Cationic lipids and polymers mediated vectors for delivery of siRNA

Poly(2-(diethylamino)ethyl methacrylate)-Functionalized Carbon Nanodots as Theranostic Platforms for siRNA Delivery and Survivin Silencing in Triple-Negative Breast Cancer

This study describes the development of carbon nanodot (CDs)-based theranostic nanocarriers that integrate gene silencing with fluorescence imaging. Nitrogen- and sulfur-doped CDs were functionalized through controlled radical surface polymerization of 2-(diethylamino)ethyl methacrylate (DEAEMA), yielding self-tracking, cationic siRNA carriers CDs-pDEAEMA. The functionalization of CDs enhanced their fluorescence, broadening the emission spectrum toward the biologically transparent window. Fluorescent CDs-pDEAEMA effectively bound siRNA, remaining stable under physiological conditions, while in vitro studies proved their hemocompatibility and cytocompatibility on human dermal fibroblasts. Moreover, the ability to deliver BIRC5 siRNA was demonstrated in MDA-MB-231, successfully transfecting triple-negative breast cancer cells and resulting in an 80% reduction in the anti-apoptotic protein survivin. Furthermore, uptake studies demonstrated that the theranostic CDs are efficiently internalized in tumor cells and are clearly detectable by fluorescence imaging in the red region. These findings highlight the potential of CDs-pDEAEMA as an advanced theranostic tool for real-time tracking of siRNA therapy of breast cancer.

Unveiling the Interaction Mechanism of siRNA with Lipid Bilayers of Different Types for siRNA-Based Therapy

siRNA-based therapy is a new approach for the treatment of diseases, including cancer, viral infections, and so forth. When liposomes serve as an effective siRNA carrier, unveiling the siRNA-liposome interaction mechanism becomes extremely significant for siRNA-based therapy. Here, we investigate the interactions between siRNA and liposomes with different types of lipid molecules and find that the stable adsorption of siRNA on the phosphoethanolamine (PE) bilayer liposome mainly relies on hydrogen bonding between the siRNA phosphate groups and the ethanolamine structure of PE lipid molecules. On the contrary, the stability of the adsorption of siRNA on the phosphorylcholine (PC) bilayer liposome is often determined by electrostatic interactions, and the adsorption stability can be modulated by calcium ions. The concept of "bridging" is also invoked to reveal the adsorption mechanism of siRNA on the lipid bilayer after adding calcium ions. We found that adding divalent calcium ions can better regulate the stability of siRNA adsorption on the PC lipid bilayer, but calcium ions cannot regulate the adsorption of siRNA on the PE lipid bilayer, which is determined by H-bonds. In short, this work reveals the different adsorption mechanisms of siRNA on liposomes, which provides a physical insight into siRNA-based therapy at the molecular level.

Enhancing Gene Therapy through Ultradeformable Vesicles for Efficient siRNA Delivery

Gene therapy is a revolutionary approach aimed at treating various diseases by manipulating the expression of specific genes. The composition and formulation of ultra-deformable vesicles play a crucial role in determining their properties and performance as siRNA delivery vectors. In the development of ultra-deformable vesicles for siRNA delivery, careful lipid selection and optimization are crucial for achieving desirable vesicle characteristics and efficient siRNA encapsulation and delivery. The stratum corneum acts as a protective barrier, limiting the penetration of molecules, including siRNA, into the deeper layers of the skin. Ultradeformable vesicles offer a promising solution to overcome this barrier and facilitate efficient siRNA delivery to target cells in the skin. The stratum corneum, the outermost layer of the skin, acts as a significant barrier to the penetration of siRNA.These engineering approaches enable the production of uniform and well-defined vesicles with enhanced deformability and improved siRNA encapsulation efficiency. Looking ahead, advancements in ultra-deformable vesicle design and optimization, along with continued exploration of combination strategies and regulatory frameworks, will further drive the field of ultra-deformable vesicle-based siRNA delivery.

Comparison of Cell-Penetrating and Fusogenic TAT-HA2 Peptide Performance in Peptideplex, Multicomponent, and Conjugate siRNA Delivery Systems

In this study, the performance of the cell-penetrating and fusogenic peptide, TAT-HA2, which consists of a cell-permeable HIV trans-activator of transcription (TAT) protein transduction domain and a pH-responsive influenza A virus hemagglutinin protein (HA2) domain, was comparatively evaluated for the first time in peptideplex, multicomponent, and conjugate siRNA delivery systems. TAT-HA2 in all three systems protected siRNA from degradation, except in the conjugate system with a low Peptide/siRNA ratio. The synergistic effect of different peptide domains enhanced the transfection efficiency of multicomponent and conjugate systems compared to that of peptideplexes, which was attributed to the surface configuration of TAT-HA2 peptides depending on the nature of attachment. Particularly, the multicomponent system showed better cellular uptake and endosomal escape than the peptideplexes, resulting in enhanced siRNA delivery in the cytoplasm. In addition, the presence of cleavable disulfide bonds in multicomponent and conjugate systems promoted the effective siRNA delivery in the cytoplasm, resulting in improved gene silencing activity. The multicomponent system reduced the level of luciferase expression in SKOV3 cells to 45% (±4). In contrast, the conjugate system and the commercially available siRNA transfection agent, Lipofectamine RNAiMax, caused luciferase suppression down to 55% (±2) at a siRNA dose of 100 nM. For the same dose, the peptideplex system could only reduce the luciferase expression to 65% (±5). None of the developed systems showed significant toxicity at any dose. Overall, the TAT-HA2 peptide is promising as a siRNA delivery vector; however, its performance depends on the nature of attachment and, as a result, its surface configuration on the developed delivery system.

Co-delivery of Interferon Regulatory Factor 5 (IRF5) siRNA and dasatinib by a disulfide bond bearing polymeric carrier for enhanced anti-inflammatory effects

Co-delivery of chemical drugs and nucleic acids has attracted a great interest recently for treatment of inflammatory diseases. Dasatinib (DB), a tyrosine kinase inhibitor with anti-cancer effects, and Interferon Regulatory Factor 5 (IRF5) siRNA have shown anti-inflammatory effects. In the present study, a novel redox-responsive polymeric micelle was designed for co-delivery of DB and IRF5 siRNA-expressing plasmid (psiRF5) to enhance anti-inflammatory effects on macrophages. psiRF5 was condensed efficiently to redox-responsive micelles of DB-conjugated chitosan (CN) composed of disulfide bond, from different molecular weights of CN to form CN-SS-DB/psiRF5 micelles. The micelles with optimum N/P ratios had particle sizes of 287.8 and 245.4 nm and positive zeta potentials. The disulfide bond bearing micelles showed a redox-responsive drug release, protected the plasmid from being dissociated or degraded in exposure with heparin, serum and DNase I, and significantly enhanced the transfection efficiency and IRF5-gene silencing compared to naked psiRF5. The optimum micelles exhibited a dramatic reduction in IRF5 expression and revealed a notably higher anti-inflammatory effect than either DB or psiRF5, as indicated by more IL-10 and less IL-6 and TNF-α production by LPS-stimulated RAW264.7 macrophages incubated with the co-delivery system. The resultant nanocarriers might be promising for more effective treatment of inflammatory diseases.

