Recent Advances in RNA Therapeutics and RNA Delivery Systems Based on Nanoparticles

Evaluation of mRNA Transfection Reagents for mRNA Delivery and Vaccine Efficacy via Intramuscular Injection in Mice

The selection of an effective delivery carrier is crucial to assessing mRNA-based vaccines and therapeutics in vivo. Although lipid nanoparticles (LNPs) are commonly used for mRNA delivery, the LNP-mRNA formulation process is laborious and time-consuming and requires a high-cost microfluidic device. Instead, mixing with commercial reagents may simplify mRNA transfection into cells. However, their potential as in vivo carriers in intramuscular vaccination in mouse models remains unclear. In this study, we used three types of commercial RNA transfection reagents, MessengerMAX (MAX; liposome), TransIT-mRNA (IT; cationic polymer), and Invivofectamine (IVF; LNP), to produce nanoparticles directly by pipetting. The particle characteristics and mRNA delivery efficacy of the mRNA-transfection reagent mixtures were analyzed. Additionally, immune responses to vaccine efficacy and protective immunity of the mRNA mixtures as vaccine antigens were evaluated in a mouse model. Although MAX and IT showed high in vitro transfection efficiencies, their in vivo performances were limited. In contrast, IVF exhibited notable particle stability and homogeneity, making it a promising delivery carrier. Intramuscular IVF injection significantly enhanced both innate and adaptive immune responses with a robust systemic protein expression. Notably, when using SARS-CoV-2 Spike mRNA, IVF showed robust humoral immune responses, including production of IgG and neutralizing antibodies, thereby resulting in complete protection against SARS-CoV-2 infection. Therefore, these findings position IVF as an accessible and efficient mRNA carrier for evaluating mRNA vaccines and therapeutic efficacy in basic research.

Selenium-loaded porous silica nanospheres improve cardiac repair after myocardial infarction by enhancing antioxidant activity and mitophagy

Myocardial infarction (MI) is the leading cause of death globally, often resulting to significant loss of cardiac function. A key factor in the pathological progression of MI is the excessive generation of reactive oxygen species (ROS) by dysfunctional mitochondria. However, no antioxidant therapy has been approved for clinical treatment of MI to date. In this study, selenium-loaded porous silica nanospheres (Se@PSN) are synthesized as a novel therapeutic approach for MI. These nanospheres are capable of neutralizing various ROS, thereby reducing hypoxia-induced myocardial cell damage. Additionally, Se@PSN promote the upregulation of antioxidant proteins, providing sustained intracellular ROS scavenging, which helps reduce infarct size and preserve cardiac function post-MI. The sustained antioxidant effects of Se@PSN are attributed to their ability to safeguard mitochondrial function by modulating oxidative phosphorylation, mitochondrial dynamics, and mitophagy. The activation of mitophagy by Se@PSN is achieved through the upregulation of HIF-1α expression. In conclusion, Se@PSN show significant potential for clinical translation as a novel therapeutic strategy for MI.

MicroRNA-targeted nanoparticle delivery systems for cancer therapy: current status and future prospects

Recently, the regulatory effects of microRNAs (miRNAs) on gene expression have been exploited for applications in the diagnosis and treatment of cancer, neurological diseases, and cardiovascular diseases. However, the susceptibility of miRNAs to degradation during somatic circulation and the challenges associated with their delivery to target tissues and cells have limited the clinical application of miRNAs. For application in tumor therapy, it is essential for miRNAs to specifically target cancer cells. Therefore, various novel miRNA delivery systems that protect miRNA against the activity of serum nuclease and deliver miRNA to target cells have been developed and optimized. This review introduces the passive and active targeting strategies of nanoparticles, summarizes the recent progress of miRNA nanocarriers with tumor-targeting ability, and discusses various nanoparticle delivery systems and their antitumor applications. Additionally, this review focuses on the translational challenges and potential strategies for advancing miRNA-based therapies into the clinic.

Spray-induced gene silencing to control plant pathogenic fungi: A step-by-step guide

RNA interference (RNAi)-based control technologies are gaining popularity as potential alternatives to synthetic fungicides in the ongoing effort to manage plant pathogenic fungi. Among these methods, spray-induced gene silencing (SIGS) emerges as particularly promising due to its convenience and feasibility for development. This approach is a new technology for plant disease management, in which double-stranded RNAs (dsRNAs) targeting essential or virulence genes are applied to plants or plant products and subsequently absorbed by plant pathogens, triggering a gene silencing effect and the inhibition of the infection process. Spray-induced gene silencing has demonstrated efficacy in laboratory settings against various fungal pathogens. However, as research progressed from the laboratory to the greenhouse and field environments, novel challenges arose, such as ensuring the stability of dsRNAs and their effective delivery to fungal targets. Here, we provide a practical guide to SIGS for the control of plant pathogenic fungi. This guide outlines the essential steps and considerations needed for designing and assessing dsRNA molecules. It also addresses key challenges inherent to SIGS, including delivery and stability of dsRNA molecules, and how nanoencapsulation of dsRNAs can aid in overcoming these obstacles. Additionally, the guide underscores existing knowledge gaps that warrant further research and aims to provide assistance to researchers, especially those new to the field, encouraging the advancement of SIGS for the control of a broad range of fungal pathogens.

siRNA-Mimetic Ratiometric pH (sMiRpH) Probes for Improving Cell Delivery and mRNA Knockdown

Second-generation siRNA-mimetic ratiometric pH probes (sMiRpH-2) were developed by hybridizing a 3'-FAM-labeled 2'-OMe RNA strand with a 3'-Cy5-labeled 25mer RNA strand. These duplexes demonstrated the silencing of cytoplasmic mRNA targets in HeLa cells as measured by RT-qPCR and supported by western blot analysis. Fluorescence intensity and lifetime measurements revealed that a single guanosine (G) positioned adjacent to FAM achieves substantial static quenching at pH 5, with additional collisional quenching rendering the dye almost nonemissive. A FAM-G π-π stacking interaction was evidenced by a red-shifted absorbance spectrum for FAM. Decreased quenching at near-neutral pH enhances the FAM dynamic range in the physiologic pH window and improves the differentiation in cells between endocytic entrapment and cytoplasmic release. Flow cytometric analysis of intracellular pH and uptake using sMiRpH-2 was corroborated by live cell confocal microscopy and found to be predictive of knockdown efficacy. A sMiRpH-2 probe successfully predicted the relative efficacy of two transfection agents in more challenging SK-OV-3 cells, which highlights its use for the rapid assessment of nonviral siRNA delivery vectors.

