Cationic lipid/DNA complexes manufactured by microfluidics and bulk self-assembly exhibit different transfection behavior

A new microfluidic platform for the highly reproducible preparation of non-viral gene delivery complexes

Transfection describes the delivery of exogenous nucleic acids (NAs) to cells utilizing non-viral means. In the last few decades, scientists have been doing their utmost to design ever more effective transfection reagents. These are eventually mixed with NAs to give rise to gene delivery complexes, which must undergo characterization, testing, and further refinement through the sequential reiteration of these steps. Unfortunately, although microfluidics offers distinct advantages over the canonical approaches to preparing particles, the systems available do not address the most frequent and practical quest for the simultaneous generation of multiple polymer-to-NA ratios (N/Ps). Herein, we developed a user-friendly microfluidic cartridge to repeatably prepare non-viral gene delivery particles and screen across a range of seven N/Ps at once or significant volumes of polyplexes at a given N/P. The microchip is equipped with a chaotic serial dilution generator for the automatic linear dilution of the polymer to the downstream area, which encompasses the NA divider to dispense equal amounts of DNA to the mixing area, enabling the formation of particles at seven N/Ps eventually collected in individual built-in tanks. This is the first example of a stand-alone microfluidic cartridge for the fast and repeatable preparation of non-viral gene delivery complexes at different N/Ps and their storage.

Microfluidic Formulation of DNA-Loaded Multicomponent Lipid Nanoparticles for Gene Delivery

In recent years, lipid nanoparticles (LNPs) have gained considerable attention in numerous research fields ranging from gene therapy to cancer immunotherapy and DNA vaccination. While some RNA-encapsulating LNP formulations passed clinical trials, DNA-loaded LNPs have been only marginally explored so far. To fulfil this gap, herein we investigated the effect of several factors influencing the microfluidic formulation and transfection behavior of DNA-loaded LNPs such as PEGylation, total flow rate (TFR), concentration and particle density at the cell surface. We show that PEGylation and post-synthesis sample concentration facilitated formulation of homogeneous and small size LNPs with high transfection efficiency and minor, if any, cytotoxicity on human Embryonic Kidney293 (HEK-293), spontaneously immortalized human keratinocytes (HaCaT), immortalized keratinocytes (N/TERT) generated from the transduction of human primary keratinocytes, and epidermoid cervical cancer (CaSki) cell lines. On the other side, increasing TFR had a detrimental effect both on the physicochemical properties and transfection properties of LNPs. Lastly, the effect of particle concentration at the cell surface on the transfection efficiency (TE) and cell viability was largely dependent on the cell line, suggesting that its case-by-case optimization would be necessary. Overall, we demonstrate that fine tuning formulation and microfluidic parameters is a vital step for the generation of highly efficient DNA-loaded LNPs.

A Comprehensive Review on Intracellular Delivery

Intracellular delivery is considered an indispensable process for various studies, ranging from medical applications (cell-based therapy) to fundamental (genome-editing) and industrial (biomanufacture) approaches. Conventional macroscale delivery systems critically suffer from such issues as low cell viability, cytotoxicity, and inconsistent material delivery, which have opened up an interest in the development of more efficient intracellular delivery systems. In line with the advances in microfluidics and nanotechnology, intracellular delivery based on micro- and nanoengineered platforms has progressed rapidly and held great promises owing to their unique features. These approaches have been advanced to introduce a smorgasbord of diverse cargoes into various cell types with the maximum efficiency and the highest precision. This review differentiates macro-, micro-, and nanoengineered approaches for intracellular delivery. The macroengineered delivery platforms are first summarized and then each method is categorized based on whether it employs a carrier- or membrane-disruption-mediated mechanism to load cargoes inside the cells. Second, particular emphasis is placed on the micro- and nanoengineered advances in the delivery of biomolecules inside the cells. Furthermore, the applications and challenges of the established and emerging delivery approaches are summarized. The topic is concluded by evaluating the future perspective of intracellular delivery toward the micro- and nanoengineered approaches.

Recent advancements in liposome technology

The liposomes have continued to be well-recognized as an important nano-sized drug delivery system with attractive properties, such a characteristic bilayer structure assembling the cellular membrane, easy-to-prepare and high bio-compatibility. Extensive effort has been devoted to the development of liposome-based drug delivery systems during the past few decades. Many drug candidates have been encapsulated in liposomes and investigated for reduced toxicity and extended duration of therapeutic effect. The liposomal encapsulation of hydrophilic and hydrophobic small molecule therapeutics as well as other large molecule biologics have been established among different academic and industrial research groups. To date, there has been an increasing number of FDA-approved liposomal-based therapeutics together with more and more undergoing clinical trials, which involve a wide range of applications in anticancer, antibacterial, and antiviral therapies. In order to meet the continuing demand for new drugs in clinics, more recent advancements have been investigated for optimizing liposomal-based drug delivery system with more reproducible preparation technique and a broadened application to novel modalities, including nucleic acid therapies, CRISPR/Cas9 therapies and immunotherapies. This review focuses on the recent liposome' preparation techniques, the excipients of liposomal formulations used in various novel studies and the routes of administration used to deliver liposomes to targeted areas of disease. It aims to update the research in liposomal delivery and highlights future nanotechnological approaches.

