PECAM-1 directed re-targeting of exogenous mRNA providing two orders of magnitude enhancement of vascular delivery and expression in lungs independent of apolipoprotein E-mediated uptake

Targeted mRNA delivery with bispecific antibodies that tether LNPs to cell surface markers

Efficient delivery of mRNA-lipid nanoparticles (LNPs) to specific cell types remains a major challenge for mRNA therapeutics. Conventional targeting approaches involve modifying the lipid composition or functionalizing the surface of LNPs, which complicates manufacturing and alters nanoparticle size, charge, and stealth, impacting their delivery and immunogenicity. Here, we present a generalizable method for targeted mRNA-LNP delivery that uses bispecific antibodies (BsAbs) to form a bridge between LNPs and cell surface markers. BsAbs can be combined with LNPs or administered first, binding to surface proteins on target cells and later retaining unmodified LNPs in affected tissues. We demonstrate the efficient and cell-type-specific delivery of mRNA-LNPs beyond the liver, targeting epidermal growth factor receptor (EGFR)- and folate hydrolase 1 (PSMA)-positive cells in vitro and in vivo. The flexibility of this technology, achieved by substituting the cell-targeting region of the BsAbs, enables the rapid development of next-generation targeted mRNA drugs.

Targeted immunotherapy rescues pulmonary fibrosis by reducing activated fibroblasts and regulating alveolar cell profile

Idiopathic pulmonary fibrosis (IPF) is a severe lung disease occurring throughout the world; however, few clinical therapies are available for treating this disorder. Overactivated fibroblasts drive abnormal fibrosis accumulation to maintain dynamic balance between inflammation and extracellular matrix (ECM) stiffness. Given pulmonary cell can regenerate, the lung may possess self-repairing abilities if fibrosis is removed via clearance of overactivated fibroblasts. The aim of this study was to evaluate the therapeutic activity of transient antifibrotic chimeric antigen receptor (CAR) T cells (generated via a novelly-designed lipid nanoparticle-messenger RNA (LNP-mRNA) system) and explore the regeneration mechanisms of lung in a male mouse model of bleomycin-induced pulmonary fibrosis. Here we found that fibrosis-induced ECM stiffening impaired alveolar epithelial cell compensation. The proposed LNP-mRNA therapy eliminated overactivated fibroblasts to rescue pulmonary fibrosis. The restored ECM environment regulated the cellular profile. The elevated plasticity of AT2 and Pclaf+ cells increased AT1 cell population via polarization. Apoe+ macrophages and increased numbers of effector T cells were shown to reestablish pulmonary immunity. Hence, LNP-mRNA treatment for fibrosis can restore pulmonary structure and function to similar degrees to those of a healthy lung. This therapy is a potential treatment for IPF patients.

Size-Tunable Micro-Nano Liposomes: Enhanced Lung Targeting and Tumor Penetration for Combination Treatment of Lung Cancer

The inefficient delivery of nanocarriers and drug resistance seriously limit therapeutic effects of lung cancer. Here, a size-tunable micro-nano liposome system, PCAL@TM, is designed for targeted delivery of paclitaxel (PTX) and oxygen to lung tumors. PTX-loaded corosolic acid (CA) nano-liposomes (PCAL, 100 nm) are anchored to the surface of oxygenated perfluorotributylamine (TBA)-loaded multivesicular liposomes (TM, 10 µm) via the biotin-avidin interactions with matrix metalloproteinase-9 (MMP-9) cleavable linker. After intravenous administration to lung tumor-bearing mice, the distribution amount of PCAL@TM in the lungs is extremely higher than that in the liver and spleen. The MMP-9-sensitive PCAL@TM can decouple into nano-PCAL and micro-TM in tumors; while, TMs enable breaking into smaller vesicles under vascular pressure, and release oxygen leading to the downregulation of HIF-1α and platelet-activated TGF-β. Meanwhile, PCAL can penetrate deeply into tumor by the tumor-targeted-penetrable CA liposomes, to promote the reduction of inflammation levels and enhance PTX-induced immunogenic cell death (ICD). Together, these results lead to the reversals of chemoresistance and tumor immunosuppressive, achieving significant improvement in PTX chemotherapy and α-PD-1 immunotherapy. The PCAL@TM system presents a novel strategy to enhance the efficiency of nano-drug delivery and the outcome of combined therapy for lung tumor.

Nature-inspired platform nanotechnology for RNA delivery to myeloid cells and their bone marrow progenitors

Nucleic acid therapeutics are used for silencing, expressing or editing genes in vivo. However, their systemic stability and targeted delivery to bone marrow resident cells remains a challenge. In this study we present a nanotechnology platform based on natural lipoproteins, designed for delivering small interfering RNA (siRNA), antisense oligonucleotides and messenger RNA to myeloid cells and haematopoietic stem and progenitor cells in the bone marrow. We developed a prototype apolipoprotein nanoparticle (aNP) that stably incorporates siRNA into its core. We then created a comprehensive library of aNP formulations and extensively characterized their physicochemical properties and in vitro performance. From this library, we selected eight representative aNP-siRNA formulations and evaluated their ability to silence lysosomal-associated membrane protein 1 (Lamp1) expression in immune cell subsets in mice after intravenous administration. Using the most effective aNP identified from the screening process, we tested the platform's potential for therapeutic gene silencing in a syngeneic murine tumour model. We also demonstrated the aNP platform's suitability for splice-switching with antisense oligonucleotides and for protein production with messenger RNA by myeloid progenitor cells in the bone marrow. Our data indicate that the aNP platform holds translational potential for delivering various types of nucleic acid therapeutics to myeloid cells and their progenitors.

The Interplay of Endosomal Escape and RNA Release from Polymeric Nanoparticles

Ribonucleic acid (RNA) nanocarriers, specifically lipid nanoparticles and polymeric nanoparticles, enable RNA transfection both in vitro and in vivo; however, only a small percentage of RNA endocytosed by a cell is delivered to the cytosolic machinery, minimizing its effect. RNA nanocarriers face two major obstacles after endocytosis: endosomal escape and RNA release. Overcoming both obstacles simultaneously is challenging because endosomal escape is usually achieved by using high positive charge to disrupt the endosomal membrane. However, this high positive charge typically also inhibits RNA release because anionic RNA is strongly bound to the nanocarrier by electrostatic interactions. Many nanocarriers address one over the other despite a growing body of evidence demonstrating that both are crucial for RNA transfection. In this review, we survey the various strategies that have been employed to accomplish both endosomal escape and RNA release with a focus on polymeric nanomaterials. We first consider the various requirements a nanocarrier must achieve for RNA delivery including protection from degradation, cellular internalization, endosomal escape, and RNA release. We then discuss current polymers used for RNA delivery and examine the strategies for achieving both endosomal escape and RNA release. Finally, we review various stimuli-responsive strategies for RNA release. While RNA release continues to be a challenge in achieving efficient RNA transfection, many new innovations in polymeric materials have elucidated promising strategies.

Technological breakthroughs and advancements in the application of mRNA vaccines: a comprehensive exploration and future prospects

mRNA vaccines utilize single-stranded linear DNA as a template for in vitro transcription. The mRNA is introduced into the cytoplasm via the corresponding delivery system to express the target protein, which then performs its relevant biological function. mRNA vaccines are beneficial in various fields, including cancer vaccines, infectious disease vaccines, protein replacement therapy, and treatment of rare diseases. They offer advantages such as a simple manufacturing process, a quick development cycle, and ease of industrialization. Additionally, mRNA vaccines afford flexibility in adjusting antigen designs and combining sequences of multiple variants, thereby addressing the issue of frequent mutations in pathogenic microorganisms. This paper aims to provide an extensive review of the global development and current research status of mRNA vaccines, with a focus on immunogenicity, classification, design, delivery vector development, stability, and biomedical application. Moreover, the study highlights current challenges and offers insights into future directions for development.

