Anionic polymers for decreased toxicity and enhanced in vivo delivery of siRNA complexed with cationic liposomes

Synthesis, Biological Evaluation and Reversal of Sulfonated Di- and Triblock Copolymers as Novel Parenteral Anticoagulants

Despite targeting different coagulation cascade sites, all Food and Drug Administration-approved anticoagulants present an elevated risk of bleeding, including potentially life-threatening intracranial hemorrhage. Existing studies have not thoroughly investigated the efficacy and safety of sulfonate polymers in animal models and fully elucidate the precise mechanisms by which these polymers act. The activity and safety of sulfonated di- and triblock copolymers containing poly(sodium styrenesulfonate) (PSSS), poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS), poly(ethylene glycol) (PEG), poly(sodium methacrylate) (PMAAS), poly(acrylic acid) (PAA), and poly(sodium 11-acrylamidoundecanoate) (PAaU) blocks are synthesized and assessed. PSSS-based copolymers exhibit greater anticoagulant activity than PAMPS-based ones. Their activity is mainly affected by the total concentration of sulfonate groups and molecular weight. PEG-containing copolymers demonstrate a better safety profile than PAA-containing ones. The selected copolymer PEG47-PSSS32 exhibits potent anticoagulant activity in rodents after subcutaneous and intravenous administration. Heparin Binding Copolymer (HBC) completely reverses the anticoagulant activity of polymer in rat and human plasma. No interaction with platelets is observed. Selected copolymer targets mainly factor XII and fibrinogen, and to a lesser extent factors X, IX, VIII, and II, suggesting potential application in blood-contacting biomaterials for anticoagulation purposes. Further studies are needed to explore its therapeutic applications fully.

Liposomes in the cosmetics: present and outlook

Liposomes are small spherical vesicles composed of phospholipid bilayers capable of encapsulating a variety of ingredients, including water- and oil-soluble compound, which are one of the most commonly used piggybacking and delivery techniques for many active ingredients and different compounds in biology, medicine and cosmetics. With the increasing number of active cosmetic ingredients, the concomitant challenge is to effectively protect, transport, and utilize these substances in a judicious manner. Many cosmetic ingredients are ineffective both topically and systemically when applied to the skin, thus changing the method of delivery and interaction with the skin of the active ingredients is a crucial step toward improving their effectiveness. Liposomes can improve the delivery of active ingredients to the skin, enhance their stability, and ultimately, improve the efficacy of cosmetics and and pharmaceuticals. In this review, we summarized the basic properties of liposomes and their recent advances of functionalities in cosmetics and and pharmaceuticals. Also, the current state of the art in the field is discussed and the prospects for future research areas are highlighted. We hope that this review will provide ideas and inspiration on the application and development of cosmetics and pharmaceuticals.

Incorporation of poly(γ-glutamic acid) in lipid nanoparticles for enhanced mRNA delivery efficiency in vitro and in vivo

Messenger RNA (mRNA)-based therapy shows immense potential for broad biomedical applications. However, the development of safe and efficacious mRNA delivery vectors remains challenging due to delivery barriers and inefficient intracellular payload release. Herein, we presented a simple strategy to boost the mRNA intracellular release by incorporation of anionic poly(γ-glutamic acid) (PGA) into an ionizable lipid-based LNP/mRNA. We systematically investigated the impact of PGA incorporation on mRNA transfection both in vitro and in vivo. The molecular weights and formulation ratios of PGA greatly affected the transfection efficacy of LNP/mRNA. From in vitro study, the optimized LNP/mRNA/PGA was formulated by incorporation of PGA with the molecular weight of 80 kDa or 200 kDa and the charge ratio (N/P/C) of 25/1/1. The optimized formulation achieved around 3-fold mRNA expression in HeLa cells compared to the bare LNP/mRNA. The intracellular releasing study using specific DNA probe revealed that this enhancement of transfection efficacy was attributed to the elevated mRNA release into cytoplasm. Moreover, the optimized LNP/mRNA/PGA achieved up to 5-fold or 3-fold increase of luciferase mRNA expression in vivo after being injected into mice systematically or intramuscularly, respectively. In addition, the incorporation of PGA did not significantly alter the biodistribution profile of the complexes on both organ and cellular levels. Therefore, our work provides a simple strategy to boost mRNA delivery, which holds great promise to improve the efficacy of mRNA therapeutics for various biomedical applications. STATEMENT OF SIGNIFICANCE: The process of designing and screening potent mRNA carriers is complicated and time-consuming, while the efficacy is not always satisfying due to the delivery barriers and inefficient mRNA release. This work presented an alternative strategy to boost the mRNA delivery efficacy by incorporating an anionic natural polymer poly(γ-glutamic acid) (PGA) into LNP/mRNA complexes. The optimized LNP/mRNA/PGA achieved up to 3-fold and 5-fold increase in transfection efficacy in vitro and in vivo, respectively. Intracellular releasing analysis revealed that the enhancement of transfection efficacy was mainly attributed to the elevated intracellular release of mRNA. In addition, the incorporation of PGA did not alter the biodistribution or the biosafety profile of the complexes. These findings indicate that PGA incorporation is a promising strategy to improve the efficacy of mRNA therapeutics.

Elevating nucleic acid delivery via a stable anionic peptide-dextran ternary system

Nucleic acid-based therapies hold promise for treating previously intractable diseases but require effective delivery vectors to protect the therapeutic agents and ensure efficient transfection. Cationic polymeric vectors are particularly notable for their adaptability, high transfection efficiency, and low cost, but their positive charge often attracts blood proteins, causing aggregation and reduced transfection efficiency. Addressing this, we designed an anionic peptide-grafted dextran (Dex-LipE5H) to serve as a cross-linkable coating to bolster the stability of cationic polymer/nucleic acid complexes. The Dex-LipE5H was synthesized through a Michael addition reaction, combining an anionic peptide (LipE5H) with dextran modified by divinyl sulfone. We demonstrated Dex-lipE5H utility in a novel ternary nucleic acid delivery system, CDex-LipE5H/PEI/nucleic acid. CDex-LipE5H/PEI/nucleic acid demonstrated lower cytotoxicity and superior anti-protein absorption ability compared to PEI/pDNA and Dex-LipE5H/PEI/pDNA. Most notably, the crosslinked CDex-LipE5H/PEI/pDNA demonstrated remarkable transfection performance in HepG2 cells, which poses significant transfection challenges, even in a medium with 20% serum. This system's effective siRNA interference performance was further validated through a PCSK9 gene knockdown assay. This investigation provides novel insights and contributes to the design of cost-effective, next-generation nucleic acid delivery systems with enhanced blood stability and transfection efficiency.

