The immunostimulatory nature of mRNA lipid nanoparticles

Targeted lipid nanoparticles to prevent trans-placental passage in the ex vivo human placental cotyledon perfusion model

Medication use during pregnancy poses risks to both the mother and the fetus. These risks include an elevated potential for fetotoxicity due to placental drug transport. Nanomedicines offer a promising solution by potentially preventing trans-placental passage. Targeted nanomedicines could enhance safety and efficacy in treating maternal or placental pathophysiology. Our study investigates placental transfer kinetics of targeted lipid nanoparticles (LNPs) in an ex vivo human placenta cotyledon perfusion model. We collected human placentas for dual-side ex vivo placental perfusions. Targeted LNPs with a fluorescence tag were introduced into the maternal circuit of each placenta. To establish if there was trans-placental passage of LNPs to the fetal circuit, we collected samples from maternal and fetal circuits throughout the six hours of the perfusion. We determined the fluorescence signal using a multi-mode microplate reader and Multiphoton microscopy to localize the LNPs in the placenta tissue. Data from perfused placenta tissue showed no significant transfer of the fluorescently labeled LNPs across the placental barrier to the fetal circuit. Localization of targeted LNPs in tissue samples is mainly observed in the maternal blood space of the placenta. Our results suggest that targeted LNPs present a promising strategic approach to prevent trans-placental passage to the fetus. Our future perspectives involve investigating the efficacy of targeted LNPs as well as loading targeted LNPs with nucleic acid-based therapeutics to investigate their therapeutic potential.

Histidine Decapeptide-Incorporating Lipid Nanoparticles with Low Ionizable Lipids Proportion for Efficient Small Interfering RNA Delivery

The diversification of lipid compositions in lipid nanoparticles (LNPs) is crucial for expanding their clinical applications and overcoming current limitations. In this study, LNPs with varying lipid compositions are fabricated using three different mixing processes (pipette, vortex, and microfluidic mixing) for small interfering RNA (siRNA) delivery. While both siRNA and hydrophobic fluorescent dye are successfully incorporated within LNPs using pipette- and vortex-mixing, hydrophilic peptides cannot be encapsulated. Following optimization of ionizable lipid proportion via cost-efficient vortex-mixing method, LNPs with a lower ionizable lipid proportion (27.72%), termed LNP5, are selected and fabricated with histidine decapeptide (His10) during formulation via microfluidic mixing method to supplement the function of approximately half of the ionizable lipids by simple addition of His10. His10- incorporated LNP5 (LNP5H) exhibited a 1.6-fold increase in gene silencing efficiency, compared to conventional LNPs (cLNPs; ionizable lipid proportion of 47.95%). Furthermore, LNP5H maintained siRNA potency for 4 weeks when stored in a 1% sucrose solution at -70 °C. Taken together, it fabricates potent LNP5H with low proportion of ionizable lipids via fast and easy processes, which can be applied to a variety of siRNA therapeutics for their efficient intracellular delivery.

Apolipoprotein E4 facilitates transfection of human monocyte-derived dendritic cells by lipid nanoparticles

The use of mRNA as a therapeutic drug class is a safe and fast alternative to viral vector or plasmid DNA therapies. Nevertheless, free mRNA will be rapidly degraded after administration to the body and only reach the cytosol of desired cells with difficulty. Lipid nanoparticles (LNP) safely deliver mRNA to cells of interest and can be used in the treatment of different diseases. Dendritic cells are the primary antigen-presenting cells and important for mRNA vaccine delivery. Efforts to increase LNP transfection of these cells are necessary and can be achieved by different approaches. Here, we present apolipoprotein E4 addition to LNP administration as one mean of increasing LNP-mediated eGFP mRNA delivery to dendritic cells. We also show some steps in the preparation method for LNP optimization using MS2 RNA as a novel model nucleic acid.

