Polymers in small-interfering RNA delivery

RNA therapeutics in targeting G protein-coupled receptors: Recent advances and challenges

G protein-coupled receptors (GPCRs) are the major targets of existing drugs for a plethora of human diseases and dominate the pharmaceutical market. However, over 50% of the GPCRs remain undruggable. To pursue a breakthrough and overcome this situation, there is significant clinical research for developing RNA-based drugs specifically targeting GPCRs, but none has been approved so far. RNA therapeutics represent a unique and promising approach to selectively targeting previously undruggable targets, including undruggable GPCRs. However, the development of RNA therapeutics faces significant challenges in areas of RNA stability and efficient in vivo delivery. This review presents an overview of the advances in RNA therapeutics and the diverse types of nanoparticle RNA delivery systems. It also describes the potential applications of GPCR-targeted RNA drugs for various human diseases.

Closing the Gap between Experiment and Simulation─A Holistic Study on the Complexation of Small Interfering RNAs with Polyethylenimine

Rational design is pivotal in the modern development of nucleic acid nanocarrier systems. With the rising prominence of polymeric materials as alternatives to lipid-based carriers, understanding their structure-function relationships becomes paramount. Here, we introduce a newly developed coarse-grained model of polyethylenimine (PEI) based on the Martini 3 force field. This model facilitates molecular dynamics simulations of true-sized PEI molecules, exemplified by molecules with molecular weights of 1.3, 5, 10, and 25 kDa, with degrees of branching between 50.0 and 61.5%. We employed this model to investigate the thermodynamics of small interfering RNA (siRNA) complexation with PEI. Our simulations underscore the pivotal role of electrostatic interactions in the complexation process. Thermodynamic analyses revealed a stronger binding affinity with increased protonation, notably in acidic (endosomal) pH, compared to neutral conditions. Furthermore, the molecular weight of PEI was found to be a critical determinant of binding dynamics: smaller PEI molecules closely enveloped the siRNA, whereas larger ones extended outward, facilitating the formation of complexes with multiple RNA molecules. Experimental validations, encompassing isothermal titration calorimetry and single-molecule fluorescence spectroscopy, aligned well with our computational predictions. Our findings not only validate the fidelity of our PEI model but also accentuate the importance of in silico data in the rational design of polymeric drug carriers. The synergy between computational predictions and experimental validations, as showcased here, signals a refined and precise approach to drug carrier design.

Nucleic acids based integrated macromolecular complexes for SiRNA delivery: Recent advancements

The therapeutic potential of small interfering RNA (siRNA) is monumental, offering a pathway to silence disease-causing genes with precision. However, the delivery of siRNA to target cells in-vivo remains a formidable challenge, owing to degradation by nucleases, poor cellular uptake and immunogenicity. This overview examines recent advancements in the design and application of nucleic acid-based integrated macromolecular complexes for the efficient delivery of siRNA. We dissect the innovative delivery vectors developed in recent years, including lipid-based nanoparticles, polymeric carriers, dendrimer complexes and hybrid systems that incorporate stimuli-responsive elements for targeted and controlled release. Advancements in bioconjugation techniques, active targeting strategies and nanotechnology-enabled delivery platforms are evaluated for their contribution to enhancing siRNA delivery. It also addresses the complex interplay between delivery system design and biological barriers, highlighting the dynamic progress and remaining hurdles in translating siRNA therapies from bench to bedside. By offering a comprehensive overview of current strategies and emerging technologies, we underscore the future directions and potential impact of siRNA delivery systems in personalized medicine.

pH-sensitive dual-preventive siRNA-based nanomicrobicide reactivates autophagy and inhibits HIV infection in vaginal CD4+ cells

Women are more susceptible to HIV transmission through unprotected heterosexual intercourse due to biological and social vulnerabilities. Intravaginal delivery of siRNAs targeting viral genes, host genes, or in combination has shown promising outcomes against HSV, HPV and HIV. Therefore, in this study, we designed, developed and evaluated a pH-sensitive RNAi-based combination nanomicrobide for the prevention/reduction of vaginal transmission of HIV. The nanomicrobide was composed of siRNA-PEI encapsulated PLGA-PEG nanoparticles (siRNA NP) loaded in a HEC gel dosage form with siRNA targeting host gene CCR5 and the viral gene Nef as a dual preventive strategy. Knocking down CCR5, a co-receptor for HIV could prevent HIV from attaching to and entering host cells and knocking down Nef could reactivate autophagy that was inhibited by Nef to improve the elimination of intracellular virus that escaped the first line of defense. The siRNA NP showed a desirable particle size and zeta potential for intravaginal delivery and a pH-dependent release profile whereby low amounts of siRNA was released under acidic vaginal conditions (vaginal fluid simulant; VFS, pH 4.2) (6.0 ± 0.4% released over 15 days) but significantly higher amounts of siRNA was released under neutral pH conditions (phosphate buffered saline; PBS, pH 7.4) (22.9 ± 0.4% released over 15 days). The CCR5-Nef-specific siRNA NP efficiently knocked down CCR5 and Nef protein expression by 43% and 63%, respectively, reactivated Nef-blocked autophagy and inhibited the replication of HIV in vitro (71.8% reduction in p24 expression). After being formulated into a gel dosage form, siRNA NP could be readily released from the gel, penetrate the vaginal epithelial layer, get taken up into the target cells and knockdown Nef and CCR5 without causing cytotoxicity in a vaginal mucosal co-culture model. Functionalization of siRNA NP with anti-CD4 antibody and loaded into a 0.5% HEC gel improved vaginal distribution and uptake of siRNA in a mouse model with distribution of siRNA restricted to the reproductive tract without any unwanted systemic uptake. The 0.5% HEC gel loaded with siRNA NP-(m)CD4 significantly downregulated approximately 40% of CCR5 protein in the lower vagina and 36% of CCR5 protein in the upper vaginal and cervical region. In contrast, 0.5% HEC gel loaded with siRNA NP-IgG did not result in significant gene knockdown.

Non-Viral RNA Delivery During Pregnancy: Opportunities and Challenges

During pregnancy, the risk of maternal and fetal adversities increases due to physiological changes, genetic predispositions, environmental factors, and infections. Unfortunately, treatment options are severely limited because many essential interventions are unsafe, inaccessible, or lacking in sufficient scientific data to support their use. One potential solution to this challenge may lie in emerging RNA therapeutics for gene therapy, protein replacement, maternal vaccination, fetal gene editing, and other prenatal treatment applications. In this review, the current landscape of RNA platforms and non-viral RNA delivery technologies that are under active development for administration during pregnancy is explored. Advancements of pregnancy-specific RNA drugs against SARS-CoV-2, Zika, influenza, preeclampsia, and for in-utero gene editing are discussed. Finally, this study highlights bottlenecks that are impeding translation efforts of RNA therapies, including the lack of accurate cell-based and animal models of human pregnancy and concerns related to toxicity and immunogenicity during pregnancy. Overcoming these challenges will facilitate the rapid development of this new class of pregnancy-safe drugs.

A Strategy Utilizing Protein-Protein Interaction Hubs for the Treatment of Cancer Diseases

We describe a strategy for the development of a rational approach of neoplastic disease therapy based on the demonstration that scale-free networks are susceptible to specific attacks directed against its connective hubs. This strategy involves the (i) selection of up-regulated hubs of connectivity in the tumors interactome, (ii) drug repurposing of these hubs, (iii) RNA silencing of non-druggable hubs, (iv) in vitro hub validation, (v) tumor-on-a-chip, (vi) in vivo validation, and (vii) clinical trial. Hubs are protein targets that are assessed as targets for rational therapy of cancer in the context of personalized oncology. We confirmed the existence of a negative correlation between malignant cell aggressivity and the target number needed for specific drugs or RNA interference (RNAi) to maximize the benefit to the patient's overall survival. Interestingly, we found that some additional proteins not generally targeted by drug treatments might justify the addition of inhibitors designed against them in order to improve therapeutic outcomes. However, many proteins are not druggable, or the available pharmacopeia for these targets is limited, which justifies a therapy based on encapsulated RNAi.