The contribution of endocytosis to sensitization of nociceptors and synaptic transmission in nociceptive circuits

ABSTRACT

Chronic pain involves sensitization of nociceptors and synaptic transmission of painful signals in nociceptive circuits in the dorsal horn of the spinal cord. We investigated the contribution of clathrin-dependent endocytosis to sensitization of nociceptors by G protein-coupled receptors (GPCRs) and to synaptic transmission in spinal nociceptive circuits. We determined whether therapeutic targeting of endocytosis could ameliorate pain. mRNA encoding dynamin (Dnm) 1 to 3 and adaptor-associated protein kinase 1 (AAK1), which mediate clathrin-dependent endocytosis, were localized to primary sensory neurons of dorsal root ganglia of mouse and human and to spinal neurons in the dorsal horn of the mouse spinal cord by RNAScope. When injected intrathecally to mice, Dnm and AAK1 siRNA or shRNA knocked down Dnm and AAK1 mRNA in dorsal root ganglia neurons, reversed mechanical and thermal allodynia and hyperalgesia, and normalized nonevoked behavior in preclinical models of inflammatory and neuropathic pain. Intrathecally administered inhibitors of clathrin, Dnm, and AAK1 also reversed allodynia and hyperalgesia. Disruption of clathrin, Dnm, and AAK1 did not affect normal motor functions of behaviors. Patch clamp recordings of dorsal horn neurons revealed that Dnm1 and AAK1 disruption inhibited synaptic transmission between primary sensory neurons and neurons in lamina I/II of the spinal cord dorsal horn by suppressing release of synaptic vesicles from presynaptic primary afferent neurons. Patch clamp recordings from dorsal root ganglion nociceptors indicated that Dnm siRNA prevented sustained GPCR-mediated sensitization of nociceptors. By disrupting synaptic transmission in the spinal cord and blunting sensitization of nociceptors, endocytosis inhibitors offer a therapeutic approach for pain treatment.

Oral insulin delivery: Barriers, strategies, and formulation approaches: A comprehensive review

Diabetes Mellitus is characterized by a hyperglycemic condition which can either be caused by the destruction of the beta cells or by the resistance developed against insulin in the cells. Insulin is a peptide hormone that regulates the metabolism of carbohydrates, proteins, and fats. Type 1 Diabetes Mellitus needs the use of Insulin for efficient management. However invasive methods of administration may lead to reduced adherence by the patients. Hence there is a need for a non-invasive method of administration. Oral Insulin has several merits over the conventional method including patient compliance, and reduced cost, and it also mimics endogenous insulin and hence reaches the liver by the portal vein at a higher concentration and thereby showing improved efficiency. However oral Insulin must pass through several barriers in the gastrointestinal tract. Some strategies that could be utilized to bypass these barriers include the use of permeation enhancers, absorption enhancers, use of suitable polymers, use of suitable carriers, and other agents. Several formulation types have been explored for the oral delivery of Insulin like hydrogels, capsules, tablets, and patches which have been described briefly by the article. A lot of attempts have been made for developing oral insulin delivery however none of them have been commercialized due to numerous shortcomings. Currently, there are several formulations from the companies that are still in the clinical phase, the success or failure of some is yet to be seen in the future.

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.

Spheroplexes: Hybrid PLGA-cationic lipid nanoparticles, for in vitro and oral delivery of siRNA

Vectorized small interfering RNAs (siRNAs) are widely used to induce gene silencing. Among the delivery systems used, lipid-based particles are the most effective. Our objective was the development of novel lipid-polymer hybrid nanoparticles, from lipoplexes (complexes of cationic lipid and siRNAs), and poly (lactic-co-glycolic acid) (PLGA), using a simple modified nanoprecipitation method. Due to their morphology, we called these hybrid nanoparticles Spheroplexes. We elucidated their structure using several physico-chemical techniques and showed that they are composed of a hydrophobic PLGA matrix, surrounded by a lipid envelope adopting a lamellar structure, in which the siRNA is complexed, and they retain surface characteristics identical to the starting nanoparticles, i.e. lipoplexes siRNA. We analyzed the composition of the particle population and determined the final percentage of spheroplexes within this population, 80 to 85% depending on the preparation conditions, using fluorescent markers and the ability of flow cytometry to detect nanometric particles (approximately 200 nm). Finally, we showed that spheroplexes are very stable particles and more efficient than siRNA lipoplexes for the delivery of siRNA to cultured cells. We administered spheroplexes contain siRNAs targeting TNF-α to mice with ulcerative colitis induced by dextran sulfate and our results indicate a disease regression effect with a response probably mediated by their uptake by macrophages / monocytes at the level of lamina propria of the colon. The efficacy of decreased level of TNF-α in vivo seemed to be an association of spheroplexes polymer-lipid composition and the specific siRNA. These results demonstrate that spheroplexes are a promising hybrid nanoparticle for the oral delivery of siRNA to the colon.