Engineering Lipid Nanoparticles for mRNA Immunotherapy

Over the last decades, messenger RNA (mRNA) has emerged as a promising therapeutic modality, enabling the delivery of genetic instructions to cells for producing therapeutic proteins or antigens. As such, mRNA-based therapies can be developed for a wide range of conditions, including infections, cancer, metabolic disorders, and genetic diseases. Nevertheless, using mRNA therapeutically requires chemical modifications to reduce immunostimulatory effects and nanotechnology to prevent degradation and ensure intracellular delivery. Lipid nanoparticles (LNPs) have become the most effective delivery platform for mRNA therapeutics, which are primarily employed for vaccine purposes following local administration and hepatic applications following systemic administration. Here, we review the state-of-the-art LNP-mRNA technology and discuss its potential for immunotherapy. We first outline the requirements for mRNA to be used therapeutically, including the role of LNP-mediated delivery. Next, we highlight LNP-mRNA immunotherapy approaches for vaccination, immuno-oncology, and autoimmune disorders. In addition, we discuss challenges that are limiting LNP-mRNA's widespread use, including tunable biodistribution and immunostimulatory effects. Finally, we provide an outlook on how implementing approaches such as library screening and machine learning will guide the development of next-generation mRNA therapeutics.

Pharmaceutical strategies for optimized mRNA expression

Messenger RNA (mRNA)-based immunotherapies and protein in situ production therapies hold great promise for addressing theoretically all the diseases characterized by aberrant protein levels. The safe, stable, and precise delivery of mRNA to target cells via appropriate pharmaceutical strategies is a prerequisite for its optimal efficacy. In this review, we summarize the structural characteristics, mode of action, development prospects, and limitations of existing mRNA delivery systems from a pharmaceutical perspective, with an emphasis on the impacts from formulation adjustments and preparation techniques of non-viral vectors on mRNA stability, target site accumulation and transfection efficiency. In addition, we introduce strategies for synergistical combination of mRNA and small molecules to augment the potency or mitigate the adverse effects of mRNA therapeutics. Lastly, we delve into the challenges impeding the development of mRNA drugs while exploring promising avenues for future advancements.

Developing mRNA Nanomedicines with Advanced Targeting Functions

The emerging messenger RNA (mRNA) nanomedicines have sprung up for disease treatment. Developing targeted mRNA nanomedicines has become a thrilling research hotspot in recent years, as they can be precisely delivered to specific organs or tissues to enhance efficiency and avoid side effects. Herein, we give a comprehensive review on the latest research progress of mRNA nanomedicines with targeting functions. mRNA and its carriers are first described in detail. Then, mechanisms of passive targeting, endogenous targeting, and active targeting are outlined, with a focus on various biological barriers that mRNA may encounter during in vivo delivery. Next, emphasis is placed on summarizing mRNA-based organ-targeting strategies. Lastly, the advantages and challenges of mRNA nanomedicines in clinical translation are mentioned. This review is expected to inspire researchers in this field and drive further development of mRNA targeting technology.

Ionizable Cholesterol Analogs as the Fifth Component of Lipid Nanoparticles for Selective Targeting Delivery of mRNA

Lipid nanoparticles (LNP) have shown great promise in clinical applications for delivering mRNA. Targeted delivery of mRNA to particular tissues or organs is essential for precise therapeutic outcomes and minimized side effects in various disease models. However, achieving targeted delivery beyond the liver is a challenge based on current LNP formulations. In this report, we synthesized four ionizable cholesterol analogs by attaching two tertiary amine groups onto the head of a cholesterol-like structure and incorporated them as a fifth component into conventional commercial LNPs based on ALC-0315 or SM-102. Selective targeting delivery of mRNA is achieved by adjusting the proportion of the fifth component in the LNP. Specifically, a spleen-targeted 0315-Ergo-40% formulation demonstrated an impressive 95% delivery efficiency, while a lung-targeted 102-Sito-40% formulation achieved up to 78%. Moreover, when this strategy is applied to a self-developed ionizable lipid named U-101 instead of ALC-0315 or SM-102, the targeting delivery efficiencies to the spleen and lungs reach 96 and 71%, respectively. Multiple assessments suggest that inclusion of the fifth component does not compromise LNP stability, as indicated by consistent particle size, polydispersity index (PDI), and encapsulation efficiency. Furthermore, the test results of liver and kidney function and immunogenicity reveal no increase of toxicity in vivo following the introduction of the fifth component. Additional studies on in vitro cytotoxicity, lysosomal escape, and cellular transfection efficiency confirm that the fifth component does not diminish delivery performance. Taken together, the incorporation of ionizable cholesterol analogs leads to targeting of LNP delivery, which features strong organ selectivity, high safety, and suitability for further evaluation.

Peptide-Functionalized Lipid Nanoparticles for Targeted Systemic mRNA Delivery to the Brain

Systemic delivery of large nucleic acids, such as mRNA, to the brain remains challenging in part due to the blood-brain barrier (BBB) and the tendency of delivery vehicles to accumulate in the liver. Here, we design a peptide-functionalized lipid nanoparticle (LNP) platform for targeted mRNA delivery to the brain. We utilize click chemistry to functionalize LNPs with peptides that target receptors overexpressed on brain endothelial cells and neurons, namely the RVG29, T7, AP2, and mApoE peptides. We evaluate the effect of LNP targeting on brain endothelial and neuronal cell transfection in vitro, investigating factors such as serum protein adsorption, intracellular trafficking, endothelial transcytosis, and exosome secretion. Finally, we show that LNP peptide functionalization enhances mRNA transfection in the mouse brain and reduces hepatic delivery after systemic administration. Specifically, RVG29 LNPs improved neuronal transfection in vivo, establishing its potential as a nonviral platform for delivering mRNA to the brain.

Nonviral targeted mRNA delivery: principles, progresses, and challenges

Messenger RNA (mRNA) therapeutics have garnered considerable attention due to their remarkable efficacy in the treatment of various diseases. The COVID-19 mRNA vaccine and RSV mRNA vaccine have been approved on the market. Due to the inherent nuclease-instability and negative charge of mRNA, delivery systems are developed to protect the mRNA from degradation and facilitate its crossing cell membrane to express functional proteins or peptides in the cytoplasm. However, the deficiency in transfection efficiency and targeted biological distribution are still the major challenges for the mRNA delivery systems. In this review, we first described the physiological barriers in the process of mRNA delivery and then discussed the design approach and recent advances in mRNA delivery systems with an emphasis on their tissue/cell-targeted abilities. Finally, we pointed out the existing challenges and future directions with deep insights into the design of efficient mRNA delivery systems. We believe that a high-precision targeted delivery system can greatly improve the therapeutic effects and bio-safety of mRNA therapeutics and accelerate their clinical transformations. This review may provide a new direction for the design of mRNA delivery systems and serve as a useful guide for researchers who are looking for a suitable mRNA delivery system.

