Cationic lipid-DNA complexes-lipoplexes-for gene transfer and therapy

3D-printed microfluidic device for high-throughput production of lipid nanoparticles incorporating SARS-CoV-2 spike protein mRNA

Lipid nanoparticles (LNPs) are drug carriers for protecting nucleic acids for cellular delivery. The first mRNA vaccines authorized by the United States Food and Drug Administration are the mRNA-1273 (Moderna) and BNT162b (BioNTech/Pfizer) vaccines against coronavirus disease 2019 (COVID-19). We designed a 3D printed Omnidirectional Sheath-flow Enabled Microfluidics (OSEM) device for producing mRNA-loaded LNPs that closely resemble the Moderna vaccine: we used the same lipid formulations to encapsulate mRNA encoding SARS-CoV-2 spike protein. The OSEM device is made of durable methacrylate-based materials that can support flow rates in the mL min-1 range and was fabricated by stereolithography (SLA), incorporating readily adaptable interfaces using commercial fluidic connectors. Two key features of the OSEM device are: 1) a 4-way hydrodynamic flow focusing region and 2) a staggered herringbone mixer (SHM). Superior to conventional planar fluid junctions, the 4-way sheath flow channel generates an evenly focused, circular center flow that facilitates the formation of LNPs with low polydispersity. Downstream, fluid mixing in the SHM is intensified by incorporating a zig-zag fluidic pathway to deliver high mRNA encapsulation efficiency. We characterized the mRNA-loaded LNPs produced in the OSEM device and showed that the enhanced 3D microfluidic structures enable a 5-fold higher throughput production rate (60 mL min-1) of LNPs compared to commercial multi-thousand-dollar micromixers. The device produced LNPs of diameter less than 90 nm, with low polydispersity (2-8%) and high mRNA encapsulation efficiency (>90%). The 3D-printed device provides a cost-effective and easily prepared solution for high-throughput LNP production.

Modulation of Phase Behavior and Microscopic Dynamics in Cationic Vesicles by 1-Decyl-3-methylimidazolium Bromide

Synthetic cationic lipids have garnered significant attention as promising candidates for gene/DNA transfection in therapeutic applications. The phase behavior of the vesicles formed by these lipids is intriguing, revealing intricate connections to the structure and dynamics of the membrane. These phenomena emerge from the complex interplay between hydrophobic and electrostatic interactions of the lipids. In this study, we explore the impact of an ionic liquid-based surfactant, 1-decyl-3-methylimidazolium bromide (DMIM[Br]), on the structural, dynamical, and phase behavior of cationic dihexadecyldimethylammonium bromide (DHDAB) vesicles. Our investigations indicate that the addition of DMIM[Br] increases the vesicle size while thinning the membrane. Further, DMIM[Br] also induces substantial changes in the membrane phase behavior. At 10 and 25 mol %, DMIM[Br] eliminates the pre-transition from coagel to intermediate crystalline (IC) phase and decreases the onset temperature of the main phase transition to the fluid phase. In the cooling cycle, the addition of DMIM[Br] further induces the formation of an intermediate gel phase. This behavior is reminiscent of the non-synchronous ordering observed in the DODAB membrane, a longer-chain counterpart of DHDAB. Interestingly, at 40 mol % of DMIM[Br], the formation of the intermediate gel phase is largely suppressed. Neutron scattering data provide evidence that the addition of DMIM[Br] enhances lipid mobility in coagel and fluid phases, suggesting that DMIM[Br] acts as a plasticizer, enhancing membrane fluidity across all of the phases. Our findings infer that DMIM[Br] modulates the membrane's phase behavior and fluidity, two essential ingredients for the efficient transport of cargo, by controlling the balance of electrostatic and hydrophobic interactions.

Review on Different Vesicular Drug Delivery Systems (VDDSs) and Their Applications

BACKGROUND

Colloidal dispersions, also known as vesicular drug delivery systems (VDDSs), are highly ordered assemblies composed of one or more concentric bilayers formed by the self-assembly of amphiphilic building blocks in the presence of water.

OBJECTIVE

VDDSs are important to target the entrapped drugs at specific sites inside the body, control the drug release, enhance the drug bioavailability, and reduce undesired side effects.

METHODS

There are different types of VDDSs suitable for the entrapment of both hydrophilic and lipophilic drugs. According to the patent composition, VDDSs are classified into lipid-based and nonlipid- based VDDSs.

RESULTS

There are different types of VDDSs which include liposomes, ethosomes, transferosomes, ufasomes, colloidosomes, cubosomes, niosomes, bilosomes, aquasomes, etc. Conclusion: This review article aims to address the different types of VDDSs, their advantages and disadvantages, and their therapeutic applications.