Influence of Liposomes’ and Lipoplexes’ Physicochemical Characteristics on Their Uptake Rate and Mechanisms by the Placenta

Pregnant women are still considered as drug orphans. Developing new medications for pregnancy complications is an urgent need. Nanomedicines seem to be a promising approach to control the biodistribution of drugs to ensure both the mother’s and the fetus’ safety. Understanding the interaction between nanoparticles and the placental barrier is a key factor to the success of the development of nanomedicines for pregnant women. In this study, we evaluated the behavior of fluorescent PEGylated liposomes and lipoplexes in human placental tissue using in vitro and ex vivo models, BeWo cell culture and suspended villous placental explants, respectively. Fluorescent based analytical tools such as Fluorescence activated cells sorting (FACS), confocal microscopy and HPLC coupled to fluorescence detection were used to assess liposomes penetration and their endocytosis mechanisms in the placenta. First, no influence of the PEGylation density was observed on the cellular internalization of liposomal formulations using both models. The comparison between neutral and cationic liposomes exhibits a significant higher internalization of the cationic formulation compared to the neutral ones. In addition, the HPLC quantification of the fluorescent liposomes in human villous explants demonstrated an increase of cationic liposomes uptake with increasing incubation concentrations. Similar uptake of cationic liposomes and lipoplexes, containing the same cationic lipid, the DMAPAP but with an overall neutral surface charge, was observed and evidenced the higher effect of composition than charge surface on trophoblast penetration. Moreover, both cationic liposomes and lipoplexes exhibited an endocytosis mechanism of internalization via pathways implicating dynamin. These data highlight the key role of the liposome’s lipid composition and the possibility to modulate their internalization in the placenta by adjusting their design.

Fate of Tableted Freeze-Dried siRNA Lipoplexes in Gastrointestinal Environment

The incorporation of siRNA into nanocarriers is mandatory to facilitate its intracellular delivery, as siRNA itself cannot enter cells. However, the incorporation of these nanocarriers into oral, solid dosage forms and their fate in the gastrointestinal environment is yet to be explored. In the present work, the fate of, (i) naked siRNA, (ii) freshly prepared siRNA lipoplexes, and (iii) tableted siRNA lipoplexes, in simulated gastric and intestinal fluids was studied. The siRNA, either released from or protected within the lipoplexes, was quantified by gel electrophoresis and siRNA efficacy was assessed in cell transfection. The freshly prepared lipoplexes kept their siRNA load and transfection efficiency totally preserved during 1 h of incubation in simulated gastric fluid at 37 °C. However, in simulated intestinal fluid, despite no release of siRNA from lipoplexes after 6 h of incubation, gene silencing efficacy was dramatically decreased even after 1 h of exposure. The lipoplexes obtained from tablets efficiently protected siRNA in simulated gastric fluid, thus preserving the gene silencing efficacy, whereas their incubation in simulated intestinal fluid resulted in a marked siRNA release and decreased gene silencing efficacy. These results provided a detailed explanation for understanding the fate of siRNA in gastrointestinal conditions, when simply loaded in lipoplexes or formulated in the form of tablets.

Innovations in Biomaterial Design toward Successful RNA Interference Therapy for Cancer Treatment

Gene regulation using RNA interference (RNAi) therapy has been developed as one of the frontiers in cancer treatment. The ability to tailor the expression of genes by delivering synthetic oligonucleotides to tumor cells has transformed the way scientists think about treating cancer. However, its clinical application has been limited due to the need to deliver synthetic RNAi oligonucleotides efficiently and effectively to target cells. Advances in nanotechnology and biomaterials have begun to address the limitations to RNAi therapeutic delivery, increasing the likelihood of RNAi therapeutics for cancer treatment in clinical settings. Herein, innovations in the design of nanocarriers for the delivery of oligonucleotides for successful RNAi therapy are discussed.

Cationic lipid nanoparticle production by microfluidization for siRNA delivery

Microfluidization has been investigated as a new, scalable, and basic component saving method to produce cationic lipid nanoparticles, in particular for the delivery of short interfering RNAs (siRNAs). The design of experiment (DoE) allowed to reach optimized characteristics in terms of nanocarrier size reduction and low polydispersity. The structure of cationic liposomes and siRNA-lipoplexes was characterized. The optimized preparation parameters were identified as three microfluidization passages at a pressure of 10,000 psi, with a thin film hydration volume of 4 ml. Microfluidized liposomes mean size was 160 nm, with a polydispersity index of 0.2-0.3 and a zeta potential of +40 mV to +60 mV. Positive versus negative charge ratio between the charges of the cationic lipid and the phosphate charges of the siRNAs is a key factor determining the structure and silencing efficacy of siRNA lipoplexes. At a (+/-) charge ratio of 8, a proportion of 88% of the siRNA was associated to microfluidized lipoplexes, which remained stable for one month. These lipoplexes exhibited moderate cytotoxicity and gene silencing efficacy, which should be further optimized.

MicroRNA Targets for Asthma Therapy

Asthma is a chronic inflammatory obstructive lung disease that is stratified into endotypes. Th2 high asthma is due to an imbalance of Th1/Th2 signaling leading to abnormally high levels of Th2 cytokines, IL-4, IL-5, and IL-13 and in some cases a reduction in type I interferons. Some asthmatics express Th2 low, Th1/Th17 high phenotypes with or without eosinophilia. Most asthmatics with Th2 high phenotype respond to beta-adrenergic agonists, muscarinic antagonists, and inhaled corticosteroids. However, 5-10% of asthmatics are not well controlled by these therapies despite significant advances in lung immunology and the pathogenesis of severe asthma. This problem is being addressed by developing novel classes of anti-inflammatory agents. Numerous studies have established efficacy of targeting pro-inflammatory microRNAs in mouse models of mild/moderate and severe asthma. Current approaches employ microRNA mimics and antagonists designed for use in vivo. Chemically modified oligonucleotides have enhanced stability in blood, increased cell permeability, and optimized target specificity. Delivery to lung tissue limits clinical applications, but it is a tractable problem. Future studies need to define the most effective microRNA targets and effective delivery systems. Successful oligonucleotide drug candidates must have adequate lung cell uptake, high target specificity, and efficacy with tolerable off-target effects.

