Enhancing the immunogenicity of lipid-nanoparticle mRNA vaccines by adjuvanting the ionizable lipid and the mRNA

Engineering LNPs with polysarcosine lipids for mRNA delivery

Since the approval of the lipid nanoparticles (LNP)-mRNA vaccines against the SARS-CoV-2 virus, there has been an increased interest in the delivery of mRNA through LNPs. However, current LNP formulations contain PEG lipids, which can stimulate the generation of anti-PEG antibodies. The presence of these antibodies can potentially cause adverse reactions and reduce therapeutic efficacy after administration. Given the widespread deployment of the COVID-19 vaccines, the increased exposure to PEG may necessitate the evaluation of alternative LNP formulations without PEG components. In this study, we investigated a series of polysarcosine (pSar) lipids as alternatives to the PEG lipids to determine whether pSar lipids could still provide the functionality of the PEG lipids in the ALC-0315 and SM-102 LNP systems. We found that complete replacement of the PEG lipid with a pSar lipid can increase or maintain mRNA delivery efficiency and exhibit similar safety profiles in vivo.

A Nanoparticle Vaccine Displaying Conserved Epitopes of the Preexisting Neutralizing Antibody Confers Broad Protection against SARS-CoV-2 Variants

The rapid development of the SARS-CoV-2 vaccine has been used to prevent the spread of coronavirus 2019 (COVID-19). However, the ongoing and future pandemics caused by SARS-CoV-2 variants and mutations underscore the need for effective vaccines that provide broad-spectrum protection. Here, we developed a nanoparticle vaccine with broad protection against divergent SARS-CoV-2 variants. The corresponding conserved epitopes of the preexisting neutralizing (CePn) antibody were presented on a self-assembling Helicobacter pylori ferritin to generate the CePnF nanoparticle. Intranasal immunization of mice with CePnF nanoparticles induced robust humoral, cellular, and mucosal immune responses and a long-lasting immunity. The CePnF-induced antibodies exhibited cross-reactivity and neutralizing activity against different coronaviruses (CoVs). CePnF vaccination significantly inhibited the replication and pathology of SARS-CoV-2 Delta, WIV04, and Omicron strains in hACE2 transgenic mice and, thus, conferred broad protection against these SARS-CoV-2 variants. Our constructed nanovaccine targeting the conserved epitopes of the preexisting neutralizing antibodies can serve as a promising candidate for a universal SARS-CoV-2 vaccine.

Dual Effect by Chemical Electron Transfer Enhanced siRNA Lipid Nanoparticles: Reactive Oxygen Species-Triggered Tumor Cell Killing Aggravated by Nrf2 Gene Silencing

Insufficient endosomal escape presents a major hurdle for successful nucleic acid therapy. Here, for the first time, a chemical electron transfer (CET) system was integrated into small interfering RNA (siRNA) lipid nanoparticles (LNPs). The CET acceptor can be chemically excited using the generated energy between the donor and hydrogen peroxide, which triggers the generation of reactive oxygen species (ROS), promoting endosomal lipid membrane destabilization. Tetra-oleoyl tri-lysino succinoyl tetraethylene pentamine was included as an ionizable lipopeptide with a U-shaped topology for effective siRNA encapsulation and pH-induced endosomal escape. LNPs loaded with siRNA and CET components demonstrated a more efficient endosomal escape, as evidenced by a galectin-8-mRuby reporter; ROS significantly augmented galectin-8 recruitment by at least threefold compared with the control groups, with a p value of 0.03. Moreover, CET-enhanced LNPs achieved a 24% improvement in apoptosis level by knocking down the tumor-protective gene nuclear factor erythroid 2-related factor 2, boosting the CET-mediated ROS cell killing.