Liposomal delivery of CRISPR/Cas9

Liposomes are one of the most widely investigated carriers for CRISPR/Cas9 delivery. The surface properties of liposomal carriers, including the surface charge, PEGylation, and ligand modification can significantly affect the gene silencing efficiency. Three barriers of systemic CRISPR/Cas9 delivery (long blood circulation, efficient tumor penetration, and efficient cellular uptake/endosomal escape) are analyzed on liposomal carriers with different surface charges, PEGylations, and ligand modifications. Cationic formulations dominate CRISPR/Cas9 delivery and neutral formulations also have good performance while anionic formulations are generally not proper for CRISPR/Cas9 delivery. The PEG dilemma (prolonged blood circulation vs. reduced cellular uptake/endosomal escape) and the side effect of repeated PEGylated formulation (accelerated blood clearance) were discussed. Effects of ligand modification on cationic and neutral formulations were analyzed. Finally, we summarized the achievements in liposomal CRISPR/Cas9 delivery, outlined existing problems, and provided some future perspectives. Liposomes are one of the most widely investigated carriers for CRISPR/Cas9 delivery. The surface properties of liposomal carriers, including the surface charge, PEGylation, and ligand modification can significantly affect the gene silencing efficiency. Three barriers of systemic siRNA delivery (long blood circulation, efficient tumor penetration, and efficient cellular uptake/endosomal escape) are analyzed on liposomal carriers with different surface charges, PEGylations, and ligand modifications. Cationic formulations dominate CRISPR/Cas9 delivery and neutral formulations also have good performance while anionic formulations are generally not proper for CRISPR/Cas9 delivery. The PEG dilemma (prolonged blood circulation vs. reduced cellular uptake/endosomal escape) and the side effect of repeated PEGylated formulation (accelerated blood clearance) were discussed. Effects of ligand modification on cationic and neutral formulations were analyzed. Finally, we summarized the achievements in liposomal CRISPR/Cas9 delivery, outlined existing problems, and provided some future perspectives.

Ectopic chondrogenesis of nude mouse induced by nano gene delivery enhanced tissue engineering technology

Background: Many techniques and methods have been used clinically to relieve pain from cartilage repair, but the long-term effect is still unsatisfactory. Purpose: The objective of this study was to form an artificial chondroid tissue gene enhanced tissue engineering system to repair cartilage defects via nanosized liposomes. Methods: Cationic nanosized liposomes were prepared and characterized using transmission electron microscope (TEM) and dynamic laser light scattering (DLS). The rat mesenchymal stem cells (rMSCs) were isolated, cultivated, and induced by SRY (Sex-Determining Region Y)-Box 9 (Sox9) via cationic nanosized liposomes. The induced rMSCs were mixed with a thermo-sensitive chitosan hydrogel and subcutaneously injected into the nude mice. Finally, the newly-formed chondroid tissue obtained in the injection parts, and the transparent parts were detected by HE, collagen II, and safranin O. Results: It was found that the presently prepared cationic nanosized liposomes had the diameter of 85.76±3.48 nm and the zeta potential of 15.76±2.1 mV. The isolated rMSCs proliferation was fibroblast-like, with a cultivated confluence of 90% confluence in 5-8 days, and stained positive for CD29 and CD44 while negative for CD34 and CD45. After transfection with cationic nanosized liposomes, we observed changes of cellular morphology and a higher expression of SOX9 compared with control groups, which indicated that rMSCs could differentiate into chondrocyte in vitro. By mixing transfected rMSCs with the thermo-sensitive hydrogel of chitosan in nude mice, chondroid tissue was successfully obtained, demonstrating that rMSCs can differentiate into chondrogenic cells in vivo. Conclusion: This study explored new ways to improve the quality of tissue engineered cartilage, thus accelerating clinical transformation and reducing patient pain.

Microfluidic manufacturing of surface-functionalized graphene oxide nanoflakes for gene delivery

Graphene oxide (GO) is a single-atomic-layered material made of a sheet of oxidized carbon atoms arranged in a honeycomb structure. Thanks to the notable physical and chemical properties of GO, GO-based nanomaterials have applications in many fields of research, including gene delivery. It has been reported that pristine GO can absorb single-stranded DNA and RNA through π-π stacking, which cannot be used as a gene carrier because it is hard to load double-stranded DNA (dsDNA). To tackle this issue, this work was aimed at developing a hybrid nanoparticle (NP) system made of GO coated with cationic lipids (hereafter referred to as GOCL) with suitable physical-chemical properties for gene delivery applications. To this end, nanosized GO flakes (nGO) were coated with the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) by microfluidic mixing. Comprehensive characterization of GOCL NPs was performed by a combination of dynamic light scattering (DLS), micro-electrophoresis and atom force microscopy (AFM). Our results show that GOCL NPs exhibit adequate size (<150 nm) and surface charge (ξ = +15 mV) for gene delivery purposes. Complexes made of GOCL NPs and plasmid DNA (pDNA) were used to transfect human cervical cancer cells (HeLa) and human embryonic kidney (HEK-293) cells. Pristine nGO and DOTAP cationic liposomes were used as a reference. GOCL NPs exhibited a similar TE but a much higher cell viability compared with DOTAP cationic liposomes. Confocal fluorescence microscopy provided a reasonable explanation for the superior performance of GOCL/DNA complexes showing that they are much more numerous, regular in size and homogeneously distributed than DOTAP/DNA complexes, thus splitting their gene payload over the entire cell population. Because of the imperative demand for efficient and safe nanocarriers, this study will contribute to the development of novel surface-functionalized GO-based hybrid gene vectors.