Targeted intracellular delivery of antisense oligonucleotides via conjugation with small-molecule ligands

Effect of chemical modification on the exon-skipping activity of heteroduplex oligonucleotides

We applied heteroduplex oligonucleotide (HDO) technology, which uses an oligonucleotide hybridized with a complementary strand, to efficiently deliver locked nucleic acid (LNA)-based splice-switching oligonucleotides (SSOs) to the nucleus. Using an in vitro assay involving cationic lipids, we revealed that HDO technology increased the exon-skipping activity of LNA-based SSOs. To assess the effect of heteroduplex SSOs (HDSSOs) on exon-skipping activity, we designed and evaluated various HDSSOs using a series of complementary oligonucleotides with different sugar chemistries (DNA, RNA, and LNA), linkages (phosphodiester; PO and phosphorothioate; PS linkages), and lengths. HDO with different complementary oligonucleotide designs demonstrated a variety of exon-skipping activities. Next, we investigated the intracellular behavior of HDOs, which seemed to affect their efficient exon-skipping activity. We found that HDO technology increased the uptake of both SSOs and complementary oligonucleotides into the nuclei. Additionally, a series of complementary oligonucleotides showed different intracellular stabilities, and complementary oligonucleotide design appears to be one of the key factors affecting efficient exon skipping. Finally, we examined the exon-skipping activity of HDSSOs in mdx mice and found that HDSSOs exhibited higher exon-skipping activity than single-stranded LNA-based SSOs in these mice under intramuscular injections.

Nucleic Acid Conjugates: Unlocking Therapeutic Potential

Nucleic acids have emerged as a powerful class of therapeutics. Through simple base pair complementarity, nucleic acids allow the targeting of a variety of pathologically relevant proteins and RNA molecules. However, despite the preliminary successes of nucleic acids as drugs in the clinic, limited biodistribution, inadequate delivery mechanisms, and target engagement remain key challenges in the field. A key area of research has been the chemical optimization of nucleic acid backbones to significantly enhance their "drug-like" properties. Alternatively, this review focuses on the next generation of nucleic acid chemical modifications: covalent biochemical conjugates. These conjugates are being applied to improve the delivery, functionality, and targeting. Exploiting research on heterobifunctionals, such as PROTACs, RIBOTACs, molecular glues, etc., has the potential to dramatically expand nucleic acid drug functionality and target engagement capabilities. Such next-generation chemistry-based enhancements have the potential to unlock nucleic acids as effective and versatile therapeutic agents.

Nano-encapsulation of drugs to target hepatic stellate cells: Toward precision treatments of liver fibrosis

Liver fibrosis is characterized by excessive extracellular matrix (ECM) deposition triggered by hepatic stellate cells (HSCs). As central players in fibrosis progression, HSCs are the most important therapeutic targets for antifibrotic therapy. However, owing to the limitations of systemic drug administration, there is still no suitable and effective clinical treatment. In recent years, nanosystems have demonstrated expansive therapeutic potential and evolved into a clinical modality. In liver fibrosis, nanosystems have undergone a paradigm shift from targeting the whole liver to locally targeted modifying processes. Nanomedicine delivered to HSCs has significant potential in managing liver fibrosis, where optimal management would benefit from targeted delivery, personalized therapy based on the specific site of interest, and minor side effects. In this review, we present a brief overview of the role of HSCs in the pathogenesis of liver fibrosis, summarize the different types of nanocarriers and their specific delivery applications in liver fibrosis, and highlight the biological barriers associated with the use of nanosystems to target HSCs and approaches available to solve this issue. We further discuss in-depth all the molecular target receptors overexpressed during HSC activation in liver fibrosis and their corresponding ligands that have been used for drug or gene delivery targeting HSCs.

Supramolecular Bioconjugation Strategy for Antibody-Targeted Delivery of siRNA

RNA interference is a widely used biological process by which double-stranded RNA induces sequence-specific gene silencing by targeting mRNA for degradation. However, the physicochemical properties of siRNAs make their delivery extremely challenging, thus limiting their bioavailability at the target site. In this context, we developed a versatile and selective siRNA delivery system of a trastuzumab-conjugated nanocarrier. These immunoconjugates consist of the assembly by electrostatic interactions of an oligonucleotide-modified antibody with a cationic micelle for the targeted delivery of siRNA in HER2-overexpressing cancer cells. Results show that, when associated with the corresponding siRNA at the appropriate N/P ratio, our supramolecular assembly was able to efficiently induce luciferase and PLK-1 gene silencing in a cell-selective manner in vitro.

Favorable efficacy and reduced acute neurotoxicity by antisense oligonucleotides with 2',4'-BNA/LNA with 9-(aminoethoxy)phenoxazine

An increasing number of antisense oligonucleotides (ASOs) have been approved for clinical use. However, improvements of both efficacy and safety in the central nervous system (CNS) are crucial for the treatment with CNS diseases. We aimed to overcome the crucial issues by our development of various gapmer ASOs with a novel nucleoside derivative including a 2',4'-BNA/LNA with 9-(aminoethoxy)phenoxazine (BNAP-AEO). The various gapmer ASOs with BNAP-AEO were evaluated for thermal stability, in vitro and in vivo efficacy, and acute CNS toxicity. Thermal stability analysis of the duplexes with their complementary RNAs showed that ASOs with BNAP-AEO had a higher binding affinity than those without BNAP-AEO. In vitro assays, when transfected into neuroblastoma cell lines, demonstrated that ASOs with BNAP-AEO, had a more efficient gene silencing effect than those without BNAP-AEO. In vivo assays, involving intracerebroventricular injections into mice, revealed ASOs with BNAP-AEO potently suppressed gene expression in the brain. Surprisingly, the acute CNS toxicity in mice, as assessed through open field tests and scoring systems, was significantly lower for ASOs with BNAP-AEO than for those without BNAP-AEO. This study underscores the efficient gene-silencing effect and low acute CNS toxicity of ASOs incorporating BNAP-AEO, indicating the potential for future therapeutic applications.