Optimizing mRNA-Loaded Lipid Nanoparticles as a Potential Tool for Protein-Replacement Therapy

Lipid nanoparticles (LNPs) tailored for mRNA delivery were optimized to serve as a platform for treating metabolic diseases. Four distinct lipid mixes (LMs) were formulated by modifying various components: LM1 (ALC-0315/DSPC/Cholesterol/ALC-0159), LM2 (ALC-0315/DOPE/Cholesterol/ALC-0159), LM3 (ALC-0315/DSPC/Cholesterol/DMG-PEG2k), and LM4 (DLin-MC3-DMA/DSPC/Cholesterol/ALC-0159). LNPs exhibited stability and homogeneity with a mean size of 75 to 90 nm, confirmed by cryo-TEM and SAXS studies. High mRNA encapsulation (95-100%) was achieved. LNPs effectively delivered EGFP-encoding mRNA to HepG2 and DC2.4 cell lines. LNPs induced cytokine secretion from human peripheral blood mononuclear cells (PBMCs), revealing that LM1, LM2, and LM4 induced 1.5- to 4-fold increases in IL-8, TNF-α, and MCP-1 levels, while LM3 showed minimal changes. Reporter mRNA expression was observed in LNP-treated PBMCs. Hemotoxicity studies confirmed formulation biocompatibility with values below 2%. In vivo biodistribution in mice post intramuscular injection showed significant mRNA expression, mainly in the liver. The modification of LNP components influenced reactogenicity, inflammatory response, and mRNA expression, offering a promising platform for selecting less reactogenic carriers suitable for repetitive dosing in metabolic disease treatment.

Lipid nanoparticles-based RNA therapies for breast cancer treatment

Breast cancer (BC) prevails as a major burden on global healthcare, being the most prevalent form of cancer among women. BC is a complex and heterogeneous disease, and current therapies, such as chemotherapy and radiotherapy, frequently fall short in providing effective solutions. These treatments fail to mitigate the risk of cancer recurrence and cause severe side effects that, in turn, compromise therapeutic responses in patients. Over the last decade, several strategies have been proposed to overcome these limitations. Among them, RNA-based technologies have demonstrated their potential across various clinical applications, notably in cancer therapy. However, RNA therapies are still limited by a series of critical issues like off-target effect and poor stability in circulation. Thus, novel approaches have been investigated to improve the targeting and bioavailability of RNA-based formulations to achieve an appropriate therapeutic outcome. Lipid nanoparticles (LNPs) have been largely proven to be an advantageous carrier for nucleic acids and RNA. This perspective explores the most recent advances on RNA-based technology with an emphasis on LNPs' utilization as effective nanocarriers in BC therapy and most recent progresses in their clinical applications.

Leveraging high-throughput screening technologies in targeted mRNA delivery

Messenger ribonucleic acid (mRNA) has emerged as a promising molecular preventive and therapeutic approach that opens new avenues for healthcare. Although the use of delivery systems, especially lipid nanoparticles (LNPs), greatly improves the efficiency and stability of mRNA, mRNA tends to accumulate in the liver and hardly penetrates physiological barriers to reach the target site after intravenous injection. Hence, the rational design of targeting strategies aimed at directing mRNA to specific tissues and cells remains an enormous challenge in mRNA therapy. High-throughput screening (HTS) is a cutting-edge targeted technique capable of synthesizing chemical compound libraries for the large-scale experiments to validate the efficiency of mRNA delivery system. In this review, we firstly provide an overview of conventional low-throughput targeting strategies. Then the latest advancements in HTS techniques for mRNA targeted delivery, encompassing optimizing structures of large-scale delivery vehicles and developing large-scale surface ligands, as well as the applications of HTS techniques in extrahepatic systemic diseases are comprehensively summarized. Moreover, we illustrate the selection of administration routes for targeted mRNA delivery. Finally, challenges in the field and potential solutions to tackle them are proposed, offering insights for future development toward mRNA targeted therapy.

Accelerating ionizable lipid discovery for mRNA delivery using machine learning and combinatorial chemistry

To unlock the full promise of messenger (mRNA) therapies, expanding the toolkit of lipid nanoparticles is paramount. However, a pivotal component of lipid nanoparticle development that remains a bottleneck is identifying new ionizable lipids. Here we describe an accelerated approach to discovering effective ionizable lipids for mRNA delivery that combines machine learning with advanced combinatorial chemistry tools. Starting from a simple four-component reaction platform, we create a chemically diverse library of 584 ionizable lipids. We screen the mRNA transfection potencies of lipid nanoparticles containing those lipids and use the data as a foundational dataset for training various machine learning models. We choose the best-performing model to probe an expansive virtual library of 40,000 lipids, synthesizing and experimentally evaluating the top 16 lipids flagged. We identify lipid 119-23, which outperforms established benchmark lipids in transfecting muscle and immune cells in several tissues. This approach facilitates the creation and evaluation of versatile ionizable lipid libraries, advancing the formulation of lipid nanoparticles for precise mRNA delivery.