The emerging potential of siRNA nanotherapeutics in treatment of arthritis

RNA interference (RNAi) using small interfering RNA (siRNA) has shown potential as a therapeutic option for the treatment of arthritis by silencing specific genes. However, siRNA delivery faces several challenges, including stability, targeting, off-target effects, endosomal escape, immune response activation, intravascular degradation, and renal clearance. A variety of nanotherapeutics like lipidic nanoparticles, liposomes, polymeric nanoparticles, and solid lipid nanoparticles have been developed to improve siRNA cellular uptake, protect it from degradation, and enhance its therapeutic efficacy. Researchers are also investigating chemical modifications and bioconjugation to reduce its immunogenicity. This review discusses the potential of siRNA nanotherapeutics as a therapeutic option for various immune-mediated diseases, including rheumatoid arthritis, osteoarthritis, etc. siRNA nanotherapeutics have shown an upsurge of interest and the future looks promising for such interdisciplinary approach-based modalities that combine the principles of molecular biology, nanotechnology, and formulation sciences.

Unraveling Therapeutic Opportunities and the Diagnostic Potential of microRNAs for Human Lung Cancer

Lung cancer is a major public health problem and a leading cause of cancer-related deaths worldwide. Despite advances in treatment options, the five-year survival rate for lung cancer patients remains low, emphasizing the urgent need for innovative diagnostic and therapeutic strategies. MicroRNAs (miRNAs) have emerged as potential biomarkers and therapeutic targets for lung cancer due to their crucial roles in regulating cell proliferation, differentiation, and apoptosis. For example, miR-34a and miR-150, once delivered to lung cancer via liposomes or nanoparticles, can inhibit tumor growth by downregulating critical cancer promoting genes. Conversely, miR-21 and miR-155, frequently overexpressed in lung cancer, are associated with increased cell proliferation, invasion, and chemotherapy resistance. In this review, we summarize the current knowledge of the roles of miRNAs in lung carcinogenesis, especially those induced by exposure to environmental pollutants, namely, arsenic and benzopyrene, which account for up to 1/10 of lung cancer cases. We then discuss the recent advances in miRNA-based cancer therapeutics and diagnostics. Such information will provide new insights into lung cancer pathogenesis and innovative diagnostic and therapeutic modalities based on miRNAs.

siRNA therapeutics: insights, challenges, remedies and future prospects

INTRODUCTION

Among conventional and novel therapeutic approaches, the siRNA strategy stands out for treating disease by silencing the gene responsible for the corresponding disorder. Gene silencing is supposedly intended to target any disease-causing gene, and therefore, several attempts and investments were made to exploit siRNA gene therapy and advance it into clinical settings. Despite the remarkable beneficial prospects, the applicability of siRNA therapeutics is very challenging due to various pathophysiological barriers that hamper its target reach, which is the cytosol, and execution of gene silencing action.

AREAS COVERED

The present review provides insights into the field of siRNA therapeutics, significant in vivo hurdles that mitigate the target accessibility of siRNA, and remedies to overcome these siRNA delivery challenges. Nonetheless, the current review also highlights the on-going clinical trials and the regulatory aspects of siRNA modalities.

EXPERT OPINION

The siRNAs have the potential to reach previously untreated target sites and silence the concerned gene owing to their modification as polymeric or lipidic nanoparticles, conjugates, and the application of advanced drug delivery strategies. With such mounting research attempts to improve the delivery of siRNA to target tissue, we might shortly witness revolutionary therapeutic outcomes, new approvals, and clinical implications.

Optimization and characterization of miRNA-129-5p-encapsulated poly (lactic-co-glycolic acid) nanoparticles to reprogram activated microglia

Microglia have become a therapeutic target of many inflammation-mediated diseases in the central nervous system (CNS). Recently, microRNA (miRNA) has been proposed as an important regulator of immune responses. Specifically, miRNA-129-5p has been shown to play critical roles in the regulation of microglia activation. We have demonstrated that biodegradable poly (lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs) modulated innate immune cells and limited neuroinflammation after injury to the CNS. In this study, we optimized and characterized PLGA-based NPs for miRNA-129-5p delivery to utilize their synergistic immunomodulatory features for activated microglia modulation. A series of nanoformulations employing multiple excipients including epigallocatechin gallate (EGCG), spermidine (Sp), or polyethyleneimine (PEI) for miRNA-129-5p complexation and miRNA-129-5p conjugation to PLGA (PLGA-miR) were utilized. We characterized a total of six nanoformulations through physicochemical, biochemical, and molecular biological methods. In addition, we investigated the immunomodulatory effects of multiple nanoformulations. The data indicated that the immunomodulatory effects of nanoformulation, PLGA-miR with the excipient Sp (PLGA-miR+Sp) and PEI (PLGA-miR+PEI) were significant compared to other nanoformulations including naked PLGA-based NP. These nanoformulations promoted a sustained release of miRNA-129-5p and polarization of activated microglia into a more pro-regenerative phenotype. Moreover, they enhanced the expression of multiple regeneration-associated factors, while alleviating the expression of pro-inflammatory factors. Collectively, the proposed nanoformulations in this study highlight the promising therapeutic tools for synergistic immunomodulatory effects between PLGA-based NPs and miRNA-129-5p to modulate activated microglia which will have numerous applications for inflammation-derived diseases.

Emergence of Small Interfering RNA-Based Gene Drugs for Various Diseases

Small molecule, peptide, and protein-based drugs have been developed over decades to treat various diseases. The importance of gene therapy as an alternative to traditional drugs has increased after the discovery of gene-based drugs such as Gendicine for cancer and Neovasculgen for peripheral artery disease. Since then, the pharma sector is focusing on developing gene-based drugs for various diseases. After the discovery of the RNA interference (RNAi) mechanism, the development of siRNA-based gene therapy has been accelerated immensely. siRNA-based treatment for hereditary transthyretin-mediated amyloidosis (hATTR) using Onpattro and acute hepatic porphyria (AHP) by Givlaari and three more FDA-approved siRNA drugs has set up a milestone and further improved the confidence for the development of gene therapeutics for a spectrum of diseases. siRNA-based gene drugs have more advantages over other gene therapies and are under study to treat different types of diseases such as viral infections, cardiovascular diseases, cancer, and many more. However, there are a few bottlenecks to realizing the full potential of siRNA-based gene therapy. They include chemical instability, nontargeted biodistribution, undesirable innate immune responses, and off-target effects. This review provides a comprehensive view of siRNA-based gene drugs: challenges associated with siRNA delivery, their potential, and future prospects.