Persistent Targeting DNA Nanocarrier Made of 3D Structural Unit Assembled from Only One Basic Multi-Palindromic Oligonucleotide for Precise Gene Cancer Therapy

Construction of a simple, reconfigurable, and stimuli-responsive DNA nanocarrier remains a technical challenge. In this contribution, by designing three palindromic fragments, a simplest four-sticky end-contained 3D structural unit (PS-unit) made of two same DNA components is proposed. Via regulating the rotation angle of central longitudinal axis of PS-unit, the oriented assembly of one-component spherical architecture is accomplished with high efficiency. Introduction of an aptamer and sticky tail warehouse into one component creates a size-change-reversible targeted siRNA delivery nanovehicle. Volume swelling of 20 nm allows one carrier to load 1987 siPLK1s. Once entering cancer cells and responding to glutathione (GSH) stimuli, siPLK1s are almost 100% released and original size of nanovehicle is restored, inhibiting the expression of PLK1 protein and substantially suppressing tumor growth (superior to commercial transfection agents) in tumor-bearing mice without systemic toxicity.

Preparation of genetically or chemically engineered exosomes and their therapeutic effects in bone regeneration and anti-inflammation

The treatment of bone or cartilage damage and inflammation-related diseases has been a long-standing research hotspot. Traditional treatments such as surgery and cell therapy have only displayed limited efficacy because they can't avoid potential deterioration and ensure cell activity. Recently, exosomes have become a favorable tool for various tissue reconstruction due to their abundant content of proteins, lipids, DNA, RNA and other substances, which can promote bone regeneration through osteogenesis, angiogenesis and inflammation modulation. Besides, exosomes are also promising delivery systems because of stability in the bloodstream, immune stealth capacity, intrinsic cell-targeting property and outstanding intracellular communication. Despite having great potential in therapeutic delivery, exosomes still show some limitations in clinical studies, such as inefficient targeting ability, low yield and unsatisfactory therapeutic effects. In order to overcome the shortcomings, increasing studies have prepared genetically or chemically engineered exosomes to improve their properties. This review focuses on different methods of preparing genetically or chemically engineered exosomes and the therapeutic effects of engineering exosomes in bone regeneration and anti-inflammation, thereby providing some references for future applications of engineering exosomes.

Development of nucleic acid medicines based on chemical technology

Oligonucleotide-based therapeutics have attracted attention as an emerging modality that includes the modulation of genes and their binding proteins related to diseases, allowing us to take action on previously undruggable targets. Since the late 2010s, the number of oligonucleotide medicines approved for clinical uses has dramatically increased. Various chemistry-based technologies have been developed to improve the therapeutic properties of oligonucleotides, such as chemical modification, conjugation, and nanoparticle formation, which can increase nuclease resistance, enhance affinity and selectivity to target sites, suppress off-target effects, and improve pharmacokinetic properties. Similar strategies employing modified nucleobases and lipid nanoparticles have been used for developing coronavirus disease 2019 mRNA vaccines. In this review, we provide an overview of the development of chemistry-based technologies aimed at using nucleic acids for developing therapeutics over the past several decades, with a specific emphasis on the structural design and functionality of chemical modification strategies.

Future directions for medicinal chemistry in the field of oligonucleotide therapeutics

In the last decade, the field of oligonucleotide therapeutics has matured, with the regulatory approval of several single-stranded and double-stranded RNA drugs. In this Perspective, I discuss enabling developments and likely future directions in the field from the perspective of oligonucleotide chemistry.

Convenient Solid-Phase Attachment of Small-Molecule Ligands to Oligonucleotides via a Biodegradable Acid-Labile P-N-Bond

One of the key problems in the design of therapeutic and diagnostic oligonucleotides is the attachment of small-molecule ligands for targeted deliveries in such a manner that provides the controlled release of the oligonucleotide at a certain moment. Here, we propose a novel, convenient approach for attaching ligands to the 5'-end of the oligonucleotide via biodegradable, acid-labile phosphoramide linkage. The method includes the activation of the 5'-terminal phosphate of the fully protected, support-bound oligonucleotide, followed by interaction with a ligand bearing the primary amino group. This technique is simple to perform, allows for forcing the reaction to completion by adding excess soluble reactant, eliminates the problem of the limited solubility of reagents, and affords the possibility of using different solvents, including water/organic media. We demonstrated the advantages of this approach by synthesizing and characterizing a wide variety of oligonucleotide 5'-conjugates with different ligands, such as cholesterol, aliphatic oleylamine, and p-anisic acid. The developed method suits different types of oligonucleotides (deoxyribo-, 2'-O-methylribo-, ribo-, and others).

Ligand-tethered lipid nanoparticles for targeted RNA delivery to treat liver fibrosis

Lipid nanoparticle-mediated RNA delivery holds great potential to treat various liver diseases. However, targeted delivery of RNA therapeutics to activated liver-resident fibroblasts for liver fibrosis treatment remains challenging. Here, we develop a combinatorial library of anisamide ligand-tethered lipidoids (AA-lipidoids) using a one-pot, two-step modular synthetic method and adopt a two-round screening strategy to identify AA-lipidoids with both high potency and selectivity to deliver RNA payloads to activated fibroblasts. The lead AA-lipidoid AA-T3A-C12 mediates greater RNA delivery and transfection of activated fibroblasts than its analog without anisamide and the FDA-approved MC3 ionizable lipid. In a preclinical model of liver fibrosis, AA-T3A-C12 enables ~65% silencing of heat shock protein 47, a therapeutic target primarily expressed by activated fibroblasts, which is 2-fold more potent than MC3, leading to significantly reduced collagen deposition and liver fibrosis. These results demonstrate the potential of AA-lipidoids for targeted RNA delivery to activated fibroblasts. Furthermore, these synthetic methods and screening strategies open a new avenue to develop and discover potent lipidoids with targeting properties, which can potentially enable RNA delivery to a range of cell and tissue types that are challenging to access using traditional lipid nanoparticle formulations.

Bone-Targeted Dual Functional Lipid-coated Drug Delivery System for Osteosarcoma Therapy

PURPOSE OR OBJECTIVE

Osteosarcoma is well-known for its high incidence in children and adolescents and long-term bone pain, which seriously reduces the life quality of patients. Cisplatin (CDDP), as the first-line anti-osteosarcoma drug, has been used in many anticancer treatments. At the same time, the serious side effects of platinum (Pt) drugs have also attracted widespread attention. To accurately deliver Pt drugs to the lesion site and realize controlled release of Pt drugs, certain modified delivery systems have been extensively studied.

METHODS

Among them, liposomes have been approved for clinical cancer treatment due to their highly biocompatibility and superior modifiability. Here, we developed a bone-targeted dual functional lipid-coated drug delivery system, lipid-coated CDDP alendronate nanoparticles (LCA NPs) to target the bone and precisely deliver the drugs to the tumor site. Cell toxicity, apoptosis and cellular uptake were detected to evaluate the anticancer effect for LCA NPs. Furthermore, transwell assay and wound healing assay were conducted to estimate the osteosarcoma cell migration and invasion. Hemolysis assay was utilized to assess the biocapitibility of the kind of NPs.