Development of Theranostic Cationic Liposomes Designed for Image-Guided Delivery of Nucleic Acid

Cationic liposomes have been considered as potential vectors for gene delivery thanks to their ability to transfect cells with high efficiency. Recently, the combination of diagnostic agent and therapeutic agents in the same particle to form a theranostic system has been reported. Magnetic liposomes are one of these examples. Due to the magnetic nanoparticles encapsulated in the liposomes, they can act as a drug delivery system and, at the same time, a magnetic resonance imaging contrast enhancement agent or hyperthermia. In this work, nucleic acid delivery systems based on magnetic cationic liposomes (MCLs) were developed. Two different techniques, reverse phase evaporation and cosolvent sonication, were employed for liposome preparation. Both strategies produced MCLs of less than 200 nm with highly positive charge. Enhancement of their transverse and longitudinal relaxivities r₂ and r₁ was obtained with both kinds of magnetic liposomes compared to free magnetic nanoparticles. Moreover, these MCLs showed high capacity to form complexes and transfect CT-26 cells using the antibiotic-free pFAR4-luc plasmid. The transfection enhancement with magnetofection was also carried out in CT26 cells. These results suggested that our MCLs could be a promising candidate for image-guided gene therapy.

Compression of Vectors for Small Interfering RNAs Delivery: Toward Oral Administration of siRNA Lipoplexes in Tablet Forms

Currently, most nonviral nucleic acid vectors are in the form of colloidal suspensions administered primarily parenterally. This type of formulation and the mode of administration impose strong constraints such as the size of the administered vectors or the production of sterile preparations. The tablet form provides access to easy oral administration, well accepted by patients; As regards nucleic acid vectors, a dry form represents an advance in terms of stability. Using an optimized lipid-based small interfering RNA-delivery system, we studied the tabletability of a liquid suspension of these vectors. We optimized the conditions of freeze-drying by choosing excipients and process, allowing for the conservation of both the gene-silencing efficacy of the formulated siRNAs and the supramolecular structure of the lipid particulate system. Gene-silencing efficacy was assayed on luciferase-expressing cells and the structure of the siRNA vector in freeze-dried and tablet forms was examined using small-angle X-ray scattering (SAXS) synchrotron radiation. The freeze-dried powders were then mixed with excipients necessary for the good progress of the compression by allowing for a regular supply of the matrix and the reduction of friction. The compression was carried out using a rotary press simulator that allows for complete monitoring of the compression conditions. After compression, formulated siRNAs retained more than 60% of their gene-silencing efficacy. Within the tablets, a specific SAXS signal was detectable and the lamellar and cubic phases of the initial liquid suspension were restored after resuspension of siRNA vectors by disintegration of the tablets. These results show that the bilayer lipid structures of the particles were preserved despite the mechanical constraints imposed by the compression. If such a result could be expected after the freeze-drying step, it was never shown, to our knowledge, that siRNA-delivery systems could retain their efficacy and structure after mechanical stress such as compression. This opens promising perspectives to oral administration of siRNA as an alternative to parenteral administration.

Co-delivery of VEGF siRNA and Etoposide for Enhanced Anti-angiogenesis and Anti-proliferation Effect via Multi-functional Nanoparticles for Orthotopic Non-Small Cell Lung Cancer Treatment

Targeting tumor angiogenesis pathway via VEGF siRNA (siVEGF) has shown great potential in treating highly malignant and metastatic non-small cell lung cancer (NSCLC). However, anti-angiogenic monotherapy lacked sufficient antitumor efficacy which suffered from malignant tumor proliferation. Therefore, the combined application of siVEGF and chemotherapeutic agents for simultaneous targeting of tumor proliferation and angiogenesis has been a research hotspot to explore a promising NSCLC therapy regimen.

Methods: We designed, for the first time, a rational therapy strategy via intelligently co-delivering siVEGF and chemotherapeutics etoposide (ETO) by multi-functional nanoparticles (NPs) directed against the orthotopic NSCLC. These NPs consisted of cationic liposomes loaded with siVEGF and ETO and then coated with versatile polymer PEGylated histidine-grafted chitosan-lipoic acid (PHCL). We then comprehensively evaluated the anti-angiogenic and anti-proliferation efficiency in the in vitro tumor cell model and in bioluminescent orthotopic lung tumor bearing mice model.

Results: The NPs co-delivering siVEGF and ETO exhibited tailor-made surface charge reversal features in mimicking tumor extracellular environment with improved internal tumor penetration capacity and higher cellular internalization. Furthermore, these NPs with flexible particles size triggered by intracellular acidic environment and redox environment showed pinpointed and sharp intracellular cargo release guaranteeing adequate active drug concentration in tumor cells. Enhanced VEGF gene expression silencing efficacy and improved tumor cell anti-proliferation effect were demonstrated in vitro. In addition, the PHCL layer improved the stability of these NPs in neutral environment allowing enhanced orthotopic lung tumor targeting efficiency in vivo. The combined therapy by siVEGF and ETO co-delivered NPs for orthotopic NSCLC simultaneously inhibited tumor proliferation and tumor angiogenesis resulting in more significant suppression of tumor growth and metastasis than monotherapy.

Conclusion: Combined application of siVEGF and ETO by the multi-functional NPs with excellent and on-demand properties exhibited the desired antitumor effect on the orthotopic lung tumor. Our work has significant potential in promoting combined anti-angiogenesis therapy and chemotherapy regimen for clinical NSCLC treatment.

Modifying internal organization and surface morphology of siRNA lipoplexes by sodium alginate addition for efficient siRNA delivery

Vectorized small interfering RNAs (siRNAs) are widely used to induce specific mRNA degradation in the intracellular compartment of eukaryotic cells. Recently, we developed efficient cationic lipid-based siRNA vectors (siRNA lipoplexes or siLex) containing sodium alginate (Nalg-siLex) with superior efficiency and stability properties than siLex. In this study, we assessed the physicochemical and some biological properties of Nalg-siLex compared to siLex. While no significant differences in size, ζ potential and siRNA compaction were detected, the addition of sodium alginate modified the particle morphology, producing smoother and heterogeneous particles characterized by transmission electron microscopy. We also noted that Nalg-siLex have surface differences observed by X-ray photoelectron spectroscopy. These differences could arise from an internal reorganization of components induced by the addition of sodium alginate, that is indicated by Small-Angle X-ray Scattering results. Moreover, Nalg-siLex did not trigger significant hepatotoxicity nor inflammatory cytokine secretion compared to siLex. Taken together these results suggest that sodium alginate played a key role by structuring and reinforcing siRNA lipoplexes, leading to more stable and efficient delivery vector.