Evaluation of Poly(N-Ethyl Pyrrolidine Methacrylamide) (EPA) and Derivatives as Polymeric Vehicles for miRNA Delivery to Neural Cells

MicroRNAs (miRNAs) are endogenous, short RNA oligonucleotides that regulate the expression of hundreds of proteins to control cells' function in physiological and pathological conditions. miRNA therapeutics are highly specific, reducing the toxicity associated with off-target effects, and require low doses to achieve therapeutic effects. Despite their potential, applying miRNA-based therapies is limited by difficulties in delivery due to their poor stability, fast clearance, poor efficiency, and off-target effects. To overcome these challenges, polymeric vehicles have attracted a lot of attention due to their ease of production with low costs, large payload, safety profiles, and minimal induction of the immune response. Poly(N-ethyl pyrrolidine methacrylamide) (EPA) copolymers have shown optimal DNA transfection efficiencies in fibroblasts. The present study aims to evaluate the potential of EPA polymers as miRNA carriers for neural cell lines and primary neuron cultures when they are copolymerized with different compounds. To achieve this aim, we synthesized and characterized different copolymers and evaluated their miRNA condensation ability, size, charge, cytotoxicity, cell binding and internalization ability, and endosomal escape capacity. Finally, we evaluated their miRNA transfection capability and efficacy in Neuro-2a cells and rat primary hippocampal neurons. The results indicate that EPA and its copolymers, incorporating β-cyclodextrins with or without polyethylene glycol acrylate derivatives, can be promising vehicles for miRNA administration to neural cells when all experiments on Neuro-2a cells and primary hippocampal neurons are considered together.

Research progress on non-protein-targeted drugs for cancer therapy

Non-protein target drugs, especially RNA-based gene therapies for treating hereditary diseases, have been recognized worldwide. As cancer is an insurmountable challenge, no miracle drug is currently available. With the advancements in the field of biopharmaceuticals, research on cancer therapy has gradually focused on non-protein target-targeted drugs, especially RNA therapeutics, including oligonucleotide drugs and mRNA vaccines. This review mainly summarizes the clinical research progress in RNA therapeutics and highlights that appropriate target selection and optimized delivery vehicles are key factors in increasing the effectiveness of cancer treatment in vivo.

Engineering poly- and micelleplexes for nucleic acid delivery - A reflection on their endosomal escape

For the longest time, the field of nucleic acid delivery has remained skeptical whether or not polycationic drug carrier systems would ever make it into clinical practice. Yet, with the disclosure of patents on polyethyleneimine-based RNA carriers through leading companies in the field of nucleic acid therapeutics such as BioNTech SE and the progress in clinical studies beyond phase I trials, this aloofness seems to regress. As one of the most striking characteristics of polymer-based vectors, the extraordinary tunability can be both a blessing and a curse. Yet, knowing about the adjustment screws and how they impact the performance of the drug carrier provides the formulation scientist committed to its development with a head start. Here, we equip the reader with a toolbox - a toolbox that should advise and support the developer to conceptualize a cutting-edge poly- or micelleplex system for the delivery of therapeutic nucleic acids; to be specific, to engineer the vector towards maximum endosomal escape performance at minimum toxicity. Therefore, after briefly sketching the boundary conditions of polymeric vector design, we will dive into the topic of endosomal trafficking. We will not only discuss the most recent knowledge of the endo-lysosomal compartment but further depict different hypotheses and mechanisms that facilitate the endosomal escape of polyplex systems. Finally, we will combine the different facets introduced in the previous chapters with the fundamental building blocks of polymer vector design and evaluate the advantages and drawbacks. Throughout the article, a particular focus will be placed on cellular peculiarities, not only as an additional barrier, but also to give inspiration to how such cell-specific traits might be capitalized on.

Recent Advances of Chitosan Formulations in Biomedical Applications

Chitosan, a naturally abundant cationic polymer, is chemically composed of cellulose-based biopolymers derived by deacetylating chitin. It offers several attractive characteristics such as renewability, hydrophilicity, biodegradability, biocompatibility, non-toxicity, and a broad spectrum of antimicrobial activity towards gram-positive and gram-negative bacteria as well as fungi, etc., because of which it is receiving immense attention as a biopolymer for a plethora of applications including drug delivery, protective coating materials, food packaging films, wastewater treatment, and so on. Additionally, its structure carries reactive functional groups that enable several reactions and electrochemical interactions at the biomolecular level and improves the chitosan’s physicochemical properties and functionality. This review article highlights the extensive research about the properties, extraction techniques, and recent developments of chitosan-based composites for drug, gene, protein, and vaccine delivery applications. Its versatile applications in tissue engineering and wound healing are also discussed. Finally, the challenges and future perspectives for chitosan in biomedical applications are elucidated.

Polymeric nanoparticles-siRNA as an emerging nano-polyplexes against ovarian cancer

Ovarian cancer (OC) is considered fifth-deadliest cancer globally responsible for high mortality in women. As the conventional therapeutic and diagnostic approaches are ineffective in increasing the survival rates of advanced staged patients by more than 5 years, OC has resulted in high morbidity and mortality rates over the last two decades. As a result, there is a dire need for innovative treatment approaches to address the issues. RNAi and nanotechnology can be considered the most appropriate strategies that can be used to improve OC therapy and help circumvent the chemo-resistance. siRNA is considered highly successful in facilitating the knockdown of specific genes on entering the cytosol when administered in-vivo via inhibiting the mRNA expression responsible for translation of those specific genes through the mechanism called RNA interference (RNAi). However, the primary barrier of utmost importance in the clinical efficacy of employed siRNA for the treatment of OC is the systemic distribution to the targeted site from the administration site. As a result, nanoparticles are constructed to carry the siRNA molecules inside them to the targeted site by preventing serum degradation and enhancing the serum stability of administered siRNA. The present review assesses the developments made in the polymeric-based nanoparticle siRNA delivery for targeting particular genes involved in the prognosis of ovarian cancers and surpassing the chemo-resistance and thus improving the therapeutic potentials of administered agents.

Trends in iron oxide nanoparticles: a nano-platform for theranostic application in breast cancer

Breast cancer (BC) is the deadliest malignant disorder globally, with a significant mortality rate. The development of tolerance throughout cancer treatment and non-specific targeting limits the drug's response. Currently, nano therapy provides an interdisciplinary area for imaging, diagnosis, and targeted drug delivery for BC. Several overexpressed biomarkers, proteins, and receptors are identified in BC, which can be potentially targeted by using nanomaterial for drug/gene/immune/photo-responsive therapy and bio-imaging. In recent applications, magnetic iron oxide nanoparticles (IONs) have shown tremendous attention to the researcher because they combine selective drug delivery and imaging functionalities. IONs can be efficaciously functionalised for potential application in BC therapy and diagnosis. In this review, we explored the current application of IONs in chemotherapeutics delivery, gene delivery, immunotherapy, photo-responsive therapy, and bio-imaging for BC based on their molecular mechanism. In addition, we also highlighted the effect of IONs' size, shape, dimension, and functionalization on BC targeting and imaging. To better comprehend the functionalization potential of IONs, this paper provides an outline of BC cellular development. IONs for BC theranostic are also reviewed based on their clinical significance and future aspects.

Targeted Nanocarrier Delivery of RNA Therapeutics to Control HIV Infection

Our understanding of HIV infection has greatly advanced since the discovery of the virus in 1983. Treatment options have improved the quality of life of people living with HIV/AIDS, turning it from a fatal disease into a chronic, manageable infection. Despite all this progress, a cure remains elusive. A major barrier to attaining an HIV cure is the presence of the latent viral reservoir, which is established early in infection and persists for the lifetime of the host, even during prolonged anti-viral therapy. Different cure strategies are currently being explored to eliminate or suppress this reservoir. Several studies have shown that a functional cure may be achieved by preventing infection and also inhibiting reactivation of the virus from the latent reservoir. Here, we briefly describe the main HIV cure strategies, focussing on the use of RNA therapeutics, including small interfering RNA (siRNA) to maintain HIV permanently in a state of super latency, and CRISPR gRNA to excise the latent reservoir. A challenge with progressing RNA therapeutics to the clinic is achieving effective delivery into the host cell. This review covers recent nanotechnological strategies for siRNA delivery using liposomes, N-acetylgalactosamine conjugation, inorganic nanoparticles and polymer-based nanocapsules. We further discuss the opportunities and challenges of those strategies for HIV treatment.