Impact of Peptide Sequence on Functional siRNA Delivery and Gene Knockdown with Cyclic Amphipathic Peptide Delivery Agents

Short-interfering RNA (siRNA) oligonucleotide therapeutics that modify gene expression by accessing RNA-interference (RNAi) pathways have great promise for the treatment of a range of disorders; however, their application in clinical settings has been limited by significant challenges in cellular delivery. Herein, we report a structure-function study using a series of modified cyclic amphipathic cell-penetrating peptides (CAPs) to determine the impact of peptide sequence on (1) siRNA-binding efficiency, (2) cellular delivery and knockdown efficiency, and (3) the endocytic uptake mechanism. Nine cyclic peptides of the general sequence Ac-C[XZ]4CG-NH2 in which X residues are hydrophobic/aromatic (Phe, Tyr, Trp, or Leu) and Z residues are charged/hydrophilic (Arg, Lys, Ser, or Glu) are assessed along with one acyclic peptide, Ac-(WR)4G-NH2. Cyclization is enforced by intramolecular disulfide bond formation between the flanking Cys residues. Binding analyses indicate that strong cationic character and the presence of aromatic residues that are competent to participate in CH-π interactions lead to CAP sequences that most effectively interact with siRNA. CAP-siRNA binding increases in the following order as a function of CAP hydrophobic/aromatic content: His < Phe < Tyr < Trp. Both cationic charge and disulfide-constrained cyclization of CAPs improve uptake of siRNA in vitro. Net neutral CAPs and an acyclic peptide demonstrate less-efficient siRNA translocation compared to the cyclic, cationic CAPs tested. All CAPs tested facilitated efficient siRNA target gene knockdown of at least 50% (as effective as a lipofectamine control), with the best CAPs enabling >80% knockdown. Significantly, gene knockdown efficiency does not strongly correlate with CAP-siRNA internalization efficiency but moderately correlates with CAP-siRNA-binding affinity. Finally, utilization of small-molecule inhibitors and targeted knockdown of essential endocytic pathway proteins indicate that most CAP-siRNA nanoparticles facilitate siRNA delivery through clathrin- and caveolin-mediated endocytosis. These results provide insight into the design principles for CAPs to facilitate siRNA delivery and the mechanisms by which these peptides translocate siRNA into cells. These studies also demonstrate the nature of the relationships between peptide-siRNA binding, cellular delivery of siRNA cargo, and functional gene knockdown. Strong correlations between these properties are not always observed, which illustrates the complexity in the design of optimal next-generation materials for oligonucleotide delivery.

Delivery of siRNA using cationic rosette nanotubes for gene silencing

The quest for new therapeutic treatments for hereditary diseases has led to many advances in RNA interference (RNAi) and gene silencing. While this technique has the potential to address many problems, the key to its continued use is the development of effective delivery strategies that would reduce cellular toxicity and increase silencing efficiency. Rosette nanotubes (RNTs) are biomimetic supramolecular nanostructures formed through the self-assembly of hybrid guanine-cytosine (G∧C) DNA bases. Here, we used bioactive RNTs for siRNA delivery and gene silencing. Fifteen lysine-functionalized twin-G∧C motifs (KnT, n = 1 to 15) were synthesized using solid phase peptide synthesis to produce building blocks that self-assembled to produce cationic RNTs under physiological conditions. The intracellular uptake of siRNA delivered by the oligo-L-lysine RNTs was examined and it was found that the complexation of siRNA was affected by the cationic charges from the lysine residues and the length of RNTs formed, with the higher charged KnT RNTs delivering siRNA to the cells at a faster rate. In addition, by protecting siRNA from serum degradation, KnT RNTs were shown to deliver their cargo to the cells effectively via the endocytic pathway. A reduction in the expression (∼70%) of the target stat3 protein was observed during gene expression analysis in HCT116 and A549 cell lines.

Light controlled self-escape capability of non-cationic carbon nitride-based nanosheets in lysosomes for hepatocellular carcinoma targeting stimulus-responsive gene delivery

High positive charge-induced toxicity, easy lysosomal degradation of nucleic acid drugs, and poor lesion sites targeting are major problems faced in the development of gene carriers. Herein, we proposed the concept of self-escape non-cationic gene carriers for targeted delivery and treatment of photocontrolled hepatocellular carcinoma (HCC) with sufficient lysosome escape and multiple response capacities. Functional DNA was bound to the surface of biotin-PEG2000-modified graphitic carbon nitride (Bio-PEG-CN) nanosheets to form non-cationic nanocomplexes Bio-PEG-CN/DNA. These nanocomposites could actively target HCC tissue. Once these nanocomplexes were taken up by tumor cells, the accumulated reactive oxygen species (ROS) generated by Bio-PEG-CN under LED irradiation would disrupt the lysosome structure, thereby facilitating nanocomposites escape. Due to the acidic microenvironment and lipase in the HCC tissue, the reversible release of DNA could be promoted to complete the transfection process. Meanwhile, the fluorescence signal of Bio-PEG-CN could be monitored in real time by fluorescence imaging technology to investigate the transfection process and mechanism. In vitro and in vivo results further demonstrated that these nanocomplexes could remarkably upregulate the expression of tumor suppressor protein P53, increased tumor sensitivity to ROS generated by nanocarriers, and realized effective gene therapy for HCC via loading P53 gene.

Amphiphilic Polypeptides Obtained by Post-Polymerization Modification of Poly-l-Lysine as Systems for Combined Delivery of Paclitaxel and siRNA

The development of effective anti-cancer therapeutics remains one of the current pharmaceutical challenges. The joint delivery of chemotherapeutic agents and biopharmaceuticals is a cutting-edge approach to creating therapeutic agents of enhanced efficacy. In this study, amphiphilic polypeptide delivery systems capable of loading both hydrophobic drug and small interfering RNA (siRNA) were developed. The synthesis of amphiphilic polypeptides included two steps: (i) synthesis of poly-αl-lysine by ring-opening polymerization and (ii) its post-polymerization modification with hydrophobic l-amino acid and l-arginine/l-histidine. The obtained polymers were used for the preparation of single and dual delivery systems of PTX and short double-stranded nucleic acid. The obtained double component systems were quite compact and had a hydrodynamic diameter in the range of 90-200 nm depending on the polypeptide. The release of PTX from the formulations was studied, and the release profiles were approximated using a number of mathematical dissolution models to establish the most probable release mechanism. A determination of the cytotoxicity in normal (HEK 293T) and cancer (HeLa and A549) cells revealed the higher toxicity of the polypeptide particles to cancer cells. The separate evaluation of the biological activity of PTX and anti-GFP siRNA formulations testified the inhibitory efficiency of PTX formulations based on all polypeptides (IC₅₀ 4.5-6.2 ng/mL), while gene silencing was effective only for the Tyr-Arg-containing polypeptide (56-70% GFP knockdown).

Cytoplasmic delivery of siRNA using human-derived membrane penetration-enhancing peptide

BACKGROUND

Although protein-based methods using cell-penetrating peptides such as TAT have been expected to provide an alternative approach to siRNA delivery, the low efficiency of endosomal escape of siRNA/protein complexes taken up into cells by endocytosis remains a problem. Here, to overcome this problem, we adopted the membrane penetration-enhancing peptide S19 from human syncytin 1 previously identified in our laboratory.

RESULTS

We prepared fusion proteins in which the S19 and TAT peptides were fused to the viral RNA-binding domains (RBDs) as carrier proteins, added the RBD-S19-TAT/siRNA complex to human cultured cells, and investigated the cytoplasmic delivery of the complex and the knockdown efficiency of target genes. We found that the intracellular uptake of the RBD-S19-TAT/siRNA complex was increased compared to that of the RBD-TAT/siRNA complex, and the expression level of the target mRNA was decreased. Because siRNA must dissociate from RBD and bind to Argonaute 2 (Ago2) to form the RNA-induced silencing complex (RISC) after the protein/siRNA complex is delivered into the cytoplasm, a dilemma arises: stronger binding between RBD and siRNA increases intracellular uptake but makes RISC formation more difficult. Thus, we next prepared fusion proteins in which the S19 and TAT peptides were fused with Ago2 instead of RBD and found that the efficiencies of siRNA delivery and knockdown obtained using TAT-S19-Ago2 were higher than those using TAT-Ago2. In addition, we found that the smallest RISC delivery induced faster knockdown than traditional siRNA lipofection, probably due to the decreased time required for RISC formation in the cytoplasm.

CONCLUSION

These results indicated that S19 and TAT-fused siRNA-binding proteins, especially Ago2, should be useful for the rapid and efficient delivery of siRNA without the addition of any endosome-disrupting agent.