Lipid-Based Nanocarriers for Targeted Gene Delivery in Lung Cancer Therapy: Exploring a Novel Therapeutic Paradigm

Lung cancer is a significant cause of cancer-related death worldwide. It can be broadly categorised into small-cell lung cancer (SCLC) and Non-small cell lung cancer (NSCLC). Surgical intervention, radiation therapy, and the administration of chemotherapeutic medications are among the current treatment modalities. However, the application of chemotherapy may be limited in more advanced stages of metastasis due to the potential for adverse effects and a lack of cell selectivity. Although small-molecule anticancer treatments have demonstrated effectiveness, they still face several challenges. The challenges at hand in this context comprise insufficient solubility in water, limited bioavailability at specific sites, adverse effects, and the requirement for epidermal growth factor receptor inhibitors that are genetically tailored. Bio-macromolecular drugs, including small interfering RNA (siRNA) and messenger RNA (mRNA), are susceptible to degradation when exposed to the bodily fluids of humans, which can reduce stability and concentration. In this context, nanoscale delivery technologies are utilised. These agents offer encouraging prospects for the preservation and regulation of pharmaceutical substances, in addition to improving the solubility and stability of medications. Nanocarrier-based systems possess the notable advantage of facilitating accurate and sustained drug release, as opposed to traditional systemic methodologies. The primary focus of scientific investigation has been to augment the therapeutic efficacy of nanoparticles composed of lipids. Numerous nanoscale drug delivery techniques have been implemented to treat various respiratory ailments, such as lung cancer. These technologies have exhibited the potential to mitigate the limitations associated with conventional therapy. As an illustration, applying nanocarriers may enhance the solubility of small-molecule anticancer drugs and prevent the degradation of bio-macromolecular drugs. Furthermore, these devices can administer medications in a controlled and extended fashion, thereby augmenting the therapeutic intervention's effectiveness and reducing adverse reactions. However, despite these promising results, challenges remain that must be addressed. Multiple factors necessitate consideration when contemplating the application of nanoparticles in medical interventions. To begin with, the advancement of more efficient delivery methods is imperative. In addition, a comprehensive investigation into the potential toxicity of nanoparticles is required. Finally, additional research is needed to comprehend these treatments' enduring ramifications. Despite these challenges, the field of nanomedicine demonstrates considerable promise in enhancing the therapy of lung cancer and other respiratory diseases.

The role of polymers in enabling RNAi-based technology for sustainable pest management

The growing global food demand, coupled with the limitations of traditional pest control methods, has driven the search for innovative and sustainable solutions in agricultural pest management. In this review, we highlight polymeric nanocarriers for their potential to deliver double-stranded RNA (dsRNA) and control pests through the gene-silencing mechanism of RNA interference (RNAi). Polymer-dsRNA systems have shown promise in protecting dsRNA, facilitating cellular uptake, and ensuring precise release. Despite these advances, challenges such as scalability, cost-efficiency, regulatory approval, and public acceptance persist, necessitating further research to overcome these obstacles and fully unlock the potential of RNAi in sustainable agriculture.

A Single-Dose mRNA Vaccine Employing Porous Silica Nanoparticles Induces Robust Immune Responses Against the Zika Virus

Recently, lipid nanoparticles (LNPs)-based mRNA delivery has been approved by the FDA for SARS-CoV-2 vaccines. However, there are still considerable points for improvement in LNPs. Especially, local administration of LNPs-formulated mRNA can cause off-target translation of mRNA in distal organs which can induce unintended adverse effects. With the hypothesis that large and rigid nanoparticles can be applied to enhance retention of nanoparticles at the injection site, a polyethyleneimine (PEI)-coated porous silica nanoparticles (PPSNs)-based mRNA delivery platform is designed. PPSNs not only facilitate localized translation of mRNA at the site of injection but also prolonged protein expression. It is further demonstrated that the development of a highly efficacious Zika virus (ZIKV) vaccine using mRNA encoding full-length ZIKV pre-membrane (prM) and envelope (E) protein delivered by PPSNs. The ZIKV prME mRNA-loaded PPSNs vaccine elicits robust immune responses, including high levels of neutralizing antibodies and ZIKV E-specific T cell responses in C57BL/6 mice. Moreover, a single injection of prME-PPSNs vaccine provided complete protection against the ZIKV challenge in mice.

Advancing cancer immunotherapy through siRNA-based gene silencing for immune checkpoint blockade

Cancer immunotherapy represents a revolutionary strategy, leveraging the patient's immune system to inhibit tumor growth and alleviate the immunosuppressive effects of the tumor microenvironment (TME). The recent emergence of immune checkpoint blockade (ICB) therapies, particularly following the first approval of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors like ipilimumab, has led to significant growth in cancer immunotherapy. The extensive explorations on diverse immune checkpoint antibodies have broadened the therapeutic scope for various malignancies. However, the clinical response to these antibody-based ICB therapies remains limited, with less than 15% responsiveness and notable adverse effects in some patients. This review introduces the emerging strategies to overcome current limitations of antibody-based ICB therapies, mainly focusing on the development of small interfering ribonucleic acid (siRNA)-based ICB therapies and innovative delivery systems. We firstly highlight the diverse target immune checkpoint genes for siRNA-based ICB therapies, incorporating silencing of multiple genes to boost anti-tumor immune responses. Subsequently, we discuss improvements in siRNA delivery systems, enhanced by various nanocarriers, aimed at overcoming siRNA's clinical challenges such as vulnerability to enzymatic degradation, inadequate pharmacokinetics, and possible unintended target interactions. Additionally, the review presents various combination therapies that integrate chemotherapy, phototherapy, stimulatory checkpoints, ICB antibodies, and cancer vaccines. The important point is that when used in combination with siRNA-based ICB therapy, the synergistic effect of traditional therapies is strengthened, improving host immune surveillance and therapeutic outcomes. Conclusively, we discuss the insights into innovative and effective cancer immunotherapeutic strategies based on RNA interference (RNAi) technology utilizing siRNA and nanocarriers as a novel approach in ICB cancer immunotherapy.

Advances in traditional herbal formulation based nano-vaccine for cancer immunotherapy: Unraveling the enigma of complex tumor environment and multidrug resistance

Cancer is attributed to uncontrolled cell growth and is among the leading causes of death with no known effective treatment while complex tumor microenvironment (TME) and multidrug resistance (MDR) are major challenges for developing an effective therapeutic strategy. Advancement in cancer immunotherapy has been limited by the over-activation of the host immune response that ultimately affects healthy tissues or organs and leads to a feeble response of the patient's immune system against tumor cells. Besides, traditional herbal medicines (THM) have been well-known for their essential role in the treatment of cancer and are considered relatively safe due to their compatibility with the human body. Yet, poor solubility, low bio-availability, and lack of understanding about their pathophysiological mechanism halt their clinical application. Moreover, considering the complex TME and drug resistance, the most precarious and least discussed concerns for developing THM-based nano-vaccination, are identification of specific biomarkers for drug inhibitory protein and targeted delivery of bioactive ingredients of THM on the specific sites in tumor cells. The concept of THM-based nano-vaccination indicates immunomodulation of TME by THM-based bioactive adjuvants, exerting immunomodulatory effects, via targeted inhibition of key proteins involved in the metastasis of cancer. However, this concept is at its nascent stage and very few preclinical studies provided the evidence to support clinical translation. Therefore, we attempted to capsulize previously reported studies highlighting the role of THM-based nano-medicine in reducing the risk of MDR and combating complex tumor environments to provide a reference for future study design by discussing the challenges and opportunities for developing an effective and safe therapeutic strategy against cancer.