Microbubbles for Nucleic Acid Delivery in Liver Using Mild Sonoporation

Ultrasound-mediated gene delivery is an interesting approach, which could help in increasing gene transfer in deep tissues. Moreover, it allows for performing experiments guided by the image to determine which elements are required. Microbubbles complexed with a eukaryotic expression cassette are excellent agents as they are responsive to ultrasounds and, upon oscillation, can destabilize membranes to enhance gene transfer. Here, we describe the preparation of positively charged microbubbles, plasmid free of antibiotic resistance marker, their combination and the conditions of ultrasound-mediated liver transfection post-systemic administration in mice. This association allowed us to obtain a superior liver gene expression at least over 8 months after a single injection.

Liposomes as Gene Delivery Vectors for Human Placental Cells

Nanomedicine as a therapeutic approach for pregnancy-related diseases could offer improved treatments for the mother while avoiding side effects for the fetus. In this study, we evaluated the potential of liposomes as carriers for small interfering RNAs to placental cells. Three neutral formulations carrying rhodamine-labelled siRNAs were evaluated on an in vitro model, i.e., human primary villous cytotrophoblasts. siRNA internalization rate from lipoplexes were compared to the one in the presence of the lipofectamine reagent and assessed by confocal microscopy. Results showed cellular internalization of nucleic acid with all three formulations, based on two cationic lipids, either DMAPAP or CSL-3. Moreover, incubation with DMAPAP+AA provided a rate of labelled cells as high as with lipofectamine (53 ± 15% and 44 ± 12%, respectively) while being more biocompatible. The proportion of cells which internalized siRNA were similar when using DMAPAP/DDSTU (16 ± 5%) and CSL-3 (22 ± 5%). This work highlights that liposomes could be a promising approach for gene therapy dedicated to pregnant patients.

Neurokinin 1 receptor signaling in endosomes mediates sustained nociception and is a viable therapeutic target for prolonged pain relief

Typically considered to be cell surface sensors of extracellular signals, heterotrimeric GTP-binding protein (G protein)-coupled receptors (GPCRs) control many pathophysiological processes and are the target of 30% of therapeutic drugs. Activated receptors redistribute to endosomes, but researchers have yet to explore whether endosomal receptors generate signals that control complex processes in vivo and are viable therapeutic targets. We report that the substance P (SP) neurokinin 1 receptor (NK₁R) signals from endosomes to induce sustained excitation of spinal neurons and pain transmission and that specific antagonism of the NK₁R in endosomes with membrane-anchored drug conjugates provides more effective and sustained pain relief than conventional plasma membrane-targeted antagonists. Pharmacological and genetic disruption of clathrin, dynamin, and β-arrestin blocked SP-induced NK₁R endocytosis and prevented SP-stimulated activation of cytosolic protein kinase C and nuclear extracellular signal-regulated kinase, as well as transcription. Endocytosis inhibitors prevented sustained SP-induced excitation of neurons in spinal cord slices in vitro and attenuated nociception in vivo. When conjugated to cholestanol to promote endosomal targeting, NK₁R antagonists selectively inhibited endosomal signaling and sustained neuronal excitation. Cholestanol conjugation amplified and prolonged the antinociceptive actions of NK₁R antagonists. These results reveal a critical role for endosomal signaling of the NK₁R in the complex pathophysiology of pain and demonstrate the use of endosomally targeted GPCR antagonists.

Poly(ethylene glycol)-poly-l-glutamate complexed with polyethyleneimine−polyglycine for highly efficient gene delivery in vitro and in vivo

The highly efficient gene delivery system with effective serum resistant capacity is promising for cancer therapy.

Attenuation of Maladaptive Responses in Aortic Adventitial Fibroblasts through Stimuli-Triggered siRNA Release from Lipid-Polymer Nanocomplexes

Lipid-siRNA assemblies are modified with photo-responsive polymers to enable spatiotemporally-controlled silencing of interleukin 1 beta (IL1β) and cadherin 11 (CDH11), two genes that are essential drivers of maladaptive responses in human aortic adventitial fibroblasts (AoAFs). These hybrid nanocomplexes address the critical challenge of locally mitigating fibrotic actions that lead to the high rates of vascular graft failures. In particular, the lipid-polymer formulations provide potent silencing of IL1β and CDH11 that is precisely modulated by a photo-release stimulus. Moreover, a dynamic modeling framework is used to design a multi-dose siRNA regimen that sustains knockdown of both genes over clinically-relevant timescales. Multi-dose suppression illuminates a cooperative role for IL1β and CDH11 in pathogenic adventitial remodeling and is directly linked to desirable functional outcomes. Specifically, myofibroblast differentiation and cellular proliferation, two of the primary hallmarks of fibrosis, are significantly attenuated by IL1β silencing. Meanwhile, the effects of CDH11 siRNA treatment on differentiation become more pronounced at higher cell densities characteristic of constrictive adventitial remodeling in vivo. Thus, this work offers a unique formulation design for photo-responsive gene suppression in human primary cells and establishes a new dosing method to satisfy the critical need for local attenuation of fibrotic responses in the adventitium surrounding vascular grafts.