Liposomes: An emerging carrier for targeting Alzheimer's and Parkinson's diseases

The function of the brain can be affected by various factors that include infection, tumor, and stroke. The major disorders reported with altered brain function are Alzheimer's disease (AD), Parkinson's disease (PD), dementia, brain cancer, seizures, mental disorders, and other movement disorders. The major barrier in treating CNS disease is the blood-brain barrier (BBB), which protects the brain from toxic molecules, and the cerebrospinal fluid (CSF) barrier, which separates blood from CSF. Brain endothelial cells and perivascular elements provide an integrated cellular barrier, the BBB, which hamper the invasion of molecules from the blood to the brain. Even though many drugs are available to treat neurological disorders, it fails to reach the desired site with the required concentration. In this purview, liposomes can carry required concentrations of molecules intracellular by diverse routes such as carrier-mediated transport and receptor-mediated transcytosis. Surface modification of liposomes enables them to deliver drugs to various brain cells, including neurons, astrocytes, oligodendrocytes, and microglia. The research studies supported the role of liposomes in delivering drugs across BBB and in reducing the pathogenesis of AD and PD. The liposomes were surface-functionalized with various molecules to reach the cells intricated with the AD or PD pathogenesis. The targeted and sustained delivery of drugs by liposomes is disturbed due to the antibody formation, renal clearance, accelerated blood clearance, and complement activation-related pseudoallergy (CARPA). Hence, this review will focus on the characteristics, surface functionalization, drug loading, and biodistribution of liposomes respective to AD and PD. In addition, the alternative strategies to overcome immunogenicity are discussed briefly.

CT/bioluminescence dual-modal imaging tracking of stem cells labeled with Au@PEI@PEG nanotracers and RfLuc in nintedanib-assisted pulmonary fibrosis therapy

Mesenchymal stem cells (MSCs) are promising in idiopathic pulmonary fibrosis (IPF) therapy. However, low survival rate and ambiguous behavior of MSCs after transplantation impede their clinical translation. To this end, we have developed a new strategy to improve the survival rate and monitor the behavior of the transplanted MSCs simultaneously. In our strategy, nintedanib, a tyrosine kinase inhibitor, is employed to protect the human MSCs (hMSCs) from excessive oxidative stress responses and inflammatory environment in the damaged lung. Moreover, by labeling of the transplanted hMSCs with a computed tomography (CT) nanotracer, Au nanoparticles functionalized with polyethylenimine (PEI) and polyethylene glycol (PEG) (Au@PEI@PEG), in combination with red-emitting firefly luciferase (RfLuc), in vivo CT/bioluminescence (BL) dual-modal imaging tracking of the location, distribution, and survival of the transplanted hMSCs in presence of nintedanib were achieved, which facilitates the profound understanding of the role the stem cells play in IPF therapy.

Photothermal Transfection for Effective Nonviral Genome Editing

The efficient nonviral delivery of nucleic acids into the cytoplasm is needed to fully realize the potential of gene therapy. Although cationic lipids and nanoparticles have been widely used to improve the intracellular delivery of nucleic acids, they suffer from cytotoxicity and poor endosomal escape, thus limiting the transfection efficacy. Here, we developed a photothermal transfection platform for efficient and biosafe intracellular delivery of nucleic acids. Photothermal transfection was carried out by irradiation of cells co-treated with Lipofectamine-plasmid DNA complexes and PEGylated gold nanorods (GNRs) using an NIR laser for 30 min and subsequent incubation of the cells for 30 min without laser irradiation. Compared to conventional Lipofectamine-based transfection, our photothermal transfection platform significantly improved the transfection efficiency in difficult-to-transfect human primary cells including human dermal fibroblasts while maintaining the cell viability. The photothermal heating did not leave the GNRs inside the cell, thereby minimizing the cellular damage. Furthermore, the photothermal transfection platform showed superior genome editing abilities (both gene cleavage and insertion) in human dermal fibroblasts than conventional Lipofectamine-based transfection.

Improving Molecular Therapy in the Kidney

Mutations in approximately 80 genes have been implicated as the cause of various genetic kidney diseases. However, gene delivery to kidney cells from the blood is inefficient because of the natural filtering functions of the glomerulus, and research into and development of gene therapy directed toward kidney disease has lagged behind as compared with hepatic, neuromuscular, and ocular gene therapy. This lack of progress is in spite of numerous genetic mouse models of human disease available to the research community and many vectors in existence that can theoretically deliver genes to kidney cells with high efficiency. In the past decade, several groups have begun to develop novel injection techniques in mice, such as retrograde ureter, renal vein, and direct subcapsular injections to help resolve the issue of gene delivery to the kidney through the blood. In addition, the ability to retarget vectors specifically toward kidney cells has been underutilized but shows promise. This review discusses how recent advances in gene delivery to the kidney and the field of gene therapy can leverage the wealth of knowledge of kidney genetics to work toward developing gene therapy products for patients with kidney disease.

Mesenchymal Stem Cells Engineered by Nonviral Vectors: A Powerful Tool in Cancer Gene Therapy

Due to their "tumor homing" and "immune privilege" characteristics, the use of mesenchymal stem cells (MSCs) has been proposed as a novel tool against cancer. MSCs are genetically engineered in vitro and then utilized to deliver tumoricidal agents, including prodrugs and bioactive molecules, to tumors. The genetic modification of MSCs can be achieved by various vectors, and in most cases viral vectors are used; however, viruses may be associated with carcinogenesis and immunogenicity, restricting their clinical translational potential. As such, nonviral vectors have emerged as a potential solution to address these limitations and have gradually attracted increasing attention. In this review, we briefly revisit the current knowledge about MSC-based cancer gene therapy. Then, we summarize the advantages and challenges of nonviral vectors for MSC transfection. Finally, we discuss recent advances in the development of new nonviral vectors, which have provided promising strategies to overcome obstacles in the gene modulation of MSCs.

