocarcinoma (MCF-7) and colon carcinoma (HT-29) cells, which overexpress c-myc. Lipoplexes directed against the c-myc transcript mediated a dramatic reduction in c-myc mRNA and protein levels. Moreover, oncogene knockdown and anti-cancer effects were superior to that of Lipofectamine™ 3000. Conclusion: This anti- c-myc MS09:Chol lipoplex exemplifies a simple anticancer agent with enhanced c-myc gene silencing potential in vitro.

Synthetic Approaches for Nucleic Acid Delivery: Choosing the Right Carriers

The discovery of the genetic roots of various human diseases has motivated the exploration of different exogenous nucleic acids as therapeutic agents to treat these genetic disorders (inherited or acquired). However, the physicochemical properties of nucleic acids render them liable to degradation and also restrict their cellular entrance and gene translation/inhibition at the correct cellular location. Therefore, gene condensation/protection and guided intracellular trafficking are necessary for exogenous nucleic acids to function inside cells. Diversified cationic formulation materials, including natural and synthetic lipids, polymers, and proteins/peptides, have been developed to facilitate the intracellular transportation of exogenous nucleic acids. The chemical properties of different formulation materials determine their special features for nucleic acid delivery, so understanding the property-function correlation of the formulation materials will inspire the development of next-generation gene delivery carriers. Therefore, in this review, we focus on the chemical properties of different types of formulation materials and discuss how these formulation materials function as protectors and cellular pathfinders for nucleic acids, bringing them to their destination by overcoming different cellular barriers.

Nanoscale platforms for messenger RNA delivery

Messenger RNA (mRNA) has become a promising class of drugs for diverse therapeutic applications in the past few years. A series of clinical trials are ongoing or will be initiated in the near future for the treatment of a variety of diseases. Currently, mRNA-based therapeutics mainly focuses on ex vivo transfection and local administration in clinical studies. Efficient and safe delivery of therapeutically relevant mRNAs remains one of the major challenges for their broad applications in humans. Thus, effective delivery systems are urgently needed to overcome this limitation. In recent years, numerous nanoscale biomaterials have been constructed for mRNA delivery in order to protect mRNA from extracellular degradation and facilitate endosomal escape after cellular uptake. Nanoscale platforms have expanded the feasibility of mRNA-based therapeutics, and enabled its potential applications to protein replacement therapy, cancer immunotherapy, therapeutic vaccines, regenerative medicine, and genome editing. This review focuses on recent advances, challenges, and future directions in nanoscale platforms designed for mRNA delivery, including lipid and lipid-derived nanoparticles, polymer-based nanoparticles, protein derivatives mRNA complexes, and other types of nanomaterials. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Lipid-Based Structures Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Lipoplex-Mediated Single-Cell Transfection via Droplet Microfluidics

While lipoplex (cationic lipid-nucleic acid complex)-mediated intracellular delivery is widely adopted in mammalian cell transfection, its transfection efficiency for suspension cells, e.g., lymphatic and hematopoietic cells, is reported at only ≈5% or even lower. Here, efficient and consistent lipoplex-mediated transfection is demonstrated for hard-to-transfect suspension cells via a single-cell, droplet-microfluidics approach. In these microdroplets, monodisperse lipoplexes for effective gene delivery are generated via chaotic mixing induced by the serpentine microchannel and co-confined with single cells. Moreover, the cell membrane permeability increases due to the shear stress exerted on the single cells when they pass through the droplet pinch-off junction. The transfection efficiency, examined by the delivery of the pcDNA3-EGFP plasmid, improves from ≈5% to ≈50% for all three tested suspension cell lines, i.e., K562, THP-1, Jurkat, and with significantly reduced cell-to-cell variation, compared to the bulk method. Efficient targeted knockout of the TP53BP1 gene for K562 cells via the CRISPR (clustered regularly interspaced short palindromic repeats)-CAS9 (CRISPR-associated nuclease 9) mechanism is also achieved using this platform. Lipoplex-mediated single-cell transfection via droplet microfluidics is expected to have broad applications in gene therapy and regenerative medicine by providing high transfection efficiency and low cell-to-cell variation for hard-to-transfect suspension cells.

Comparative study on preparative methods of DC-Chol/DOPE liposomes and formulation optimization by determining encapsulation efficiency

Three most commonly used preparative methods, dry-film, reverse phase evaporation and ethanol injection were employed to prepare cationic liposomes composed of DC-Chol and DOPE, respectively. The resulting samples were contrasted through morphology observation, particle size and zeta potential analysis. Sephadex filtration method with high selectivity was developed to determine the encapsulation efficiency of plasmid DNA-loaded cationic vectors, on this basis, cationic liposomes formulation was further optimized by applying Box Behnken design with encapsulation efficiency as evaluation index. The results showed that liposomes prepared by dry-film method were of best quality and stability, moreover, the optimum formulation of cationic liposomes and optimal value of each influencing factors were quantitatively obtained, measured value was highly consistent with predicted results. These findings preliminarily clarified the effect of preparative methods on performance of cationic liposome, as well as formulation factors on encapsulation efficiency, and will provide important methodological reference for further study of liposomes carriers for gene delivery.