Mechanistic insights into interactions between ionizable lipid nanodroplets and biomembranes

Delivery of RNA into cells using lipid nanoparticles (LNPs) has been a significant breakthrough in RNA-based medicine, with clinical applicability expanded through the use of ionizable lipids (ILs). These unique lipids can alter their charge state in response to pH changes, which is crucial for pH-triggered endosomal escape and effective lipid-mediated RNA delivery. In this study, we conducted a comprehensive set of molecular dynamics (MD) simulations to investigate interactions between IL-containing lipid nanodroplets (LNDs) and cell membrane models. Using an atomistic resolution model, we investigated the merging process of LNDs with cell membrane models under neutral conditions relevant to an intercellular environment and acidic pH conditions found in late endosomes. Our observations revealed that at neutral pH, LNDs merged with lipid membranes while preserving the bilayer structure. Under acidic conditions, the LNDs remained attached to the bilayer without fusing into the membranes. Importantly, the presence of ILs did not disrupt the original biomembrane structure during the simulation period. The MD simulations provided valuable atomistic insights into the mechanism of interaction between IL-containing nanodroplets and biomembranes, which could aid the rational design of ILs to develop more efficient LNPs for RNA therapies.

SPIONs: Superparamagnetic iron oxide-based nanoparticles for the delivery of microRNAi-therapeutics in cancer

Non-coding RNA (ncRNA)-based therapeutics that induce RNA interference (RNAi), such as microRNAs (miRNAs), have drawn considerable attention as a novel class of targeted cancer therapeutics because of their capacity to specifically target oncogenes/protooncogenes that regulate key signaling pathways involved in carcinogenesis, tumor growth and progression, metastasis, cell survival, proliferation, angiogenesis, and drug resistance. However, clinical translation of miRNA-based therapeutics, in particular, has been challenging due to the ineffective delivery of ncRNA molecules into tumors and their uptake into cancer cells. Recently, superparamagnetic iron oxide-based nanoparticles (SPIONs) have emerged as highly effective and efficient for the delivery of therapeutic RNAs to malignant tissues, as well as theranostic (therapy and diagnostic) applications, due to their excellent biocompatibility, magnetic responsiveness, broad functional surface modification, safety, and biodistribution profiles. This review highlights recent advances in the use of SPIONs for the delivery of ncRNA-based therapeutics with an emphasis on their synthesis and coating strategies. Moreover, the advantages and current limitations of SPIONs and their future perspectives are discussed.

RNA therapeutics for respiratory diseases

It has become increasingly common to utilize RNA treatment to treat respiratory illnesses. Experimental research on both people and animals has advanced quickly since the turn of the twenty-first century in an effort to discover a treatment for respiratory ailments that could not be accomplished with earlier techniques, specifically in treating prevalent respiratory diseases such as lung cancer, chronic obstructive pulmonary disease (COPD), respiratory infections caused by viruses, and asthma. This chapter has provided a comprehensive overview of the scientific evidence in applying RNA therapy to treat respiratory diseases. The chapter describes the development of this therapy for respiratory diseases. At the same time, the types of RNA therapy for respiratory diseases have been highlighted. In addition, the mechanism of this therapy for respiratory diseases has also been covered. These insights are indispensable if this therapy is to be developed widely.

Advances in RNA therapeutics for modulation of 'undruggable' targets

Over the past decades, drug discovery utilizing small pharmacological compounds, fragment-based therapeutics, and antibody therapy have significantly advanced treatment options for many human diseases. However, a major bottleneck has been that>70% of human proteins/genomic regions are 'undruggable' by the above-mentioned approaches. Many of these proteins constitute essential drug targets against complex multifactorial diseases like cancer, immunological disorders, and neurological diseases. Therefore, alternative approaches are required to target these proteins or genomic regions in human cells. RNA therapeutics is a promising approach for many of the traditionally 'undruggable' targets by utilizing methods such as antisense oligonucleotides, RNA interference, CRISPR/Cas-based genome editing, aptamers, and the development of mRNA therapeutics. In the following chapter, we will put emphasis on recent advancements utilizing these approaches against challenging drug targets, such as intranuclear proteins, intrinsically disordered proteins, untranslated genomic regions, and targets expressed in inaccessible tissues.

Building a Better Silver Bullet: Current Status and Perspectives of Non-Viral Vectors for mRNA Vaccines

In recent years, messenger RNA (mRNA) vaccines have exhibited great potential to replace conventional vaccines owing to their low risk of insertional mutagenesis, safety and efficacy, rapid and scalable production, and low-cost manufacturing. With the great achievements of chemical modification and sequence optimization methods of mRNA, the key to the success of mRNA vaccines is strictly dependent on safe and efficient gene vectors. Among various delivery platforms, non-viral mRNA vectors could represent perfect choices for future clinical translation regarding their safety, sufficient packaging capability, low immunogenicity, and versatility. In this review, the recent progress in the development of non-viral mRNA vectors is focused on. Various organic vectors including lipid nanoparticles (LNPs), polymers, peptides, and exosomes for efficient mRNA delivery are presented and summarized. Furthermore, the latest advances in clinical trials of mRNA vaccines are described. Finally, the current challenges and future possibilities for the clinical translation of these promising mRNA vectors are also discussed.

RNA-Based Vaccines and Therapeutics Against Intracellular Pathogens

RNA-based vaccines have sparked a paradigm shift in the treatment and prevention of diseases by nucleic acid medicines. There has been a notable surge in the development of nucleic acid therapeutics and vaccines following the global approval of the two messenger RNA-based COVID-19 vaccines. This growth is fueled by the exploration of numerous RNA products in preclinical stages, offering several advantages over conventional methods, i.e., safety, efficacy, scalability, and cost-effectiveness. In this chapter, we provide an overview of various types of RNA and their mechanisms of action for stimulating immune responses and inducing therapeutic effects. Furthermore, this chapter delves into the varying delivery systems, particularly emphasizing the use of nanoparticles to deliver RNA. The choice of delivery system is an intricate process involved in developing nucleic acid medicines that significantly enhances their stability, biocompatibility, and site-specificity. Additionally, this chapter sheds light on the current landscape of clinical trials of RNA therapeutics and vaccines against intracellular pathogens.