Extended-release of therapeutic microRNA via a host-guest supramolecular hydrogel to locally alleviate renal interstitial fibrosis

Activated fibroblasts are critical contributors to renal interstitial fibrosis thus becoming the cellular target for fibrosis treatment. Previously, microRNA 29 b (miR-29 b) is shown to be down-regulated in various animal models of renal fibrosis. Herein, we describe a facile strategy to achieve localized and sustained delivery of therapeutic microRNA to the kidney via a host-guest supramolecular hydrogel. Specifically, cationic bovine serum albumin is used to complex with miR-29 b to afford nanocomplexes (cBSA/miR-29 b), which is proven to specifically inhibit fibroblast activation in a dose-dependent manner in vitro. Following unilateral ureteral obstruction in mice, a single injection of the hydrogel loaded with cBSA/miR-29 b in vivo, significantly down-regulated proteins and genes related to fibrosis for up to 21 days without affecting the normal liver or kidney functions. Overall, the localized delivery of cBSA/miR-29 b via a host-guest supramolecular hydrogel represents a safe and effective intervention strategy to delay and reverse the progression of interstitial renal fibrosis.

Lipid nanovesicles for biomedical applications: 'What is in a name'?

Vesicles, generally defined as self-assembled structures formed by single or multiple concentric bilayers that surround an aqueous core, have been widely used for biomedical applications. They can either occur naturally (e.g. exosomes) or be produced artificially and range from the micrometric scale to the nanoscale. One the most well-known vesicle is the liposome, largely employed as a drug delivery nanocarrier. Liposomes have been modified along the years to improve physicochemical and biological features, resulting in long-circulating, ligand-targeted and stimuli-responsive liposomes, among others. In this process, new nomenclatures were reported in an extensive literature. In many instances, the new names suggest the emergence of a new nanocarrier, which have caused confusion as to whether the vesicles are indeed new entities or could simply be considered modified liposomes. Herein, we discussed the extensive nomenclature of vesicles based on the suffix "some" that are employed for drug delivery and composed of various types and proportions of lipids and others amphiphilic compounds. New names have most often been selected based on changes of vesicle lipid composition, but the payload, structural complexity (e.g. multicompartment) and new/improved proprieties (e.g. elasticity) have also inspired new vesicle names. Based on this discussion, we suggested a rational classification for vesicles.

Polymeric nano-carriers for on-demand delivery of genes via specific responses to stimuli

Polymeric nano-carriers have been developed as a most capable and feasible technology platform for gene therapy. As vehicles, polymeric nano-carriers are obliged to possess high gene loading capability, low immunogenicity, safety, and the ability to transfer various genetic materials into specific sites of target cells to express therapeutic proteins or block a process of gene expression. To this end, various types of polymeric nano-carriers have been prepared to release genes in response to stimuli such as pH, redox, enzymes, light and temperature. These stimulus-responsive nano-carriers exhibit high gene transfection efficiency and low cytotoxicity. In particular, dual- and multi-stimulus-responsive polymeric nano-carriers can respond to a combination of signals. Markedly, these combined responses take place either simultaneously or in a sequential manner. These dual-stimulus-responsive polymeric nano-carriers can control gene delivery with high gene transfection both in vitro and in vivo. In this review paper, we highlight the recent exciting developments in stimulus-responsive polymeric nano-carriers for gene delivery applications.

Tb-Doped core-shell-shell nanophosphors for enhanced X-ray induced luminescence and sensitization of radiodynamic therapy

The development of radiation responsive materials, such as nanoscintillators, enables a variety of exciting new theranostic applications. In particular, the ability of nanophosphors to serve as molecular imaging agents in novel modalities, such as X-ray luminescence computed tomography (XLCT), has gained significant interest recently. Here, we present a radioluminescent nanoplatform consisting of Tb-doped nanophosphors with an unique core/shell/shell (CSS) architecture for improved optical emission under X-ray excitation. Owing to the spatial confinement and separation of luminescent activators, these CSS nanophosphors exhibited bright optical luminescence upon irradiation. In addition to standard physiochemical characterization, these CSS nanophosphors were evaluated for their ability to serve as energy mediators in X-ray stimulated photodynamic therapy, also known as radiodynamic therapy (RDT), through attachment of a photosensitizer, rose bengal (RB). Furthermore, cRGD peptide was used as a model targeting agent against U87 MG glioblastoma cells. In vitro RDT efficacy studies suggested the RGD-CSS-RB in combination with X-ray irradiation could induce enhanced DNA damage and increased cell killing, while the nanoparticles alone are well tolerated. These studies support the utility of CSS nanophosphors and warrants their further development for theranostic applications.