TLR7-Adjuvanted Ionizable Lipid Nanoparticles for mRNA Vaccine Delivery

Ionizable lipid nanoparticles (LNPs) are clinically relevant non-viral vectors that allow intracellular delivery of mRNA vaccines to immune cells. To fight against notorious pathogens and cancer, mRNA vaccines necessitate the addition of an adjuvant to induce strong and durable cell-mediated immune responses. Adjuvants that stimulate Toll-like receptor 7 (TLR7) induce the secretion of type I interferons and proinflammatory cytokines, vital for generating strong immune responses. However, the intracellular delivery of TLR7 adjuvants to precisely stimulate the endosomal TLR7 receptor remains a huge challenge. This issue can be addressed by exploiting ionizable LNP platforms, which can encapsulate and carry mRNA vaccines and small molecule hydrophobic adjuvants to immune cells. CL347 is a potent lipid-based adjuvant that selectively stimulates the TLR7 receptor. In this study, we developed ionizable LNPs incorporating SM102 and CL347 adjuvant as the ionizable lipid and TLR7 adjuvant, respectively. CL347-SM102 LNPs exhibited particle sizes of less than 150 nm with spherical morphology and mRNA encapsulation efficiency of greater than 95%. In vivo studies showed a two-fold increase in IFN-γ producing CD4 and CD8 T cells in the lymphoid organs of the mice immunized with adjuvanted LNPs compared to the non-adjuvanted LNPs. Human PBMCs treated with adjuvanted LNPs exhibited significantly higher CD40 expression and pro-inflammatory cytokine (IL-6 and IFN-γ) secretion than non-adjuvanted LNPs. Together, these results suggest the potential of ionizable LNPs as a platform for concurrent delivery of mRNA and adjuvants for prophylactic and therapeutic vaccine applications.

Fluorinated Ribonucleocarbohydrate Nanoparticles Allow Ultraefficient mRNA Delivery and Protein Expression in Tumor-Associated Myeloid Cells

Ribonucleic acids (RNA) are commonly formulated into lipid nanoparticles (LNP) for in vivo use, but challenges exist with systemic delivery and low in vivo expression efficiency. Inspired by ribonucleoprotein complexes in cells, we created synthetic ribonucleocarbohydrate (RNC) complexes based on cyclodextrin nanoparticles with ferrocenyl fluorocarbons capable of carrying mRNA and additional small-molecule drug payloads, facilitating lysosomal escape and immune stimulation all in the same nanoparticle. We show that this strategy results in highly efficient myeloid cell targeting (dendritic cells and MHC expressing macrophages) and protein expression following systemic administration. The RNC platform should have broad applications in vaccine development, immunosuppression, and immunostimulation for various diseases.

Expanded Spectrum and Increased Incidence of Adverse Events Linked to COVID-19 Genetic Vaccines: New Concepts on Prophylactic Immuno-Gene Therapy, Iatrogenic Orphan Disease, and Platform-Inherent Challenges

The mRNA- and DNA-based "genetic" COVID-19 vaccines can induce a broad range of adverse events (AEs), with statistics showing significant variation depending on the timing and data analysis methods used. Focusing only on lipid nanoparticle-enclosed mRNA (mRNA-LNP) vaccines, this review traces the evolution of statistical conclusions on the prevalence of AEs and incidents associated with these vaccines, from initial underestimation of atypical, severe toxicities to recent claims suggesting the possible contribution of COVID-19 vaccinations to the excess deaths observed in many countries over the past few years. Among hundreds of different AEs listed in Pfizer's pharmacovigilance survey, the present analysis categorizes the main symptoms according to organ systems, with nearly all of them being affected. Using data from the US Vaccine Adverse Event Reporting System and a global vaccination dataset, a comparison of the prevalence and incidence rates of AEs induced by genetic versus flu vaccines revealed an average 26-fold increase in AEs with the use of genetic vaccines. The difference is especially pronounced in the case of severe 'Brighton-listed' AEs, which are also observed in COVID-19 and post-COVID conditions. Among these, the increases in incidence rates relative to flu vaccines, given as x-fold rises, were 1152x, 455x, 226x, 218x, 162x, 152x, and 131x for myocarditis, thrombosis, death, myocardial infarction, tachycardia, dyspnea, and hypertension, respectively. The review delineates the concept that genetic vaccines can be regarded as prophylactic immuno-gene therapies and that the observed chronic disabling AEs might be categorized as iatrogenic orphan diseases. It also examines the unique vaccine characteristics that could be causally related to abnormal immune responses which potentially lead to adverse events and complications. These new insights may contribute to improving the safety of this platform technology and assessing the risk/benefit balance of various products.