Enhanced Local Delivery of Engineered IL-2 mRNA by Porous Silica Nanoparticles to Promote Effective Antitumor Immunity

Localized expression of immunomodulatory molecules can stimulate immune responses against tumors in the tumor microenvironment while avoiding toxicities associated with systemic administration. In this study, we developed a polyethylenimine-modified porous silica nanoparticle (PPSN)-based delivery platform carrying cytokine mRNA for local immunotherapy in vivo. Our delivery platform was significantly more efficient than FDA-approved lipid nanoparticles for localized mRNA translation. We observed no off-target translation of mRNA in any organs and no evidence of systemic toxicity. Intratumoral injection of cytokine mRNA-loaded PPSNs led to high-level expression of protein within the tumor and stimulated immunogenic cancer cell death. Additionally, combining cytokine mRNA with an immune checkpoint inhibitor enhanced anticancer responses in several murine cancer models and enabled the inhibition of distant metastatic tumors. Our results demonstrate the potential of PPSNs-mediated mRNA delivery as a specific, effective, and safe platform for mRNA-based therapeutics in cancer immunotherapy.

Highly Efficient Messenger RNA Transfection of Hard-to-Transfect Cells using Carbon Nanodots

Although messenger RNA (mRNA)-based therapeutics opened up new avenues for treating various diseases, intracellular delivery of mRNA is still challenging, especially to hard-to-transfect cells. For successful mRNA therapy, the development of a delivery vehicle that can effectively transport mRNA into cells is essential. In this study, we synthesized carbon nanodots (CNDs) as an efficient mRNA delivery vehicle via a one-step microwave-assisted method. CNDs easily formed complexes with mRNA molecules by electrostatic interactions, and the gene delivery performance of CNDs was highly effective in hard-to-transfect cells. Considering their outstanding transfection ability, CNDs are expected to be further applied for mRNA-based cellular engineering.

A New Perspective for the Treatment of Alzheimer's Disease: Exosome-like Liposomes to Deliver Natural Compounds and RNA Therapies

With the increment of the aging population in recent years, neurodegenerative diseases exert a major global disease burden, essentially as a result of the lack of treatments that stop the disease progression. Alzheimer's Disease (AD) is an example of a neurodegenerative disease that affects millions of people globally, with no effective treatment. Natural compounds have emerged as a viable therapy to fill a huge gap in AD management, and in recent years, mostly fueled by the COVID-19 pandemic, RNA-based therapeutics have become a hot topic in the treatment of several diseases. Treatments of AD face significant limitations due to the complex and interconnected pathways that lead to their hallmarks and also due to the necessity to cross the blood-brain barrier. Nanotechnology has contributed to surpassing this bottleneck in the treatment of AD by promoting safe and enhanced drug delivery to the brain. In particular, exosome-like nanoparticles, a hybrid delivery system combining exosomes and liposomes' advantageous features, are demonstrating great potential in the treatment of central nervous system diseases.

Lipid nanoparticle-based mRNA delivery systems for cancer immunotherapy

Cancer immunotherapy, which harnesses the power of the immune system, has shown immense promise in the fight against malignancies. Messenger RNA (mRNA) stands as a versatile instrument in this context, with its capacity to encode tumor-associated antigens (TAAs), immune cell receptors, cytokines, and antibodies. Nevertheless, the inherent structural instability of mRNA requires the development of effective delivery systems. Lipid nanoparticles (LNPs) have emerged as significant candidates for mRNA delivery in cancer immunotherapy, providing both protection to the mRNA and enhanced intracellular delivery efficiency. In this review, we offer a comprehensive summary of the recent advancements in LNP-based mRNA delivery systems, with a focus on strategies for optimizing the design and delivery of mRNA-encoded therapeutics in cancer treatment. Furthermore, we delve into the challenges encountered in this field and contemplate future perspectives, aiming to improve the safety and efficacy of LNP-based mRNA cancer immunotherapies.

Multidimensional futuristic approaches to address the pandemics beyond COVID-19

Globally, the impact of the coronavirus disease 2019 (COVID-19) pandemic has been enormous and unrelenting with ∼6.9 million deaths and ∼765 million infections. This review mainly focuses on the recent advances and potentially novel molecular tools for viral diagnostics and therapeutics with far-reaching implications in managing the future pandemics. In addition to briefly highlighting the existing and recent methods of viral diagnostics, we propose a couple of potentially novel non-PCR-based methods for rapid, cost-effective, and single-step detection of nucleic acids of viruses using RNA mimics of green fluorescent protein (GFP) and nuclease-based approaches. We also highlight key innovations in miniaturized Lab-on-Chip (LoC) devices, which in combination with cyber-physical systems, could serve as ideal futuristic platforms for viral diagnosis and disease management. We also discuss underexplored and underutilized antiviral strategies, including ribozyme-mediated RNA-cleaving tools for targeting viral RNA, and recent advances in plant-based platforms for rapid, low-cost, and large-scale production and oral delivery of antiviral agents/vaccines. Lastly, we propose repurposing of the existing vaccines for newer applications with a major emphasis on Bacillus Calmette-Guérin (BCG)-based vaccine engineering.

Integrated Osteoinductive Factors─Exosome@MicroRNA-26a Hydrogel Enhances Bone Regeneration

MicroRNAs (miRNAs) are a new therapeutic tool that can target multiple genes by inducing translation repression and target mRNA degradation. Although miRNAs have gained significant attention in oncology and in work on genetic disorders and autoimmune diseases, their application in tissue regeneration remains hindered by several challenges, such as miRNA degradation. Here, we reported Exosome@MicroRNA-26a (Exo@miR-26a), an osteoinductive factor that can be substituted for routinely used growth factors, which was constructed using bone marrow stem cell (BMSC)-derived exosomes and microRNA-26a (miR-26a). Exo@miR-26a-integrated hydrogels significantly promoted bone regeneration when implanted into defect sites; as the exosome stimulated angiogenesis, miR-26a promoted osteogenesis while the hydrogel enabled a site-directed release. Moreover, BMSC-derived exosomes further facilitated healthy bone regeneration by repressing osteoclast differentiation-related genes rather than damaging osteoclasts. Taken together, our findings demonstrate the promising potential of Exo@miR-26a for bone regeneration and provide a new strategy for the application of miRNA therapy in tissue engineering.

Ratiometric, pH-Sensitive Probe for Monitoring siRNA Delivery

Many RNA delivery strategies require efficient endosomal uptake and release. To monitor this process, we developed a 2'-OMe RNA-based ratiometric pH probe with a pH-invariant 3'-Cy5 and 5'-FAM whose pH sensitivity is enhanced by proximal guanines. The probe, in duplex with a DNA complement, exhibits a 48.9-fold FAM fluorescence enhancement going from pH 4.5 to pH 8.0 and reports on both endosomal entrapment and release when delivered to HeLa cells. In complex with an antisense RNA complement, the probe constitutes an siRNA mimic capable of protein knockdown in HEK293T cells. This illustrates a general approach for measuring the localization and pH microenvironment of any oligonucleotide.