Prussian blue nanoparticles: synthesis, surface modification, and biomedical applications

Prussian blue nanoparticles (PBNPs) are a nanomaterial that presents unique properties and an excellent biocompatibility. They can be synthesized in mild conditions and can be derivatized with polymers and/or biomolecules. PBNPs are used in biomedicine as therapy and diagnostic agents. In biomedical imaging, PBNPs constitute contrast agents in photoacoustic and magnetic resonance imaging (MRI). They are a good adsorbent to be used as antidotes for poisoning with cesium and/or thallium ions. Moreover, the ability to convert energy into heat makes them useful photothermal agents (PAs) in photothermal therapy (PTT) or as nonantibiotic substances with antibacterial properties. Finally, PBNPs can be both reduced to Prussian white and oxidized to Prussian green. A large window of redox potential exists between reduction and oxidation, which result in the enzyme-like characteristics of these NPs.

CT/Bioluminescence Dual-Modal Imaging Tracking of Mesenchymal Stem Cells in Pulmonary Fibrosis

Human mesenchymal stem cells (hMSCs), due to their immune regulation and collateral secretion effects, are currently explored for potential therapy of idiopathic pulmonary fibrosis (IPF). Understanding the migration, homing, functions, and survival of transplanted hMSCs in vivo is critical to successful IPF treatment. Therefore, it is highly desired to develop noninvasive and effective imaging technologies to track the transplanted hMSCs, providing experimental basis for improving the efficacy of hMSCs in the treatment of IPF. The rational design and development of a dual-labeling strategy are reported by integrating gold nanoparticle (AuNP)-based computed tomography (CT) nanotracers and red-emitting firefly luciferase (RfLuc)-based bioluminescence (BL) tags for CT/BL multimodal imaging tracking of the transplanted hMSCs in a murine model of IPF. In this approach, the CT nanotracer is prepared by sequential coupling of AuNPs with polyethylene glycol and trans-activator of transcription (TAT) peptide (Au@TAT), and employed it to monitor the location and distribution of the transplanted hMSCs in vivo by CT imaging, while RfLuc is used to monitor hMSCs viability by BLI. This facile strategy allows for visualization of the transplanted hMSCs in vivo, thereby enabling profound understanding of the role of hMSCs in the IPF treatment, and advancing stem cell-based regenerative medicine.

Synthesis and evaluation of mono- and multi-hydroxyl low toxicity pH-sensitive cationic lipids for drug delivery

Cationic lipids can easily assemble into spherical liposomes in aqueous phase which showed unique superiority in drug and gene delivery. However, the toxicity of cationic lipids is still an obstacle to application. To develop low toxicity cationic lipids, we designed two cationic lipids contained different number of hydroxyl groups. Biocompatible mono-hydroxyl and multi-hydroxyl galactose head group was respectively modified to a biodegradable quaternary amine lipid, and two novel hydroxyl cationic lipids were synthesized and characterized by MS, ¹H NMR and ¹³C NMR. Two lipids showed good surface activity and both of them can assemble to about 80 nm stable small unilamellar vesicles (SUVs) with cholesterol in aqueous phase. Both of lipids showed relatively lower toxicity than the well-known cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). In vitro 24 h IC₅₀ of two assemblies were more than 50 μg/mL, which were about 10 μg/mL higher than the IC₅₀ of DOTAP. Multi-hydroxyl galactose lipids group showed much lower toxicity than mono-hydroxyl lipids group. Moreover, Both of the assemblies with lower hemolysis were nearly non-hemolytic risk under the concentration of 30 μg/mL. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) showed that the average sizes of both doxorubicin (DOX) loaded liposomes were about 110 nm. The DOX entrapment efficiencies of galactose liposome and mono-hydroxyl liposome were 58% and 91%, respectively. Both of the DOX loaded liposomes were stable after one month placed at room temperature. Two DOX loaded liposomes showed better anti-cancer effect than free DOX above 5 μg/mL, and they can be internalized into cells and produce more release of DOX inside MCF-7 cells and HepG2 cells at pH 5.0. These results suggested that synthesized lipids are suitable as potential low toxicity cationic drug delivery systems.

Non-viral nanocarriers for intracellular delivery of microRNA therapeutics

MicroRNAs are small regulatory noncoding RNAs that regulate various biological processes. Herein, we will present the development of the strategies for intracellular miRNAs delivery, and specially focus on the rational designed routes, their mechanisms of action, as well as potential therapeutics used in the host cells orin vivostudies.

α-Tocopherol-ascorbic acid hybrid antioxidant based cationic amphiphile for gene delivery: Design, synthesis and transfection