RESULTS

With the aim of bone-targeted unit alendronate (ALD), LCA NPs serve as a rich bone homing Pt delivery system to exert efficient anticancer effects and synergistically reduce bone resorption and bone loss potentially.

CONCLUSIONS

By providing a highly biocompatible platform for osteosarcoma therapy, LCA NPs may help to significantly enhance the anticancer effect of Pt and greatly reduce the systemic toxicity and side effects of Pt towards osteosarcoma.

A Combination Therapy Using Electrical Stimulation and Adaptive, Conductive Hydrogels Loaded with Self-Assembled Nanogels Incorporating Short Interfering RNA Promotes the Repair of Diabetic Chronic Wounds

In addition to oxidative stress and impaired angiogenesis, the overexpression of metalloproteinases (MMPs) and proinflammatory cytokines, which are promoted by hyperglycemia, causes chronic inflammation in diabetic wounds. Herein, TA-siRNA nanogels are prepared for the first time on the basis of the self-assembling interaction between tannic acid (TA) and short interfering RNA (siRNA). The efficient, biodegradable nanogels are cross-linked with poly(vinyl alcohol) (PVA), human-like collagen (HLC), TA, and borax to prepare adaptive, conductive PHTB (TA-siRNA) hydrogels. In response to high levels of reactive oxygen species (ROS), the ROS-responsive borate ester bonds in the hydrogels are oxidized and broken, and TA-siRNA nanogels are released into cells to reduce the expression of the MMP-9. Moreover, the TA and HLC promote collagen expression, reduce inflammation, and ROS level. It is found that electrical stimulation (ES) promotes the in vivo release of TA-siRNA nanogels from PHTB (TA-siRNA) hydrogels and endocytosis of the nanogels. The combination therapy using ES and PHTB (TA-siRNA) hydrogels accelerates the healing of diabetic wounds by reducing the levels of ROS and MMP-9 and promoting the polarization of macrophages, production of collagen, and angiogenesis. This study provides insights on the design of functional gene-delivery and efficient therapeutic strategies to promote the repair of diabetic chronic wounds.

A pH-responsive mesoporous silica nanoparticle-based drug delivery system for targeted breast cancer therapy

In order to make the drug specifically aggregate at the tumor site, we had developed a targeted drug delivery system based on pH responsive mesoporous silica nanoparticles. Mesoporous silica nanoparticles (MSN-COOH) were prepared and doxorubicin (DOX) was loaded into the pores of MSN-COOH, and then polyethyleneimine (PEI) and anisamide (AA) were modified on the surface of mesoporous silica, named DOX@MSN-PEI-AA(DMPA). DMPA specifically entered tumor cells through AA-mediated receptor endocytosis; PEI dissociated from the surface of the MSN in the acidic environment of cellular lysosomes/endosomes due to protonation of PEI, resulting in steady release of the encapsulated DOX from the pores of MSN in the cytoplasm of the target cells. In vitro and in vivo anti-tumor experiments and hemolytic experiments indicated that DMPA can accurately target breast cancer cells and show excellent safety at the same time, showing great potential for tumor therapy.

Targeted Delivery Methods for Anticancer Drugs

Several drug-delivery systems have been reported on and often successfully applied in cancer therapy. Cell-targeted delivery can reduce the overall toxicity of cytotoxic drugs and increase their effectiveness and selectivity. Besides traditional liposomal and micellar formulations, various nanocarrier systems have recently become the focus of developmental interest. This review discusses the preparation and targeting techniques as well as the properties of several liposome-, micelle-, solid-lipid nanoparticle-, dendrimer-, gold-, and magnetic-nanoparticle-based delivery systems. Approaches for targeted drug delivery and systems for drug release under a range of stimuli are also discussed.

Evolution of complexity in non-viral oligonucleotide delivery systems: from gymnotic delivery through bioconjugates to biomimetic nanoparticles

From the early days of research on RNA biology and biochemistry, there was an interest to utilize this knowledge and RNA itself for therapeutic applications. Today, we have a series of oligonucleotide therapeutics on the market and many more in clinical trials. These drugs - exploit different chemistries of oligonucleotides, such as modified DNAs and RNAs, peptide nucleic acids (PNAs) or phosphorodiamidate morpholino oligomers (PMOs), and different mechanisms of action, such as RNA interference (RNAi), targeted RNA degradation, splicing modulation, gene expression and modification. Despite major successes e.g. mRNA vaccines developed against SARS-CoV-2 to control COVID-19 pandemic, development of therapies for other diseases is still limited by inefficient delivery of oligonucleotides to specific tissues and organs and often prohibitive costs for the final drug. This is even more critical when targeting multifactorial disorders and patient-specific biological variations. In this review, we will present the evolution of complexity of oligonucleotide delivery methods with focus on increasing complexity of formulations from gymnotic delivery to bioconjugates and to lipid nanoparticles in respect to developments that will enable application of therapeutic oligonucleotides as drugs in personalized therapies.

Cell Membrane Vesicles with Enriched CXCR4 Display Enhances Their Targeted Delivery as Drug Carriers to Inflammatory Sites

Cell membrane vesicles (CMVs) are composed of natural cell membranes which makes them effective drug delivery systems with low immunogenicity and prolonged circulation time. However, targeting delivery of CMVs in vivo for clinical applications is still a major challenge. In this study, CXCR4 recombinant lentivirus is transfected into MC-3T3 cells and membrane CXCR4-enriched MC-3T3 cells are obtained. CMVs with enriched membrane CXCR4 display (CXCR4-CMVs) are obtained from the transfected MC-3T3 cells. Curcumin, an effective natural anti-inflammatory compound, is encapsulated into CXCR4-CMVs through physical entrapment (CXCR4/Cur-CMVs), with the membrane integrity of CXCR4/Cur-CMVs being well-preserved. CXCR4/Cur-CMVs induce enhanced M2 macrophage polarization, exhibit anti-inflammatory effects, and significantly improve homing via the CXCR4/CXCL12 axis in vitro. Utilizing ulcerative colitis and apical periodontitis as inflammatory disease models, it is found that CXCR4/Cur-CMVs are obviously aggregated within inflammatory areas after intravenous administration, which results in significant amelioration of ulcerative colitis and apical periodontitis. Therefore, this research may provide a feasible and innovative approach for fabricating an inflammatory site-targeting delivery system, by engineering CMVs to increase membrane-presenting CXCR4 receptor.