Insight into RNA-based Therapies for Ovarian Cancer

Ovarian cancer (OC) is one of the most common malignancies in women and is associated with poor outcomes. The treatment for OC is often associated with resistance to therapies and hence this has stimulated the search for alternative therapeutic approaches, including RNA-based therapeutics. However, this approach has some challenges that include RNA degradation. To solve this critical issue, some novel delivery systems have been proposed. In current years, there has been growing interest in the improvement of RNAbased therapeutics as a promising approach to target ovarian cancer and improve patient outcomes. This paper provides a practical insight into the use of RNA-based therapeutics in ovarian cancers, highlighting their potential benefits, challenges, and current research progress. RNA-based therapeutics offer a novel and targeted approach to treat ovarian cancer by exploiting the unique characteristics of RNA molecules. By targeting key oncogenes or genes responsible for drug resistance, siRNAs can effectively inhibit tumor growth and sensitize cancer cells to conventional therapies. Furthermore, messenger RNA (mRNA) vaccines have emerged as a revolutionary tool in cancer immunotherapy. MRNA vaccines can be designed to encode tumor-specific antigens, stimulating the immune system to distinguish and eliminate ovarian cancer cells. A nano-based delivery platform improves the release of loaded RNAs to the target location and reduces the off-target effects. Additionally, off-target effects and immune responses triggered by RNA molecules necessitate careful design and optimization of these therapeutics. Several preclinical and clinical researches have shown promising results in the field of RNA-based therapeutics for ovarian cancer. In a preclinical study, siRNA-mediated silencing of the poly (ADP-ribose) polymerase 1 (PARP1) gene, involved in DNA repair, sensitized ovarian cancer cells to PARP inhibitors, leading to enhanced therapeutic efficacy. In clinical trials, mRNA-based vaccines targeting tumor-associated antigens have demonstrated safety and efficacy in stimulating immune responses in ovarian cancer patients. In aggregate, RNA-based therapeutics represent a promising avenue for the therapy of ovarian cancers. The ability to specifically target oncogenes or stimulate immune responses against tumor cells holds great potential for improving patient outcomes. However, further research is needed to address challenges related to delivery, permanence, and off-target effects. Clinical trials assessing the care and effectiveness of RNAbased therapeutics in larger patient cohorts are warranted. With continued advancements in the field, RNAbased therapeutics have the potential to develop the management of ovarian cancer and provide new hope for patients.

Clinical translation of gold nanoparticles

Gold nanoparticles display unique physicochemical features, which can be useful for therapeutic purposes. After two decades of preclinical progress, gold nanoconstructs are slowly but steadily transitioning into clinical trials. Although initially thought to be "magic golden bullets" that could be used to treat a wide range of diseases, current consensus has moved toward a more realistic approach, where gold nanoformulations are being investigated to treat specific disorders. These therapeutic applications are dictated by the pharmacokinetics and biodistribution profiles of gold nanoparticles. Here, we analyze the current clinical landscape of therapeutic gold nanoconstructs, discuss the shared characteristics that allowed for their transition from bench to bedside, and examine existing hurdles that need to be overcome before they can be approved for clinical use.

Recent approaches to mRNA vaccine delivery by lipid-based vectors prepared by continuous-flow microfluidic devices

Advancements in nanotechnology have resulted in the introduction of several nonviral delivery vectors for the nontoxic, efficient delivery of encapsulated mRNA-based vaccines. Lipid- and polymer-based nanoparticles (NP) have proven to be the most potent delivery systems, providing increased delivery efficiency and protection of mRNA molecules from degradation. Here, the authors provide an overview of the recent studies carried out using lipid NPs and their functionalized forms, polymeric and lipid-polymer hybrid nanocarriers utilized mainly for the encapsulation of mRNAs for gene and immune therapeutic applications. A microfluidic system as a prevalent methodology for the preparation of NPs with continuous flow enables NP size tuning, rapid mixing and production reproducibility. Continuous-flow microfluidic devices for lipid and polymeric encapsulated RNA NP production are specifically reviewed.

Perspectives on plant virus diseases in a climate change scenario of elevated temperatures

Global food production is at risk from many abiotic and biotic stresses and can be affected by multiple stresses simultaneously. Virus diseases damage cultivated plants and decrease the marketable quality of produce. Importantly, the progression of virus diseases is strongly affected by changing climate conditions. Among climate-changing variables, temperature increase is viewed as an important factor that affects virus epidemics, which may in turn require more efficient disease management. In this review, we discuss the effect of elevated temperature on virus epidemics at both macro- and micro-climatic levels. This includes the temperature effects on virus spread both within and between host plants. Furthermore, we focus on the involvement of molecular mechanisms associated with temperature effects on plant defence to viruses in both susceptible and resistant plants. Considering various mechanisms proposed in different pathosystems, we also offer a view of the possible opportunities provided by RNA -based technologies for virus control at elevated temperatures. Recently, the potential of these technologies for topical field applications has been strengthened through a combination of genetically modified (GM)-free delivery nanoplatforms. This approach represents a promising and important climate-resilient substitute to conventional strategies for managing plant virus diseases under global warming scenarios. In this context, we discuss the knowledge gaps in the research of temperature effects on plant-virus interactions and limitations of RNA-based emerging technologies, which should be addressed in future studies.

Protein-Encoding Free-Standing RNA Hydrogel for Sub-Compartmentalized Translation

RNA can self-fold into complex structures that can serve as major biological regulators in protein synthesis and in catalysis. Due to the abundance of structural primitives and functional diversity, RNA has been utilized for designing nature-defined goals despite its intrinsic chemical instability and lack of technologies. Here, a robust, free-standing RNA hydrogel is developed through a sequential process involving both ligation and rolling circle transcription to form RNA G-quadruplexes, capable of both catalytic activity and enhancing expression of several proteins in sub-compartmentalized, phase-separated translation environments. The observations suggest that this hydrogel will expand RNA research and impact practical RNA principles and applications.

RNAi-based therapeutics and tumor targeted delivery in cancer

Over the past decade, non-coding RNA-based therapeutics have proven as a great potential for the development of targeted therapies for cancer and other diseases. The discovery of the critical function of microRNAs (miRNAs) has generated great excitement in developing miRNA-based therapies. The dysregulation of miRNAs contributes to the pathogenesis of various human diseases and cancers by modulating genes that are involved in critical cellular processes, including cell proliferation, differentiation, apoptosis, angiogenesis, metastasis, drug resistance, and tumorigenesis. miRNA (miRNA mimic, anti-miRNA/antagomir) and small interfering RNA (siRNA) can inhibit the expression of any cancer-related genes/mRNAs with high specificity through RNA interference (RNAi), thus representing a remarkable therapeutic tool for targeted therapies and precision medicine. siRNA and miRNA-based therapies have entered clinical trials and recently three novel siRNA-based therapeutics were approved by the Food and Drug Administration (FDA), indicating the beginning of a new era of targeted therapeutics. The successful clinical applications of miRNA and siRNA therapeutics rely on safe and effective nanodelivery strategies for targeting tumor cells or tumor microenvironment. For this purpose, promising nanodelivery/nanoparticle-based approaches have been developed using a variety of molecules for systemic administration and improved tumor targeted delivery with reduced side effects. In this review, we present an overview of RNAi-based therapeutics, the major pharmaceutical challenges, and the perspectives for the development of promising delivery systems for clinical translation. We also highlight the passive and active tumor targeting nanodelivery strategies and primarily focus on the current applications of nanoparticle-based delivery formulations for tumor targeted RNAi molecules and their recent advances in clinical trials in human cancers.