Natural antioxidants and vitamins have potential to protect biological systems from peroxidative damage induced by peroxyl radicals, α-tocopherol (Vitamin E, lipid soluble) and ascorbic acid (vitamin C, water soluble), well known natural antioxidant molecules. In the present study we described the synthesis and biological evaluation of hybrid of these two natural antioxidants with each other via ammonium di-ethylether linker, Toc-As in gene delivery. Two control cationic lipids N14-As and Toc-NOH are designed in such a way that one is with ascorbic acid moiety and no tocopherol moiety; another is with tocopherol moiety and no ascorbic acid moiety respectively. All the three cationic lipids can form self-assembled aggregates. The antioxidant efficiencies of the three lipids were compared with free ascorbic acid. The cationic lipids (Toc-As, N14-As and Toc-NOH) were formulated individually with a well-known fusogenic co-lipid DOPE and characterization studies such as DNA binding, heparin displacement, size, charge, circular dichroism were performed. The biological characterization studies such as cell viability assay and in vitro transfection studies were carried out with the above formulations in HepG2, Neuro-2a, CHO andHEK-293T cell lines. The three formulations showed their transfection efficiencies with highest in Toc-As, moderate inN14-As and least in Toc-NOH. Interestingly, the transfection efficiency observed with the antioxidant based conjugated lipid Toc-As is found to be approximately two and half fold higher than the commercially available lipofectamine 2000 at 4:1 charge ratio in Hep G2 cell lines. In the other cell lines studied the efficiency of Toc-As is found to be either higher or similarly active compared to lipofectamine 2000. The physicochemical characterization results show that Toc-As lipid is showing maximum antioxidant potency, strong binding with pDNA, least size and optimal zeta potential. It is also found to be least toxic in all the cell lines studied especially in Neuro-2a cell lines when compared to other two lipids. In summary, the designed antioxidant lipid can be exploited as a delivering system for treating ROS related diseases such as malignancy, brain stroke, etc.

Photoacoustic Imaging of Human Mesenchymal Stem Cells Labeled with Prussian Blue-Poly(l-lysine) Nanocomplexes

Acoustic imaging is affordable and accessible without ionizing radiation. Photoacoustic imaging increases the contrast of traditional ultrasound and can offer good spatial resolution when used at high frequencies with excellent temporal resolution. Prussian blue nanoparticles (PBNPs) are an emerging photoacoustic contrast agent with strong optical absorption in the near-infrared region. In this study, we developed a simple and efficient method to label human mesenchymal stem cells (hMSCs) with PBNPs and imaged them with photoacoustic imaging. First, PBNPs were synthesized by the reaction of FeCl₃ with K₄[Fe(CN)₆] in the presence of citric acid and complexed with the cationic transfection agent poly-l-lysine (PLL). The PLL-coated PBNPs (PB-PLL nanocomplexes) have a maximum absorption peak at 715 nm and could efficiently label hMSCs. Cellular uptake of these nanocomplexes was studied using bright field, fluorescence, and transmission electron microscopy. The labeled stem cells were successfully differentiated into two downstream lineages of adipocytes and osteocytes, and they showed positive expression for surface markers of CD73, CD90, and CD105. No changes in viability or proliferation of the labeled cells were observed, and the secretome cytokine analysis indicated that the expression levels of 12 different proteins were not dysregulated by PBNP labeling. The optical properties of PBNPs were preserved postlabeling, suitable for the sensitive and quantitative detection of implanted cells. Labeled hMSCs exhibited strong photoacoustic contrast in vitro and in vivo when imaged at 730 nm, and the detection limit was 200 cells/μL in vivo. The photoacoustic signal increased as a function of cell concentration, indicating that the number of labeled cells can be quantified during and after cell transplantations. In hybrid ultrasound/photoacoustic imaging, this approach offers real-time and image-guided cellular injection even through an intact skull for brain intraparenchymal injections. Our labeling and imaging technique allowed the detection and monitoring of 5 × 10⁴ mesenchymal stem cells in living mice over a period of 14 days.

Novel siRNA formulation to effectively knockdown mutant p53 in osteosarcoma

Objectives

The tumor suppressor p53 plays a crucial role in the development of osteosarcoma. The primary objective of this study is to develop and optimize lipid based nanoparticle formulations that can carry siRNA and effectively silence mutant p53 in 318–1, a murine osteosarcoma cell line.

Methods

The nanoparticles were composed of a mixture of two lipids (cholesterol and DOTAP) and either PLGA or PLGA-PEG and prepared by using an EmulsiFlex-B3 high pressure homogenizer. A series of studies that include using different nanoparticles, different amount of siRNAs, cell numbers, incubation time, transfection media volume, and storage temperature was performed to optimize the gene silencing efficiency.

Key findings

Replacement of lipids by PLGA or PLGA-PEG decreased the particle size and overall cytotoxicity. Among all lipid-polymer nanoformulations, nanoparticles with 10% PLGA showed highest mutant p53 knockdown efficiency while maintaining higher cell viability when a nanoparticle to siRNA ratio equal to 6.8:0.66 and 75 nM siRNA was used. With long term storage the mutant p53 knockdown efficiency decreased to a greater extent.

Conclusions

This study warrants a future evaluation of this formulation for gene silencing efficiency of mutant p53 in tissue culture and animal models for the treatment of osteosarcoma.

A comparison of plasmid DNA delivery efficiency and cytotoxicity of two cationic diblock polyoxazoline copolymers

Cationic polymers as non-viral gene delivery carriers are widely used because of their strong condensing properties and long-term safety, but acute cytotoxicity is a persistent challenge. In this study, two types of polyplexes were prepared by co-formulating plasmid DNA and two cationic diblock copolymers PABOXA₅-b-PMOXA₃₃-PA (primary amine) and PABOXA₅-b-PMOXA₃₃-TA (tertiary amine) to check their transfection efficacies in HeLa cells and HEK293T cells, respectively. The plasmid DNA/PABOXA₅-b-PMOXA₃₃-PA polyplex showed higher transfection efficacy compared to the plasmid DNA/PABOXA₅-b-PMOXA₃₃-TA polyplex under an N/P ratio of 40. Both polymers exhibited low toxicity, attributed to the shielding effect of a hydrophilic, noncharged block. Mechanistic insight into differential transfection efficiencies of the polymers were gained by visualization and comparison of the condensates via transmission electron and atomic force microscopy. The results provide information suited for further structure optimization of polymers that are aimed for targeted gene delivery.