Tumor-targeted nano-delivery system of therapeutic RNA

The birth of RNAi technology has pioneered actionability at the molecular level. Compared to DNA, RNA is less stable and therefore requires more demanding delivery vehicles. With their flexible size, shape, structure, and accessible surface modification, non-viral vectors show great promise for application in RNA delivery. Different non-viral vectors have different ways of binding to RNA. Low immunotoxicity gives RNA significant advantages in tumor treatment. However, the delivery of RNA still has many limitations in vivo. This manuscript summarizes the size-targeting dependence of different organs, followed by a summary of nanovesicles currently in or undergoing clinical trials. It also reviews all RNA delivery systems involved in the current study, including natural, bionic, organic, and inorganic systems. It summarizes the advantages and disadvantages of different delivery methods, which will be helpful for future RNA vehicle design. It is hoped that this will be helpful for gene therapy of clinical tumors.

Small interfering RNAs based therapies for intracerebral hemorrhage: challenges and progress in drug delivery systems

Intracerebral hemorrhage (ICH) is a subtype of stroke associated with higher rates of mortality. Currently, no effective drug treatment is available for ICH. The molecular pathways following ICH are complicated and diverse. Nucleic acid therapeutics such as gene knockdown by small interfering RNAs (siRNAs) have been developed in recent years to modulate ICH’s destructive pathways and mitigate its outcomes. However, siRNAs delivery to the central nervous system is challenging and faces many roadblocks. Existing barriers to systemic delivery of siRNA limit the use of naked siRNA; therefore, siRNA-vectors developed to protect and deliver these therapies into the specific-target areas of the brain, or cell types seem quite promising. Efficient delivery of siRNA via nanoparticles emerged as a viable and effective alternative therapeutic tool for central nervous system-related diseases. This review discusses the obstacles to siRNA delivery, including the advantages and disadvantages of viral and nonviral vectors. Additionally, we provide a comprehensive overview of recent progress in nanotherapeutics areas, primarily focusing on the delivery system of siRNA for ICH treatment.

Nanoparticle-Based RNAi Therapeutics Targeting Cancer Stem Cells: Update and Prospective

Cancer stem cells (CSCs) are characterized by intrinsic self-renewal and tumorigenic properties, and play important roles in tumor initiation, progression, and resistance to diverse forms of anticancer therapy. Accordingly, targeting signaling pathways that are critical for CSC maintenance and biofunctions, including the Wnt, Notch, Hippo, and Hedgehog signaling cascades, remains a promising therapeutic strategy in multiple cancer types. Furthermore, advances in various cancer omics approaches have largely increased our knowledge of the molecular basis of CSCs, and provided numerous novel targets for anticancer therapy. However, the majority of recently identified targets remain ‘undruggable’ through small-molecule agents, whereas the implications of exogenous RNA interference (RNAi, including siRNA and miRNA) may make it possible to translate our knowledge into therapeutics in a timely manner. With the recent advances of nanomedicine, in vivo delivery of RNAi using elaborate nanoparticles can potently overcome the intrinsic limitations of RNAi alone, as it is rapidly degraded and has unpredictable off-target side effects. Herein, we present an update on the development of RNAi-delivering nanoplatforms in CSC-targeted anticancer therapy and discuss their potential implications in clinical trials.

Lipid Nanoparticle-mRNA Formulations for Therapeutic Applications

After decades of extensive fundamental studies and clinical trials, lipid nanoparticles (LNPs) have demonstrated effective mRNA delivery such as the Moderna and Pfizer-BioNTech vaccines fighting against COVID-19. Moreover, researchers and clinicians have been investigating mRNA therapeutics for a variety of therapeutic indications including protein replacement therapy, genome editing, and cancer immunotherapy. To realize these therapeutics in the clinic, there are many formidable challenges. First, novel delivery systems such as LNPs with high delivery efficiency and low toxicity need to be developed for different cell types. Second, mRNA molecules need to be engineered for improved pharmaceutical properties. Lastly, the LNP-mRNA nanoparticle formulations need to match their therapeutic applications.In this Account, we summarize our recent advances in the design and development of various classes of lipids and lipid derivatives, which can be formulated with multiple types of mRNA molecules to treat diverse diseases. For example, we conceived a series of ionizable lipid-like molecules based on the structures of a benzene core, an amide linker, and hydrophobic tails. We identified N¹,N³,N⁵-tris(3-(didodecylamino)propyl)benzene-1,3,5-tricarboxamide (TT3) as a lead compound for mRNA delivery both in vitro and in vivo. Moreover, we tuned the biodegradability of these lipid-like molecules by introducing branched ester or linear ester chains. Meanwhile, inspired by biomimetic compounds, we synthesized vitamin-derived lipids, chemotherapeutic conjugated lipids, phospholipids, and glycolipids. These scaffolds greatly broaden the chemical space of ionizable lipids for mRNA delivery. In another section, we highlight our efforts on the research direction of mRNA engineering. We previously optimized mRNA chemistry using chemically-modified nucleotides to increase the protein expression, such as pseudouridine (ψ), 5-methoxyuridine (5moU), and N¹-methylpseudouridine (me¹ψ). Also, we engineered the sequences of mRNA 5' untranslated regions (5'-UTRs) and 3' untranslated regions (3'-UTRs), which dramatically enhanced protein expression. With the progress of LNP development and mRNA engineering, we consolidate these technologies and apply them to treat diseases such as genetic disorders, infectious diseases, and cancers. For instance, TT3 and its analog-derived lipid-like nanoparticles can effectively deliver factor IX or VIII mRNA and recover the clotting activity in hemophilia mouse models. Engineered mRNAs encoding SARS-CoV-2 antigens serve well as vaccine candidates against COVID-19. Vitamin-derived lipid nanoparticles loaded with antimicrobial peptide-cathepsin B mRNA enable adoptive macrophage transfer to treat multidrug resistant bacterial sepsis. Biomimetic lipids such as phospholipids formulated with mRNAs encoding costimulatory receptors lead to enhanced cancer immunotherapy.Overall, lipid-mRNA nanoparticle formulations have considerably benefited public health in the COVID-19 pandemic. To expand their applications in clinical use, research work from many disciplines such as chemistry, engineering, materials, pharmaceutical sciences, and medicine need to be integrated. With these collaborative efforts, we believe that more and more lipid-mRNA nanoparticle formulations will enter the clinic in the near future and benefit human health.

Multifunctional Nanoparticles Loaded with Vascular Endothelial Growth Factor Inhibitors and MED1 siRNA to Inhibit Breast Cancer Progression by Targeting Tumor-Associated Macrophages and Breast Cancer Cells

Breast cancer is still threatening many people' lives, hence novel targeted therapies are urgently required to improve the poor outcome of breast cancer patients. Herein, our study aimed to explore the potential of nanoparticles (NPs)-loaded with VEGF inhibitors and MED1 siRNA for treatment of the disorder. PEG and MTC conjugates were synthesized by ion gelation, and equipped with VEGF inhibitor (siV) and MED1 (siD) siRNA (MT/PC/siV-D NPs). The size and morphology of the NPs were detected by TEM. Agarose gel experiment was performed to detect drug encapsulation rate and NPs stability. Zeta potential was assessed by immunofluorescence assay and cell uptake was detected by fluorescence analysis. After cancer cells were treated with NPs or PBS, cell proliferation and invasion were evaluated with VEGF and MED1 expression was detected by Western blot and RT-qPCR analyses. Animal model was conducted to confirm the role of NPs in tumor growth. Results showed that, the MT/PC/siV-D NPs exhibited great stability, drug encapsulation and internalization ability. The combined NPs caused decreased proliferation and invasion of tumor cells, inducing M2 macrophages to re-polarize to M1 type with declined expression of VEGF and MED1. Moreover, the NPs remarkably alleviated breast tumor progression. The multifunctional NPs equipped with EGF inhibitors and MED1 siRNA can inhibit tumor progression by targeting TAMs and cancer cells during breast cancer.