Investigation of the ionic conditions in SiRNA-mediated delivery through its carriers in the cell membrane: a molecular dynamic simulation

SiRNA is a new generation of drug molecules and a new approach for treating a variety of diseases such as cancer and viral infections. SiRNA delivery to cells and translocation into cytoplasm are the main challenges in the clinical application of siRNA. Lipid carriers are one of the most successful carriers for siRNA delivery. In this study, we investigated the interaction of siRNA with a zwitterionic bilayer and how ion concentration and lipid conjugation can affect it. The divalent cation such as Mg²⁺ ions could promote the siRNA adsorption on the bilayer surface. The cation ions can bind to the head groups of lipids and the grooves of siRNA molecules and form bridges between the siRNA and bilayer surface. Our findings demonstrated the bridges formed by divalent ions could facilitate the attachment of siRNA to the membrane surface. We showed that the divalent cations can regulate the bridging-driven membrane attachment and it seems the result of this modulation can be used for designing biomimetic devices. In the following, we examined the effect of cations on the interaction between siRNA modified by cholesterol and the membrane surface. Our MD simulations showed that in the presence of Mg²⁺, the electrostatic and vdW energy between the membrane and siRNA were higher compared to those in the presence of NA⁺. We showed that the electrostatic interaction between membrane and siRNA cannot be facilitated only by cholesterol conjugated. Indeed, cations are essential to create coulomb repulsion and enable membrane attachment. This study provides important insight into liposome carriers for siRNA delivery and could help us in the development of siRNA-based therapeutics. Due to the coronavirus pandemic outbreak, these results may shed light on the new approach for treating these diseases and their molecular details.

Oral Nanomedicines for siRNA Delivery to Treat Inflammatory Bowel Disease

RNA interference (RNAi) therapies have significant potential for the treatment of inflammatory bowel diseases (IBD). Although administering small interfering RNA (siRNA) via an oral route is desirable, various hurdles including physicochemical, mucus, and cellular uptake barriers of the gastrointestinal tract (GIT) impede both the delivery of siRNA to the target site and the action of siRNA drugs at the target site. In this review, we first discuss various physicochemical and biological barriers in the GI tract. Furthermore, we present recent strategies and the progress of oral siRNA delivery strategies to treat IBD. Finally, we consider the challenges faced in the use of these strategies and future directions of oral siRNA delivery strategies.

VEGF Overexpression Significantly Increases Nanoparticle-Mediated siRNA Delivery and Target-Gene Downregulation

The availability of nanoparticles (NPs) to deliver small interfering RNA (siRNA) has significantly expanded the specificity and range of ‘druggable’ targets for precision medicine in cancer. This is especially important for cancers such as triple negative breast cancer (TNBC) for which there are no targeted treatments. Our purpose here was to understand the role of tumor vasculature and vascular endothelial growth factor (VEGF) overexpression in a TNBC xenograft in improving the delivery and function of siRNA NPs using in vivo as well as ex vivo imaging. We used triple negative MDA-MB-231 human breast cancer xenografts derived from cells engineered to overexpress VEGF to understand the role of VEGF and vascularization in NP delivery and function. We used polyethylene glycol (PEG) conjugated polyethylenimine (PEI) NPs to deliver siRNA that downregulates choline kinase alpha (Chkα), an enzyme that is associated with malignant transformation and tumor progression. Because Chkα converts choline to phosphocholine, effective delivery of Chkα siRNA NPs resulted in functional changes of a significant decrease in phosphocholine and total choline that was detected with ¹H magnetic resonance spectroscopy (MRS). We observed a significant increase in NP delivery and a significant decrease in Chkα and phosphocholine in VEGF overexpressing xenografts. Our results demonstrated the importance of tumor vascularization in achieving effective siRNA delivery and downregulation of the target gene Chkα and its function.

Tracing New Landscapes in the Arena of Nanoparticle-Based Cancer Immunotherapy

Over the past two decades, unique and comprehensive cancer treatment has ushered new hope in the holistic management of the disease. Cancer immunotherapy, which harnesses the immune system of the patient to attack the cancer cells in a targeted manner, scores over others by being less debilitating compared to the existing treatment strategies. Significant advancements in the knowledge of immune surveillance in the last few decades have led to the development of several types of immune therapy like monoclonal antibodies, cancer vaccines, immune checkpoint inhibitors, T-cell transfer therapy or adoptive cell therapy (ACT) and immune system modulators. Intensive research has established cancer immunotherapy to be a safe and effective method for improving survival and the quality of a patient’s life. However, numerous issues with respect to site-specific delivery, resistance to immunotherapy, and escape of cancer cells from immune responses, need to be addressed for expanding and utilizing this therapy as a regular mode in the clinical treatment. Development in the field of nanotechnology has augmented the therapeutic efficiency of treatment modalities of immunotherapy. Nanocarriers could be used as vehicles because of their advantages such as increased surface areas, targeted delivery, controlled surface and release chemistry, enhanced permeation and retention effect, etc. They could enhance the function of immune cells by incorporating immunomodulatory agents that influence the tumor microenvironment, thus enabling antitumor immunity. Robust validation of the combined effect of nanotechnology and immunotherapy techniques in the clinics has paved the way for a better treatment option for cancer than the already existing procedures such as chemotherapy and radiotherapy. In this review, we discuss the current applications of nanoparticles in the development of ‘smart’ cancer immunotherapeutic agents like ACT, cancer vaccines, monoclonal antibodies, their site-specific delivery, and modulation of other endogenous immune cells. We also highlight the immense possibilities of using nanotechnology to accomplish leveraging the coordinated and adaptive immune system of a patient to tackle the complexity of treating unique disease conditions and provide future prospects in the field of cancer immunotherapy.

Novel molecular approaches to combat vectors and vector-borne viruses: Special focus on RNA interference (RNAi) mechanisms

Vector-borne diseases, such as dengue, chikungunya, zika, yellow fever etc pose significant burden among the infectious diseases globally, especially in tropical and sub-tropical regions. Globalization, deforestation, urbanization, climate change, uncontrolled population growth, inadequate waste management and poor vector-management infrastructure have all contributed to the expansion of vector habitats and subsequent increase in vector-borne diseases throughout the world. Conventional vector control methods, such as use of insecticides, have significant negative environmental repercussions in addition to developing resistance in vectors. Till date, a very few vaccines or antiviral therapies have been approved for the treatment of vector borne diseases. In this review, we have discussed emerging molecular approaches like CRISPR (clustered regularly interspaced short palindromic repeats)/Cas-9, sterile insect technique (SIT), release of insects carrying a dominant lethal (RIDL), Wolbachia (virus transmission blocking) and RNA interference (RNAi) to combat vector and vector-borne viruses. Due to the extensive advancements in RNAi research, a special focus has been given on its types, biogenesis, mechanism of action, delivery and experimental studies evaluating their application as anti-mosquito and anti-viral agent. These technologies appear to be highly promising in terms of contributing to vector control and antiviral drug development, and hence can be used to reduce global vector and vector-borne disease burden.

Structural Exploration of Polycationic Nanoparticles for siRNA Delivery

RNA interference (RNAi) is a promising approach to the treatment of genetic diseases by the specific knockdown of target genes. Functional polymers are potential vehicles for the effective delivery of vulnerable small interfering RNA (siRNA), which is required for the broad application of RNAi-based therapeutics. The development of methods for the facile modulation of chemical structures of polymeric carriers and an elucidation of detailed delivery mechanisms remain important areas of research. In this paper, we synthesized a series of methacrylate-based polymers with controllable structures and narrow distributions by atom transfer radical polymerization using various combinations of cationic monomers (2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, and 2-dibutylaminoethyl methacrylate) and hydrophobic monomers (2-butyl methacrylate (BMA), cyclohexyl methacrylate, and 2-ethylhexyl methacrylate). These polymers exhibited varying hydrophobicities, charge densities, and pK_a values, enabling the discovery of effective carriers for siRNA by in vitro delivery assays. For the polymers with BMA segments, 50% of cationic segments were beneficial to the formation of siRNA nanoparticles (NPs) and the in vitro delivery of siRNA. The optimal ratio varied for different combinations of cationic and hydrophobic segments. In particular, 20k PMB 0.5, PME 0.5, and PEB 1.0 showed >75% luciferase knockdown. Efficacious delivery was dependent on high siRNA binding, the small size of NPs, and balanced hydrophobicity and charge density. Cellular uptake and endosomal escape experiments indicated that carboxybetaine modification of 20k PMB 0.5 did not remarkably affect the internalization of corresponding NPs after incubation for 6 h but significantly reduced the endosomal escape of NPs, which leads to the notable decrease in delivery efficacy of polymers. These results provide insights into the mechanism of polymer-based siRNA delivery and may inspire the development of novel polymeric carriers.