Tumor-Associated Fibroblast-Targeting Nanoparticles for Enhancing Solid Tumor Therapy: Progress and Challenges

Even though nanoparticle drug delivery systems (nanoDDSs) have improved antitumor efficacy by delivering more drugs to tumor sites compared to free and unencapsulated therapeutics, achieving satisfactory distribution and penetration of nanoDDSs inside solid tumors, especially in stromal fibrous tumors, remains challenging. As one of the most common stromal cells in solid tumors, tumor-associated fibroblasts (TAFs) not only promote tumor growth and metastasis but also reduce the drug delivery efficiency of nanoparticles through the tumor's inherent physical and physiological barriers. Thus, TAFs have been emerging as attractive targets, and TAF-targeting nanotherapeutics have been extensively explored to enhance the tumor delivery efficiency and efficacy of various anticancer agents. The purpose of this Review is to opportunely summarize the underlying mechanisms of TAFs on obstructing nanoparticle-mediated drug delivery into tumors and discuss the current advances of a plethora of nanotherapeutic approaches for effectively targeting TAFs.

Chemical Manipulation of the Endosome Trafficking Machinery: Implications for Oligonucleotide Delivery

Antisense oligonucleotides (ASOs), siRNA and splice switching oligonucleotides (SSOs) all have immense potential as therapeutic agents, potential that is now being validated as oligonucleotides enter the clinic. However, progress in oligonucleotide-based therapeutics has been limited by the difficulty in delivering these complex molecules to their sites of action in the cytosol or nucleus of cells within specific tissues. There are two aspects to the delivery problem. The first is that most types of oligonucleotides have poor uptake into non-hepatic tissues. The second is that much of the oligonucleotide that is taken up by cells is entrapped in endosomes where it is pharmacologically inert. It has become increasingly recognized that endosomal trapping is a key constraint on oligonucleotide therapeutics. Thus, many approaches have been devised to address this problem, primarily ones based on various nanoparticle technologies. However, recently an alternative approach has emerged that employs small molecules to manipulate intracellular trafficking processes so as to enhance oligonucleotide actions. This review presents the current status of this chemical biology approach to oligonucleotide delivery and seeks to point out possible paths for future development.

Oligonucleotides as therapeutic tools for brain disorders: Focus on major depressive disorder and Parkinson's disease

Remarkable advances in understanding the role of RNA in health and disease have expanded considerably in the last decade. RNA is becoming an increasingly important target for therapeutic intervention; therefore, it is critical to develop strategies for therapeutic modulation of RNA function. Oligonucleotides, including antisense oligonucleotide (ASO), small interfering RNA (siRNA), microRNA mimic (miRNA), and anti-microRNA (antagomir) are perhaps the most direct therapeutic strategies for addressing RNA. Among other mechanisms, most oligonucleotide designs involve the formation of a hybrid with RNA that promotes its degradation by activation of endogenous enzymes such as RNase-H (e.g., ASO) or the RISC complex (e.g. RNA interference - RNAi for siRNA and miRNA). However, the use of oligonucleotides for the treatment of brain disorders is seriously compromised by two main limitations: i) how to deliver oligonucleotides to the brain compartment, avoiding the action of peripheral RNAses? and once there, ii) how to target specific neuronal populations? We review the main molecular pathways in major depressive disorder (MDD) and Parkinson's disease (PD), and discuss the challenges associated with the development of novel oligonucleotide therapeutics. We pay special attention to the use of conjugated ligand-oligonucleotide approach in which the oligonucleotide sequence is covalently bound to monoamine transporter inhibitors (e.g. sertraline, reboxetine, indatraline). This strategy allows their selective accumulation in the monoamine neurons of mice and monkeys after their intranasal or intracerebroventricular administration, evoking preclinical changes predictive of a clinical therapeutic action after knocking-down disease-related genes. In addition, recent advances in oligonucleotide therapeutic clinical trials are also reviewed.

Intracerebral Administration of a Ligand-ASO Conjugate Selectively Reduces α-Synuclein Accumulation in Monoamine Neurons of Double Mutant Human A30P*A53T*α-Synuclein Transgenic Mice

α-Synuclein (α-Syn) protein is involved in the pathogenesis of Parkinson's disease (PD). Point mutations and multiplications of the α-Syn, which encodes the SNCA gene, are correlated with early-onset PD, therefore the reduction in a-Syn synthesis could be a potential therapy for PD if delivered to the key affected neurons. Several experimental strategies for PD have been developed in recent years using oligonucleotide therapeutics. However, some of them have failed or even caused neuronal toxicity. One limiting step in the success of oligonucleotide-based therapeutics is their delivery to the brain compartment, and once there, to selected neuronal populations. Previously, we developed an indatraline-conjugated antisense oligonucleotide (IND-1233-ASO), that selectively reduces α-Syn synthesis in midbrain monoamine neurons of mice, and nonhuman primates. Here, we extended these observations using a transgenic male mouse strain carrying both A30P and A53T mutant human α-Syn (A30P*A53T*α-Syn). We found that A30P*A53T*α-Syn mice at 4-5 months of age showed 3.5-fold increases in human α-Syn expression in dopamine (DA) and norepinephrine (NE) neurons of the substantia nigra pars compacta (SNc) and locus coeruleus (LC), respectively, compared with mouse α-Syn levels. In parallel, transgenic mice exhibited altered nigrostriatal DA neurotransmission, motor alterations, and an anxiety-like phenotype. Intracerebroventricular IND-1233-ASO administration (100 µg/day, 28 days) prevented the α-Syn synthesis and accumulation in the SNc and LC, and recovered DA neurotransmission, although it did not reverse the behavioral phenotype. Therefore, the present therapeutic strategy based on a conjugated ASO could be used for the selective inhibition of α-Syn expression in PD-vulnerable monoamine neurons, showing the benefit of the optimization of ASO molecules as a disease modifying therapy for PD and related α-synucleinopathies.