Nucleic acid delivery for therapeutic applications

Recent medical advances have exploited the ability to address a given disease at the underlying level of transcription and translation. These treatment paradigms utilize nucleic acids - including short interfering RNA (siRNA), microRNA (miRNA), antisense oligonucleotides (ASO), and messenger RNA (mRNA) - to achieve a desired outcome ranging from gene knockdown to induced expression of a selected target protein. Towards this end, numerous strategies for encapsulation or stabilization of various nucleic acid structures have been developed in order to achieve intracellular delivery. In this review, we discuss several therapeutic applications of nucleic acids directed towards specific diseases and tissues of interest, in particular highlighting recent technologies which have reached late-stage clinical trials and received FDA approval.

Lipids and Lipid Derivatives for RNA Delivery

RNA-based therapeutics have shown great promise in treating a broad spectrum of diseases through various mechanisms including knockdown of pathological genes, expression of therapeutic proteins, and programmed gene editing. Due to the inherent instability and negative-charges of RNA molecules, RNA-based therapeutics can make the most use of delivery systems to overcome biological barriers and to release the RNA payload into the cytosol. Among different types of delivery systems, lipid-based RNA delivery systems, particularly lipid nanoparticles (LNPs), have been extensively studied due to their unique properties, such as simple chemical synthesis of lipid components, scalable manufacturing processes of LNPs, and wide packaging capability. LNPs represent the most widely used delivery systems for RNA-based therapeutics, as evidenced by the clinical approvals of three LNP-RNA formulations, patisiran, BNT162b2, and mRNA-1273. This review covers recent advances of lipids, lipid derivatives, and lipid-derived macromolecules used in RNA delivery over the past several decades. We focus mainly on their chemical structures, synthetic routes, characterization, formulation methods, and structure-activity relationships. We also briefly describe the current status of representative preclinical studies and clinical trials and highlight future opportunities and challenges.

Cyclic Peptide-Gadolinium Nanocomplexes as siRNA Delivery Tools

We have recently reported that a cyclic peptide containing five tryptophan, five arginine, and one cysteine amino acids [(WR)₅C], was able to produce peptide-capped gadolinium nanoparticles, [(WR)₅C]-GdNPs, in the range of 240 to 260 nm upon mixing with an aqueous solution of GdCl₃. Herein, we report [(WR)₅C]-GdNPs as an efficient siRNA delivery system. The peptide-based gadolinium nanoparticles (50 µM) did not exhibit significant cytotoxicity (~93% cell viability at 50 µM) in human leukemia T lymphoblast cells (CCRF-CEM) and triple-negative breast cancer cells (MDA-MB-231) after 48 h. Fluorescence-activated cell sorting (FACS) analysis indicated that the cellular uptakes of Alexa-488-labeled siRNA were found to be enhanced by more than 10 folds in the presence of [(WR)₅C]-GdNPs compared with siRNA alone in CCRF-CEM and MDA-MB-231 cells after 6 h of incubation at 37 °C. The gene silencing efficacy of the nanoparticles was determined via the western blot technique using an over-expressed gene, STAT-3 protein, in MDA-MB-231 cells. The results showed ~62% reduction of STAT-3 was observed in MDA-MB-231 with [(WR)₅C]-GdNPs at N/P 40. The integrity of the cellular membrane of CCRF-CEM cells was found to be intact when incubated with [(WR)₅C]-Gd nanoparticles (50 µM) for 2 h. Confocal microscopy reveals higher internalization of siRNA in MDA-MB-231 cells using [(WR)₅C]-GdNPs at N/P 40. These results provided insight about the use of the [(WR)₅C]-GdNPs complex as a potent intracellular siRNA transporter that could be a nontoxic choice to be used as a transfection agent for nucleic-acid-based therapeutics.

Recent Advances in Exosome-Based Drug Delivery for Cancer Therapy

Simple Summary

Exosomes derived from various sources can deliver therapeutic agents such as small molecule drugs, nucleic acids, and proteins to cancer cells by passive or active targeting. These exosomes can encapsulate drugs inside the exosomes, extending drug half-life and increasing drug release stability. In addition, exosomes are highly biocompatible due to their endogenous origin and can be used as nanocarriers for tissue-specific targeted delivery. This review discusses recent advances in exosome-based drug delivery for cancer therapy.

Abstract

Exosomes are a class of extracellular vesicles, with a size of about 100 nm, secreted by most cells and carrying various bioactive molecules such as nucleic acids, proteins, and lipids, and reflect the biological status of parent cells. Exosomes have natural advantages such as high biocompatibility and low immunogenicity for efficient delivery of therapeutic agents such as chemotherapeutic drugs, nucleic acids, and proteins. In this review, we introduce the latest explorations of exosome-based drug delivery systems for cancer therapy, with particular focus on the targeted delivery of various types of cargoes.

New Perspectives of Gene Therapy on Polyglutamine Spinocerebellar Ataxias: From Molecular Targets to Novel Nanovectors

Seven of the most frequent spinocerebellar ataxias (SCAs) are caused by a pathological expansion of a cytosine, adenine and guanine (CAG) trinucleotide repeat located in exonic regions of unrelated genes, which in turn leads to the synthesis of polyglutamine (polyQ) proteins. PolyQ proteins are prone to aggregate and form intracellular inclusions, which alter diverse cellular pathways, including transcriptional regulation, protein clearance, calcium homeostasis and apoptosis, ultimately leading to neurodegeneration. At present, treatment for SCAs is limited to symptomatic intervention, and there is no therapeutic approach to prevent or reverse disease progression. This review provides a compilation of the experimental advances obtained in cell-based and animal models toward the development of gene therapy strategies against polyQ SCAs, providing a discussion of their potential application in clinical trials. In the second part, we describe the promising potential of nanotechnology developments to treat polyQ SCA diseases. We describe, in detail, how the design of nanoparticle (NP) systems with different physicochemical and functionalization characteristics has been approached, in order to determine their ability to evade the immune system response and to enhance brain delivery of molecular tools. In the final part of this review, the imminent application of NP-based strategies in clinical trials for the treatment of polyQ SCA diseases is discussed.

In Vivo Follow-Up of Gene Inhibition in Solid Tumors Using Peptide-Based Nanoparticles for siRNA Delivery

Small interfering RNA (siRNA) exhibits a high degree of specificity for targeting selected genes. They are efficient on cells in vitro, but in vivo siRNA therapy remains a challenge for solid tumor treatment as siRNAs display difficulty reaching their intracellular target. The present study was designed to show the in vivo efficiency of a new peptide (WRAP5), able to form peptide-based nanoparticles (PBN) that can deliver siRNA to cancer cells in solid tumors. WRAP5:siRNA nanoparticles targeting firefly luciferase (Fluc) were formulated and assayed on Fluc-expressing U87 glioblastoma cells. The mode of action of WRAP5:siRNA by RNA interference was first confirmed in vitro and then investigated in vivo using a combination of bioluminescent reporter genes. Finally, histological analyses were performed to elucidate the cell specificity of this PBN in the context of brain tumors. In vitro and in vivo results showed efficient knock-down of Fluc expression with no toxicity. WRAP5:siFluc remained in the tumor for at least 10 days in vivo. Messenger RNA (mRNA) analyses indicated a specific decrease in Fluc mRNA without affecting tumor growth. Histological studies identified PBN accumulation in the cytoplasm of tumor cells but also in glial and neuronal cells. Through in vivo molecular imaging, our findings established the proof of concept for specific gene silencing in solid tumors. The evidence generated could be translated into therapy for any specific gene in different types of tumors without cell type specificity but with high molecular specificity.