Biotechnological Evolution of siRNA Molecules: From Bench Tool to the Refined Drug

The depth and versatility of siRNA technologies enable their use in disease targets that are undruggable by small molecules or that seek to achieve a refined turn-off of the genes for any therapeutic area. Major extracellular barriers are enzymatic degradation of siRNAs by serum endonucleases and RNAases, renal clearance of the siRNA delivery system, the impermeability of biological membranes for siRNA, activation of the immune system, plasma protein sequestration, and capillary endothelium crossing. To overcome the intrinsic difficulties of the use of siRNA molecules, therapeutic applications require nanometric delivery carriers aiming to protect double-strands and deliver molecules to target cells. This review discusses the history of siRNAs, siRNA design, and delivery strategies, with a focus on progress made regarding siRNA molecules in clinical trials and how siRNA has become a valuable asset for biopharmaceutical companies.

Synergistic Silencing of Skp2 by siRNA Self-Assembled Nanoparticles as a Therapeutic Strategy for Advanced Prostate Cancer

Advanced prostate cancer, harboring multiple mutations of tumor suppressor genes, is refractory to conventional therapies. Knockout of the Skp2 gene blocks pRb/p53 doubly deficient prostate cancer in mice, which inspired the authors to develop an approach for delivering siRNA that would efficiently silence Skp2 (siSkp2) in vivo. Here, a facile strategy is reported to directly assemble siSkp2 with the natural compound quercetin (Que) into supramolecular nanoparticles (NPs). This carrier-free siSkp2 delivery system could effectively protect siSkp2 from degradation in serum and enhance its cellular internalization. Furthermore, the siSkp2/Que NPs exhibit synergistic effects in Skp2 silencing, because they can degrade the mRNA and protein of Skp2 simultaneously. Indeed, siSkp2/Que NPs remarkably diminish the Skp2 abundance and further inhibit the proliferation and migration of TMU cells (RB1/TP53/KRAS triple mutations) in vitro. The in vivo results further show that i.v. administration of siSkp2/Que NPs efficiently accumulates in tumor sites and strongly inhibits the growth of TMU tumors in nude mice. Importantly, the siSkp2/Que NPs do not induce any abnormality in the treated mice, which suggests satisfactory biocompatibility. Collectively, this study describes a tractable siRNA self-assembled strategy for Skp2 silencing, which might be a promising nanodrug to cure multitherapy-resistant advanced prostate cancer.

RNA-mediated immunotherapy regulating tumor immune microenvironment: next wave of cancer therapeutics

Accumulating research suggests that the tumor immune microenvironment (TIME) plays an essential role in regulation of tumor growth and metastasis. The cellular and molecular nature of the TIME influences cancer progression and metastasis by altering the ratio of immune- suppressive versus cytotoxic responses in the vicinity of the tumor. Targeting or activating the TIME components show a promising therapeutic avenue to combat cancer. The success of immunotherapy is both astounding and unsatisfactory in the clinic. Advancements in RNA-based technology have improved understanding of the complexity and diversity of the TIME and its effects on therapy. TIME-related RNA or RNA regulators could be promising targets for anticancer immunotherapy. In this review, we discuss the available RNA-based cancer immunotherapies targeting the TIME. More importantly, we summarize the potential of various RNA-based therapeutics clinically available for cancer treatment. RNA-dependent targeting of the TIME, as monotherapy or combined with other evolving therapeutics, might be beneficial for cancer patients’ treatment in the near future.

Specific Silencing of Microglial Gene Expression in the Rat Brain by Nanoparticle-Based Small Interfering RNA Delivery

Microglia are the major innate immune cells in the brain and are essential for maintaining homeostasis in a neuronal microenvironment. Currently, a genetic tool to modify microglial gene expression in specific brain regions is not available. In this report, we introduce a tailor-designed method that uses lipid and polymer hybridized nanoparticles (LPNPs) for the local delivery of small interfering RNAs (siRNAs), allowing the silencing of specific microglial genes in the hypothalamus. Our physical characterization proved that this LPNP-siRNA was uniform and stable. We demonstrated that, due to their natural phagocytic behavior, microglial cells are the dominant cell type taking up these LPNPs in the hypothalamus of rats. We then tested the silencing efficiency of LPNPs carrying a cluster of differentiation molecule 11b (CD11b) or Toll-like receptor 4 (TLR4) siRNA using different in vivo and in vitro approaches. In cultured microglial cells treated with LPNP-CD11b siRNA or LPNP-TLR4 siRNA, we found a silencing efficiency at protein expression levels of 65 or 77%, respectively. In line with this finding, immunohistochemistry and western blotting results from in vivo experiments showed that LPNP-CD11b siRNA significantly inhibited microglial CD11b protein expression in the hypothalamus. Furthermore, following lipopolysaccharide (LPS) stimulation of cultured microglial cells, gene expression of the TLR4 downstream signaling component myeloid differentiation factor 88 and its associated cytokines was significantly inhibited in LPNP-TLR4 siRNA-treated microglial cells compared with cells treated with LPNP-scrambled siRNA. Finally, after LPNP-TLR4 siRNA injection into the rat hypothalamus, we observed a significant reduction in microglial activation in response to LPS compared with the control rats injected with LPNP-scrambled siRNA. Our results indicate that LPNP-siRNA is a promising tool to manipulate microglial activity locally in the brain and may serve as a prophylactic approach to prevent microglial dysfunction-associated diseases.

siRNA-Based Carrier-Free System for Synergistic Chemo/Chemodynamic/RNAi Therapy of Drug-Resistant Tumors

Multiple drug-resistance mechanisms originate from defensive pathways in cancer and are associated with the unsatisfied efficacy of chemotherapy. The combination of small interfering RNA (siRNA) and chemotherapeutics provides a strategy for reducing drug efflux but requires more delivery options for clinical translation. Herein, multidrug resistance protein 1 (MDR1) siRNA is used as the skeleton to assemble chemotherapeutic cisplatin (CDDP) and divalent copper ion (Cu²⁺) for constructing a carrier-free Cu-siMDR-CDDP system. Cu-siMDR-CDDP specifically responds and disassembles in the acidic tumor microenvironment (TME). The released CDDP activates cascade bioreactions of NADPH oxidases and superoxide dismutase to generate hydrogen peroxide (H₂O₂). Then a Cu²⁺-catalyzed Fenton-like reaction transforms H₂O₂ to hydroxyl radicals (HO^•) and causes glutathione (GSH) depletion to disrupt the redox adaptation mechanism of drug-resistant cancer cells. Besides, delivery of MDR1 siRNA is facilitated by HO^•-triggered lysosome destruction, thus inhibiting P-glycoprotein (P-gp) expression and CDDP efflux. The unique design of Cu-siMDR-CDDP is to exploit siRNA as building blocks in regulating the self-assembly behavior, and integration of functional units simultaneously alleviates limitations caused by drug-resistance mechanisms. Such a carrier-free system shows synergistic chemo/chemodynamic/RNA interference therapy in suppressing tumor growth in vivo and has the reference value for overcoming drug resistance.

Induced Pluripotent Stem Cells (iPSCs) and Gene Therapy: A New Era for the Treatment of Neurological Diseases

To date, gene therapy has employed viral vectors to deliver therapeutic genes. However, recent progress in molecular and cell biology has revolutionized the field of stem cells and gene therapy. A few years ago, clinical trials started using stem cell replacement therapy, and the induced pluripotent stem cells (iPSCs) technology combined with CRISPR-Cas9 gene editing has launched a new era in gene therapy for the treatment of neurological disorders. Here, we summarize the latest findings in this research field and discuss their clinical applications, emphasizing the relevance of recent studies in the development of innovative stem cell and gene editing therapeutic approaches. Even though tumorigenicity and immunogenicity are existing hurdles, we report how recent progress has tackled them, making engineered stem cell transplantation therapy a realistic option.