Viral Mimicry as a Design Template for Nucleic Acid Nanocarriers

Therapeutic nucleic acids hold immense potential in combating undruggable, gene-based diseases owing to their high programmability and relative ease of synthesis. While the delivery of this class of therapeutics has successfully entered the clinical setting, extrahepatic targeting, endosomal escape efficiency, and subcellular localization. On the other hand, viruses serve as natural carriers of nucleic acids and have acquired a plethora of structures and mechanisms that confer remarkable transfection efficiency. Thus, understanding the structure and mechanism of viruses can guide the design of synthetic nucleic acid vectors. This review revisits relevant structural and mechanistic features of viruses as design considerations for efficient nucleic acid delivery systems. This article explores how viral ligand display and a metastable structure are central to the molecular mechanisms of attachment, entry, and viral genome release. For comparison, accounted for are details on the design and intracellular fate of existing nucleic acid carriers and nanostructures that share similar and essential features to viruses. The review, thus, highlights unifying themes of viruses and nucleic acid delivery systems such as genome protection, target specificity, and controlled release. Sophisticated viral mechanisms that are yet to be exploited in oligonucleotide delivery are also identified as they could further the development of next-generation nonviral nucleic acid vectors.

Perspectives on the Designation of Oligonucleotide Starting Materials

The designation of starting materials (SMs) for pharmaceuticals has been a topic of great interest and debate since the first ICH quality guidance was published. The increase in the number and variety of commercialized oligonucleotides (antisense oligonucleotides—ASOs, small interfering RNAs—siRNAs, etc.) in recent years has reignited dialogue on this topic because of the unique complexity of the monomeric nucleotides and other contributory materials used to manufacture oligonucleotides. The SM working group in the European Pharma Oligonucleotide Consortium (EPOC) was formed to help establish simple, risk-based criteria to guide the justification of oligonucleotide SMs. This article provides a description of the common types of SMs, classes of SM impurities, and control strategies that will be helpful to maintain manufacturing consistency.

Expanding the Scope of the Cleavable N-(methoxy)oxazolidine Linker for the Synthesis of Oligonucleotide Conjugates

Oligonucleotides modified by a 2'-deoxy-2'-(N-methoxyamino) ribonucleotide react readily with aldehydes in slightly acidic conditions to yield the corresponding N-(methoxy)oxazolidine-linked oligonucleotide-conjugates. The reaction is reversible and dynamic in slightly acidic conditions, while the products are virtually stable above pH 7, where the reaction is in a ''switched off-state''. Small molecular examinations have demonstrated that aldehyde constituents affect the cleavage rate of the N-(methoxy)oxazolidine-linkage. This can be utilized to adjust the stability of this pH-responsive cleavable linker for drug delivery applications. In the present study, Fmoc-β-Ala-H was immobilized to a serine-modified ChemMatrix resin and used for the automated assembly of two peptidealdehydes and one aldehyde-modified peptide nucleic acid (PNA). In addition, a triantennary N-acetyl-d-galactosamine-cluster with a β-Ala-H unit has been synthesized. These aldehydes were conjugated via N-(methoxy)oxazolidine-linkage to therapeutically relevant oligonucleotide phosphorothioates and one DNA-aptamer in 19-47% isolated yields. The cleavage rates of the conjugates were studied in slightly acidic conditions. In addition to the diverse set of conjugates synthesized, these experiments and a comparison to published data demonstrate that the simple conversion of Gly-H to β-Ala-H residue resulted in a faster cleavage of the N-(methoxy)oxazolidine-linker at pH 5, being comparable (T0.5 ca 7 h) to hydrazone-based structures.

Cellular Targeting of Oligonucleotides by Conjugation with Small Molecules

Drug candidates derived from oligonucleotides (ON) are receiving increased attention that is supported by the clinical approval of several ON drugs. Such therapeutic ON are designed to alter the expression levels of specific disease-related proteins, e.g., by displaying antigene, antisense, and RNA interference mechanisms. However, the high polarity of the polyanionic ON and their relatively rapid nuclease-mediated cleavage represent two major pharmacokinetic hurdles for their application in vivo. This has led to a range of non-natural modifications of ON structures that are routinely applied in the design of therapeutic ON. The polyanionic architecture of ON often hampers their penetration of target cells or tissues, and ON usually show no inherent specificity for certain cell types. These limitations can be overcome by conjugation of ON with molecular entities mediating cellular 'targeting', i.e., enhanced accumulation at and/or penetration of a specific cell type. In this context, the use of small molecules as targeting units appears particularly attractive and promising. This review provides an overview of advances in the emerging field of cellular targeting of ON via their conjugation with small-molecule targeting structures.

Microneedles loaded with anti-PD-1-cisplatin nanoparticles for synergistic cancer immuno-chemotherapy

Programmed cell death protein-1 (PD-1) on T-cells combined with programmed cell death ligand-1 (PD-L1) critically accounts for tumor immune evasion. Anti-PD-1 (aPD-1) blocks the binding of PD-1 to PD-L1, thus allowing T-cell activation for tumor cell eradication. Currently, the major challenges for cancer immunotherapy are how to improve the response rate and overcome drug resistance. Dermal administration turns out to be a promising route for immunotherapy since skin is a highly active immune organ containing a large population of resident antigen-presenting cells. Microneedle arrays can pierce the immune-cell-rich epidermis, leading to a robust T-cell response in the microenvironment of tumor cells. Herein, we successfully developed a microneedle patch loaded with pH-responsive tumor-targeted lipid nanoparticles (NPs), which allows local delivery of aPD-1 and cisplatin (CDDP) precisely to cancer tissues for cancer therapy. For in vivo studies, aPD-1/CDDP@NPs delivered through microneedles effectively boosted the immune response, thereby a remarkable effect on tumor regression was realized. Synergistic anticancer mechanisms were therefore activated through robust microneedle-induced T-cell response, blockage of PD-1 in T-cells by aPD-1, and an increase in direct cytotoxicity of CDDP in tumor cells. Strikingly, transdermal delivery using MNs increased the response rate in the animal model unresponsive to aPD-1 systemic therapy. This exhibited promise in the treatment of immunotherapy-unresponsive cancers. Taken together, microneedle-mediated local delivery of nano-encapsulated chemotherapeutic and immunotherapeutic agents at tumor skin sites provides a novel treatment strategy and insights into cancer therapy.

Polymer Capsules with Hydrophobic Liquid Cores as Functional Nanocarriers

Recent developments in the fabrication of core-shell polymer nanocapsules, as well as their current and future applications, are reported here. Special attention is paid to the newly introduced surfactant-free fabrication method of aqueous dispersions of nanocapsules with hydrophobic liquid cores stabilized by amphiphilic copolymers. Various approaches to the efficient stabilization of such vehicles, tailoring their cores and shells for the fabrication of multifunctional, navigable nanocarriers and/or nanoreactors useful in various fields, are discussed. The emphasis is placed on biomedical applications of polymer nanocapsules, including the delivery of poorly soluble active compounds and contrast agents, as well as their use as theranostic platforms. Other methods of fabrication of polymer-based nanocapsules are briefly presented and compared in the context of their biomedical applications.