Role of the Mediator Complex and MicroRNAs in Breast Cancer Etiology

Transcriptional coactivators play a key role in RNA polymerase II transcription and gene regulation. One of the most important transcriptional coactivators is the Mediator (MED) complex, which is an evolutionary conserved large multiprotein complex. MED transduces the signal between DNA-bound transcriptional activators (gene-specific transcription factors) to the RNA polymerase II transcription machinery to activate transcription. It is known that MED plays an essential role in ER-mediated gene expression mainly through the MED1 subunit, since estrogen receptor (ER) can interact with MED1 by specific protein–protein interactions; therefore, MED1 plays a fundamental role in ER-positive breast cancer (BC) etiology. Additionally, other MED subunits also play a role in BC etiology. On the other hand, microRNAs (miRNAs) are a family of small non-coding RNAs, which can regulate gene expression at the post-transcriptional level by binding in a sequence-specific fashion at the 3′ UTR of the messenger RNA. The miRNAs are also important factors that influence oncogenic signaling in BC by acting as both tumor suppressors and oncogenes. Moreover, miRNAs are involved in endocrine therapy resistance of BC, specifically to tamoxifen, a drug that is used to target ER signaling. In metazoans, very little is known about the transcriptional regulation of miRNA by the MED complex and less about the transcriptional regulation of miRNAs involved in BC initiation and progression. Recently, it has been shown that MED1 is able to regulate the transcription of the ER-dependent miR-191/425 cluster promoting BC cell proliferation and migration. In this review, we will discuss the role of MED1 transcriptional coactivator in the etiology of BC and in endocrine therapy-resistance of BC and also the contribution of other MED subunits to BC development, progression and metastasis. Lastly, we identified miRNAs that potentially can regulate the expression of MED subunits.

Delivery strategies of RNA therapeutics to leukocytes

Harnessing RNA-based therapeutics for cancer, inflammation, and viral diseases is hindered by poor delivery of therapeutic RNA molecules. Targeting leukocytes to treat these conditions holds great promise, as they are key participants in their initiation, drug response, and treatment. The various extra- and intra-cellular obstacles that impediment the clinical implementation of therapeutic RNA can be overcome by utilizing drug delivery systems. However, delivery of therapeutic RNA to leukocytes poses an even greater challenge as these cells are difficult to reach and transfect upon systemic administration. This review briefly describes the existing successful delivery strategies that efficiently target leukocytes in vivo and discuss their potential clinical applicability.

The infinite possibilities of RNA therapeutics

Although the study of ribonucleic acid (RNA) therapeutics started decades ago, for many years, this field of research was overshadowed by the growing interest in DNA-based therapies. Nowadays, the role of several types of RNA in cell regulation processes and the development of various diseases have been elucidated, and research in RNA therapeutics is back with force. This short literature review aims to present general aspects of many of the molecules currently used in RNA therapeutics, including in vitro transcribed mRNA (IVT mRNA), antisense oligonucleotides (ASOs), aptamers, small interfering RNAs (siRNAs), and microRNAs (miRNAs). In addition, we describe the state of the art of technologies applied for synthetic RNA manufacture and delivery. Likewise, we detail the RNA-based therapies approved by the FDA so far, as well as the ongoing clinical investigations. As a final point, we highlight the current and potential advantages of working on RNA-based therapeutics and how these could lead to a new era of accessible and personalized healthcare.

mRNA, a Revolution in Biomedicine

The perspective of using messenger RNA (mRNA) as a therapeutic molecule first faced some uncertainties due to concerns about its instability and the feasibility of large-scale production. Today, given technological advances and deeper biomolecular knowledge, these issues have started to be addressed and some strategies are being exploited to overcome the limitations. Thus, the potential of mRNA has become increasingly recognized for the development of new innovative therapeutics, envisioning its application in immunotherapy, regenerative medicine, vaccination, and gene editing. Nonetheless, to fully potentiate mRNA therapeutic application, its efficient production, stabilization and delivery into the target cells are required. In recent years, intensive research has been carried out in this field in order to bring new and effective solutions towards the stabilization and delivery of mRNA. Presently, the therapeutic potential of mRNA is undoubtedly recognized, which was greatly reinforced by the results achieved in the battle against the COVID-19 pandemic, but there are still some issues that need to be improved, which are critically discussed in this review.

Nanotechnology-Assisted RNA Delivery: From Nucleic Acid Therapeutics to COVID-19 Vaccines

In recent years, the main quest of science has been the pioneering of the groundbreaking biomedical strategies needed for achieving a personalized medicine. Ribonucleic acids (RNAs) are outstanding bioactive macromolecules identified as pivotal actors in regulating a wide range of biochemical pathways. The ability to intimately control the cell fate and tissue activities makes RNA-based drugs the most fascinating family of bioactive agents. However, achieving a widespread application of RNA therapeutics in humans is still a challenging feat, due to both the instability of naked RNA and the presence of biological barriers aimed at hindering the entrance of RNA into cells. Recently, material scientists' enormous efforts have led to the development of various classes of nanostructured carriers customized to overcome these limitations. This work systematically reviews the current advances in developing the next generation of drugs based on nanotechnology-assisted RNA delivery. The features of the most used RNA molecules are presented, together with the development strategies and properties of nanostructured vehicles. Also provided is an in-depth overview of various therapeutic applications of the presented systems, including coronavirus disease vaccines and the newest trends in the field. Lastly, emerging challenges and future perspectives for nanotechnology-mediated RNA therapies are discussed.

Aptamers: Cutting edge of cancer therapies

The development of an aptamer-based therapeutic has rapidly progressed following the first two reports in the 1990s, underscoring the advantages of aptamer drugs associated with their unique binding properties. In 2004, the US Food and Drug Administration (FDA) approved the first therapeutic aptamer for the treatment of neovascular age-related macular degeneration, Macugen developed by NeXstar. Since then, eleven aptamers have successfully entered clinical trials for various therapeutic indications. Despite some of the pre-clinical and clinical successes of aptamers as therapeutics, no aptamer has been approved by the FDA for the treatment of cancer. This review highlights the most recent and cutting-edge approaches in the development of aptamers for the treatment of cancer types most refractory to conventional therapies. Herein, we will review (1) the development of aptamers to enhance anti-cancer immunity and as delivery tools for inducing the expression of immunogenic neoantigens; (2) the development of the most promising therapeutic aptamers designed to target the hard-to-treat cancers such as brain tumors; and (3) the development of "carrier" aptamers able to target and penetrate tumors and metastasis, delivering RNA therapeutics to the cytosol and nucleus.