In Vivo Micro-CT Imaging of Human Mesenchymal Stem Cells Labeled with Gold-Poly-L-Lysine Nanocomplexes

Developing in vivo cell tracking is an important prerequisite for further development of cell-based therapy. So far, few computed tomography (CT) cell tracking studies have been described due to its notoriously low sensitivity and lack of efficient labeling protocols. We present a simple method to render human mesenchymal stem cells (hMSCs) sufficiently radiopaque by complexing 40 nm citrate-stabilized gold nanoparticles (AuNPs) with poly-L-lysine (PLL) and rhodamine B isothiocyanate (RITC). AuNP-PLL-RITC labeling did not affect cellular viability, proliferation, or downstream cell differentiation into adipocytes and osteocytes. Labeled hMSCs could be clearly visualized in vitro and in vivo with a micro-CT scanner, with a detection limit of approximately 2×104 cells/μl in vivo. Calculated HU values were 2.27 /pg of intracellular Au as measured with inductively coupled plasma mass spectrophotometry (ICP-MS), and were linear over a wide range of cell concentrations. This linear CT attenuation was observed for both naked AuNPs and those that were taken up by hMSCs, indicating that the number of labeled cells can be quantified similar to the use of radioactive or fluorine tracers. This approach for CT cell tracking may find applications in CT image-guided interventions and fluoroscopic procedures commonly used for the injection of cellular therapeutics.

Ligand-Modified Human Serum Albumin Nanoparticles for Enhanced Gene Delivery

The development of nonviral gene delivery systems is a great challenge to enable safe gene therapy. In this study, ligand-modified nanoparticles based on human serum albumin (HSA) were developed and optimized for an efficient gene therapy. Different glutaraldehyde cross-linking degrees were investigated to optimize the HSA nanoparticles for gene delivery. The peptide sequence arginine-glycine-aspartate (RGD) and the HIV-1 transactivator of transduction sequence (Tat) are well-known as promising targeting ligands. Plasmid DNA loaded HSA nanoparticles were covalently modified on their surface with these different ligands. The transfection potential of the obtained plasmid DNA loaded RGD- and Tat-modified nanoparticles was investigated in vitro, and optimal incubation conditions for these preparations were studied. It turned out that Tat-modified HSA nanoparticles with the lowest cross-linking degree of 20% showed the highest transfection potential. Taken together, ligand-functionalized HSA nanoparticles represent promising tools for efficient and safe gene therapy.

A delocalizable cationic headgroup together with an oligo-oxyethylene spacer in gemini cationic lipids improves their biological activity as vectors of plasmid DNA

Lipoplexes of plasmid DNA and mixed liposomes, with a gemini cationic lipid of the 1,2-bis(hexadecyl imidazolium) oxyethylene series, improves their biological activity.

Flexible cyclic siloxane core enhances the transfection efficiency of polyethylenimine-based non-viral gene vectors

cD₄^H–AGE–PEI conjugates, with a favorable balance between hydrophilic and hydrophobic moieties, are promising carriers for gene delivery.

Nanoparticle-mediated systemic delivery of siRNA for treatment of cancers and viral infections

RNA interference (RNAi) is an endogenous post-transcriptional gene regulatory mechanism, where non-coding, double-stranded RNA molecules interfere with the expression of certain genes in order to silence it. Since its discovery, this phenomenon has evolved as powerful technology to diagnose and treat diseases at cellular and molecular levels. With a lot of attention, short interfering RNA (siRNA) therapeutics has brought a great hope for treatment of various undruggable diseases, including genetic diseases, cancer, and resistant viral infections. However, the challenge of their systemic delivery and on how they are integrated to exhibit the desired properties and functions remains a key bottleneck for realizing its full potential. Nanoparticles are currently well known to exhibit a number of unique properties that could be strategically tailored into new advanced siRNA delivery systems. This review summarizes the various nanoparticulate systems developed so far in the literature for systemic delivery of siRNA, which include silica and silicon-based nanoparticles, metal and metal oxides nanoparticles, carbon nanotubes, graphene, dendrimers, polymers, cyclodextrins, lipids, hydrogels, and semiconductor nanocrystals. Challenges and barriers to the delivery of siRNA and the role of different nanoparticles to surmount these challenges are also included in the review.

Design and application of multifunctional DNA nanocarriers for therapeutic delivery

The unique programmability of nucleic acids offers versatility and flexibility in the creation of self-assembled DNA nanostructures. To date, many three-dimensional DNA architectures of varying sizes and shapes have been precisely formed. Their biocompatibility, biodegradability and high intrinsic stability in physiological environments emphasize their emerging use as carriers for drug and gene delivery. Furthermore, DNA nanocarriers have been shown to enter cells efficiently and without the aid of transfection reagents. A key strength of DNA nanocarriers over other delivery systems is their modularity and their ability to control the spatial distribution of cargoes and ligands. Optimizing DNA nanocarrier properties to dictate their localization, uptake and intracellular trafficking is also possible. This review presents design considerations for DNA nanocarriers and examples of their use in the context of therapeutic delivery applications. The assembly of DNA nanocarriers and approaches for loading and releasing cargo are described. The stability and safety of DNA nanocarriers are also discussed, with particular attention to the in vivo physiological environment. Mechanisms of cellular uptake and intracellular trafficking are examined, and the paper concludes with strategies to enhance the delivery efficiency of DNA nanocarriers.