Biomineralized metal-organic framework nanoparticles enable a primer exchange reaction-based DNA machine to work in living cells for imaging and gene therapy

Sensitive tumor imaging and precise tumor therapy play critical roles in the cancer combat. Herein, we build a DNA machine based on a primer exchange reaction (PER) for mRNA imaging and gene therapy. By using zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) to co-deliver the components including a primer, hairpin and strand displacing polymerase to the living cells, the PER-based DNA machine can be initiated by intracellular survivin mRNA and continuously produce Bcl-2 antisense DNA (ASD), which enables the DNA machine not only to image survivin mRNA but also to implement gene therapy. The results demonstrate that ZIF-8 NPs can protect the polymerases and nucleic acid probes from protease attack and nuclease degradation. After internalization, pH-responsive ZIF-8 NPs can efficiently release cargos from endo-lysosomes due to the protonation effect. The intracellular PER-based DNA machine has been demonstrated to be able to sensitively image survivin mRNA expression levels and selectively kill the cancer cells and has no effect on the normal cells. The PER-based DNA machine may provide a promising platform for early stage tumor diagnosis and more precise tumor therapy.

Novel thymoquinone lipidic core nanocapsules with anisamide-polymethacrylate shell for colon cancer cells overexpressing sigma receptors

The biggest challenge in colorectal cancer therapy is to avoid intestinal drug absorption before reaching the colon, while focusing on tumor specific delivery with high local concentration and minimal toxicity. In our work, thymoquinone (TQ)-loaded polymeric nanocapsules were prepared using the nanoprecipitation technique using Eudragit S100 as polymeric shell. Conjugation of anisamide as a targeting ligand for sigma receptors overexpressed by colon cancer cells to Eudragit S100 was carried out via carbodiimide coupling reaction, and was confirmed by thin layer chromatography and ¹H-NMR. TQ nanocapsules were characterized for particle size, surface morphology, zeta potential, entrapment efficiency % (EE%), in vitro drug release and physical stability. A cytotoxicity study on three colon cancer cell lines (HT-29, HCT-116, Caco-2) was performed. Results revealed that the polymeric nanocapsules were successfully prepared, and the in vitro characterization showed a suitable size, zeta potential, EE% and physical stability. TQ exhibited a delayed release pattern from the nanocapsules in vitro. Anisamide-targeted TQ nanocapsules showed higher cytotoxicity against HT-29 cells overexpressing sigma receptors compared to their non-targeted counterparts and free TQ after incubation for 48 h, hence delineating anisamide as a promising ligand for active colon cancer targeting.

Phase-Change Materials for Controlled Release and Related Applications

Phase-change materials (PCMs) have emerged as a novel class of thermo-responsive materials for controlled release, where the payloads encapsulated in a solid matrix are released only upon melting the PCM to trigger a solid-to-liquid phase transition. Herein, the advances over the past 10 years in utilizing PCMs as a versatile platform for the encapsulation and release of various types of therapeutic agents and biological effectors are highlighted. A brief introduction to PCMs in the context of desired properties for controlled release and related applications is provided. Among the various types of PCMs, a specific focus is placed on fatty acids and fatty alcohols for their natural availability, low toxicity, biodegradability, diversity, high abundance, and low cost. Then, various methods capable of processing PCMs, and their mixtures with payloads, into stable suspensions of colloidal particles, and the different means for triggering the solid-to-liquid phase transition are discussed. Finally, a range of applications enabled by the controlled release system based on PCMs are presented together with some perspectives on future directions.

Tissue-Specific Delivery of Oligonucleotides

From the initial discovery of short-interfering RNA (siRNA) and antisense oligonucleotides for specific gene knockdown at the posttranscriptional level to the current CRISPR-Cas9 system offering gene editing at the genomic level, oligonucleotides, in addition to their biological functions in storing and conveying genetic information, provide the most prominent solutions to targeted gene therapies. Nonetheless, looking into the future of curing cancer and acute diseases, researchers are only cautiously optimistic as the cellular delivery of these polyanionic biomacromolecules is still the biggest hurdle for their therapeutic realization. To overcome the delivery obstacle, oligonucleotides have been encapsulated within or conjugated with delivery vehicles for enhanced membrane penetration, improved payload, and tissue-specific delivery. Such delivery systems include but not limited to virus-based vehicles, gold-nanoparticle vehicles, formulated liposomes, and synthetic polymers. In this chapter, delivery challenges imposed by biological barriers are briefly discussed; followed by recent advances in tissue-specific oligonucleotide delivery utilizing both viral and nonviral delivery vectors, discussing their advantages, and how judicious design and formulation could improve and expand their potential as delivery vehicles.

Advances in Receptor-Mediated, Tumor-Targeted Drug Delivery

Receptor-mediated drug delivery presents an opportunity to enhance therapeutic efficiency by accumulating drug within the tissue of interest and reducing undesired, off-target effects. In cancer, receptor overexpression is a platform for binding and inhibiting pathways that shape biodistribution, toxicity, cell binding and uptake, and therapeutic function. This review will identify tumor-targeted drug delivery vehicles and receptors that show promise for clinical translation based on quantitative in vitro and in vivo data. The authors describe the rationale to engineer a targeted drug delivery vehicle based on the ligand, chemical conjugation method, and type of drug delivery vehicle. Recent advances in multivalent targeting and ligand organization on tumor accumulation are discussed. Revolutionizing receptor-mediated drug delivery may be leveraged in the therapeutic delivery of chemotherapy, gene editing tools, and epigenetic drugs.

Microneedle-Mediated Delivery of Lipid-Coated Cisplatin Nanoparticles for Efficient and Safe Cancer Therapy

Cisplatin is the first-line chemotherapeutic agent, but its systemic toxicity and side effects severely limit its clinical use. We report a microneedle technique to mediate the transdermal delivery of lipid-coated cisplatin nanoparticles (LCC-NPs) for efficient and safe cancer therapy. Cisplatin was encapsulated by tumor-targeting pH-responsive lipid nanoparticles with a high loading rate of 80%, and the encapsulation substantially increased the solubility of cisplatin and enhanced its antitumor efficiency in vitro. The LCC-NPs were embedded in dissolvable microneedles, and released from the microneedles after inserting into the skin. This enabled the nanoparticles to pass the stratum corneum for safe local delivery. An in vivo study with a xenograft tumor animal model demonstrated that microneedle arrays loaded with cisplatin nanoparticles significantly increased cytotoxicity and apoptosis in cancer cells with an apoptotic index of 58.6%, resulting in significantly reduced tumor volume and weight. Moreover, serum platinum, pulmonary toxicity, hepatotoxicity, and nephrotoxicity were not detected in vivo, indicating that this technique is biosafe. The cisplatin-nanoparticle microneedle system developed in this study may offer promising opportunities in cancer therapy for enhancing antitumor effects and reducing systemic toxicity and side effects.