Anionic Polymer and Quantum Dot Excipients to Facilitate siRNA Release and Self-Reporting of Disassembly in Stimuli-Responsive Nanocarrier Formulations

The incorporation of anionic excipients into polyplexes is a promising strategy for modulating siRNA binding versus release and integrating diagnostic capabilities; however, specific design criteria and structure-function relationships are needed to facilitate the development of nanocarrier-based theranostics. Herein, we incorporated poly(acrylic acid) (PAA) and quantum dot (QD) excipients into photolabile siRNA polyplexes to increase gene silencing efficiencies by up to 100% and enable self-reporting of nanocarrier disassembly. Our systematic approach identified the functional relationships between gene silencing and key parameters such as excipient loading fractions and molecular weights that facilitated the establishment of design rules for optimization of nanocarrier efficacy. For example, we found that PAA molecular weights ∼10-20× greater than that of the coencapsulated siRNA exhibited the most efficient release and silencing. Furthermore, siRNA release assays and RNAi modeling allowed us to generate a PAA "heat map" that predicted gene silencing a priori as a function of PAA molecular weight and loading fraction. QDs further promoted selective siRNA release and provided visual as well as Förster resonance energy transfer (FRET)-based monitoring of the dynamic changes in nanostructure in situ. Moreover, even with the addition of anionic components, our formulations exhibited substantially improved stability and shelf life relative to typical formulations, with complete stability after a week of storage and full activity in the presence of serum. Taken together, this study enabled synergistic improvements in siRNA release and diagnostic capabilities, along with the development of mechanistic insights that are critical for advancing the translation of nucleic acid theranostics into the clinic.

Polyanionic Antimicrobial Membranes: An Experimental and Theoretical Study

Polycationic polymers have been widely used as antimicrobial materials because of their broad spectrum activity and potential use as new antibiotics. Herein, we report the synthesis of polyanionic antimicrobial membranes by in situ photo-cross-linking of a sulfate based anionic monomer, followed by cation-exchange with organic (quaternary ammonium or imidazolium) or metal (Ag⁺, Cu²⁺, Fe³⁺, Zn²⁺, Na⁺, K⁺) cations. The resultant polyanionic membranes show high and broad spectrum antibacterial activities against both bacteria (Escherichia coli, Staphylococcus aureus) and fungi (Candida albicans ). In addition, the polyanionic antimicrobial membranes efficiently inhibited the formation of biofilms by SC5314 and its crk1 gene deleted (Δcrk1) C. albicans strains. Furthermore, the synthesized polyanionic membranes exhibit good blood compatibility, low cytotoxicity and long-term antibacterial stability, demonstrating safe antimicrobial materials in the application of healthcare.

Physical properties and biological interactions of liposomes developed as a drug carrier in the field of regenerative medicine

Liposomes are used for encapsulation of the active compounds in different therapies, with the increasing frequency. The important areas of clinical applications of liposomes are cancer targeted treatment, antibiotic delivery or regenerative medicine. The liposomes can transfer both hydrophilic and hydrophobic compounds and have the lipid bilayer which imitates the cell membrane. Liposomes additionally may extend half-live period of drugs and protect them against the elimination in different ways, such as phagocytosis, enzymatic cleavage or exclusion by detoxification. The size and charge of liposomes play an important role in drug distribution and absorption into the cell. Limited data is available on the effects of liposomes on stem cells and progenitor cells. In this article, we examined the effect of charged conventional liposomes on growth of mesenchymal and blood stem cells isolated from umbilical cord. The data suggest a likelihood, that positively charged liposomes could impair stem cell growth and metabolism. Different methodological approaches allowed for the selection of negatively charged liposomes for further experiments, as the only type of liposomes which has the lowest cytotoxicity and does not affect hematopoietic cell proliferation.

Genetic pharmacology: progresses in siRNA delivery and therapeutic applications

In the RNA interference process, the catalytic degradation of an endogenous mRNA results from the Watson-Crick complementary recognition by either a small silencing synthetic double-stranded ribonucleotide (siRNA) or by a small hairpin RNA (shRNA) produced in the cell by transcription from a DNA template. This interference process ideally results in an exquisitely specific mRNA suppression. The present review is dedicated to siRNAs. It describes the mechanism of RNA silencing and the main siRNA delivery techniques, with a focus on siRNA self-complexing to cationic lipids to form nanoparticles, which are called lipoplexes. The addition to lipoplexes of an anionic polymer leads to the ternary formulation APIRL (Anionic-Polymer-Interfering-RNA-Lipoplexes) with increased in vivo stability and biological efficacy. In terms of clinical development, the review focuses on therapeutic applications by intravenous delivery to the liver and inflammatory joints, and to localized siRNA delivery to the ocular sphere.

Pharmacokinetics and biodistribution of recently-developed siRNA nanomedicines

Small interfering RNA (siRNA) is a promising drug candidate, expected to have broad therapeutic potentials toward various diseases including viral infections and cancer. With recent advances in bioconjugate chemistry and carrier technology, several siRNA-based drugs have advanced to clinical trials. However, most cases address local applications or diseases in the filtering organs, reflecting remaining challenges in systemic delivery of siRNA. The difficulty in siRNA delivery is in large part due to poor circulation stability and unfavorable pharmacokinetics and biodistribution profiles of siRNA. This review describes the pharmacokinetics and biodistribution of siRNA nanomedicines, focusing on those reported in the past 5years, and their pharmacological effects in selected disease models such as hepatocellular carcinoma, liver infections, and respiratory diseases. The examples discussed here will provide an insight into the current status of the art and unmet needs in siRNA delivery.

Application of biodegradable dendrigraft poly-l-lysine to a small interfering RNA delivery system

Dendrigraft poly-l-lysine (DGL), including its central core, consists entirely of lysine, hence it is completely biodegradable. We applied DGL in a small interfering RNA (siRNA) delivery system. Binary complexes with siRNA and DGL had particle sizes of 23-73 nm and ζ-potentials of 34-42 mV. The siRNA-DGL complexes showed significant silencing effects in a mouse colon carcinoma cell line expressing luciferase (Colon26/Luc cells). The siRNA-DGL complexes induced slight cytotoxicity and hematological toxicity at a high charge ratio of DGL to siRNA, probably because of their cationic charges. Therefore, we recharged the siRNA-DGL complexes with γ-polyglutamic acid (γ-PGA), a biodegradable anionic compound, which was reported to reduce the cytotoxicity of cationic complexes. The ternary complexes showed particle sizes of 35-47 nm at a charge ratio of greater than 14 to siRNA with negative charges. Strong silencing effects of the ternary complexes were observed in Colon26/Luc cells without cytotoxicity or hematological toxicity. The cellular uptake and degradation of the binary and ternary complexes were confirmed by fluorescence microscopy. The ternary complexes suppressed luciferase activity in the tumor after direct injection into the tumors of mice bearing Colon26/Luc cells. Thus, a potentially important siRNA delivery system was constructed using biodegradable DGL.