Nanosac, a Noncationic and Soft Polyphenol Nanocapsule, Enables Systemic Delivery of siRNA to Solid Tumors

For systemic delivery of small interfering RNA (siRNA) to solid tumors, the carrier must circulate avoiding premature degradation, extravasate and penetrate tumors, enter target cells, traffic to the intracellular destination, and release siRNA for gene silencing. However, existing siRNA carriers, which typically exhibit positive charges, fall short of these requirements by a large margin; thus, systemic delivery of siRNA to tumors remains a significant challenge. To overcome the limitations of existing approaches, we have developed a carrier of siRNA, called "Nanosac", a noncationic soft polyphenol nanocapsule. A siRNA-loaded Nanosac is produced by sequential coating of mesoporous silica nanoparticles (MSNs) with siRNA and polydopamine, followed by removal of the sacrificial MSN core. The Nanosac recruits serum albumin, co-opts caveolae-mediated endocytosis to enter tumor cells, and efficiently silences target genes. The softness of Nanosac improves extravasation and penetration into tumors compared to its hard counterpart. As a carrier of siRNA targeting PD-L1, Nanosac induces a significant attenuation of CT26 tumor growth by immune checkpoint blockade. These results support the utility of Nanosac in the systemic delivery of siRNA for solid tumor therapy.

Insight Into the Prospects for RNAi Therapy of Cancer

RNA interference (RNAi), also known as gene silencing, is a biological process that prevents gene expression in certain diseases such as cancer. It can be used to improve the accuracy, efficiency, and stability of treatments, particularly genetic therapies. However, challenges such as delivery of oligonucleotide drug to less accessible parts of the body and the high incidence of toxic side effects are encountered. It is therefore imperative to improve their delivery to target sites and reduce their harmful effects on noncancerous cells to harness their full potential. In this study, the role of RNAi in the treatment of COVID-19, the novel coronavirus disease plaguing many countries, has been discussed. This review aims to ascertain the mechanism and application of RNAi and explore the current challenges of RNAi therapy by identifying some of the cancer delivery systems and providing drug information for their improvement. It is worth mentioning that delivery systems such as lipid-based delivery systems and exosomes have revolutionized RNAi therapy by reducing their immunogenicity and improving their cellular affinity. A deeper understanding of the mechanism and challenges associated with RNAi in cancer therapy can provide new insights into RNAi drug development.

The importance of co-delivery of nanoparticle-siRNA and anticancer agents in cancer therapy

According to global statistics, cancer is the second leading cause of death worldwide. Because of the heterogeneity of cancer, single-drug therapy has many limitations due to low efficacy. Therefore, combination therapy with two or more therapeutic agents is being arisen. One of the most important approaches in cancer therapy is the shot down of key genes involved in apoptotic processes and cell cycle. In this regard, siRNA is a good candidate, a highly attractive method to suppressing tumor growth and invasion. Combination therapy with siRNAs and chemotherapeutic agents can overcome the multidrug resistance and increase apoptosis. The efficient delivery of siRNA to the target cell/tissue/organ has been a challenge. To overcome these challenges, the presence of suitable delivery systems by using nanoparticles is interesting. In this review, we discuss the current challenges for successful RNA interference. Also, we suggested proper a strategy for delivering siRNA that can be useful in targeting therapy. Finally, the combination of a variety of anticancer drugs and siRNA through acceptable delivery systems and their effects on cell cycle and apoptosis will be evaluated.

Folate Receptor-Mediated siRNA Delivery: Recent Developments and Future Directions for RNAi Therapeutics

RNA interference (RNAi), a gene regulatory process mediated by small interfering RNAs (siRNAs), has made remarkable progress as a potential therapeutic agent against various diseases. However, RNAi is associated with fundamental challenges such as poor systemic delivery and susceptibility to the nucleases. Targeting ligand-bound delivery vehicles has improved the accumulation of drug at the target site, which has resulted in high transfection efficiency and enhanced gene silencing. Recently, folate receptor (FR)-mediated targeted delivery of siRNAs has garnered attention due to their enhanced cellular uptake and high transfection efficiency toward tumor cells. Folic acid (FA), due to its small size, low immunogenicity, high in vivo stability, and high binding affinity toward FRs, has attracted much attention for targeted siRNA delivery. FRs are overexpressed in a large number of tumors, including ovarian, breast, kidney, and lung cancer cells. In this review, we discuss recent advances in FA-mediated siRNA delivery to treat cancers and inflammatory diseases. This review summarizes various FA-conjugated nanoparticle systems reported so far in the literature, including liposome, silica, metal, graphene, dendrimers, chitosan, organic copolymers, and RNA nanoparticles. This review will help in the design and development of potential delivery vehicles for siRNA drug targeting to tumor cells using an FR-mediated approach.

DDAB cationic lipid-mPEG, PCL copolymer hybrid nano-carrier synthesis and application for delivery of siRNA targeting IGF-1R into breast cancer cells

BACKGROUND AND OBJECTIVE

To use siRNA molecule as a therapeutic agent in gene silencing, an efficient delivery system is necessary. Stability and clearance by reticuloendothelial of siRNA still remains the major challenges for clinical application. Herein, we could develop new lipid-polymer hybrid nanoparticles (LPHNP) as a siRNA carrier to silence insulin-like growth factor type I (IGF-1R) gene overexpression in MCF-7 human breast cancer cell line.

METHODS

Dimethyldioctadecylammonium bromide-methoxy poly(ethylene glycol)-poly (ε-caprolactone) (DDAB-mPEG-PCL) LPHNPs were synthesized using a single step nanoprecipitation method and characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) microscope. Cytotoxicity of the nanoparticles was assessed in the MCF7 cell line using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Desired LPHNP-siRNA complex was determined using different Nitrogen:Phosphate ratio (N/P) ratios and gel retardation. To determine the encapsulation efficiency of siRNA (%) in LPHNP, its absorbance was measured. The effect of the siRNA-LPHNP complex on IGF-1R silencing was assessed by reverse transcription-polymerase chain reaction (RT-PCR) RESULTS: LPHNP was synthesized using a single-step sonication method with a size below 100 nM. The viability of cells treated with hybrid nanoparticles was significantly greater than the corresponding cationic lipid (P < 0.01). As demonstrated by gel retardation assay, efficient siRNA binding to LPHNP occurred at N/P equal to 40 and siRNA encapsulation efficiency was found to be 95% ± 4 at this ratio. LPHNP-IGF-1R siRNA complex could be able to down-regulate the target more efficiently when it compared with the corresponded controls (P < 0.001).

CONCLUSION

In conclusion, our results suggest that DDAB cationic lipid and mPEG-PCL copolymer hybrid nanoparticle may be a good candidate for efficient siRNA delivery.