Surface modification with cholesteryl acetyl carnitine, a novel cationic agent, elevates cancer cell uptake of the PEGylated liposomes

The present study aimed to synthesize cholesteryl acetyl carnitine (CAC), and surface modify the PEGylated liposomes with the intention of enhanced cancer cell uptake. For this, CAC synthesis was performed in amine-free esterification conditions and then four liposomal formulations of unmodified, CAC/PEG, and CAC + PEG-modified were prepared by ethanol injection method. Cytotoxicity of the liposomes was investigated in A549 cells, followed by cellular uptake assessments of coumarin 6 (C6)-loaded liposomes. The results of ATR-FTIR, ¹HNMR, and ¹³CNMR demonstrated successful formation of CAC. A molecular docking study showed efficient binding affinities rather than carnitine to the active site of four carnitine transporters. Liposomal formulations possessed spherical morphology with a mean particle size range of 112-138 nm, narrow size distribution, and negative surface charge. All formulations had low cytotoxicity at 0.5 mg/ml, but high cytotoxicity at around 2.5 mg/ml. The lowest IC50 was obtained for CAC modified liposomes. CAC + PEG-modified liposomes had the highest cellular uptake. In conclusion, CAC + PEG modification of liposomes is an effective approach for increasing A549 cellular uptake, with low cytotoxicity at commonly applied liposome concentrations. The elevated uptake may be due to the involvement of the organic cation transporter, cationic structure, and the metabolic preference of CAC in cancer cells.

Role of Metastasis-Related microRNAs in Prostate Cancer Progression and Treatment

Simple Summary

In this review article we summarize the current literature on the pro- and anti-metastatic roles of distinct microRNAs in prostate cancer with a particular focus on their impact on invasion, migration and epithelial-to-mesenchymal transition. Moreover, we give a brief overview on how this knowledge developed so far into novel therapeutic approaches to target metastatic prostate cancer.

Abstract

Prostate cancer (PCa) is one of the most prevalent cancer types in males and the consequences of its distant metastatic deposits are the leading cause of PCa mortality. Therefore, identifying the causes and molecular mechanisms of hematogenous metastasis formation is of considerable clinical importance for the future development of improved therapeutic approaches. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the post-transcriptional level by targeting messenger RNAs. Numerous studies have identified miRNAs as promotors or inhibitors of metastasis and revealed, in part, their targeting pathways in PCa. Because miRNAs are remarkably stable and can be detected in both tissue and body fluid, its potential as specific biomarkers for metastasis and therapeutic response is also currently under preclinical evaluation. In the present review, we focus on miRNAs that are supposed to initiate or suppress metastasis by targeting several key mRNAs in PCa. Metastasis-suppressing miRNAs include miR-33a-5p, miR-34, miR-132 and miR-212, miR-145, the miR-200 family (incl. miR-141-3p), miR-204-5p, miR-532-3p, miR-335, miR-543, miR-505-3p, miR 19a 3p, miR-802, miR-940, and miR-3622a. Metastasis-promoting RNAs, such as miR-9, miR-181a, miR-210-3, miR-454, miR-671-5p, have been shown to increase the metastatic potential of PCa cells. Other metastasis-related miRNAs with conflicting reports in the literature are also discussed (miR-21 and miR-186). Finally, we summarize the recent developments of miRNA-based therapeutic approaches, as well as current limitations in PCa. Taken together, the metastasis-controlling miRNAs provide the potential to be integrated in the strategy of diagnosis, prognosis, and treatment of metastatic PCa. Nevertheless, there is still a lack of consistency between certain miRNA signatures and reproducibility, which impedes clinical implementation.

PEGylated cationic nanoassemblies based on triblock copolymers to combine siRNA therapeutics with anticancer drugs

Nowadays, the clinical administration of siRNA therapeutics is still challenging due to the need of safe and efficient delivery carriers. In this context, biodegradable and amphiphilic triblock copolymers (ABC) containing amine-based cationic segments could be a powerful tool for siRNA delivery. Herein, we propose a range of poly(ethylene glycol) (PEG)-poly(2-dimethyl(aminoethyl) methacrylate) (pDMAEMA)-polycaprolactone (PCL) copolymers with different lengths of the blocks and hydrophilic/lipophilic balance to deliver siRNA alone or in association with a conventional anticancer drug. mPEG-pDMAEMA-PCL copolymers were synthesized by a combination of techniques and characterized by NMR analysis, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Copolymers were then employed to prepare NPs through nanoprecipitation. NPs based on copolymers with long PCL chains (SSL-NPs and LLL-NPs) showed the best colloidal properties and a highly stable core-shell structure with a better orientation of the PEG fringe on the surface. Concerning siRNA delivery, SSL-NPs based on copolymers with short PEG and pDMAEMA chains showed optimized ability to complex and then deliver siRNA at the cell level. The strong interaction between the nucleic acid and the cationic pDMAEMA blocks of NPs was then confirmed by release studies that showed a sustained release of siRNA within 48 h. The transfection efficiency of NPs was assessed in human melanoma cells. NPs were complexed with a therapeutic siRNA against TUBB3 (TUB-siRNA). We observed the best results with SSL-NPs, probably due to the higher preserved buffer capacity of the pDMAEMA blocks. Finally, in order to give a proof of concept of a possible application in the combined chemo/gene-therapy of cancer, SSL-NPs complexed with TUB-siRNA were loaded with docetaxel (DTX) and then cytotoxicity was evaluated in the same cell line. The co-delivery of TUB-siRNA into NPs appeared to strongly potentiate the anti-proliferative activity of DTX, thus highlighting the combinatory activity of the NPs.

Long Non-Coding RNAs in the Tumor Immune Microenvironment: Biological Properties and Therapeutic Potential

Cancer immunotherapy (CIT) is considered a revolutionary advance in the fight against cancer. The complexity of the immune microenvironment determines the success or failure of CIT. Long non-coding RNA (lncRNA) is an extremely versatile molecule that can interact with RNA, DNA, or proteins to promote or inhibit the expression of protein-coding genes. LncRNAs are expressed in many different types of immune cells and regulate both innate and adaptive immunity. Recent studies have shown that the discovery of lncRNAs provides a novel perspective for studying the regulation of the tumor immune microenvironment (TIME). Tumor cells and the associated microenvironment can change to escape recognition and elimination by the immune system. LncRNA induces the formation of an immunosuppressive microenvironment through related pathways, thereby controlling the escape of tumors from immune surveillance and promoting the development of metastasis and drug resistance. Using lncRNA as a therapeutic target provides a strategy for studying and improving the efficacy of immunotherapy.

Membrane Derived Vesicles as Biomimetic Carriers for Targeted Drug Delivery System

Extracellular vesicles (EVs) are membrane vesicles (MVs) playing important roles in various cellular and molecular functions in cell-to-cell signaling and transmitting molecular signals to adjacent as well as distant cells. The preserved cell membrane characteristics in MVs derived from live cells, give them great potential in biological applications. EVs are nanoscale particulates secreted from living cells and play crucial roles in several important cellular functions both in physiological and pathological states. EVs are the main elements in intercellular communication in which they serve as carriers for various endogenous cargo molecules, such as RNAs, proteins, carbohydrates, and lipids. High tissue tropism capacity that can be conveniently mediated by surface molecules, such as integrins and glycans, is a unique feature of EVs that makes them interesting candidates for targeted drug delivery systems. The cell-derived giant MVs have been exploited as vehicles for delivery of various anticancer agents and imaging probes and for implementing combinational phototherapy for targeted cancer treatment. Giant MVs can efficiently encapsulate therapeutic drugs and deliver them to target cells through the membrane fusion process to synergize photodynamic/photothermal treatment under light exposure. EVs can load diagnostic or therapeutic agents using different encapsulation or conjugation methods. Moreover, to prolong the blood circulation and enhance the targeting of the loaded agents, a variety of modification strategies can be exploited. This paper reviews the EVs-based drug delivery strategies in cancer therapy. Biological, pharmacokinetics and physicochemical characteristics, isolation techniques, engineering, and drug loading strategies of EVs are discussed. The recent preclinical and clinical progresses in applications of EVs and oncolytic virus therapy based on EVs, the clinical challenges and perspectives are discussed.