Nonviral gene vector formation in monodispersed picolitre incubator for consistent gene delivery

A novel picolitre incubator based microfluidic system for consistent nonviral gene carrier formulation is presented. A cationic lipid-based carrier is the most attractive nonviral solution for delivering plasmid DNA, shRNA, or drugs for pharmaceutical research and RNAi applications. The size of the cationic lipid and DNA complex (CL-DNA), or the lipoplex, is one of the important variations for consistency of gene transfection. CL-DNA size, in turn, may be controlled by factors such as the cationic lipid and DNA mixing order, mixing rate, and mixture incubation time. The Picolitre Microfluidic Reactor and Incubator (PMRI) system described here is able to control these parameters in order to create homogeneous CL-DNA. Compared with conventional CL-DNA preparation techniques involving hand-shaking or vortexing, the PMRI system demonstrates a greater ability to constantly and uniformly mix cationic lipids and DNA simultaneously. After mixing in the picolitre droplet reactors, the cationic lipid and DNA is incubated within the picolitre incubator to form CL-DNA. The PMRI generates a narrower size distribution band, while also turning the sample loading, mixing and incubation steps into an integrated process enabling the consistent formation of CL-DNA. The coefficient of variation (CV) of transfection efficiency is 0.05 and 0.30 for PMRI-based and conventional methods, respectively. In addition, this paper demonstrates that the gene transfection efficiency of lipoplex created in the PMRI is more reproducible.

Cationic liposome (DC-Chol/DOPE=1:2) and a modified ethanol injection method to prepare liposomes, increased gene expression

Cationic liposomes composed of 3beta-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol) and dioleoylphosphatidylethanolamine (DOPE) (DC-Chol/DOPE liposome, molar ratio, 1:1 or 3:2) prepared by the dry-film method have been often used as non-viral gene delivery vectors. The formulation and preparation of DC-Chol/DOPE liposomes, as well as the formation of their lipoplexes were investigated in an attempt to improve transfection efficiency in vitro. A more efficient transfection in medium with serum was achieved using DC-Chol/DOPE liposomes (molar ratio, 1:2) than those (3:2), and preparation method by a modified ethanol injection than the dry-film. The most efficient DC-Chol/DOPE liposome for gene transfer was molar ratio (1:2) and prepared by a modified ethanol injection method. The enhanced transfection might be related to an increase in the release of DNA in the cytoplasm by the large lipoplex during incubation in optiMEM, not to an increased cellular association with the lipoplex. The use of a modified ethanol injection method might enhance the role of DOPE that is aid in destabilization of the plasma membrane and/or endosome. These findings suggested that cationic liposomes rich in DOPE prepared by a modified ethanol injection method will help to improve the efficacy of liposome vector systems for gene delivery.

Transfection efficiency and cytotoxicity of cationic liposomes in primary cultures of rainbow trout (Oncorhynchus mykiss) gill cells

Immunisation of fish by immersion has been applied for inactivated, whole cell bacterins, where the gill epithelial cells are considered as one of the prime uptake sites. Antigen entry is a critical factor for delivery of vaccine antigens through the immersion route, also for DNA vaccines, and delivery systems like cationic liposomes may enhance uptake. In this study, the aim was to examine the efficiency of cationic liposomes as a means to transfect primary cultures of rainbow trout gill cells with plasmids encoding viral or reporter proteins. Furthermore, the effects of the concentration and composition of liposomes/lipoplex on the viability of the cells were evaluated. Transfection of the gill cells was possible with both plasmids following transfection with lipoplexes of a neutral charge. Low concentrations and neutral/negatively charged formulations were favourable with respect to the toxicity of the formulations. Given that the mucous barrier covering the gills is overcome, this system might be useful for the priming of the local immunity in the fish gills.

Correlation between structure and transfection efficiency: a study of DC-Chol−DOPE/DNA complexes

The supramolecular structural nature of some cationic liposomes-DNA complexes, currently used as vehicles in non-viral gene delivery, has been elucidated by recent X-ray diffraction experiments. The relationship between the chemico-physical properties of these self-assembled structures and their transfection efficiency is extensively studied. Here we report a first comprehensive structural study by using energy dispersive X-ray diffraction, of the complex DC-Chol--DOPE/DNA (3beta[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol dioleoylphosphatidylethanolamine/DNA), which has been classified as one of the most effective in in-vivo experiments. Our results show that DC-Chol--DOPE/DNA lipoplexes have a columnar inverted hexagonal structure, which is not influenced by the cationic liposome/DNA charge ratio. The transfection efficiency of C6 rat glioma cells by DC-Chol--DOPE/DNA lipoplexes and the toxicity of lipoplexes to cells are dramatically affected by cationic liposome/DNA weight ratio. It seems therefore that the lipoplex structures have not any influence on transfection efficiency and toxicity in our experimental system.

Tools and techniques for craniofacial tissue engineering

Craniofacial surgery is an important conduit for tissue-engineering applications. As interdisciplinary collaborations improve, we can expect to see remarkable progress in de novo tissue synthesis, replacement, and repair. Ultimately, we may one day find that gene-modified cell-based tissue-engineering strategies will succeed today's reconstructive strategies. In this review, we highlight the major gene- and cell-based preclinical tools and techniques that are currently being developed to solve common craniofacial problems.