Lipoplexes Strengthened by Anionic Polymers: Easy Preparation of Highly Effective siRNA Vectors Based on Cationic Lipids and Anionic Polymers

RNA interference is an invaluable tool in biology to specifically silence a given gene. Synthetic duplexes of RNA oligonucleotides are widely used to induce mRNA degradation in cultured cells or in whole organisms. They have to be vectorized to reach their target site. Here, we describe the preparation of highly efficient siRNA vectors based on cationic liposomes and polyanionic polymers and their application in cultured cells to silence reporter and/or endogenous genes.

Inhibition of replication of hepatitis B virus in transgenic mice following administration of hepatotropic lipoplexes containing guanidinopropyl-modified siRNAs

Chronic infection with hepatitis B virus (HBV) occurs commonly and complications that arise from persistence of the virus are associated with high mortality. Available licensed drugs have modest curative efficacy and advancing new therapeutic strategies to eliminate the virus is therefore a priority. HBV is susceptible to inactivation by exogenous gene silencers that harness RNA interference (RNAi) and the approach has therapeutic potential. To advance RNAi-based treatment for HBV infection, use in vivo of hepatotropic lipoplexes containing siRNAs with guanidinopropyl (GP) modifications is reported here. Lipoplexes contained polyglutamate, which has previously been shown to facilitate formulation and improve efficiency of the non-viral vectors. GP moieties were included in a previously described anti-HBV siRNA that effectively targeted the conserved viral X sequence. Particles had physical properties that were suitable for use in vivo: average diameter was approximately 50-200 nm and surface charge (zeta potential) was +65 mV. Efficient hepatotropic delivery of labeled siRNA was observed following systemic intravenous injection of the particles into HBV transgenic mice. Good inhibition of markers of viral replication was observed without evidence of toxicity. Efficacy of the GP-modified siRNAs was significantly more durable and formulations made up with chemically modified siRNAs were less immunostimulatory. An RNAi-mediated mechanism was confirmed by demonstrating that HBV mRNA cleavage occurred in vivo at the intended target site. Collectively these data indicate that GP-modified siRNAs formulated in anionic polymer-containing lipoplexes are effective silencers of HBV replication in vivo and have therapeutic potential.

Calcium-activated gene transfection from DNA/poly(amic acid-co-imide) complexes

In this study, we synthesized a water-soluble poly(amic acid-co-imide) (PA-I) from ethylenediaminetetraacetic dianhydride (EDTA) and 2,2′-(ethylenedioxy)bis(ethylamine) that possesses comparable transfection efficiency to that of polyethylenimine (PEI), when prepared in combination with divalent calcium cations. The polycondensation of monomers afforded poly(amic acid) (PA) precursors, and subsequent thermal imidization resulted in the formation of PA-I. At a polymer/DNA ratio (indicated by the molar ratio of nitrogen in the polymer to phosphate in DNA) of 40, complete retardation of the DNA band was observed by gel electrophoresis, indicating the strong association of DNA with PA-I. A zeta potential of −22 mV was recorded for the PA-I polymer solution, and no apparent cytotoxicity was observed at concentrations up to 500 μg·mL⁻¹. In the presence of divalent Ca²⁺, the transfection efficiency of PA-I was higher than that of PA, due to the formation of a copolymer/Ca²⁺/DNA polyplex and the reduction in negative charge due to thermal cyclization. Interestingly, a synergistic effect of Ca²⁺ and the synthesized copolymer on DNA transfection was observed. The use of Ca²⁺ or copolymer alone resulted in unsatisfactory delivery, whereas the formation of three-component polyplexes synergistically increased DNA transfection. Our findings demonstrated that a PA-I/Ca²⁺/DNA polyplex could serve as a promising candidate for gene delivery.

Cyclodextrin-based switchable DNA condenser

Switchable DNA condensers based on β-CD bearing imidazolium and hydrolysable linkages were synthesized, showing base or enzyme-responsive switchable condensation ability.

Decationized polyplexes for gene delivery

Gene therapy has received much attention in the field of drug delivery. Synthetic, nonviral gene delivery systems have gained increasing attention as vectors for gene therapy mainly due to a favorable immunogenicity profile and ease of manufacturing as compared to viral vectors. The great majority of these formulations are based on polycationic structures, due to their ability to interact with negatively charged nucleic acids to spontaneously form nanoparticles. In recent years, several polycationic systems have demonstrated high transfection in vitro. However, progress toward clinical applications has been slow, mainly because the cationic nature of these systems leads to intolerable toxicity levels, inappropriate biodistribution and unsatisfactory efficiency in vivo, particularly after systemic administration. Decationized polyplexes are a new class of gene delivery systems that have been developed as an alternative for conventional polycation-based systems. The major innovation introduced by decationized polyplexes is that these systems are based on neutral polymers, without any detrimental effect on the physicochemical stability or encapsulation ability, due to the transient presence of cationic charge and disulfide cross-links between the polymer chains by which the nucleic acids are physically entrapped in the particles. This editorial summarizes the most important features of decationized polyplexes and discusses potential implications for the development of new safe and efficient gene delivery systems.