Placenta-tropic VEGF mRNA lipid nanoparticles ameliorate murine pre-eclampsia

Pre-eclampsia is a placental disorder that affects 3-5% of all pregnancies and is a leading cause of maternal and fetal morbidity worldwide1,2. With no drug available to slow disease progression, engineering ionizable lipid nanoparticles (LNPs) for extrahepatic messenger RNA (mRNA) delivery to the placenta is an attractive therapeutic option for pre-eclampsia. Here we use high-throughput screening to evaluate a library of 98 LNP formulations in vivo and identify a placenta-tropic LNP (LNP 55) that mediates more than 100-fold greater mRNA delivery to the placenta in pregnant mice than a formulation based on the Food and Drug Administration-approved Onpattro LNP (DLin-MC3-DMA)3. We propose an endogenous targeting mechanism based on β2-glycoprotein I adsorption that enables LNP delivery to the placenta. In both inflammation- and hypoxia-induced models of pre-eclampsia, a single administration of LNP 55 encapsulating vascular endothelial growth factor (VEGF) mRNA resolves maternal hypertension until the end of gestation. In addition, with our VEGF mRNA LNP 55 therapeutic, we demonstrate improvements in fetal health and partially restore placental vasculature, the local and systemic immune landscape and serum levels of soluble Fms-like tyrosine kinase-1, a clinical biomarker of pre-eclampsia1. Together, these results demonstrate the potential of this mRNA LNP platform for treating placental disorders such as pre-eclampsia.

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.

Bispecific antibody targeting of lipid nanoparticles

Lipid nanoparticles (LNP) are the most clinically advanced non-viral gene delivery system. While progress has been made for enhancing delivery, cell specific targeting remains a challenge. Targeting moieties such as antibodies can be chemically-conjugated to LNPs however, this approach is complex and has challenges for scaling up. Here, we developed an approach to generate antibody-conjugated LNPs that utilizes a bispecific antibody (bsAb) as the targeting bridge. As a docking site for the bsAb, we generated LNPs with a short epitope, derived from hemagglutinin antigen (HA), embedded in the PEG component of the particle (LNPHA). We generated bsAb in which one domain binds HA and the other binds different cell surface proteins, including PD-L1, CD4, CD5, and SunTag. Non-chemical conjugation of the bsAb and LNP resulted in a major increase in the efficiency and specificity of transfecting cells expressing the cognate target. LNP/bsAb mediated a 4-fold increase in in vivo transfection of PD-L1 expressing cancer cells, and a 26-fold increase in ex vivo transfection of quiescent primary human T cells. Additionally, we created a universal bsAb recognizing HA and anti-rat IgG2, enabling LNP tethering to off-the-shelf antibodies such as CD4, CD8, CD20, CD45, and CD3. By utilizing a molecular dock and bsAb technology, these studies demonstrate a simple and effective strategy to generate antibody-conjugated LNPs, enabling precise and efficient mRNA delivery.

Navigating the intricate in-vivo journey of lipid nanoparticles tailored for the targeted delivery of RNA therapeutics: a quality-by-design approach

RNA therapeutics, such as mRNA, siRNA, and CRISPR-Cas9, present exciting avenues for treating diverse diseases. However, their potential is commonly hindered by vulnerability to degradation and poor cellular uptake, requiring effective delivery systems. Lipid nanoparticles (LNPs) have emerged as a leading choice for in vivo RNA delivery, offering protection against degradation, enhanced cellular uptake, and facilitation of endosomal escape. However, LNPs encounter numerous challenges for targeted RNA delivery in vivo, demanding advanced particle engineering, surface functionalization with targeting ligands, and a profound comprehension of the biological milieu in which they function. This review explores the structural and physicochemical characteristics of LNPs, in-vivo fate, and customization for RNA therapeutics. We highlight the quality-by-design (QbD) approach for targeted delivery beyond the liver, focusing on biodistribution, immunogenicity, and toxicity. In addition, we explored the current challenges and strategies associated with LNPs for in-vivo RNA delivery, such as ensuring repeated-dose efficacy, safety, and tissue-specific gene delivery. Furthermore, we provide insights into the current clinical applications in various classes of diseases and finally prospects of LNPs in RNA therapeutics.

Simplified Lipid Nanoparticles for Tissue- And Cell-Targeted mRNA Delivery Facilitate Precision Tumor Therapy in a Lung Metastasis Mouse Model

mRNA-based applications have achieved remarkable success in the development of next-generation vaccines and the treatment of diverse liver diseases. Overcoming the challenge of delivering mRNA to extrahepatic tissues, especially specific cells within tissues, is crucial for precision therapy. In this study, a platform is developed for selective mRNA delivery to desired cells within tissues by combining lipid nanoparticle (LNP)-based targeted delivery with mRNA sequence-controlled expression. Through systematic optimization, a three-component LNP platform is developed, enabling targeted mRNA delivery to the lung, liver, and spleen. The incorporation of unique microRNA target sites into the mRNA scaffold further enhances control over protein translation in specific cells within the target tissue. This combined strategy, named SELECT (Simplified LNP with Engineered mRNA for Cell-type Targeting), demonstrates its efficacy in distinguishing mRNA expression between tumor and normal cells based on intracellular microRNA abundance. SELECT encapsulating mRNA encoding a tumor-specific cytotoxic protein, human ELANE, exhibits selective mRNA delivery to tumor lesions and significant inhibition of tumor growth in a mouse model of melanoma lung metastasis. Overall, SELECT has great potential as a new precision tumor treatment approach and also offers promising prospects for other mRNA therapies targeting specific cell types.

CXCL13 promotes broad immune responses induced by circular RNA vaccines

Antibody responses induced by current vaccines for influenza and SARS-CoV-2 often lack robust cross-reactivity. As hubs where diverse immune cells converge and interact, the alterations in the immune microenvironment within lymph nodes (LNs) are intricately linked to immune responses. Herein, we designed a lipid nanoparticle (LNP) loaded with circular RNA (circRNA) and targeted to LNs, in which CXCL13 was directly integrated into antigen-encoding circRNA strands. We demonstrated that CXCL13 alters the transcriptomic profiles of LNs, especially the upregulation of IL-21 and IL-4. Meanwhile, CXCL13 promotes the formation of germinal center and elicits robust antigen-specific T cell responses. With the codelivery of CXCL13 and the antigen, CXCL13 enhances cross-reactive antibodies against influenza virus and SARS-CoV-2, achieving protection against both homologous and heterologous influenza virus challenges in a mouse model. Notably, the targeted modification of LNP surfaces with antibodies helps address some of the challenges associated with lyophilized LNP vaccines, which is crucial for the long-term storage of LNP-circRNA vaccines. Overall, the circRNA-based antigen-CXCL13 coexpression system developed herein provides a simple and robust platform that enhances the magnitude and breadth of antibody responses against multiple viral glycoproteins, highlighting the potential utility of CXCL13 in inducing broad immune responses.

Polysorbate 80-containing ionizable lipid nanoparticles for mRNA delivery

Ionizable lipid nanoparticles have demonstrated remarkable success as mRNA vaccine carriers and represent one of the most promising gene drug delivery vehicles. However, polyethylene glycol (PEG), one of the major components, can cause immunogenic reactions, anaphylaxis and increased blood clearance, leading to toxic side effects and reduced efficacy. In this study, we utilize polysorbate 80 (PS80) as a PEG alternative in formulating eGFP mRNA-loaded ionizable lipid nanoparticles (PS80-iLNPs), aiming to enhance stealth properties, uptake efficiency, and biosafety. Our findings revealed that PS80-iLNPs enhanced the stealthiness and resistance to serum interference. Compared to PEG-containing ionizable lipid nanoparticles (PEG-iLNPs), PS80-iLNPs showed a 1.14-fold increase in stealthiness. Moreover, at a total lipid concentration of 50 μg mL-1, PS80-iLNPs exhibited 1.12 times higher cell viability compared to PEG-iLNPs. Notably, under serum interference, PEG-iLNPs showed a 44.97% uptake reduction, whereas PS80-iLNPs exhibited a modest 30.55% decrease, underscoring its superior serum resistance. This work demonstrated that PS80 could serve as a suitable substitute for PEG, thus signifying an excellent basis for the development of PEG-free ionizable lipid nanoparticles.