Cationic Dendrimers for siRNA Delivery: An Overview of Methods for In Vitro/In Vivo Characterization

This chapter reviews the different techniques for analyzing the chemical-physical properties, transfection efficiency, cytotoxicity, and stability of covalent cationic dendrimers (CCDs) and self-assembled cationic dendrons (ACDs) for siRNA delivery in the presence and absence of their nucleic cargos. On the basis of the reported examples, a standard essential set of techniques is described for each step of a siRNA/nanovector (NV) complex characterization process: (1) analysis of the basic chemical-physical properties of the NV per se; (2) characterization of the morphology, size, strength, and stability of the siRNA/NV ensemble; (3) characterization and quantification of the cellular uptake and release of the siRNA fragment; (4) in vitro and (5) in vivo experiments for the evaluation of the corresponding gene silencing activity; and (6) assessment of the intrinsic toxicity of the NV and the siRNA/NV complex.

Small interfering RNAs (siRNAs) based gene silencing strategies for the treatment of glaucoma: Recent advancements and future perspectives

RNA-interference-based mechanisms, especially the use of small interfering RNAs (siRNAs), have been under investigation for the treatment of several ailments and have shown promising results for ocular diseases including glaucoma. The eye, being a confined compartment, serves as a good target for the delivery of siRNAs. This review focuses on siRNA-based strategies for gene silencing to treat glaucoma. We have discussed the ocular structures and barriers to gene therapy (tear film, corneal, conjunctival, vitreous, and blood ocular barriers), methods of administration for ocular gene delivery (topical instillation, periocular, intracameral, intravitreal, subretinal, and suprachoroidal routes) and various viral and non-viral vectors in siRNA-based therapy for glaucoma. The components and mechanism of siRNA-based gene silencing have been mentioned briefly followed by the basic strategies and challenges faced during siRNA therapeutics development. We have emphasized different therapeutic targets for glaucoma which have been under research by scientists and the current siRNA-based drugs used in glaucoma treatment. We also mention briefly strategies for siRNA-based treatment after glaucoma surgery.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

RNA Interference Nanotherapeutics for Treatment of Glioblastoma Multiforme

Nucleic acid therapeutics for RNA interference (RNAi) are gaining attention in the treatment and management of several kinds of the so-called "undruggable" tumors via targeting specific molecular pathways or oncogenes. Synthetic ribonucleic acid (RNAs) oligonucleotides like siRNA, miRNA, shRNA, and lncRNA have shown potential as novel therapeutics. However, the delivery of such oligonucleotides is significantly hampered by their physiochemical (such as hydrophilicity, negative charge, and instability) and biopharmaceutical features (in vivo serum stability, fast renal clearance, interaction with extracellular proteins, and hindrance in cellular internalization) that markedly reduce their biological activity. Recently, several nanocarriers have evolved as suitable non-viral vectors for oligonucleotide delivery, which are known to either complex or conjugate with these oligonucleotides efficiently and also overcome the extracellular and intracellular barriers, thereby allowing access to the tumoral micro-environment for the better and desired outcome in glioblastoma multiforme (GBM). This Review focuses on the up-to-date advancements in the field of RNAi nanotherapeutics utilized for GBM treatment.

Combination Delivery of Alpha-Tocopheryl Succinate and Curcumin Using a GSH-Sensitive Micelle (PAH-SS-PLGA) to Treat Pancreatic Cancer

Pancreatic cancer is one of the highest causes of mortality throughout the world; thus, it requires an effective treatment strategy. Some chemotherapeutic agents used in the clinics or under clinical trials are hydrophobic and have poor aqueous solubility; consequently, they also have minimal systemic bioavailability. Nanoparticle-based drug delivery tactics have the potential for overcoming these limitations and enhancing their therapeutic efficacy. Herein, a glutathione (GSH)-sensitive micelle (PAH-SS-PLGA) was synthesized for the combined delivery of alpha-tocopheryl succinate (TOS) and curcumin to improve its therapeutic efficacy. The chemical structures of PAH-SS-PLGA were analyzed using Proton Nuclear Magnetic Resonance (¹H-NMR) and Fourier Transform Infrared (FTIR) spectroscopy, whereas the particle size, zeta potential, and surface morphology were observed using dynamic light scattering (DLS) and transmission electron microscopy (TEM). In vitro drug release results revealed that more TOS and curcumin were released in the presence of GSH (5 mM) than the physiological pH value. Fluorescence microscopy images revealed that nanoformulated curcumin/rhodamine was uptaken by PAN02 pancreatic cancer cells. In vitro cytotoxicity assays showed higher cytotoxicity for nanoformulated TOS and/or curcumin than free TOS and/or curcumin. In addition, higher cytotoxicity was observed for combination drugs than free drugs alone. Most interestingly, at all tested concentrations of nanoformulated drugs (PAH-SS-PLGA, TOS, and curcumin), the calculated combination index (CI) value was less than one, which shows that TOS and curcumin have a synergistic effect on cellular proliferation inhibition. Overall, synthesized co-polymers are the best carriers for combination drugs, TOS, and curcumin, because they enhance the therapeutic efficacy and improve pancreatic cancer treatments.

Nanomaterials for Autophagy-Related miRNA-34a Delivery in Cancer Treatment

Autophagy is an evolutionary conserved physiological process with a fundamental role during development, differentiation, and survival of eukaryotic cells. On the other hand, autophagy dysregulation is observed in many pathological conditions, including cancer. In particular, tumor growth and progression are accompanied and promoted by increased autophagy that allows cancer cells to escape apoptosis and to proliferate also in harsh microenvironments. It is, therefore, clear that the impairment of the autophagic process may represent a valid strategy to inhibit or reduce cancer growth and progression. Among the plethora of molecular players controlling cancer growth, a group of small endogenous noncoding RNAs called microRNAs (miRNAs) has recently emerged. In fact, miRNAs can act as either oncogenes or oncosuppressors depending on their target genes. Moreover, among miRNAs, miRNA-34a has been connected with both tumor repression and autophagy regulation, and its expression is frequently lost in many cancers. Therefore, enforced expression of miRNA-34a in cancer cells may represent a valid strategy to reduce cancer growth. However, such strategy is limited by the fast biodegradation and short half-life of miRNA-34a and by the lack of an efficient intracellular delivery system. The following review describes the autophagic process and its role in cancer as well as the role of miRNAs in general and miRNA-34a in particular in regulating tumor growth by modulating autophagy. Finally, we describe the use of nanoparticles as a promising strategy to selectively deliver miRNA-34a to tumor cells for therapeutic and diagnostic purposes.

The non-viral vectors and main methods of loading siRNA onto the titanium implants and their application

Surface modification of titanium implants by siRNA is quite efficient for improving implant osseointegration. Loading siRNA onto their surface is a crucial factor for siRNA-functionalized implants to realize their biological function. Direct binding of siRNA to implants has low siRNA binding and releasing rate, so usually it needs to be mediated by vectors. Polymeric, nonmaterial-mediated and lipid-based vectors are types of non-viral vectors which are commonly used for delivering siRNA. Three major methods of loading process, namely simple physical adsorption, layer-by-layer assembly and electrodeposition, are also summarized. A brief introduction, the basic principle and the general procedure of each method are included. The loading efficiency, which can be measured both qualitatively and quantitatively, together with gene knockdown efficiency, cytotoxicity assay and osteogenesis of the three methods are compared. A good many applications in osteogenesis have also been described in this review.