Exploring the Challenges of Lipid Nanoparticle Development: The In Vitro-In Vivo Correlation Gap

BACKGROUND/OBJECTIVES

The development of lipid nanoparticles (LNPs) as delivery platforms for nucleic acids has revolutionised possibilities for both therapeutic and vaccine applications. However, emerging studies highlight challenges in achieving reliable in vitro-in vivo correlation (IVIVC), which delays the translation of experimental findings into clinical applications. This study investigates these potential discrepancies by evaluating the physicochemical properties, in vitro efficacy (across three commonly used cell lines), and in vivo performance (mRNA expression and vaccine efficacy) of four LNP formulations.

METHODS

LNPs composed of DSPC, cholesterol, a PEGylated lipid, and one of four ionizable lipids (SM-102, ALC-0315, MC3, or C12-200) were manufactured using microfluidics.

RESULTS

All formulations exhibited comparable physicochemical properties, as expected (size 70-100 nm, low PDI, near-neutral zeta potential, and high mRNA encapsulation). In vitro studies demonstrated variable LNP-mediated mRNA expression in both immortalised and immune cells, with SM-102 inducing significantly higher protein expression (p < 0.05) than the other formulations in immortalised and immune cells. However, in vivo results revealed that ALC-0315 and SM-102-based LNPs achieved significantly (p < 0.05) higher protein expression without a significant difference between them, while MC3- and C12-200-based LNPs exhibited lower expression levels. As vaccine formulations, all LNPs elicited strong immune responses with no significant differences among them.

CONCLUSIONS

These findings highlight the complexities of correlating in vitro and in vivo outcomes in LNP development and demonstrate the importance of holistic evaluation strategies to optimise their clinical translation.

Clinical applications of oligonucleotides for cancer therapy

Oligonucleotide therapeutics (ONTs) represent a rapidly evolving modality for cancer treatment, capitalizing on their ability to modulate gene expression with high specificity. With more than 20 nucleic acid-based therapies that gained regulatory approval, advances in chemical modifications, sequence optimization, and novel delivery systems have propelled ONTs from research tools to clinical realities. ONTs, including siRNAs, antisense oligonucleotides, saRNA, miRNA, aptamers, and decoys, offer promising solutions for targeting previously "undruggable" molecules, such as transcription factors, and enhancing cancer immunotherapy by overcoming tumor immune evasion. The promise of ONT application in cancer treatment is exemplified by the recent FDA approval of the first oligonucleotide-based treatment to myeloproliferative disease. At the same time, there are challenges in delivering ONTs to specific tissues, mitigating off-target effects, and improving cellular uptake and endosomal release. This review provides a comprehensive overview of ONTs in clinical trials, emerging delivery strategies, and innovative therapeutic approaches, emphasizing the role of ONTs in immunotherapy and addressing hurdles that hinder their clinical translation. By examining advances and remaining challenges, we highlight opportunities for ONTs to revolutionize oncology and enhance patient outcomes.

Ionizable Lipids with Optimized Linkers Enable Lung-Specific, Lipid Nanoparticle-Mediated mRNA Delivery for Treatment of Metastatic Lung Tumors

Lipid nanoparticles (LNPs) have emerged as a groundbreaking delivery system for vaccines and therapeutic mRNAs. Ionizable lipids are the most pivotal component of LNPs due to their ability to electrostatically interact with mRNA, allowing its encapsulation while concurrently enabling its endosomal escape following cellular internalization. Thus, extensive research has been performed to optimize the ionizable lipid structure and to develop formulations that are well tolerated and allow efficient targeting of different organs that result in a high and sustained mRNA expression. However, one facet of the ionizable lipids' structure has been mostly overlooked: the linker segment between the ionizable headgroup and their tails. Here, we screened a rationally designed library of ionizable lipids with different biodegradable linkers. We extensively characterized LNPs formulated using these ionizable lipids and elucidated how these minor structural changes in the ionizable lipids structure radically influenced the LNPs' biodistribution in vivo. We showed how the use of amide and urea linkers can modulate the LNPs' pKa, resulting in an improved specificity for lung transfection. Finally, we demonstrated how one of these lipids (lipid 35) that form LNPs entrapping a bacterial toxin [pseudomonas exotoxin A (mmPE)] in the form of an mRNA reduced tumor burden and significantly increased the survival of mice with lung metastasis.