Innovative lipoplexes formulations with enhanced siRNA efficacy for cancer treatment: Where are we now?

Over the past two decades, RNA interference has become an extensively studied mechanism to silence gene and treat diseases including cancer. siRNA appears as a promising strategy that could avoid some side effects related to traditional chemotherapy. Considering the weak stability of naked siRNA in blood, vectors like cationic liposomes or Lipid Nanoparticles (LNPs) are widely used to carry and protect siRNA until it reaches the tumor targeted. Despite extensive research, only three RNAi drugs are currently approved by the Food and Drug Administration, including only one LNP formulation of siRNA to treat hereditary ATTR amyloidosis. This shows the difficulty of lipoplexes clinical translation, in particular in cancer therapy. To overcome the lipoplexes limitations, searches are made on innovative lipoplexes formulations with enhanced siRNA efficacy. The present review is focusing on the recent use of pH-sensitive lipids, peptides and cell-penetrating peptides or polymers. The incorporation of some of these components in the lipoplex formulation induces a fusogenic property or an enhanced endosomal escape, an enhanced cellular uptake, an enhanced tumor targeting, an improved stability in the blood stream …These innovations appear critical to obtain an efficient siRNA accumulation in tumor cells with effective antitumor effect considering the complex tumor environment.

A small interfering RNA (siRNA) database for SARS-CoV-2

Coronavirus disease 2019 (COVID-19) rapidly transformed into a global pandemic, for which a demand for developing antivirals capable of targeting the SARS-CoV-2 RNA genome and blocking the activity of its genes has emerged. In this work, we presented a database of SARS-CoV-2 targets for small interference RNA (siRNA) based approaches, aiming to speed the design process by providing a broad set of possible targets and siRNA sequences. The siRNAs sequences are characterized and evaluated by more than 170 features, including thermodynamic information, base context, target genes and alignment information of sequences against the human genome, and diverse SARS-CoV-2 strains, to assess possible bindings to off-target sequences. This dataset is available as a set of four tables, available in a spreadsheet and CSV (Comma-Separated Values) formats, each one corresponding to sequences of 18, 19, 20, and 21 nucleotides length, aiming to meet the diversity of technology and expertise among laboratories around the world. A metadata table (Supplementary Table S1), which describes each feature, is also provided in the aforementioned formats. We hope that this database helps to speed up the development of new target antivirals for SARS-CoV-2, contributing to a possible strategy for a faster and effective response to the COVID-19 pandemic.

A Simple and Quick Method for Loading Proteins in Extracellular Vesicles

Extracellular vesicles (EVs) mediate intercellular transport of biomolecular cargo in the body, making them promising delivery vehicles for bioactive compounds. Genetic engineering of producer cells has enabled encapsulation of therapeutic proteins in EVs. However, genetic engineering approaches can be expensive, time-consuming, and incompatible with certain EV sources, such as human plasma and bovine milk. The goal of this study was to develop a quick, versatile, and simple method for loading proteins in EVs post-isolation. Proteins, including CRISPR associated protein 9 (Cas9), were bound to cationic lipids that were further complexed with MDA-MB-231 cell-derived EVs through passive incubation. Size-exclusion chromatography was used to remove components that were not complexed with EVs. The ability of EVs to mediate intracellular delivery of proteins was compared to conventional methods, such as electroporation and commercial protein transfection reagents. The results indicate that EVs retain native features following protein-loading and obtain similar levels of intracellular protein delivery as conventional methods, but display less toxicity. This method opens up opportunities for rapid exploration of EVs for protein delivery.

Hyaluronic Acid-Coated MTX-PEI Nanoparticles for Targeted Rheumatoid Arthritis Therapy

Methotrexate (MTX) is an anchor drug for the treatment of rheumatoid arthritis (RA); however, long-term and high-dose usage of MTX for patients can cause many side effects and toxic reactions. To address these difficulties, selectively delivering MTX to the inflammatory site of a joint is promising in the treatment of RA. In this study, we prepared MTX-PEI@HA nanoparticles (NPs), composed of hyaluronic acid (HA) as the hydrophilic negative electrical shell, and MTX-linked branched polyethyleneimine (MTX-PEI) NPs as the core. MTX-PEI@HA NPs were prepared in the water phase by a one-pot method. The polymeric NPs were selectively internalized via CD44 receptor-mediated endocytosis in the activated macrophages. In the in vivo mice mode study, treatment with MTX-PEI@HA NPs mitigated inflammatory arthritis with notable safety at a high dose of MTX. We highlight the distinct advantages of aqueous-synthesized NPs coated with HA for arthritis-selective targeted delivery, thus verifying MTX-PEI@HA NPs as a promising MTX-based nanoplatform for treatment of RA.

miRNAs as Therapeutic Tools and Biomarkers for Prostate Cancer

Prostate cancer (PCa) is the fifth cause of tumor-related deaths in man worldwide. Despite the considerable improvement in the clinical management of PCa, several limitations emerged both in the screening for early diagnosis and in the medical treatment. The use of prostate-specific antigen (PSA)-based screening resulted in patients' overtreatment and the standard therapy of patients suffering from locally advanced/metastatic tumors (e.g., radical prostatectomy, radiotherapy, and androgen deprivation therapy) showed time-limited efficacy with patients undergoing progression toward the lethal metastatic castration-resistant PCa (mCRPC). Although valuable alternative therapeutic options have been recently proposed (e.g., docetaxel, cabazitaxel, abiraterone, enzalutamide, and sipuleucel-T), mCRPC remains incurable. Based on this background, there is an urgent need to identify new and more accurate prostate-specific biomarkers for PCa diagnosis and prognosis and to develop innovative medical approaches to counteract mCRPC. In this context, microRNA (miRNAs) emerged as potential biomarkers in prostate tissues and biological fluids and appeared to be promising therapeutic targets/tools for cancer therapy. Here we overview the recent literature and summarize the achievements of using miRNAs as biomarkers and therapeutic targets/tools for fighting PCa.

Peptide/Lipid-Associated Nucleic Acids (PLANAs) as a Multicomponent siRNA Delivery System

RNAi is a biological process that utilizes small interfering RNA (siRNA) to prevent the translation of mRNA to protein. This mechanism could be beneficial in preventing the overexpression of proteins in cancer. However, the cellular delivery of siRNA has proven to be challenging due to its inherent negative charge and relative instability. Here, we designed a multicomponent delivery system composed of a specifically designed peptide (linear or cyclic fatty acyl peptide conjugates and hybrid cyclic/linear peptides) and several lipids (DOTAP, DOPE, cholesterol, and phosphatidylcholine) to form a nanoparticle, which we have termed as peptide lipid-associated nucleic acids (PLANAs). Five formulations were prepared (a formulation with no peptide, which was named lipid-associated nucleic acid or LANA, and PLANA formulations A-D) using a mini extruder to form uniform nanoparticles around 100 nm in size with a slightly positive charge (less than +10 mv). Formulations were evaluated for peptide incorporation, siRNA encapsulation efficiency, release profile, toxicity, cellular uptake, and protein silencing. Our experiments showed effective encapsulation of siRNA (>95%), a controlled release profile, and negligible toxicity in formulations that did not contain a positively charged lipid. The results also revealed that PLANAs C and D exhibited optimum cellular uptake (with 80-90% siRNA-positive cells for most of the formulations). PLANA D formulation was selected to silence two model proteins (Src and RPS6KA5) in the triple-negative human breast cancer cell line MDA-MB-231, with promising silencing efficiency, which diminished the expression of RPS6KA5 and Src to approximately 29 and 38% compared to naïve cells, respectively. Many approaches have been investigated for safe and efficient delivery of nucleic acids in the last 20 years; however, many have failed due to the multifaceted challenges to overcome. Our results show a promising potential for a multicomponent design that incorporates different components for a variety of delivery tasks, which warrants further investigation of PLANAs in vivo.