Using Genome Sequence to Enable the Design of Medicines and Chemical Probes

Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.

New Modalities for Challenging Targets in Drug Discovery

Our ever-increasing understanding of biological systems is providing a range of exciting novel biological targets, whose modulation may enable novel therapeutic options for many diseases. These targets include protein-protein and protein-nucleic acid interactions, which are, however, often refractory to classical small-molecule approaches. Other types of molecules, or modalities, are therefore required to address these targets, which has led several academic research groups and pharmaceutical companies to increasingly use the concept of so-called "new modalities". This Review defines for the first time the scope of this term, which includes novel peptidic scaffolds, oligonucleotides, hybrids, molecular conjugates, as well as new uses of classical small molecules. We provide the most representative examples of these modalities to target large binding surface areas such as those found in protein-protein interactions and for biological processes at the center of cell regulation.

A Nanosystem of Amphiphilic Oligopeptide-Drug Conjugate Actualizing Both αvβ3 Targeting and Reduction-Triggered Release for Maytansinoid

To design a prodrug-based self-assembling nanosystem with both ligand targeting and stimuli-responsive features, and elucidate the superiority of each targeting strategy and the synergistic effect between them, we synthesized four small molecule amphiphilic peptide-drug conjugates (APDCs) using maytansinoid (DM1) as a cytotoxic agent, cRGDfK as a homing peptide, and disulfide (SS) or thioether (SMCC) as linker. Owing to their amphiphilicity, the APDCs could self-assemble into nanoparticles (APDC@NPs) which were evaluated in vitro in three different cell lines and in vivo in tumor-bearing C57BL/6 mice. The RSSD@NPs showed the strongest interaction with αvβ3 integrin, highest cell uptake and intracellular free drug level, and best antitumor efficacy in vitro and in vivo, while it shared the same goodness with other test nanosystems in terms of high drug loading, EPR effect and free of potentially toxic polymers. Especially, the in vivo efficacy of RSSD@NPs was 2 fold of free DM1 which is too cytotoxic to be a drug, while the active targeted APDC@NPs demonstrated acceptable system, tissue and blood compatibility. In αvβ3-positive cells or tumors, the RGD targeting contributed much more than disulfide in anticancer effect. The maximum synergism of the two strategies reached to 22 fold in vitro and 3 fold in vivo. Generally, the active targeting, prodrug and nanosystem could significantly decrease the toxicity of free DM1 and improve its therapy outcome via combining active targeting, prodrug and nanopreparation, especially the dual targeting strategies and their synergism.

Targeting Nanocarriers with Anisamide: Fact or Artifact?

Encapsulating chemotherapeutics in nanoparticles can reduce the side effects of intravenous administration and improve their antitumor efficacy. Additionally, surface decoration of the nanocarriers with tumor-targeting ligands may enhance their specificity for cancer cells overexpressing the corresponding ligand-binding counterpart. The focus here is on anisamide, a low-molecular-weight benzamide derivative used as a tumor-directing moiety in functionalized nanosystems, based on its alleged interaction with Sigma receptors. The scintigraphic agents that initially inspired the use of anisamide for tumor targeting are described, and the published anisamide-tethered nanocarrier formulations are reviewed, together with a critical overview of the ligand's tumor-targeting properties. Moreover, anisamide's putative but dubious cellular target, the Sigma-1 receptor, is discussed with regard to its subcellular localization and implications in cancer. Data from in vivo studies reveal that the effect of anisamide on the antitumor efficacy of the decorated nanosystems varies considerably among the published reports. Together with the evidence questioning the interaction of anisamide with the Sigma receptors, the variability of anisamide's effect on the tumor deposition and the antitumor efficacy of the decorated drug carriers calls into question the extent of the ligand's tumor-targeting effect. Further research is necessary to elucidate the ligand's utility in tumor targeting.

Targeted delivery of a guanidine-pendant Pt(iv)-backboned poly-prodrug by an anisamide-functionalized polypeptide

A guanidine-pendant Pt(iv)-backboned prodrug-like polymer was synthesized and formulated with an anisamide-functionalized polypeptide for targeted delivery and enhanced cellular uptake.

Oligonucleotide conjugates - Candidates for gene silencing therapeutics

The potential therapeutic and diagnostic applications of oligonucleotides (ONs) have attracted great attention in recent years. The capability of ONs to selectively inhibit target genes through antisense and RNA interference mechanisms, without causing un-intended sideeffects has led them to be investigated for various biomedical applications, especially for the treatment of viral diseases and cancer. In recent years, many researchers have focused on enhancing the stability and target specificity of ONs by encapsulating/complexing them with polymers or lipid chains to formulate nanoparticles/nanocomplexes/micelles. Also, chemical modification of nucleic acids has emerged as an alternative to impart stability to ONs against nucleases and other degrading enzymes and proteins found in blood. In addition to chemically modifying the nucleic acids directly, another strategy that has emerged, involves conjugating polymers/peptide/aptamers/antibodies/proteins, preferably to the sense strand (3'end) of siRNAs. Conjugation to the siRNA not only enhances the stability and targeting specificity of the siRNA, but also allows for the development of self-administering siRNA formulations, with a much smaller size than what is usually observed for nanoparticle (∼200nm). This review concentrates mainly on approaches and studies involving ON-conjugates for biomedical applications.

Development of Antisense Drugs for Dyslipidemia

Abnormal elevation of low-density lipoprotein (LDL) and triglyceride-rich lipoproteins in plasma as well as dysfunction of anti-atherogenic high-density lipoprotein (HDL) have both been recognized as essential components of the pathogenesis of atherosclerosis and are classified as dyslipidemia. This review describes the arc of development of antisense oligonucleotides for the treatment of dyslipidemia. Chemically-armed antisense candidates can act on various kinds of transcripts, including mRNA and miRNA, via several different endogenous antisense mechanisms, and have exhibited potent systemic anti-dyslipidemic effects. Here, we present specific cutting-edge technologies have recently been brought into antisense strategies, and describe how they have improved the potency of antisense drugs in regard to pharmacokinetics and pharmacodynamics. In addition, we discuss perspectives for the use of armed antisense oligonucleotides as new clinical options for dyslipidemia, in the light of outcomes of recent clinical trials and safety concerns indicated by several clinical and preclinical studies.