Recent Advances and Prospects of Nucleic Acid Therapeutics for Anti-Cancer Therapy

Nucleic acid therapeutics are promising alternatives to conventional anti-cancer therapy, such as chemotherapy and radiation therapy. While conventional therapies have limitations, such as high side effects, low specificity, and drug resistance, nucleic acid therapeutics work at the gene level to eliminate the cause of the disease. Nucleic acid therapeutics treat diseases in various forms and using different mechanisms, including plasmid DNA (pDNA), small interfering RNA (siRNA), anti-microRNA (anti-miR), microRNA mimics (miRNA mimic), messenger RNA (mRNA), aptamer, catalytic nucleic acid (CNA), and CRISPR cas9 guide RNA (gRNA). In addition, nucleic acids have many advantages as nanomaterials, such as high biocompatibility, design flexibility, low immunogenicity, small size, relatively low price, and easy functionalization. Nucleic acid therapeutics can have a high therapeutic effect by being used in combination with various nucleic acid nanostructures, inorganic nanoparticles, lipid nanoparticles (LNPs), etc. to overcome low physiological stability and cell internalization efficiency. The field of nucleic acid therapeutics has advanced remarkably in recent decades, and as more and more nucleic acid therapeutics have been approved, they have already demonstrated their potential to treat diseases, including cancer. This review paper introduces the current status and recent advances in nucleic acid therapy for anti-cancer treatment and discusses the tasks and prospects ahead.

Immunomodulatory Therapy for Ischemic Heart Disease

Ischemic heart disease is a leading cause of death worldwide, manifested clinically as myocardial infarction (and ischemic cardiomyopathy. Presently, there exists a notable scarcity of efficient interventions to restore cardiac function after myocardial infarction. Cumulative evidence suggests that impaired tissue immunity within the ischemic microenvironment aggravates cardiac dysfunction, contributing to progressive heart failure. Recent research breakthroughs propose immunotherapy as a potential approach by leveraging immune and stroma cells to recalibrate the immune microenvironment, holding significant promise for the treatment of ischemic heart disease. In this Primer, we highlight three emerging strategies for immunomodulatory therapy in managing ischemic cardiomyopathy: targeting vascular endothelial cells to rewire tissue immunity, reprogramming myeloid cells to bolster their reparative function, and utilizing adoptive T cell therapy to ameliorate fibrosis. We anticipate that immunomodulatory therapy will offer exciting opportunities for ischemic heart disease treatment.

Development of mRNA Lipid Nanoparticles: Targeting and Therapeutic Aspects

Lipid nanoparticles (LNPs) have emerged as leading non-viral carriers for messenger RNA (mRNA) delivery in clinical applications. Overcoming challenges in safe and effective mRNA delivery to target tissues and cells, along with controlling release from the delivery vehicle, remains pivotal in mRNA-based therapies. This review elucidates the structure of LNPs, the mechanism for mRNA delivery, and the targeted delivery of LNPs to various cells and tissues, including leukocytes, T-cells, dendritic cells, Kupffer cells, hepatic endothelial cells, and hepatic and extrahepatic tissues. Here, we discuss the applications of mRNA-LNP vaccines for the prevention of infectious diseases and for the treatment of cancer and various genetic diseases. Although challenges remain in terms of delivery efficiency, specific tissue targeting, toxicity, and storage stability, mRNA-LNP technology holds extensive potential for the treatment of diseases.

Current landscape of mRNA technologies and delivery systems for new modality therapeutics

Realizing the immense clinical potential of mRNA-based drugs will require continued development of methods to safely deliver the bioactive agents with high efficiency and without triggering side effects. In this regard, lipid nanoparticles have been successfully utilized to improve mRNA delivery and protect the cargo from extracellular degradation. Encapsulation in lipid nanoparticles was an essential factor in the successful clinical application of mRNA vaccines, which conclusively demonstrated the technology's potential to yield approved medicines. In this review, we begin by describing current advances in mRNA modifications, design of novel lipids and development of lipid nanoparticle components for mRNA-based drugs. Then, we summarize key points pertaining to preclinical and clinical development of mRNA therapeutics. Finally, we cover topics related to targeted delivery systems, including endosomal escape and targeting of immune cells, tumors and organs for use with mRNA vaccines and new treatment modalities for human diseases.

Strategies for Organ-Targeted mRNA Delivery by Lipid Nanoparticles

Messenger RNA (mRNA) technology has rapidly evolved, significantly impacting various therapeutic applications, including vaccines, protein replacement, and gene editing. Lipid nanoparticles (LNPs) have emerged as a pivotal nonviral vector for mRNA delivery, crucial for organ-targeted therapies. Despite their success, most LNP formulations predominantly target the liver, limiting their use in nonliver diseases. This review explores strategies to achieve organ-specific mRNA delivery using LNPs, including the discovery of new lipid structures, modification of targeting ligands, incorporation of additional components, and optimization of LNP formulations. These advancements aim to enhance the precision and efficacy of mRNA therapeutics across a broader range of diseases.

The 60-year evolution of lipid nanoparticles for nucleic acid delivery

Delivery of genetic information to the interior of target cells in vivo has been a major challenge facing gene therapies. This barrier is now being overcome, owing in part to dramatic advances made by lipid-based systems that have led to lipid nanoparticles (LNPs) that enable delivery of nucleic acid-based vaccines and therapeutics. Examples include the clinically approved COVID-19 LNP mRNA vaccines and Onpattro (patisiran), an LNP small interfering RNA therapeutic to treat transthyretin-induced amyloidosis (hATTR). In addition, a host of promising LNP-enabled vaccines and gene therapies are in clinical development. Here, we trace this success to two streams of research conducted over the past 60 years: the discovery of the transfection properties of lipoplexes composed of positively charged cationic lipids complexed with nucleic acid cargos and the development of lipid nanoparticles using ionizable cationic lipids. The fundamental insights gained from these two streams of research offer potential delivery solutions for most forms of gene therapies.

Marginated Neutrophils in the Lungs Effectively Compete for Nanoparticles Targeted to the Endothelium, Serving as a Part of the Reticuloendothelial System

Nanomedicine has long pursued the goal of targeted delivery to specific organs and cell types but has yet to achieve this goal with the vast majority of targets. One rare example of success in this pursuit has been the 25+ years of studies targeting the lung endothelium using nanoparticles conjugated to antibodies against endothelial surface molecules. However, here we show that such "endothelial-targeted" nanocarriers also effectively target the lungs' numerous marginated neutrophils, which reside in the pulmonary capillaries and patrol for pathogens. We show that marginated neutrophils' uptake of many of these "endothelial-targeted" nanocarriers is on par with endothelial uptake. This generalizes across diverse nanomaterials and targeting moieties and was even found with physicochemical lung tropism (i.e., without targeting moieties). Further, we observed this in ex vivo human lungs and in vivo healthy mice, with an increase in marginated neutrophil uptake of nanoparticles caused by local or distant inflammation. These findings have implications for nanomedicine development for lung diseases. These data also suggest that marginated neutrophils, especially in the lungs, should be considered a major part of the reticuloendothelial system (RES), with a special role in clearing nanoparticles that adhere to the lumenal surfaces of blood vessels.