Enhanced hepatic delivery of siRNA and microRNA using oleic acid based lipid nanoparticle formulations

Many cationic lipids have been developed for lipid-based nanoparticles (LNPs) for delivery of siRNA and microRNA (miRNA). However, less attention has been paid to "helper lipids". Here, we investigated several "helper lipids" and examined their effects on the physicochemical properties such as particle size and zeta potential, as well as cellular uptake and transfection efficiency. We found that inclusion of oleic acid (OA), an unsaturated fatty acid, into the LNP formulation significantly enhanced the delivery efficacy for siRNA and miRNA. For proof-of-concept, miR-122, a liver-specific microRNA associated with many liver diseases, was used as a model agent to demonstrate the hepatic delivery efficacy both in tumor cells and in animals. Compared to Lipofectamine 2000, a commercial transfection agent, LNPs containing OA delivered microRNA-122 in a more efficient manner with a 1.8-fold increase in mature miR-122 expression and a 20% decrease in Bcl-w, a target of microRNA-122. In comparison with Invivofectamine, a commercial transfection agent specifically designed for hepatic delivery, LNPs containing OA showed comparable liver accumulation and in vivo delivery efficiency. These findings demonstrated the importance of "helper lipid" components of the LNP formulation on the cellular uptake and transfection activity of siRNA and miRNA. LNPs containing OA is a promising nanocarrier system for the delivery of RNA-based therapeutics in liver diseases.

Preparation of lipid:peptide:DNA (LPD) nanoparticles and their use for gene transfection

Therapeutic gene delivery systems offer the potential for the treatment of a range of inherited and acquired inherited diseases. In contrast with viral gene vectors, the nonviral gene vectors provide a safer alternative and additional advantage such as the improved delivery efficiency, low cost, and often unlimited capacity to package DNA. Here we describe preparation of nonviral gene delivery technique based on lipid:peptide:DNA (LPD) complexes. The size of LPD particles is in the nanometre range. The use of these nanoparticulate LPDs results in high efficiency transfections and a high level of gene expression in vitro. LPDs provide a convenient and efficient tool for gene therapy for the gene delivery.

We still have a long way to go to effectively deliver genes!

Gene therapy is emerging as a revolutionary alternative to conventional therapeutic approaches. However, its clinical application is still hampered by the lack of safe and effective gene delivery techniques. Among the plethora of diverse approaches used to ferry nucleic acids into target cells, non-viral vectors represent promising and safer alternatives to viruses and physical techniques. Both cationic lipids and polymers spontaneously wrap and shrink the genetic material in complexes named lipoplexes and polyplexes, respectively, thereby protecting it and shielding its negative charges. The development of non-viral vectors commenced more than two decades ago. Since then, some major classes of interesting molecules have been identified and modified to optimize their properties. However, the way towards the final goal of gene delivery, i.e. protein expression or gene silencing, is filled with obstacles and current non-viral carriers still have concerns about their overall efficiency. We strongly believe that the future of non-viral gene delivery relies on the development of multifunctional vectors specifically tailored with diverse functionalities that act more like viruses. Although these vectors are still a long way from clinical practice they are the ideal platform to effectively shuttle the genetic material to target cells in a safe and controlled way. In this review, after briefly introducing the basis of gene delivery and therapeutic applications we discuss the main polymeric and lipidic vectors utilized for gene delivery, focusing on the strategies adopted to overcome the major weaknesses inherent to their still limited activity, on the way towards ideal multifunctional vectors.

Lipid-based vectors for siRNA delivery

siRNA therapeutics has developed rapidly and already there are clinical trials ongoing or planned; however, the delivery of siRNA into cells, tissues or organs remains to be a major obstacle. Lipid-based vectors hold the most promising position among non-viral vectors, as they have a similar structure to cell or organelle membranes. But when used in the form of liposomes, these vectors have shown some problems. Therefore, either the nature of lipids themselves or forms used should be improved. As a novel class of lipid like materials, lipidoids have the advantages of easy synthesis and the ability for delivering siRNA to obtain excellent silencing activity. However, the toxicities of lipidoids have not been thoroughly studied. pH responsive lipids have also gained great attention recently, though some of the amine-based lipids are not novel in terms of chemical structures. More complex self-assembly structures, such as LPD (LPH) and LCP, may provide a good solution to siRNA delivery. They have demonstrated controlled particle morphology and size and siRNA delivery activity for both in vitro and in vivo.