Junctional neurulation: a unique developmental program shaping a discrete region of the spinal cord highly susceptible to neural tube defects

In higher vertebrates, the primordium of the nervous system, the neural tube, is shaped along the rostrocaudal axis through two consecutive, radically different processes referred to as primary and secondary neurulation. Failures in neurulation lead to severe anomalies of the nervous system, called neural tube defects (NTDs), which are among the most common congenital malformations in humans. Mechanisms causing NTDs in humans remain ill-defined. Of particular interest, the thoracolumbar region, which encompasses many NTD cases in the spine, corresponds to the junction between primary and secondary neurulations. Elucidating which developmental processes operate during neurulation in this region is therefore pivotal to unraveling the etiology of NTDs. Here, using the chick embryo as a model, we show that, at the junction, the neural tube is elaborated by a unique developmental program involving concerted movements of elevation and folding combined with local cell ingression and accretion. This process ensures the topological continuity between the primary and secondary neural tubes while supplying all neural progenitors of both the junctional and secondary neural tubes. Because it is distinct from the other neurulation events, we term this phenomenon junctional neurulation. Moreover, the planar-cell-polarity member, Prickle-1, is recruited specifically during junctional neurulation and its misexpression within a limited time period suffices to cause anomalies that phenocopy lower spine NTDs in human. Our study thus provides a molecular and cellular basis for understanding the causality of NTD prevalence in humans and ascribes to Prickle-1 a critical role in lower spinal cord formation.

Epigenetic targets for novel therapies of lung diseases

In spite of substantial advances in defining the immunobiology and function of structural cells in lung diseases there is still insufficient knowledge to develop fundamentally new classes of drugs to treat many lung diseases. For example, there is a compelling need for new therapeutic approaches to address severe persistent asthma that is insensitive to inhaled corticosteroids. Although the prevalence of steroid-resistant asthma is 5-10%, severe asthmatics require a disproportionate level of health care spending and constitute a majority of fatal asthma episodes. None of the established drug therapies including long-acting beta agonists or inhaled corticosteroids reverse established airway remodeling. Obstructive airways remodeling in patients with chronic obstructive pulmonary disease (COPD), restrictive remodeling in idiopathic pulmonary fibrosis (IPF) and occlusive vascular remodeling in pulmonary hypertension are similarly unresponsive to current drug therapy. Therefore, drugs are needed to achieve long-acting suppression and reversal of pathological airway and vascular remodeling. Novel drug classes are emerging from advances in epigenetics. Novel mechanisms are emerging by which cells adapt to environmental cues, which include changes in DNA methylation, histone modifications and regulation of transcription and translation by noncoding RNAs. In this review we will summarize current epigenetic approaches being applied to preclinical drug development addressing important therapeutic challenges in lung diseases. These challenges are being addressed by advances in lung delivery of oligonucleotides and small molecules that modify the histone code, DNA methylation patterns and miRNA function.

Therapeutic potential of siRNA and DNAzymes in cancer

Cancer is characterized by uncontrolled cell growth, invasion, and metastasis and possess threat to humans worldwide. The scientific community is facing numerous challenges despite several efforts to cure cancer. Though a number of studies were done earlier, the molecular mechanism of cancer progression is not completely understood. Currently available treatments like surgery resection, adjuvant chemotherapy, and radiotherapy are not completely effective in curing all the cancers. Recent advances in the antisense technology provide a powerful tool to investigate various cancer pathways and target them. Small interfering RNAs (siRNAs) could be effective in downregulating the cancer-associated genes, but their in vivo delivery is the main obstacle. DNA enzymes (DNAzymes) have great potential in the treatment of cancer due to high selectivity and significant catalytic efficiency. In this review, we are focusing on antisense molecules such as siRNA and DNAzymes in cancer therapeutics development. This review also describes the challenges and approaches to overcome obstacles involved in using siRNA and DNAzymes in the treatment of cancers.

siRNA delivery to the lung: what's new?

RNA interference (RNAi) has been thought of as the general answer to many unmet medical needs. After the first success stories, it soon became obvious that short interfering RNA (siRNA) is not suitable for systemic administration due to its poor pharmacokinetics. Therefore local administration routes have been adopted for more successful in vivo RNAi. This paper reviews nucleic acid modifications, nanocarrier chemistry, animal models used in successful pulmonary siRNA delivery, as well as clinical translation approaches. We summarize what has been published recently and conclude with the potential problems that may still hamper the efficient clinical application of RNAi in the lung.

Lipid-based nanoparticles in the systemic delivery of siRNA

RNAi therapeutics are believed to be the future of personalized medicine and have shown promise in early clinical trials. However, many physiological barriers exist in the systemic delivery of siRNAs to the cytoplasm of targeted cells to perform their function. To overcome these barriers, many siRNA delivery systems have been developed. Among these, lipid-based nanoparticles have great potential owing to their biocompatibility and low toxicity in comparison with inorganic nanoparticles and viral systems. This review discusses the hurdles of systemic siRNA delivery and highlights the recent progress made in lipid-based nanoparticles, which are categorized based on their key lipid components, including cationic lipid, lipoprotein, lipidoid, neutral lipid and anionic lipid-based nanoparticles. It is expected that these lipid nanoparticle-based siRNA delivery systems will have an enabling role for personalized cancer medicine, where siRNA delivery will join forces with genetic profiling of individual patients to achieve the best treatment outcome.

Poly(ethylene glycol)-block-cationic polylactide nanocomplexes of differing charge density for gene delivery

Representing a new type of biodegradable cationic block copolymer, well-defined poly(ethylene glycol)-block-cationic polylactides (PEG-b-CPLAs) with tertiary amine-based cationic groups were synthesized by thiol-ene functionalization of an allyl-functionalized diblock precursor. Subsequently the application of PEG-b-CPLAs as biodegradable vectors for the delivery of plasmid DNAs (pDNAs) was investigated. Via the formation of PEG-b-CPLA:pDNA nanocomplexes by spontaneous electrostatic interaction, pDNAs encoding luciferase or enhanced green fluorescent protein were successfully delivered to four physiologically distinct cell lines (including macrophage, fibroblast, epithelial, and stem cell). Formulated nanocomplexes demonstrated high levels of transfection with low levels of cytotoxicity and hemolysis when compared to a positive control. Biophysical characterization of charge densities of nanocomplexes at various polymer:pDNA weight ratios revealed a positive correlation between surface charge and gene delivery. Nanocomplexes with high surface charge densities were utilized in an in vitro serum gene delivery inhibition assay, and effective gene delivery was observed despite high levels of serum. Overall, these results help to elucidate the influence of charge, size, and PEGylation of nanocomplexes upon the delivery of nucleic acids in physiologically relevant conditions.