The mRNA vaccine platform for veterinary species

Vaccination has proven to be an effective means of controlling pathogens in animals. Since the introduction of veterinary vaccines in the 19th century, several generations of vaccines have been introduced. These vaccines have had a positive impact on global animal health and production. Despite, the success of veterinary vaccines, there are still some pathogens for which there are no effective vaccines available, such as African swine fever. Further, animal health is under the constant threat of emerging and re-emerging pathogens, some of which are zoonotic and can pose a threat to human health. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has highlighted the need for new vaccine platforms that are safe and efficacious, but also importantly, are adaptable and can be modified rapidly to match the circulating pathogens. mRNA vaccines have been shown to be an effective vaccine platform against various viral and bacterial pathogens. This review will cover some of the recent advances in the field of mRNA vaccines for veterinary species. Moreover, various mRNA vaccines and their delivery methods, as well as their reported efficacy, will be discussed. Current limitations and future prospects of this vaccine platform in veterinary medicine will also be discussed.

Lipid Nanocarrier-Based mRNA Therapy: Challenges and Promise for Clinical Transformation

Due to the outbreak of novel coronavirus pneumonia, messenger RNA (mRNA) technology has attracted heated attention. A specific, safe, and efficient mRNA delivery system is needed. Lipid nanocarriers have become attractive carriers for mRNA delivery due to their high delivery efficiency, few side effects, and easy modification to change their structures and functions. To achieve the desired biological effect, lipid nanocarriers must reach the designated location for effective drug delivery. Therefore, the effects of the composition of lipid nanocarriers on their key properties are briefly reviewed. In addition, the progress of smart drug delivery by changing the composition of lipid nanocarriers is summarized, and the importance of component design and structure is emphasized. Subsequently, this review summarizes the latest progress in lipid nanocarrier-based mRNA technology and provides corresponding strategies for its current challenges, putting forward valuable information for the future design of lipid nanocarriers and mRNA.

EGFR-targeted ionizable lipid nanoparticles enhance in vivo mRNA delivery to the placenta

The full potential of ionizable lipid nanoparticles (LNPs) as an in vivo nucleic acid delivery platform has not yet been realized given that LNPs primarily accumulate in the liver following systemic administration, limiting their success to liver-centric conditions. The engineering of LNPs with antibody targeting moieties can enable extrahepatic tropism by facilitating site-specific LNP tethering and driving preferential LNP uptake into receptor-expressing cell types via receptor-mediated endocytosis. Obstetric conditions stemming from placental dysfunction, such as preeclampsia, are characterized by overexpression of cellular receptors, including the epidermal growth factor receptor (EGFR), making targeted LNP platforms an exciting potential treatment strategy for placental dysfunction during pregnancy. Herein, an EGFR antibody-conjugated LNP (aEGFR-LNP) platform was developed by engineering LNPs with increasing densities of antibody functionalization. aEGFR-LNPs were screened in vitro in immortalized placental trophoblasts and in vivo in non-pregnant and pregnant mice and compared to non-targeted formulations for extrahepatic, antibody-targeted mRNA LNP delivery to the placenta. Our top performing LNP with an intermediate density of antibody functionalization (1:5 aEGFR-LNP) mediated a ∼twofold increase in mRNA delivery in murine placentas and a ∼twofold increase in LNP uptake in EGFR-expressing trophoblasts compared to non-targeted counterparts. These results demonstrate the potential of antibody-conjugated LNPs for achieving extrahepatic tropism, and the ability of aEGFR-LNPs in promoting mRNA delivery to EGFR-expressing cell types in the placenta.

Steering the course of CAR T cell therapy with lipid nanoparticles

Lipid nanoparticles (LNPs) have proven themselves as transformative actors in chimeric antigen receptor (CAR) T cell therapy, surpassing traditional methods and addressing challenges like immunogenicity, reduced toxicity, and improved safety. Promising preclinical results signal a shift toward safer and more effective CAR T cell treatments. Ongoing research aims to validate these findings in clinical trials, marking a new era guided by LNPs utility in CAR therapy. Herein, we explore the preference for LNPs over traditional methods, highlighting the versatility of LNPs and their effective delivery of nucleic acids. Additionally, we address key challenges in clinical considerations, heralding a new era in CAR T cell therapy.

Engineering strategies to safely drive CAR T-cells into the future

Chimeric antigen receptor (CAR) T-cell therapy has proven a breakthrough in cancer treatment in the last decade, giving unprecedented results against hematological malignancies. All approved CAR T-cell products, as well as many being assessed in clinical trials, are generated using viral vectors to deploy the exogenous genetic material into T-cells. Viral vectors have a long-standing clinical history in gene delivery, and thus underwent iterations of optimization to improve their efficiency and safety. Nonetheless, their capacity to integrate semi-randomly into the host genome makes them potentially oncogenic via insertional mutagenesis and dysregulation of key cellular genes. Secondary cancers following CAR T-cell administration appear to be a rare adverse event. However several cases documented in the last few years put the spotlight on this issue, which might have been underestimated so far, given the relatively recent deployment of CAR T-cell therapies. Furthermore, the initial successes obtained in hematological malignancies have not yet been replicated in solid tumors. It is now clear that further enhancements are needed to allow CAR T-cells to increase long-term persistence, overcome exhaustion and cope with the immunosuppressive tumor microenvironment. To this aim, a variety of genomic engineering strategies are under evaluation, most relying on CRISPR/Cas9 or other gene editing technologies. These approaches are liable to introduce unintended, irreversible genomic alterations in the product cells. In the first part of this review, we will discuss the viral and non-viral approaches used for the generation of CAR T-cells, whereas in the second part we will focus on gene editing and non-gene editing T-cell engineering, with particular regard to advantages, limitations, and safety. Finally, we will critically analyze the different gene deployment and genomic engineering combinations, delineating strategies with a superior safety profile for the production of next-generation CAR T-cell.

Controlling spatial distribution of functional lipids in a supported lipid bilayer prepared from vesicles

Conjugating biomolecules, such as antibodies, to bioconjugate moieties on lipid surfaces is a powerful tool for engineering the surface of diverse biomaterials, including cells and nanoparticles. We developed supported lipid bilayers (SLBs) presenting well-defined spatial distributions of functional moieties as models for precisely engineered functional biomolecular-lipid surfaces. We used quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM) to determine how vesicles containing a mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[azido(polyethylene glycol)-2000] (DSPE-PEG-N3) form SLBs as a function of the lipid phase transition temperature (Tm). Above the DPPC Tm, DPPC/DSPE-PEG-N3 vesicles form SLBs with functional azide moieties on SiO2 substrates via vesicle fusion. Below this Tm, DPPC/DSPE-PEG-N3 vesicles attach to SiO2 intact. Intact DPPC/DSPE-PEG-N3 vesicles on the SiO2 surfaces fuse and rupture to form SLBs when temperature is brought above the DPPC Tm. AFM studies show uniform and complete DPPC/DSPE-PEG-N3 SLB coverage of SiO2 surfaces for different DSPE-PEG-N3 concentrations. As the DSPE-PEG-N3 concentration increases from 0.01 to 6 mol%, the intermolecular spacing of DSPE-PEG-N3 in the SLBs decreases from 4.6 to 1.0 nm. The PEG moiety undergoes a mushroom to brush transition as DSPE-PEG-N3 concentration varies from 0.1 to 2.0 mol%. Via copper-free click reaction, IgG was conjugated to SLB surfaces with 4.6 nm or 1.3 nm inter-DSPE-PEG-N3 spacing. QCM-D and AFM data show; 1) uniform and complete IgG layers of similar mass and thickness on the two types of SLB; 2) a higher-viscosity/less rigid IgG layer on the SLB with 4.6 nm inter-DSPE-PEG-N3 spacing. Our studies provide a blueprint for SLBs modeling spatial control of functional macromolecules on lipid surfaces, including surfaces of lipid nanoparticles and cells.