Anion complexation and transport by isophthalamide and dipicolinamide derivatives: DNA plasmid transformation in E. coli

Tris-arenes based on either isophthalic acid or 2,6-dipicolinic acid have been known for more than a decade to bind anions. Recent studies have also demonstrated their ability to transport various ions through membranes. In this report, we demonstrate two important properties of these simple diamides. First, they transport plasmid DNA into Escherichia coli about 2-fold over controls, where the ampicillin resistance gene is expressed in the bacteria. These studies were done with plasmid DNA (~2.6 kilobase (kb)) in JM109 E. coli cells. Second, known methods do not typically transport large plasmids (>15 kb). We demonstrate here that transformation of large pVIB plasmids (i.e., >20 kb) were enhanced over water controls by ~10-fold. These results are in striking contrast to the normal decrease in transformation with increasing plasmid size.

Novel neo glycolipid: formulation into pegylated cationic liposomes and targeting of DNA lipoplexes to the hepatocyte-derived cell line HepG2

Liver parenchymal cells are an important target for the treatment of several metabolic and viral disorders. Corrective gene delivery for this purpose is an avenue that is receiving increasing attention. In the present study, we report a novel neo glycolipid that may be formulated into cationic liposomes with or without poly(ethylene glycol) decoration. Lipoplexes formed with plasmid DNA are nuclease resistant and are targeted to the human hepatoblastoma cell line HepG2 by selective asialoglycoprotein receptor mediation. Transfection levels achieved by lipoplexes containing the targeting ligand cholesteryl-3β-N-(4-aminophenyl-β-D-galactopyranosyl) carbamate were sixfold greater than those obtained with similar but untargeted lipoplexes.

Efficient inhibition of ovarian cancer by recombinant CXC chemokine ligand 10 delivered by novel biodegradable cationic heparin-polyethyleneimine nanogels

Currently, great interest is focused on the anti-neoplastic effects of CXC chemokine ligand 10 (IP-10/CXCL10). IP-10 has shown significant antitumor and anti-metastatic properties via immunological, antiangiogenic and anti-neoplastic mechanisms. However, very few studies on the antitumor activity of IP-10 in human ovarian cancer have been reported. The use of polymeric nanoparticles to deliver functional genes intraperitoneally holds much promise as an effective therapy for ovarian cancer. In our study, a recombinant plasmid expressing IP-10 (pVITRO-IP-10) was constructed, and biodegradable cationic heparin-polyethyleneimine (HPEI) nanogels were prepared to deliver pVITRO-IP-10 into SKOV3 human ovarian cancer cells. Transfection efficiency was detected by expression profiling of green fluorescent protein. The expression of IP-10 was determined using RT-PCR and western blot analysis. In vitro, cell proliferation was evaluated by MTT assay. Apoptosis was examined by Hoechst33258/PI staining and flow cytometry assays. The effect on the inhibition of angiogenesis was evaluated by tube formation assay using human umbilical vein endothelial cells (HUVECs). Moreover, a SKOV3 intraperitoneal ovarian carcinomatosis model was established to investigate the antitumor activity of HPEI+pVITRO-IP-10 complexes in nude mice. Tumor weights were evaluated during the treatment course. Cell proliferation and apoptosis were evaluated by Ki-67 immunochemical staining and TUNEL assay, and the antiangiogenic effect of pVITRO-IP-10 was assessed by CD31 immunochemical staining and alginate-encapsulated tumor cell assay. pVITRO-IP-10 was efficiently transfected into SKOV3 cells by HPEI nanogels. Intraperitoneal administration of HPEI+pVITRO-IP-10 complexes led to effective growth inhibition of ovarian cancer, in which tumor weight decreased by ~69.92% in the treatment group compared with that in the empty vector control group. Meanwhile, decreased cell proliferation, increased tumor cell apoptosis and reduction in angiogenesis were observed in the HPEI+pVITRO-IP-10 group compared with those in the control groups. These results indicated that HPEI nanogel delivery of pVITRO-IP-10 may be of value in the treatment against human ovarian cancer.

A one-step process in preparation of cationic nanoparticles with poly(lactide-co-glycolide)-containing polyethylenimine gives efficient gene delivery

A one-step preparation of nanoparticles with poly(lactide-co-glycolide) (PLGA) pre-modified with polyethylenimine (PEI) is better in requirements for DNA delivery compared to those prepared in a two-step process (preformed PLGA nanoparticles and subsequently coated with PEI). The particles were prepared by emulsification of PLGA/ethyl acetate in an aqueous solution of PVA and PEI. DLS, AFM and SEM were used for the size characteristics. The cytotoxicity of PLGA/PEI nanoparticles was detected by MTT assay. The transfection activity of the particles was measured using pEGFP and pβ-gal plasmid DNA. Results showed that the PLGA/PEI nanoparticles were spherical and non-porous with a size of about 0.2 μm and a small size distribution. These particles had a positive zeta potential demonstrating that PEI was attached. Interestingly, the zeta potential of the particles (from one-step procedure) was substantially higher than that of two-step process and is ascribed to the conjugation of PEI to PLGA via aminolysis. The PLGA/PEI nanoparticles were able to bind DNA and the formed complexes had a substantially lower cytotoxicity and a higher transfection activity than PEI polyplexes. In conclusion, given their small size, stability, low cytotoxicity and good transfection activity, PLGA/PEI-DNA complexes are attractive gene delivery systems.