Therapeutic promise of engineered nonsense suppressor tRNAs

Nonsense mutations change an amino acid codon to a premature termination codon (PTC) generally through a single-nucleotide substitution. The generation of a PTC results in a defective truncated protein and often in severe forms of disease. Because of the exceedingly high prevalence of nonsense-associated diseases and a unifying mechanism, there has been a concerted effort to identify PTC therapeutics. Most clinical trials for PTC therapeutics have been conducted with small molecules that promote PTC read through and incorporation of a near-cognate amino acid. However, there is a need for PTC suppression agents that recode PTCs with the correct amino acid while being applicable to PTC mutations in many different genomic landscapes. With these characteristics, a single therapeutic will be able to treat several disease-causing PTCs. In this review, we will focus on the use of nonsense suppression technologies, in particular, suppressor tRNAs (sup-tRNAs), as possible therapeutics for correcting PTCs. Sup-tRNAs have many attractive qualities as possible therapeutic agents although there are knowledge gaps on their function in mammalian cells and technical hurdles that need to be overcome before their promise is realized. This article is categorized under: RNA Processing > tRNA Processing Translation > Translation Regulation.

Protein-based antigen presentation platforms for nanoparticle vaccines

Modern vaccine design has sought a minimalization approach, moving to the isolation of antigens from pathogens that invoke a strong neutralizing immune response. This approach has created safer vaccines but may limit vaccine efficacy due to poor immunogenicity. To combat global diseases such as COVID-19, malaria, and AIDS there is a clear urgency for more effective next-generation vaccines. One approach to improve the immunogenicity of vaccines is the use of nanoparticle platforms that present a repetitive array of antigen on its surface. This technology has been shown to improve antigen presenting cell uptake, lymph node trafficking, and B-cell activation through increased avidity and particle size. With a focus on design, we summarize natural platforms, methods of antigen attachment, and advancements in generating self-assembly that have led to new engineered platforms. We further examine critical parameters that will direct the usage and development of more effective platforms.

Disulfide Bridging Strategies in Viral and Nonviral Platforms for Nucleic Acid Delivery

Self-assembled nanostructures that are sensitive to environmental stimuli are promising nanomaterials for drug delivery. In this class, disulfide-containing redox-sensitive strategies have gained enormous attention because of their wide applicability and simplicity of nanoparticle design. In the context of nucleic acid delivery, numerous disulfide-based materials have been designed by relying on covalent or noncovalent interactions. In this review, we highlight major advances in the design of disulfide-containing materials for nucleic acid encapsulation, including covalent nucleic acid conjugates, viral vectors or virus-like particles, dendrimers, peptides, polymers, lipids, hydrogels, inorganic nanoparticles, and nucleic acid nanostructures. Our discussion will focus on the context of the design of materials and their impact on addressing the current shortcomings in the intracellular delivery of nucleic acids.

The Limitless Future of RNA Therapeutics

Recent advances in the generation, purification and cellular delivery of RNA have enabled development of RNA-based therapeutics for a broad array of applications. RNA therapeutics comprise a rapidly expanding category of drugs that will change the standard of care for many diseases and actualize personalized medicine. These drugs are cost effective, relatively simple to manufacture, and can target previously undruggable pathways. It is a disruptive therapeutic technology, as small biotech startups, as well as academic groups, can rapidly develop new and personalized RNA constructs. In this review we discuss general concepts of different classes of RNA-based therapeutics, including antisense oligonucleotides, aptamers, small interfering RNAs, microRNAs, and messenger RNA. Furthermore, we provide an overview of the RNA-based therapies that are currently being evaluated in clinical trials or have already received regulatory approval. The challenges and advantages associated with use of RNA-based drugs are also discussed along with various approaches for RNA delivery. In addition, we introduce a new concept of hospital-based RNA therapeutics and share our experience with establishing such a platform at Houston Methodist Hospital.

In-Vitro Application of Magnetic Hybrid Niosomes: Targeted siRNA-Delivery for Enhanced Breast Cancer Therapy

Even though the administration of chemotherapeutic agents such as erlotinib is clinically established for the treatment of breast cancer, its efficiency and the therapy outcome can be greatly improved using RNA interference (RNAi) mechanisms for a combinational therapy. However, the cellular uptake of bare small interfering RNA (siRNA) is insufficient and its fast degradation in the bloodstream leads to a lacking delivery and no suitable accumulation of siRNA inside the target tissues. To address these problems, non-ionic surfactant vesicles (niosomes) were used as a nanocarrier platform to encapsulate Lifeguard (LFG)-specific siRNA inside the hydrophilic core. A preceding entrapment of superparamagnetic iron-oxide nanoparticles (FexOy-NPs) inside the niosomal bilayer structure was achieved in order to enhance the cellular uptake via an external magnetic manipulation. After verifying a highly effective entrapment of the siRNA, the resulting hybrid niosomes were administered to BT-474 cells in a combinational therapy with either erlotinib or trastuzumab and monitored regarding the induced apoptosis. The obtained results demonstrated that the nanocarrier successfully caused a downregulation of the LFG gene in BT-474 cells, which led to an increased efficacy of the chemotherapeutics compared to plainly added siRNA. Especially the application of an external magnetic field enhanced the internalization of siRNA, therefore increasing the activation of apoptotic signaling pathways. Considering the improved therapy outcome as well as the high encapsulation efficiency, the formulated hybrid niosomes meet the requirements for a cost-effective commercialization and can be considered as a promising candidate for future siRNA delivery agents.

mRNA-Enhanced Cell Therapy and Cardiovascular Regeneration

mRNA has emerged as an important biomolecule in the global call for the development of therapies during the COVID-19 pandemic. Synthetic in vitro-transcribed (IVT) mRNA can be engineered to mimic naturally occurring mRNA and can be used as a tool to target "undruggable" diseases. Recent advancement in the field of RNA therapeutics have addressed the challenges inherent to this drug molecule and this approach is now being applied to several therapeutic modalities, from cancer immunotherapy to vaccine development. In this review, we discussed the use of mRNA for stem cell generation or enhancement for the purpose of cardiovascular regeneration.

A high-throughput screening platform to identify nanocarriers for efficient delivery of RNA-based therapies

RNA-based therapies are highly selective and powerful regulators of biological functions. Non-viral vectors such as nanoparticles (NPs) are very promising formulations for the delivery of RNA-based therapies but their cell targeting, cell internalization and endolysomal escape capacity is rather limited. Here, we present a methodology that combines high-throughput synthesis of light-triggerable NPs and a high-content imaging screening to identify NPs capable of efficiently delivering different type of RNAs. The NPs were generated using polymers synthesized by Michael type addition reactions and they were designed to: (i) efficiently complex coding (mRNAs) and non-coding (miRNAs and/or lncRNAs) RNA molecules, (ii) allow rapid cell uptake and cytoplasmic release of RNA molecules and (iii) target different cell types based on their composition. Furthermore, light-responsive domains were attached to the polymers by distinctive methods to provide diverse disassembly strategies. The most efficient formulations were identified using cell-based assays and high-content imaging analysis. This strategy allows precise delivery of RNA-based therapies and provides an effective design approach to address critical issues in non-viral gene delivery.