Cationic lipids for gene delivery: many players, one goal

Lipid-based carriers represent the most widely used alternative to viral vectors for gene expression and gene silencing purposes. This class of non-viral vectors is particularly attractive for their ease of synthesis and chemical modifications to endow them with desirable properties. Despite combinatorial approaches have led to the generation of a large number of cationic lipids displaying different supramolecular structures and improved behavior, additional effort is needed towards the development of more and more effective cationic lipids for transfection purposes. With this review, we seek to highlight the great progress made in the design of each and every constituent domain of cationic lipids, that is, the chemical structure of the headgroup, linker and hydrophobic moieties, and on the specific effect on the assembly with nucleic acids. Since the complexity of such systems is known to affect their performances, the role of formulation, stability and phase behavior on the transfection efficiency of such assemblies will be thoroughly discussed. Our objective is to provide a conceptual framework for the development of ever more performing lipid gene delivery vectors.

Assembly strategy of liposome and polymer systems for siRNA delivery

In recent years, gene therapy has made tremendous progress in the development of disease treatment. Among them, siRNA offers specificity of gene silencing, ease of synthesis, and short development period, and has been intensively studied worldwide. However, siRNA as the hydrophilic polyanion is easily degraded in vivo and poorly taken up into cells and so, the benefits of its powerful gene silencing ability will not be realized until better carriers are developed that are capable of protecting siRNA and delivering it intact to the cytoplasm of the target cells. Cationic liposomes (CL) and cationic polymers (CP) are the main non-viral siRNA vectors, there have been a lot of reports on the use of these two carriers to deliver siRNA. Whereas, as far as we know, there have been few review articles that provide an in-depth summary of the siRNA loading principle and internal structures of the siRNA delivery system. We summarize the formation principle and assembly structure of the cationic liposome-siRNA and polymer-siRNA complexes, and point out their advantages and characteristics and also show how to perfect their assembly and improve their clinical application in the future. It supports some useful suggestions for siRNA therapy, specifically, safe and efficient delivery.

pH-sensitive zwitterionic polycarboxybetaine as a potential non-viral vector for small interfering RNA delivery

Small interfering RNA (siRNA) has great potential for the treatment of various diseases. However, its intrinsic deficiencies seriously limit its application. Herein, pH-sensitive zwitterionic polymer polycarboxybetaine (PCB) was developed as a non-viral vector for siRNA. The PCB could be protonated in an acidic environment and become positively charged from a cancer site. After protonation, PCB could complex siRNA via electrostatic interaction, and its loading ability was enhanced with a decrease of pH value. Compared with the PEI 10k, PCB₅₀ with a similar molecular weight had comparable siRNA loading ability and lower cytotoxicity. Besides, siRNA loaded by PCB₅₀ could escape from endosomes and reduce the loss of drugs, and based on the excellent uptake and obvious apoptotic effect on HeLa cells, the pH-sensitive PCB with low cytotoxicity could be used as a non-viral vector for safe siRNA delivery for cancer treatment.

pH-sensitive zwitterionic polycarboxybetaine could complex siRNA in an acidic environment and could be used as a non-viral vector for safe siRNA delivery.

A non-viral nano-delivery system targeting epigenetic methyltransferase EZH2 for precise acute myeloid leukemia therapy

Acute myeloid leukemia (AML), which is common in the elderly population, accounts for poor long-term survival with a high possibility of relapse. The associated lack of currently developed therapeutics is directing the search for new therapeutic targets relating to AML. EZH2 (Enhancer of Zeste Homolog 2) is a histone methyltransferase member of the polycomb-group (PcG) family, and its significant overexpression in AML means it has emerged as a potential epigenetic target. Here, we propose the human serum albumin (HSA) nanoparticle based delivery of small interfering RNA (siRNA), which can target EZH2-expressing genes in AML. EZH2 specific siRNA loaded in a polyethyleneimine (PEI) conjugated HSA nanocarrier can overcome the systemic instability of siRNA and precisely target the AML cell population for increased EZH2 gene silencing. A stable nanosized complex (HSANPs-PEI@EZH2siRNA), achieved via the electrostatic interaction of PEI and EZH2 siRNA, shows increased systemic stability and hemocompatibility, and enhanced EZH2 gene silencing activity in vitro, compared to conventional transfection reagents. HSANPs-PEI@EZH2siRNA-treated AML cells showed downregulated EZH2, which is associated with a reduced level of Bmi-1 protein, and H3K27me3 and H2AK119ub modification. The ubiquitin-mediated proteasomal degradation pathway plays a critical role in the downregulation of associated proteins following HSANPs-PEI@EZH2siRNA exposure to AML cells. c-Myb is the AML-responsive transcription factor that directly binds on the EZH2 promoter and was downregulated in HSANPs-PEI@EZH2siRNA-treated AML cells. The systemic exposure to HSANPs-PEI@EZH2siRNA of AML engrafted immunodeficient nude mice displayed efficient EZH2 gene silencing and a reduced AML cell population in peripheral blood and bone marrow. The present study demonstrates a non-viral siRNA delivery system for epigenetic targeting based superior anti-leukemic therapy.

Core-shell nanostructures: perspectives towards drug delivery applications

Nanosystems have shown encouraging outcomes and substantial progress in the areas of drug delivery and biomedical applications. However, the controlled and targeted delivery of drugs or genes can be limited due to their physicochemical and functional properties. In this regard, core-shell type nanoparticles are promising nanocarrier systems for controlled and targeted drug delivery applications. These functional nanoparticles are emerging as a particular class of nanosystems because of their unique advantages, including high surface area, and easy surface modification and functionalization. Such unique advantages can facilitate the use of core-shell nanoparticles for the selective mingling of two or more different functional properties in a single nanosystem to achieve the desired physicochemical properties that are essential for effective targeted drug delivery. Several types of core-shell nanoparticles, such as metallic, magnetic, silica-based, upconversion, and carbon-based core-shell nanoparticles, have been designed and developed for drug delivery applications. Keeping the scope, demand, and challenges in view, the present review explores state-of-the-art developments and advances in core-shell nanoparticle systems, the desired structure-property relationships, newly generated properties, the effects of parameter control, surface modification, and functionalization, and, last but not least, their promising applications in the fields of drug delivery, biomedical applications, and tissue engineering. This review also supports significant future research for developing multi-core and shell-based functional nanosystems to investigate nano-therapies that are needed for advanced, precise, and personalized healthcare systems.

Evolution of drug delivery system from viewpoint of controlled intracellular trafficking and selective tissue targeting toward future nanomedicine

Due to the rapid changes that have occurred in the field of drug discovery and the recent developments in the early 21st century, the role of drug delivery systems (DDS) has become increasingly more important. For the past 20 years, our laboratory has been developing gene delivery systems based on lipid-based delivery systems. One of our efforts has been directed toward developing a multifunctional envelope-type nano device (MEND) by modifying the particle surface with octaarginine, which resulted in a remarkably enhanced cellular uptake and improved intracellular trafficking of plasmid DNA (pDNA). When we moved to in vivo applications, however, we were faced with the PEG-dilemma and we shifted our strategy to the incorporation of ionizable cationic lipids into our system. This resulted in some dramatic improvements over our original design and this can be attributed to the development of a new lipid library. We have also developed a mitochondrial targeting system based on a membrane fusion mechanism using a MITO-Porter, which can deliver nucleic acids/pDNA into the matrix of mitochondria. After the appearance of antibody medicines, Opdivo, an immune checkpoint inhibitor, has established cancer immunology as the 4th strategy in cancer therapy. Our DDS technologies can also be applied to this new field of cancer therapy to cure cancer by controlling our immune mechanisms. The latest studies are summarized in this review article.