PolyMetformin combines carrier and anticancer activities for in vivo siRNA delivery

Metformin, a widely implemented anti-diabetic drug, exhibits potent anticancer efficacies. Herein a polymeric construction of Metformin, PolyMetformin (PolyMet) is successfully synthesized through conjugation of linear polyethylenimine (PEI) with dicyandiamide. The delocalization of cationic charges in the biguanide groups of PolyMet reduces the toxicity of PEI both in vitro and in vivo. Furthermore, the polycationic properties of PolyMet permits capture of siRNA into a core-membrane structured lipid-polycation-hyaluronic acid (LPH) nanoparticle for systemic gene delivery. Advances herein permit LPH-PolyMet nanoparticles to facilitate VEGF siRNA delivery for VEGF knockdown in a human lung cancer xenograft, leading to enhanced tumour suppressive efficacy. Even in the absence of RNAi, LPH-PolyMet nanoparticles act similarly to Metformin and induce antitumour efficacy through activation of the AMPK and inhibition of the mTOR. In essence, PolyMet successfully combines the intrinsic anticancer efficacy of Metformin with the capacity to carry siRNA to enhance the therapeutic activity of an anticancer gene therapy.

The delivery of therapeutic oligonucleotides

The oligonucleotide therapeutics field has seen remarkable progress over the last few years with the approval of the first antisense drug and with promising developments in late stage clinical trials using siRNA or splice switching oligonucleotides. However, effective delivery of oligonucleotides to their intracellular sites of action remains a major issue. This review will describe the biological basis of oligonucleotide delivery including the nature of various tissue barriers and the mechanisms of cellular uptake and intracellular trafficking of oligonucleotides. It will then examine a variety of current approaches for enhancing the delivery of oligonucleotides. This includes molecular scale targeted ligand-oligonucleotide conjugates, lipid- and polymer-based nanoparticles, antibody conjugates and small molecules that improve oligonucleotide delivery. The merits and liabilities of these approaches will be discussed in the context of the underlying basic biology.

Anisamide-targeted gold nanoparticles for siRNA delivery in prostate cancer - synthesis, physicochemical characterisation and in vitro evaluation

Metastatic prostate cancer is a leading cause of cancer-related death in men and current chemotherapies are largely inadequate in terms of efficacy and toxicity. Hence improved treatments are required. The application of siRNA as a cancer therapeutic holds great promise. However, translation of siRNA into the clinic is dependent on the availability of an effective delivery system. Gold nanoparticles (AuNPs) are known to be effective and non-toxic siRNA delivery agents. In this study, a stable gold nanosphere coated with poly(ethylenimine) (PEI) was prepared to yield PEI capped AuNPs (Au-PEI). The PEI was further conjugated with the targeting ligand anisamide (AA, is known to bind to the sigma receptor overexpressed on the surface of prostate cancer cells) to produce an anisamide-targeted nanoparticle (Au-PEI-AA). The resulting untargeted and targeted nanoparticles (Au-PEI and Au-PEI-AA respectively) were positively charged and efficiently complexed siRNA. Au-PEI-AA mediated siRNA uptake into PC3 prostate cancer cells via binding to the sigma receptor. In addition, the Au-PEI-AA·siRNA complexes resulted in highly efficient knockdown of the RelA gene (∼70%) when cells were transfected in serum-free medium. In contrast, no knockdown was observed in the presence of serum, suggesting that adsorption of serum proteins inhibits the binding of the anisamide moiety to the sigma receptor. This study provides (for the first time) proof of principle that anisamide-labelled gold nanoparticles can target the sigma receptor. Further optimisation of the formulation to increase serum stability will enhance its potential to treat prostate cancer.

Findings questioning the involvement of Sigma-1 receptor in the uptake of anisamide-decorated particles

Anisamide is a small benzamide previously suggested as a tumor-targeting ligand for nanocarriers and it has been shown to enhance tumor uptake in vitro as well as in vivo when grafted on the nanoparticle surface. Anisamide has been hypothesized to interact with the Sigma-1 receptor, based on the binding of larger benzamides, which contain anisamide in their structure, to this receptor. However, the interaction between anisamide and Sigma-1 receptor has never been thoroughly studied. We developed fluorescent PEGylated particles decorated with anisamide, which were preferentially taken up in vitro by melanoma cells compared to macrophages. The anisamide-decorated particles were used to study their interaction with the Sigma-1 receptor. The absence of competition of Sigma-1 receptor ligands for the particle uptake was a first indication that the receptor might not be involved in the uptake process. In addition, the extent of particle uptake did not correlate with the levels of cellular expression of Sigma-1 receptor in the cell models tested. Immunostaining of the receptor on melanoma cells revealed intracellular localization, indirectly excluding the possibility of anisamide binding to the receptor when grafted on the particles. All these data question the previously suggested Sigma-1 receptor-mediated uptake of the anisamide-decorated particles, a finding which may have an impact on the use of anisamide as a targeting ligand.

Direct oligonucleotide-photosensitizer conjugates for photochemical delivery of antisense oligonucleotides

Activation of photosensitizers in endosomes enables release of therapeutic macromolecules into the cytosol of the target cells for pharmacological actions. In this study, we demonstrate that direct conjugation of photosensitizers to oligonucleotides (ONs) allows spatial and temporal co-localization of the two modalities in the target cells, and thus leads to superior functional delivery of ONs. Further, light-activated delivery of an anticancer ON caused cancer cell killing via modulation of an oncogene and photodynamic therapy.

Amido-bridged nucleic acids with small hydrophobic residues enhance hepatic tropism of antisense oligonucleotides in vivo

High scalability of a novel bicyclic nucleoside building block, amido-bridged nucleic acid (AmNA), to diversify pharmacokinetic properties of therapeutic antisense oligonucleotides is described. N2'-functionalization of AmNA with a variety of hydrophobic groups is straightforward. Combinations of these modules display similar antisense knockdown effects and improve cellular uptake, relative to sequence-matched conventional 2',4'-bridged nucleic acid (2',4'-BNA) in vivo.