Chemical Design Strategy of Ionizable Lipids for In Vivo mRNA Delivery

Lipid nanoparticles (LNPs) are the most clinically successful drug delivery systems that have accelerated the development of mRNA drugs and vaccines. Among various structural components of LNPs, more recent attention has been paid in ionizable lipids (ILs) that was supposed as the key component in determining the effectiveness of LNPs for in vivo mRNA delivery. ILs are typically comprised of three moieties including ionizable heads, linkers, and hydrophobic tails, which suggested that the combination of different functional groups in three moieties could produce ILs with diverse chemical structures and biological identities. In this concept article, we provide a summary of chemical design strategy for high-performing IL candidates and discuss their structure-activity relationships for shifting tissue-selective mRNA delivery. We also propose an outlook for the development of next-generation ILs, enabling the broader translation of mRNA formulated with LNPs.

Potent and long-lasting humoral and cellular immunity against varicella zoster virus induced by mRNA-LNP vaccine

Varicella zoster virus (VZV) is a highly contagious human herpes virus responsible for causing chickenpox (varicella) and shingles (herpes zoster). Despite the approval of a highly effective vaccine, Shingrix®, the global incidence of herpes zoster is increasing and the economic burden to the health care system and society are substantial due to significant loss of productivity and health complications, particularly among elderly and immunocompromised individuals. This is primarily because access to the vaccines remains mostly limited to countries within developed economies, such as USA and Canada. Therefore, similarly effective vaccines against VZV that are more accessible to the rest-of-the-world are necessary. In this study, we aimed to evaluate immunogenicity and memory response induced by three mRNA-LNP-based vaccine candidates targeting VZV's surface glycoprotein E (gE). C57BL/6 mice were immunized with each candidate vaccine, and humoral and cellular immune responses were assessed. Our results demonstrate that the mRNA-LNP-based vaccine candidates elicited robust and durable humoral responses specific to the gE antigen. Notably, mice vaccinated with the mRNA-LNP vaccines exhibited significantly higher antigen-specific T-cell cytokine production compared to the group receiving Shingrix®, the current standard of care vaccine. Additionally, mRNA-LNP vaccines induced long-lasting memory response, as evidenced by detection of persistent gE-specific Long-Lived Plasma Cells (LLPCs) and memory T cells four months after final immunization. These findings underscore the potential of our mRNA-LNP-based vaccine candidates in generating potent immune responses against VZV, offering promising prospects for their clinical development as an effective prophylactic vaccine against herpes zoster.

mRNA delivery systems for cancer immunotherapy: Lipid nanoparticles and beyond

mRNA-based vaccines are emerging as a promising alternative to standard cancer treatments and the conventional vaccines. Moreover, the FDA-approval of three nucleic acid based therapeutics (Onpattro, BNT162b2 and mRNA-1273) has further increased the interest and trust on this type of therapeutics. In order to achieve a significant therapeutic efficacy, the mRNA needs from a drug delivery system. In the last years, several delivery platforms have been explored, being the lipid nanoparticles (LNPs) the most well characterized and studied. A better understanding on how mRNA-based therapeutics operate (both the mRNA itself and the drug delivery system) will help to further improve their efficacy and safety. In this review, we will provide an overview of what mRNA cancer vaccines are and their mode of action and we will highlight the advantages and challenges of the different delivery platforms that are under investigation.

Rational design of ICD-inducing nanoparticles for cancer immunotherapy

Nanoparticle-based cancer immunotherapy has shown promising therapeutic potential in clinical settings. However, current research mainly uses nanoparticles as delivery vehicles but overlooks their potential to directly modulate immune responses. Inspired by the endogenous endoplasmic reticulum (ER) stress caused by unfolded/misfolded proteins, we present a rationally designed immunogenic cell death (ICD) inducer named NanoICD, which is a nanoparticle engineered for ER targeting and retention. By carefully controlling surface composition and properties, we have obtained NanoICD that can effectively accumulate in the ER, induce ER stress, and activate ICD-associated immune responses. In addition, NanoICD is generally applicable to various proteins and enzymes to further enhance the immunomodulatory capacity, exemplified by encapsulating catalase (CAT) to obtain NanoICD/CAT, effectively alleviated immunosuppressive tumor microenvironment and induced robust antitumor immune responses in 4T1-bearing mice. This work demonstrates engineered nanostructures' potential to autonomously regulate biological processes and provides insights into the development of advanced nanomedicines for cancer treatment.