Physiologically based modeling of LNP-mediated delivery of mRNA in the vascular system

RNA therapeutics are an emerging, powerful class of drugs with potential applications in a wide range of disorders. A central challenge in their development is the lack of clear pharmacokinetic (PK)-pharmacodynamic relationship, in part due to the significant delay between the kinetics of RNA delivery and the onset of pharmacologic response. To bridge this gap, we have developed a physiologically based PK/pharmacodynamic model for systemically administered mRNA-containing lipid nanoparticles (LNPs) in mice. This model accounts for the physiologic determinants of mRNA delivery, active targeting in the vasculature, and differential transgene expression based on nanoparticle coating. The model was able to well-characterize the blood and tissue PKs of LNPs, as well as the kinetics of tissue luciferase expression measured by ex vivo activity in organ homogenates and bioluminescence imaging in intact organs. The predictive capabilities of the model were validated using a formulation targeted to intercellular adhesion molecule-1 and the model predicted nanoparticle delivery and luciferase expression within a 2-fold error for all organs. This modeling platform represents an initial strategy that can be expanded upon and utilized to predict the in vivo behavior of RNA-containing LNPs developed for an array of conditions and across species.

Frameworks for transformational breakthroughs in RNA-based medicines

RNA has sparked a revolution in modern medicine, with the potential to transform the way we treat diseases. Recent regulatory approvals, hundreds of new clinical trials, the emergence of CRISPR gene editing, and the effectiveness of mRNA vaccines in dramatic response to the COVID-19 pandemic have converged to create tremendous momentum and expectation. However, challenges with this relatively new class of drugs persist and require specialized knowledge and expertise to overcome. This Review explores shared strategies for developing RNA drug platforms, including layering technologies, addressing common biases and identifying gaps in understanding. It discusses the potential of RNA-based therapeutics to transform medicine, as well as the challenges associated with improving applicability, efficacy and safety profiles. Insights gained from RNA modalities such as antisense oligonucleotides (ASOs) and small interfering RNAs are used to identify important next steps for mRNA and gene editing technologies.

Physicochemical Targeting of Lipid Nanoparticles to the Lungs Induces Clotting: Mechanisms and Solutions

Lipid nanoparticles (LNPs) have become the dominant drug delivery technology in industry, holding the promise to deliver RNA to up or down-regulate any protein of interest. LNPs have mostly been targeted to specific cell types or organs by physicochemical targeting in which LNP's lipid compositions are adjusted to find mixtures with the desired tropism. Here lung-tropic LNPs are examined, whose organ tropism derives from containing either a cationic or ionizable lipid conferring a positive zeta potential. Surprisingly, these LNPs are found to induce massive thrombosis. Such thrombosis is shown in the lungs and other organs, and it is shown that it is greatly exacerbated by pre-existing inflammation. This clotting is induced by a variety of formulations with cationic lipids, including LNPs and non-LNP nanoparticles, and even by lung-tropic ionizable lipids that do not have a permanent cationic charge. The mechanism depends on the LNPs binding to and then changing the conformation of fibrinogen, which then activates platelets and thrombin. Based on these mechanisms, multiple solutions are engineered that enable positively charged LNPs to target the lungs while ameliorating thrombosis. The findings illustrate how physicochemical targeting approaches must be investigated early for risks and re-engineered with a careful understanding of biological mechanisms.

Targeting lipid nanoparticles to the blood-brain barrier to ameliorate acute ischemic stroke

Effective delivery of mRNA or small molecule drugs to the brain is a significant challenge in developing treatment for acute ischemic stroke (AIS). To address the problem, we have developed targeted nanomedicine to increase drug concentrations in endothelial cells of the blood-brain barrier (BBB) of the injured brain. Inflammation during ischemic stroke causes continuous neuronal death and an increase in the infarct volume. To enable targeted delivery to the inflamed BBB, we conjugated lipid nanocarriers (NCs) with antibodies that bind cell adhesion molecules expressed at the BBB. In the transient middle cerebral artery occlusion mouse model, NCs targeted to vascular cellular adhesion molecule-1 (VCAM) achieved the highest level of brain delivery, nearly two orders of magnitude higher than untargeted ones. VCAM-targeted lipid nanoparticles with luciferase-encoding mRNA and Cre-recombinase showed selective expression in the ischemic brain. Anti-inflammatory drugs administered intravenously after ischemic stroke reduced cerebral infarct volume by 62% (interleukin-10 mRNA) or 35% (dexamethasone) only when they were encapsulated in VCAM-targeted NCs. Thus, VCAM-targeted lipid NCs represent a new platform for strongly concentrating drugs within the compromised BBB of penumbra, thereby ameliorating AIS.

Physiological Barriers and Strategies of Lipid-Based Nanoparticles for Nucleic Acid Drug Delivery

Lipid-based nanoparticles (LBNPs) are currently the most promising vehicles for nucleic acid drug (NAD) delivery. Although their clinical applications have achieved success, the NAD delivery efficiency and safety are still unsatisfactory, which are, to a large extent, due to the existence of multi-level physiological barriers in vivo. It is important to elucidate the interactions between these barriers and LBNPs, which will guide more rational design of efficient NAD vehicles with low adverse effects and facilitate broader applications of nucleic acid therapeutics. This review describes the obstacles and challenges of biological barriers to NAD delivery at systemic, organ, sub-organ, cellular, and subcellular levels. The strategies to overcome these barriers are comprehensively reviewed, mainly including physically/chemically engineering LBNPs and directly modifying physiological barriers by auxiliary treatments. Then the potentials and challenges for successful translation of these preclinical studies into the clinic are discussed. In the end, a forward look at the strategies on manipulating protein corona (PC) is addressed, which may pull off the trick of overcoming those physiological barriers and significantly improve the efficacy and safety of LBNP-based NADs delivery.

Lipid Nanoparticle-Associated Inflammation is Triggered by Sensing of Endosomal Damage: Engineering Endosomal Escape Without Side Effects

Lipid nanoparticles (LNPs) have emerged as the dominant platform for RNA delivery, based on their success in the COVID-19 vaccines and late-stage clinical studies in other indications. However, we and others have shown that LNPs induce severe inflammation, and massively aggravate pre-existing inflammation. Here, using structure-function screening of lipids and analyses of signaling pathways, we elucidate the mechanisms of LNP-associated inflammation and demonstrate solutions. We show that LNPs' hallmark feature, endosomal escape, which is necessary for RNA expression, also directly triggers inflammation by causing endosomal membrane damage. Large, irreparable, endosomal holes are recognized by cytosolic proteins called galectins, which bind to sugars on the inner endosomal membrane and then regulate downstream inflammation. We find that inhibition of galectins abrogates LNP-associated inflammation, both in vitro and in vivo . We show that rapidly biodegradable ionizable lipids can preferentially create endosomal holes that are smaller in size and reparable by the endosomal sorting complex required for transport (ESCRT) pathway. Ionizable lipids producing such ESCRT-recruiting endosomal holes can produce high expression from cargo mRNA with minimal inflammation. Finally, we show that both routes to non-inflammatory LNPs, either galectin inhibition or ESCRT-recruiting ionizable lipids, are compatible with therapeutic mRNAs that ameliorate inflammation in disease models. LNPs without galectin inhibition or biodegradable ionizable lipids lead to severe exacerbation of inflammation in these models. In summary, endosomal escape induces endosomal membrane damage that can lead to inflammation. However, the inflammation can be controlled by inhibiting galectins (large hole detectors) or by using biodegradable lipids, which create smaller holes that are reparable by the ESCRT pathway. These strategies should lead to generally safer LNPs that can be used to treat inflammatory diseases.