Nanocarriers in effective pulmonary delivery of siRNA: current approaches and challenges

Research on siRNA is increasing due to its wide applicability as a therapeutic agent in irreversible medical conditions. siRNA inhibits expression of the specific gene after its delivery from formulation to cytosol region of a cell. RNAi (RNA interference) is a mechanism by which siRNA is silencing gene expression for a particular disease. Numerous studies revealed that naked siRNA delivery is not preferred due to instability and poor pharmacokinetic performance. Nanocarriers based delivery of siRNA has the advantage to overcome physiological barriers and protect the integrity of siRNA from degradation by RNAase. Various diseases like lung cancer, cystic fibrosis, asthma, etc can be treated effectively by local lung delivery. The selective targeted therapeutic action in diseased organ and least off targeted cytotoxicity are the key benefits of pulmonary delivery. The current review highlights recent developments in pulmonary delivery of siRNA with novel nanosized formulation approach with the proven in vitro/in vivo applications.

Poly(lysine) Dendrimers Form Complexes with siRNA and Provide Its Efficient Uptake by Myeloid Cells: Model Studies for Therapeutic Nucleic Acid Delivery

The disruption of the cellular pathways of protein biosynthesis through the mechanism of RNA interference has been recognized as a tool of great diagnostic and therapeutic significance. However, in order to fully exploit the potential of this phenomenon, efficient and safe carriers capable of overcoming extra- and intracellular barriers and delivering siRNA to the target cells are needed. Recently, attention has focused on the possibility of the application of multifunctional nanoparticles, dendrimers, as potential delivery devices for siRNA. The aim of the present work was to evaluate the formation of dendriplexes using novel poly(lysine) dendrimers (containing lysine and arginine or histidine residues in their structure), and to verify the hypothesis that the use of these polymers may allow an efficient method of siRNA transfer into the cells in vitro to be obtained. The fluorescence polarization studies, as well as zeta potential and hydrodynamic diameter measurements were used to characterize the dendrimer:siRNA complexes. The cytotoxicity of dendrimers and dendriplexes was evaluated with the resazurin-based assay. Using the flow cytometry technique, the efficiency of siRNA transport to the myeloid cells was determined. This approach allowed us to determine the properties and optimal molar ratios of dendrimer:siRNA complexes, as well as to demonstrate that poly(lysine) dendrimers may serve as efficient carriers of genetic material, being much more effective than the commercially available transfection agent Lipofectamine 2000. This outcome provides the basis for further research on the application of poly(lysine) dendrimers as carriers for nucleic acids in the field of gene therapy.

A dual-functional buformin-mimicking poly(amido amine) for efficient and safe gene delivery

Biguanides (i.e. metformin, phenformin and buformin) are antidiabetic drugs with potential antitumor effects. Herein, a polycationic polymer, N,N'-bis(cystamine)acrylamide-buformin (CBA-Bu), containing multiple biodegradable disulphide bonds and buformin-mimicking side chains was synthesised. CBA-Bu was equipped with high efficiency and safety profile for gene delivery, meanwhile exhibiting potential antitumor efficacy. As a gene vector, CBA-Bu was able to condense plasmid DNA (pDNA) into nano-sized (<200 nm), positively-charged (>30 mV) uniform polyplexes that were well resistant to heparin and DNase I. Due to the reduction responsiveness of the disulphide bonds, CBA-Bu/pDNA polyplexes could release the loaded pDNA in the presence of dithiothreitol, and induce extremely low cytotoxicity in NIH/3T3 and U87 MG cells. The transfection results showed that CBA-Bu had a cellular uptake efficiency comparable to 25 kDa PEI, while a significantly higher gene expression level. Additionally, CBA-Bu had a lower IC50 value than its non-biguanide counterpart in two cancer cell lines. Furthermore, CBA-Bu could activate AMPK and inhibit mTOR pathways in U87 MG cells, a mechanism involved in the antitumor effect of biguanides. Taken together, CBA-Bu represented an advanced gene vector combining desirable gene delivery capability with potential antitumor activity, which was promising to achieve enhanced therapeutic efficacy in antitumor gene therapy.

Poly(1-vinylimidazole) polyplexes as novel therapeutic gene carriers for lung cancer therapy

The present work explores the ability of poly(1-vinylimidazole) (PVI) to complex small interfering RNA (siRNA) silencing vascular endothelial growth factor (VEGF) and the in vitro efficiency of the formed complexes in A549 lung cancer cells. The polyplex formed was found to exhibit 66% complexation efficiency. The complexation was confirmed by gel retardation assays, FTIR and thermal analysis. The blank PVI polymer was not toxic to cells. The polyplex was found to exhibit excellent internalization and escaped the endosome effectively. The polyplex was more effective than free siRNA in silencing VEGF in lung cancer cells. The silencing of VEGF was quantified using Western blot and was also reflected in the depletion of HIF-1α levels in the cells treated with the polyplex. VEGF silencing by the polyplex was found to augment the cytotoxic effects of the chemotherapeutic agent 5-fluorouracil. Microarray analysis of the mRNA isolated from cells treated with free siRNA and the polyplex reveal that the VEGF silencing by the polyplex also altered the expression levels of several other genes that have been connected to the proliferation and invasion of lung cancer cells. These results indicate that the PVI complexes can be an effective agent to counter lung cancer.

Recent advances in the combination delivery of drug for leukemia and other cancers

Introduction: Combination therapy has been explored for its potential to reduce or eliminate multidrug resistance in treating different types of cancer including leukemia. Nutraceutical, small molecular drugs, and small interfering ribonucleic acid (siRNA) are some of the effective drugs. In order to avoid off-site targeting, reduce the dosage required, and increase the half-life of the drug in the circulation system, drug delivery vehicles, such as nanoparticles and microfibers have been explored.Areas covered: This review summarizes various therapies utilized in treating leukemia based on their effectiveness in inducing protein inhibition and/or apoptosis. In particular, treatment effectiveness using combination therapy using various devices is addressed. Recently explored drug delivery methods are reviewed, providing examples and their applications in cancer treatment. The drug listing, delivery systems classifications, along with the general modeling approach in this review, provide, to a full extent, a basis for cancer drug delivery future studies.Expert opinion: The reviewer's opinion tackles the potential of using a multi-delivery system to deliver multiple drugs, providing better control upon drug release and targeting. Both local and systemic delivery are considered and explored for their potential targets. Researchers are advised to pre-consider all aspects associated with their desired delivery method.

Knockdown of human telomerase reverse transcriptase induces apoptosis in cervical cancer cell line

Background & objectives:

Human telomerase reverse transcriptase (hTERT) is the catalytic subunit of telomerase enzyme that maintains telomere ends by the addition of telomeric repeats to the ends of chromosomal DNA, and that may generate immortal cancer cells. Hence, the activity of telomerase is raised in cancer cells including cervical cancer. The present study aimed to validate the unique siRNA loaded chitosan coated poly-lactic-co-glycolic acid (PLGA) nanoparticle targeting hTERT mRNA to knock down the expression of hTERT in HeLa cells.

Methods:

The siRNA loaded chitosan coated polylactic-co-glycolic acid (PLGA) nanoparticles were synthesized by double emulsion solvent diffusion method. The characterization of nano-formulation was done to determine efficient siRNA delivery. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot were performed to evaluate silencing efficiency of nano-formulation.

Results:

Size, zeta potential and encapsulation efficiency of nanoparticles were 249.2 nm, 12.4 mV and 80.5 per cent, respectively. Sustained release of siRNA from prepared nanoparticle was studied for 72 h by ultraviolet method. Staining assays were performed to confirm senescence and apoptosis. Silencing of hTERT mRNA and protein expression were analyzed in HeLa cells by RT-PCR and Western blot.

Interpretation & conclusions:

The findings showed that biodegradable chitosan coated PLGA nanoparticles possessed an ability for efficient and successful siRNA delivery. The siRNA-loaded PLGA nanoparticles induced apoptosis in HeLa cells. Further studies need to be done with animal model.