MicroRNA: Promising Roles in Cancer Therapy

MicroRNAs (miRNA) are small non-coding RNAs that act as one of the main regulators of gene expression. They are involved in maintaining a proper balance of diverse processes, including differentiation, proliferation, and cell death in normal cells. Cancer biology can also be affected by these molecules by modulating the expression of oncogenes or tumor suppressor genes. Thus, miRNA based anticancer therapy is currently being developed either alone or in combination with chemotherapy agents used in cancer management, aiming at promoting tumor regression and increasing cure rate. Access to large quantities of RNA agents can facilitate RNA research and development. In addition to currently used in vitro methods, fermentation-based approaches have recently been developed, which can cost-effectively produce biological RNA agents with proper folding needed for the development of RNA-based therapeutics. Nevertheless, a major challenge in translating preclinical studies to clinical for miRNA-based cancer therapy is the efficient delivery of these agents to target cells. Targeting miRNAs/anti-miRNAs using antibodies and/or peptides can minimize cellular and systemic toxicity. Here, we provide a brief review of miRNA in the following aspects: biogenesis and mechanism of action of miRNAs, the role of miRNAs in cancer as tumor suppressors or oncogenes, the potential of using miRNAs as novel and promising therapeutics, miRNA-mediated chemo-sensitization, and currently utilized methods for the in vitro and in vivo production of RNA agents. Finally, an update on the viral and non-viral delivery systems is addressed.

Combinatorial expression of GPCR isoforms affects signalling and drug responses

G-protein-coupled receptors (GPCRs) are membrane proteins that modulate physiology across human tissues in response to extracellular signals. GPCR-mediated signalling can differ because of changes in the sequence1,2 or expression3 of the receptors, leading to signalling bias when comparing diverse physiological systems4. An underexplored source of such bias is the generation of functionally diverse GPCR isoforms with different patterns of expression across different tissues. Here we integrate data from human tissue-level transcriptomes, GPCR sequences and structures, proteomics, single-cell transcriptomics, population-wide genetic association studies and pharmacological experiments. We show how a single GPCR gene can diversify into several isoforms with distinct signalling properties, and how unique isoform combinations expressed in different tissues can generate distinct signalling states. Depending on their structural changes and expression patterns, some of the detected isoforms may influence cellular responses to drugs and represent new targets for developing drugs with improved tissue selectivity. Our findings highlight the need to move from a canonical to a context-specific view of GPCR signalling that considers how combinatorial expression of isoforms in a particular cell type, tissue or organism collectively influences receptor signalling and drug responses.

Therapeutic miRNA-Enriched Extracellular Vesicles: Current Approaches and Future Prospects

Extracellular vesicles (EVs) are 50–300 nm vesicles secreted by eukaryotic cells. They can carry cargo (including miRNA) from the donor cell to the recipient cell. miRNAs in EVs can change the translational profile of the recipient cell and modulate cellular morphology. This endogenous mechanism has attracted the attention of the drug-delivery community in the last few years. EVs can be enriched with exogenous therapeutic miRNAs and used for treatment of diseases by targeting pathological recipient cells. However, there are some obstacles that need to be addressed before introducing therapeutic miRNA-enriched EVs in clinics. Here, we focused on the progress in the field of therapeutic miRNA enriched EVs, highlighted important areas where research is needed, and discussed the potential to use them as therapeutic miRNA carriers in the future.

RNA-based therapeutics in cardiovascular disease

PURPOSE OF REVIEW

Cardiovascular disease is the leading cause of death globally, with the number of deaths rising every year. Much effort has gone into development of new treatment strategies. Many RNA species have important regulatory functions in disease initiation and progression, providing interesting new treatment options. This review focuses on different classes of RNA-based therapeutics and provides examples of current clinical and preclinical studies. Current challenges that prevent clinical translation and possibilities to overcome them will be discussed.

RECENT FINDINGS

Different RNA-based molecules have been developed, such as antisense oligos, microRNA mimics and small interfering RNAs. Modifications are used to prevent degradation and immune activation and improve affinity. Additionally, in order to improve delivery of the RNA molecules to the target tissues, viral or nonviral vectors can be used.

SUMMARY

RNA-based therapy has been shown to be a promising new treatment strategy for different disorders. However, several challenges, such as delivery problems and low efficacy remain. Future research will likely focus on effective delivery to target tissues in order to improve efficacy and avoid harmful side-effects.

SIDT1-dependent absorption in the stomach mediates host uptake of dietary and orally administered microRNAs

Dietary microRNAs have been shown to be absorbed by mammals and regulate host gene expression, but the absorption mechanism remains unknown. Here, we show that SIDT1 expressed on gastric pit cells in the stomach is required for the absorption of dietary microRNAs. SIDT1-deficient mice show reduced basal levels and impaired dynamic absorption of dietary microRNAs. Notably, we identified the stomach as the primary site for dietary microRNA absorption, which is dramatically attenuated in the stomachs of SIDT1-deficient mice. Mechanistic analyses revealed that the uptake of exogenous microRNAs by gastric pit cells is SIDT1 and low-pH dependent. Furthermore, oral administration of plant-derived miR2911 retards liver fibrosis, and this protective effect was abolished in SIDT1-deficient mice. Our findings reveal a major mechanism underlying the absorption of dietary microRNAs, uncover an unexpected role of the stomach and shed light on developing small RNA therapeutics by oral delivery.

Intranasal Delivery and Transfection of mRNA Therapeutics in the Brain Using Cationic Liposomes

Nucleic acid-based therapeutics, including the use of messenger RNA (mRNA) as a drug molecule, has tremendous potential in the treatment of chronic diseases, such as age-related neurodegenerative diseases. In this study, we have developed a cationic liposomal formulation of mRNA and evaluated the potential of intranasal delivery to the brain in murine model. Preliminary in vitro studies in J774A.1 murine macrophages showed GFP expression up to 24 h and stably expressed GFP protein in the cytosol. Upon intranasal administration of GFP-mRNA/cationic liposomes (3 mg/kg dose) in mice, there was significantly higher GFP-mRNA expression in the brain post 24 h as compared to either naked mRNA or the vehicle-treated group. Luciferase mRNA encapsulated in cationic liposomes was used for quantification of mRNA expression distribution in the brain. The results showed increased luciferase activity in the whole brain in a dose-dependent manner. Specifically, the luciferase-mRNA/cationic liposome group (3 mg/kg dose) showed significantly higher luciferase activity in the cortex, striatum, and midbrain regions as compared with the control groups, with minimal systemic exposure. Overall, the results of this study demonstrate the feasibility of brain-specific, nonviral mRNA delivery for the treatment of various neurological disorders.