Interview with Drew Weissman, 2023 Nobel Laureate in Physiology or Medicine

Drew Weissman, MD, PhD, received the 2023 Nobel Prize in Physiology or Medicine together with Katalin Karikó, PhD. Dr. Weissman received his bachelor's and master's degrees from Brandeis University, Waltham, MA, in 1981. He received his MD and PhD in 1987 from Boston University, Boston, MA, and this was followed by a residency at Beth Israel Deaconess Medical Center, Boston, MA. He then completed a fellowship at the National Institute of Allergy and Infectious Diseases under the supervision of Anthony Fauci, MD. He joined the Faculty at the University of Pennsylvania, Philadelphia, in 1997, where, in collaboration with Dr. Katalin Karikó, he explored the use of messenger RNA (mRNA) to drive heterologous gene expression in human cells. They overcame the notorious susceptibility of RNAs to degradation by packaging the mRNA in lipid nanoparticles and learned to both optimize protein expression and attenuate the inflammatory response to the exogenous RNAs by [covalently] modifying bases in the RNA sequence. This work has revolutionized immunization technology and allowed for the production of the most effective vaccines to prevent COVID-19.

Combination of Physicochemical Tropism and Affinity Moiety Targeting of Lipid Nanoparticles Enhances Organ Targeting

Two camps have emerged for targeting nanoparticles to specific organs and cell types: affinity moiety targeting and physicochemical tropism. Here we directly compare and combine both using intravenous (IV) lipid nanoparticles (LNPs) designed to target the lungs. We utilized PECAM antibodies as affinity moieties and cationic lipids for physicochemical tropism. These methods yield nearly identical lung uptake, but aPECAM LNPs show higher endothelial specificity. LNPs combining these targeting methods had >2-fold higher lung uptake than either method alone and markedly enhanced epithelial uptake. To determine if lung uptake is because the lungs are the first organ downstream of IV injection, we compared IV vs intra-arterial (IA) injection into the carotid artery, finding that IA combined-targeting LNPs achieve 35% of the injected dose per gram (%ID/g) in the first-pass organ, the brain, among the highest reported. Thus, combining the affinity moiety and physicochemical strategies provides benefits that neither targeting method achieves alone.

Recent Advances in Engineering Carriers for siRNA Delivery

RNA interference (RNAi) technology has been a promising treatment strategy for combating intractable diseases. However, the applications of RNAi in clinical are hampered by extracellular and intracellular barriers. To overcome these barriers, various siRNA delivery systems have been developed in the past two decades. The first approved RNAi therapeutic, Patisiran (ONPATTRO) using lipids as the carrier, for the treatment of amyloidosis is one of the most important milestones. This has greatly encouraged researchers to work on creating new functional siRNA carriers. In this review, the recent advances in siRNA carriers consisting of lipids, polymers, and polymer-modified inorganic particles for cancer therapy are summarized. Representative examples are presented to show the structural design of the carriers in order to overcome the delivery hurdles associated with RNAi therapies. Finally, the existing challenges and future perspective for developing RNAi as a clinical modality will be discussed and proposed. It is believed that the addressed contributions in this review will promote the development of siRNA delivery systems for future clinical applications.

Kinetics of RNA-LNP delivery and protein expression

Lipid nanoparticles (LNPs) employing ionizable lipids are the most advanced technology for delivery of RNA, most notably mRNA, to cells. LNPs represent well-defined core-shell particles with efficient nucleic acid encapsulation, low immunogenicity and enhanced efficacy. While much is known about the structure and activity of LNPs, less attention is given to the timing of LNP uptake, cytosolic transfer and protein expression. However, LNP kinetics is a key factor determining delivery efficiency. Hence quantitative insight into the multi-cascaded pathway of LNPs is of interest to elucidate the mechanism of delivery. Here, we review experiments as well as theoretical modeling of the timing of LNP uptake, mRNA-release and protein expression. We describe LNP delivery as a sequence of stochastic transfer processes and review a mathematical model of subsequent protein translation from mRNA. We compile probabilities and numbers obtained from time resolved microscopy. Specifically, live-cell imaging on single cell arrays (LISCA) allows for high-throughput acquisition of thousands of individual GFP reporter expression time courses. The traces yield the distribution of mRNA life-times, expression rates and expression onset. Correlation analysis reveals an inverse dependence of gene expression efficiency and transfection onset-times. Finally, we discuss why timing of mRNA release is critical in the context of codelivery of multiple nucleic acid species as in the case of mRNA co-expression or CRISPR/Cas gene editing.

Systematic development of ionizable lipid nanoparticles for placental mRNA delivery using a design of experiments approach

Ionizable lipid nanoparticles (LNPs) have gained attention as mRNA delivery platforms for vaccination against COVID-19 and for protein replacement therapies. LNPs enhance mRNA stability, circulation time, cellular uptake, and preferential delivery to specific tissues compared to mRNA with no carrier platform. However, LNPs are only in the beginning stages of development for safe and effective mRNA delivery to the placenta to treat placental dysfunction. Here, we develop LNPs that enable high levels of mRNA delivery to trophoblasts in vitro and to the placenta in vivo with no toxicity. We conducted a Design of Experiments to explore how LNP composition, including the type and molar ratio of each lipid component, drives trophoblast and placental delivery. Our data revealed that utilizing C12-200 as the ionizable lipid and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) as the phospholipid in the LNP design yields high transfection efficiency in vitro. Analysis of lipid molar composition as a design parameter in LNPs displayed a strong correlation between apparent pKa and poly (ethylene) glycol (PEG) content, as a reduction in PEG molar amount increases apparent pKa. Further, we present one LNP platform that exhibits the highest delivery of placental growth factor mRNA to the placenta in pregnant mice, resulting in synthesis and secretion of a potentially therapeutic protein. Lastly, our high-performing LNPs have no toxicity to both the pregnant mice and fetuses. Our results demonstrate the feasibility of LNPs as a platform for mRNA delivery to the placenta, and our top LNP formulations may provide a therapeutic platform to treat diseases that originate from placental dysfunction during pregnancy.

RNA-encapsulating lipid nanoparticles in cancer immunotherapy: From pre-clinical studies to clinical trials

Nanoparticle-based delivery systems such as RNA-encapsulating lipid nanoparticles (RNA LNPs) have dramatically advanced in function and capacity over the last few decades. RNA LNPs boast of a diverse array of external and core configurations that enhance targeted delivery and prolong circulatory retention, advancing therapeutic outcomes. Particularly within the realm of cancer immunotherapies, RNA LNPs are increasingly gaining prominence. Pre-clinical in vitro and in vivo studies have laid a robust foundation for new and ongoing clinical trials that are actively enrolling patients for RNA LNP cancer immunotherapy. This review explores RNA LNPs, starting from their core composition to their external membrane formulation, set against a backdrop of recent clinical breakthroughs. We further elucidate the LNP delivery avenues, broach the prevailing challenges, and contemplate the future perspectives of RNA LNP-mediated immunotherapy.