mRNA vaccines and their delivery strategies: A journey from infectious diseases to cancer

mRNA vaccines have evolved as promising cancer therapies. These vaccines can encode tumor-allied antigens, thus enabling personalized treatment approaches. They can also target cancer-specific mutations and overcome immune evasion mechanisms. They manipulate the body's cellular functions to produce antigens, elicit immune responses, and suppress tumors by overcoming limitations associated with specific histocompatibility leukocyte antigen molecules. However, successfully delivering mRNA into target cells destroys a crucial challenge. Viral and nonviral vectors (lipid nanoparticles and cationic liposomes) have shown great capacity in protecting mRNA from deterioration and assisting in cellular uptake. Cell-penetrating peptides, hydrogels, polymer-based nanoparticles, and dendrimers have been investigated to increase the delivery efficacy and immunogenicity of mRNA. This comprehensive review explores the landscape of mRNA vaccines and their delivery platforms for cancer, addressing design considerations, diverse delivery strategies, and recent advancements. Overall, this review contributes to the progress of mRNA vaccines as an innovative strategy for effective cancer treatment.

mRNA vaccine designs for optimal adjuvanticity and delivery

Adjuvanticity and delivery are crucial facets of mRNA vaccine design. In modern mRNA vaccines, adjuvant functions are integrated into mRNA vaccine nanoparticles, allowing the co-delivery of antigen mRNA and adjuvants in a unified, all-in-one formulation. In this formulation, many mRNA vaccines utilize the immunostimulating properties of mRNA and vaccine carrier components, including lipids and polymers, as adjuvants. However, careful design is necessary, as excessive adjuvanticity and activation of improper innate immune signalling can conversely hinder vaccination efficacy and trigger adverse effects. mRNA vaccines also require delivery systems to achieve antigen expression in antigen-presenting cells (APCs) within lymphoid organs. Some vaccines directly target APCs in the lymphoid organs, while others rely on APCs migration to the draining lymph nodes after taking up mRNA vaccines. This review explores the current mechanistic understanding of these processes and the ongoing efforts to improve vaccine safety and efficacy based on this understanding.

The potential of mRNA vaccines in cancer nanomedicine and immunotherapy

Owing to their outstanding performance against COVID-19, mRNA vaccines have brought great hope for combating various incurable diseases, including cancer. Differences in the encoded proteins result in different molecular and cellular mechanisms of mRNA vaccines. With the rapid development of nanotechnology and molecular medicine, personalized antigen-encoding mRNA vaccines that enhance antigen presentation can trigger effective immune responses and prevent off-target toxicities. Herein, we review new insights into the influence of encoded antigens, cytokines, and other functional proteins on the mechanisms of mRNA vaccines. We also highlight the importance of delivery systems and chemical modifications for mRNA translation efficiency, stability, and targeting, and we discuss the potential problems and application prospects of mRNA vaccines as versatile tools for combating cancer.

Activation of the complement system by nanoparticles and strategies for complement inhibition

The complement system is a multicomponent and multifunctional arm of the innate immune system. Complement contributes to non-specific host defence and maintains homeostasis through multifaceted processes and pathways, including crosstalk with the adaptive immune system, the contact (coagulation) and the kinin systems, and alarmin high-mobility group box 1. Complement is also present intracellularly, orchestrating a wide range of housekeeping and physiological processes in both immune and nonimmune cells, thus showing its more sophisticated roles beyond innate immunity, but its roles are still controversial. Particulate drug carriers and nanopharmaceuticals typically present architectures and surface patterns that trigger complement system in different ways, resulting in both beneficial and adverse responses depending on the extent of complement activation and regulation as well as pathophysiological circumstances. Here we consider the role of complement system and complement regulations in host defence and evaluate the mechanisms by which nanoparticles trigger and modulate complement responses. Effective strategies for the prevention of nanoparticle-mediated complement activation are introduced and discussed.