Light-Induced Self-Escape of Spherical Nucleic Acid from Endo/Lysosome for Efficient Non-Cationic Gene Delivery

Developing non-cationic gene carriers and achieving efficient endo/lysosome escape of functional nucleic acids in cytosol are two major challenges faced by the field of gene delivery. Herein, we demonstrate the concept of self-escape spherical nucleic acid (SNA) to achieve light controlled non-cationic gene delivery with sufficient endo/lysosome escape capacity. In this system, Bcl-2 antisense oligonucleotides (OSAs) were conjugated onto the surface of aggregation-induced emission (AIE) photosensitizer (PS) nanoparticles to form core-shell SNA. Once the SNAs were taken up by tumor cells, and upon light irradiation, the accumulative ¹ O₂ produced by the AIE PSs ruptured the lysosome structure to promote OSA escape. Prominent in vitro and in vivo results revealed that the AIE-based core-shell SNA could downregulate the anti-apoptosis protein (Bcl-2) and induce tumor cell apoptosis without any transfection reagent.

Cyclopropenium Nanoparticles and Gene Transfection in Cells

Non-viral vectors for the transfection of genetic material are at the frontier of medical science. In this article, we introduce for the first time, cyclopropenium-containing nanoparticles as a cationic carrier for gene transfection, as an alternative to the common quaternary ammonium transfection agents. Cyclopropenium-based cationic nanoparticles were prepared by crosslinking poly(ethylene imine) (PEI) with tetrachlorocyclopropene. These nanoparticles were electrostatically complexed with plasmid DNA into nanoparticles (~50 nm). Their cellular uptake into F929 mouse fibroblast cells, and their eventual expression in vitro have been described. Transfection is enhanced relative to PEI with minimal toxicity. These cyclopropenium nanoparticles possess efficient gene transfection capabilities with minimal cytotoxicity, which makes them novel and promising candidates for gene therapy.

Stimuli-Responsive Polysaccharide Enveloped Liposome for Targeting and Penetrating Delivery of survivin-shRNA into Breast Tumor

Silencing the inhibitor of apoptosis (IAP) by RNAi is a promising method for tumor therapy. One of the major challenges lies in how to sequentially overcome the system barriers in the course of the tumor targeting delivery, especially in the tumor accumulation and penetration. Herein we developed a novel stimuli-responsive polysaccharide enveloped liposome carrier, which was constructed by layer-by-layer depositing redox-sensitive amphiphilic chitosan (CS) and hyaluronic acid (HA) onto the liposome and then loading IAP inhibitor survivin-shRNA gene and permeation promoter hyaluronidase (HAase) sequentially. The as-prepared HA/HAase/CS/liposome/shRNA (HCLR) nanocarrier was verified to be stable in blood circulation due to the negative charged HA shield. The tumor targeting recognition and the enhanced tumor accumulation of HCLR were visualized by fluorescence resonance energy transfer (FRET) and in vivo fluorescence biodistribution. The deshielding of HA and the protonizing of CS in slightly acidic tumor extracellular pH environment (pH_e, 6.8-6.5) were demonstrated by ζ potential change from -23.1 to 29.9 mV. The pH_e-responsive HAase release was confirmed in the tumor extracellular mimicking environments, and the intratumoral biodistribution showed that the tumor penetration of HCLR was improved. The cell uptake of HCLR in pH_e environment was significantly enhanced compared with that in physiological pH environment. The increased shRNA release of HCLR was approved in 10 mM glutathione (GSH) and tumor cells. Surprisingly, HCLR suppressed the tumor growth markedly through survivin silencing and meanwhile maintained low toxicity to mice. This study indicates that the novel polysaccharide enveloped HCLR is promising in clinical translation, thanks to the stimuli-triggered tumor accumulation, tumor penetration, cell uptake, and intracellular gene release.

Combining Nanomaterials and Developmental Pathways to Design New Treatments for Cardiac Regeneration: The Pulsing Heart of Advanced Therapies

The research for heart therapies is challenged by the limited intrinsic regenerative capacity of the adult heart. Moreover, it has been hampered by the poor results obtained by tissue engineering and regenerative medicine attempts at generating functional beating constructs able to integrate with the host tissue. For this reason, organ transplantation remains the elective treatment for end-stage heart failure, while novel strategies aiming to promote cardiac regeneration or repair lag behind. The recent discovery that adult cardiomyocytes can be ectopically induced to enter the cell cycle and proliferate by a combination of microRNAs and cardioprotective drugs, like anti-oxidant, anti-inflammatory, anti-coagulants and anti-platelets agents, fueled the quest for new strategies suited to foster cardiac repair. While proposing a revolutionary approach for heart regeneration, these studies raised serious issues regarding the efficient controlled delivery of the therapeutic cargo, as well as its timely removal or metabolic inactivation from the site of action. Especially, there is need for innovative treatment because of evidence of severe side effects caused by pleiotropic drugs. Biocompatible nanoparticles possess unique physico-chemical properties that have been extensively exploited for overcoming the limitations of standard medical therapies. Researchers have put great efforts into the optimization of the nanoparticles synthesis and functionalization, to control their interactions with the biological milieu and use as a viable alternative to traditional approaches. Nanoparticles can be used for diagnosis and deliver therapies in a personalized and targeted fashion. Regarding the treatment of cardiovascular diseases, nanoparticles-based strategies have provided very promising outcomes, in preclinical studies, during the last years. Efficient encapsulation of a large variety of cargos, specific release at the desired site and improvement of cardiac function are some of the main achievements reached so far by nanoparticle-based treatments in animal models. This work offers an overview on the recent nanomedical applications for cardiac regeneration and highlights how the versatility of nanomaterials can be combined with the newest molecular biology discoveries to advance cardiac regeneration therapies.

Skin Delivery of siRNA Using Sponge Spicules in Combination with Cationic Flexible Liposomes

We report the topical administration of sponge Haliclona sp. Spicules (SHS) combined with cationic flexible liposomes (CFL) to increase the delivery of small interfering RNA (siRNA) into viable skin cells in vitro and in vivo. SHS can be applied topically as novel microneedles to overcome skin barrier by creating plenty of new microchannels in stratum corneum. Subsequently, well-designed CFL can be also utilized topically as nanocarriers to overcome skin cells membrane by delivering siRNA to skin deep layers through these microchannels and thereby facilitating their cell internalization. The topical application of SHS in combination with CFL (0.05% of lipids, w/v), referred to as CFL(0.05%), enhanced siRNA skin penetration in vitro by 72.95 ± 2.97-fold compared to control group (p < 0.001). Further, the topical application of SHS in combination with CFL(0.05%) on female BALB/c mice skin resulted in 29.21% ± 1.41% of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) knockdown at all application area in vivo, which was not significantly different from the GAPDH protein knockdown rate in the subcutaneous injection center. However, the high knockdown rate only appears in the vicinity (<0.5 cm) of the injection center. In sum, this study provides a promising strategy of topical delivery of siRNA by the combined used of SHS and well-designed CFL.

Lipid-based Vehicles for siRNA Delivery in Biomedical Field

BACKGROUND

Genetic drugs have aroused much attention in the past twenty years. RNA interference (RNAi) offers novel insights into discovering potential gene functions and therapies targeting genetic diseases. Small interference RNA (siRNA), typically 21-23 nucleotides in length, can specifically degrade complementary mRNA. However, targeted delivery and controlled release of siRNA remain a great challenge.

METHODS

Different types of lipid-based delivery vehicles have been synthesized, such as liposomes, lipidoids, micelles, lipoplexes and lipid nanoparticles. These carriers commonly have a core-shell structure. For active targeting, ligands may be conjugated to the surface of lipid particles.

RESULTS

Lipid-based drug delivery vehicles can be utilized in anti-viral or anti-tumor therapies. They can also be used to tackle genetic diseases or discover novel druggable genes.

CONCLUSION

In this review, the structures of lipid-based vehicles and possible surface modifications are described, and applications of delivery vehicles in biomedical field are discussed.