IL7 increases targeted lipid nanoparticle-mediated mRNA expression in T cells in vitro and in vivo by enhancing T cell protein translation

The use of lipid nanoparticles (LNP) to encapsulate and deliver mRNA has become an important therapeutic advance. In addition to vaccines, LNP-mRNA can be used in many other applications. For example, targeting the LNP with anti-CD5 antibodies (CD5/tLNP) can allow for efficient delivery of mRNA payloads to T cells to express protein. As the percentage of protein expressing T cells induced by an intravenous injection of CD5/tLNP is relatively low (4-20%), our goal was to find ways to increase mRNA-induced translation efficiency. We showed that T cell activation using an anti-CD3 antibody improved protein expression after CD5/tLNP transfection in vitro but not in vivo. T cell health and activation can be increased with cytokines, therefore, using mCherry mRNA as a reporter, we found that culturing either mouse or human T cells with the cytokine IL7 significantly improved protein expression of delivered mRNA in both CD4+ and CD8+ T cells in vitro. By pre-treating mice with systemic IL7 followed by tLNP administration, we observed significantly increased mCherry protein expression by T cells in vivo. Transcriptomic analysis of mouse T cells treated with IL7 in vitro revealed enhanced genomic pathways associated with protein translation. Improved translational ability was demonstrated by showing increased levels of protein expression after electroporation with mCherry mRNA in T cells cultured in the presence of IL7, but not with IL2 or IL15. These data show that IL7 selectively increases protein translation in T cells, and this property can be used to improve expression of tLNP-delivered mRNA in vivo.

mRNA-based therapeutics: looking beyond COVID-19 vaccines

Recent advances in mRNA technology and its delivery have enabled mRNA-based therapeutics to enter a new era in medicine. The rapid, potent, and transient nature of mRNA-encoded proteins, without the need to enter the nucleus or the risk of genomic integration, makes them desirable tools for treatment of a range of diseases, from infectious diseases to cancer and monogenic disorders. The rapid pace and ease of mass-scale manufacturability of mRNA-based therapeutics supported the global response to the COVID-19 pandemic. Nonetheless, challenges remain with regards to mRNA stability, duration of expression, delivery efficiency, and targetability, to broaden the applicability of mRNA therapeutics beyond COVID-19 vaccines. By learning from the rapidly expanding preclinical and clinical studies, we can optimise the mRNA platform to meet the clinical needs of each disease. Here, we will summarise the recent advances in mRNA technology; its use in vaccines, immunotherapeutics, protein replacement therapy, and genomic editing; and its delivery to desired specific cell types and organs for development of a new generation of targeted mRNA-based therapeutics.

Toward Ultrasound Molecular Imaging of Endothelial Dysfunction in Diabetes: Targets, Strategies, and Challenges

Diabetes vasculopathy is a significant complication of diabetes mellitus (DM), and early identification and timely intervention can effectively slow the progression. Accumulating studies have shown that diabetes causes vascular complications directly or indirectly through a variety of mechanisms. Direct imaging of the endothelial molecular changes not only identifies the early stage of diabetes vasculopathy but also sheds light on the precise treatment. Targeted ultrasound contrast agent (UCA)-based ultrasound molecular imaging (UMI) can noninvasively detect the expression status of molecular biomarkers overexpressed in the vasculature, thereby being a potential strategy for the diagnosis and treatment response evaluation of DM. Amounts of efforts have been focused on identification of the molecular targets expressed in the vasculature, manufacturing strategies of the targeted UCA, and the clinical translation for the diagnosis and evaluation of therapeutic efficacy in both micro- and macrovasculopathy in DM. This review summarizes the latest research progress on endothelium-targeted UCA and discusses their promising future and challenges in diabetes vasculopathy theranostics.

Electrostatic adsorption of polyanions onto lipid nanoparticles controls uptake, trafficking, and transfection of RNA and DNA therapies

Rapid advances in nucleic acid therapies highlight the immense therapeutic potential of genetic therapeutics. Lipid nanoparticles (LNPs) are highly potent nonviral transfection agents that can encapsulate and deliver various nucleic acid therapeutics, including but not limited to messenger RNA (mRNA), silencing RNA (siRNA), and plasmid DNA (pDNA). However, a major challenge of targeted LNP-mediated systemic delivery is the nanoparticles' nonspecific uptake by the liver and the mononuclear phagocytic system, due partly to the adsorption of endogenous serum proteins onto LNP surfaces. Tunable LNP surface chemistries may enable efficacious delivery across a range of organs and cell types. Here, we describe a method to electrostatically adsorb bioactive polyelectrolytes onto LNPs to create layered LNPs (LLNPs). LNP cores varying in nucleic acid cargo and component lipids were stably layered with four biologically relevant polyanions: hyaluronate (HA), poly-L-aspartate (PLD), poly-L-glutamate (PLE), and polyacrylate (PAA). We further investigated the impact of the four surface polyanions on the transfection and uptake of mRNA- and pDNA-loaded LNPs in cell cultures. PLD- and PLE-LLNPs increased mRNA transfection twofold over unlayered LNPs in immune cells. HA-LLNPs increased pDNA transfection rates by more than twofold in epithelial and immune cells. In a healthy C57BL/6 murine model, PLE- and HA-LLNPs increased transfection by 1.8-fold to 2.5-fold over unlayered LNPs in the liver and spleen. These results suggest that LbL assembly is a generalizable, highly tunable platform to modify the targeting specificity, stability, and transfection efficacy of LNPs, as well as incorporate other charged targeting and therapeutic molecules into these systems.

Tiny Guides, Big Impact: Focus on the Opportunities and Challenges of miR-Based Treatments for ARDS

Acute Respiratory Distress Syndrome (ARDS) is characterized by lung inflammation and increased membrane permeability, which represents the leading cause of mortality in ICUs. Mechanical ventilation strategies are at the forefront of supportive approaches for ARDS. Recently, an increasing understanding of RNA biology, function, and regulation, as well as the success of RNA vaccines, has spurred enthusiasm for the emergence of novel RNA-based therapeutics. The most common types of RNA seen in development are silencing (si)RNAs, antisense oligonucleotide therapy (ASO), and messenger (m)RNAs that collectively account for 80% of the RNA therapeutics pipeline. These three RNA platforms are the most mature, with approved products and demonstrated commercial success. Most recently, miRNAs have emerged as pivotal regulators of gene expression. Their dysregulation in various clinical conditions offers insights into ARDS pathogenesis and offers the innovative possibility of using microRNAs as targeted therapy. This review synthesizes the current state of the literature to contextualize the therapeutic potential of miRNA modulation. It considers the potential for miR-based therapeutics as a nuanced approach that incorporates the complexity of ARDS pathophysiology and the multifaceted nature of miRNA interactions.

Lipid nanovehicles overcome barriers to systemic RNA delivery: Lipid components, fabrication methods, and rational design

Lipid nanovehicles are currently the most advanced vehicles used for RNA delivery, as demonstrated by the approval of patisiran for amyloidosis therapy in 2018. To illuminate the unique superiority of lipid nanovehicles in RNA delivery, in this review, we first introduce various RNA therapeutics, describe systemic delivery barriers, and explain the lipid components and methods used for lipid nanovehicle preparation. Then, we emphasize crucial advances in lipid nanovehicle design for overcoming barriers to systemic RNA delivery. Finally, the current status and challenges of lipid nanovehicle-based RNA therapeutics in clinical applications are also discussed. Our objective is to provide a comprehensive overview showing how to utilize lipid nanovehicles to overcome multiple barriers to systemic RNA delivery, inspiring the development of more high-performance RNA lipid nanovesicles in the future.