Revolutionizing Dentistry: Preclinical Insights and Future Applications of mRNA Vaccines in Dentistry-A Narrative Review

Background: Recent advances in mRNA vaccine technology, accelerated by the global COVID-19 pandemic, have generated significant interest in their applications beyond infectious diseases. Dentistry has emerged as a promising field for exploring the potential of mRNA-based therapies in preventing and treating oral diseases. Objectives: This narrative review aims to evaluate the current status of mRNA vaccine development and its preclinical applications in oral health, focusing on periodontal disease, dental caries, regenerative medicine, implantology, and oral cancer. Methods: The review synthesizes findings from preclinical studies, including research conducted in animal models and in vitro, to assess the potential of mRNA-based therapies to modulate immune responses and promote tissue regeneration in the oral cavity. Clinical trials were only mentioned in the context of broader areas of mRNA vaccine implementation such as oncology and immunotherapy. Results: The preclinical studies highlight the capacity of mRNA vaccines to enhance the body's immune response and facilitate tissue repair processes. Despite these promising results, challenges persist in delivering mRNA vaccines effectively within the complex oral environment. These challenges include vaccine stability, delivery mechanisms, and the modulation of immune responses. Conclusions: While mRNA vaccines offer significant promise for revolutionizing oral health care, they face notable limitations concerning safety, efficacy, and clinical feasibility. Overcoming these obstacles through further research is essential to unlock their full translational potential and ensure their safe and effective integration into dental practice.

Cytokine mRNA Delivery and Local Immunomodulation in the Placenta using Lipid Nanoparticles

During pregnancy, the maternal immune system adapts to balance tolerance of the semi-allogenic fetus while protecting the fetus from pathogens. Dysregulated immune activity at the maternal-fetal interface contributes to pregnancy complications, such as recurrent pregnancy loss and preeclampsia. Compared to healthy placentas, preeclamptic placentas exhibit increased pro-inflammatory signaling, including a predominance of inflammatory macrophages, leading to impaired tissue remodeling and restricted blood flow. However, the precise mechanisms driving this immune imbalance remain poorly understood, in part due to the lack of tools to probe individual pathways. Here, we use lipid nanoparticles (LNPs) to deliver cytokine-encoded mRNA to placental cells, called trophoblasts, enabling local immunomodulation. LNP-mediated delivery of IL-4 and IL-13 mRNA induced cytokine secretion by trophoblasts, leading to polarization of primary human monocytes toward anti-inflammatory phenotypes. Notably, lowering the mRNA dose increased expression of alternatively-activated macrophage markers, revealing an inverse relationship between dose and polarization status. Intravenous injection of LNPs in pregnant mice achieved placental secretion of IL-4 and IL-13 with minimal changes to pro-inflammatory cytokines in the serum. These findings establish LNPs as a tool for local immunomodulation in the placenta, offering a strategy to study and treat immune dysfunction in pregnancy and in other inflammatory conditions.

Comparison of safety and immunogenicity in the elderly after receiving either Comirnaty or Spikevax monovalent XBB1.5 COVID-19 vaccine

BACKGROUND

The emergence of SARS-CoV-2 variants necessitates ongoing evaluation of vaccine performance. This study evaluates and compares the safety and immunogenicity of the Comirnaty and Spikevax monovalent XBB.1.5 COVID-19 vaccines in an elderly population.

METHODS

Altogether, 129 elderly individuals were recruited between 2 January and 3 February 2024, and received a booster dose of either Comirnaty (n=59) or Spikevax (n=70) monovalent XBB.1.5 COVID-19 vaccine. Blood samples were collected at before and one month after vaccination. Immunogenicity was assessed by measuring the percentage of IFNγ+CD4+ and IFNγ+CD8+ T cells, and neutralizing antibody titers (NT50) using a surrogate virus neutralization test (sVNT). Adverse reactions were recorded and analyzed.

FINDINGS

Both vaccines significantly increased the percentage of IFNγ+CD8+ T cells against XBB.1.5 and wild-type (WT) SARS-CoV-2 at one-month post-vaccination. Spikevax induced a significantly higher percentages of IFNγ+CD8+ and CD4+ T cells against XBB.1.5 than Comirnaty (p<0.001). The proportion of participants showing a positive T cell response to XBB1.5 after vaccination was higher in the Spikevax group (64.3% CD8, 71.4% CD4) than in the Comirnaty group (42.4% CD8, 57.6% CD4). Spikevax also elicited higher NT50 levels against XBB1.5, JN.1 and the latest variant KP.2 than Comirnaty (XBB1.5: p<0.01; KP.2: p<0.05). Fever was more common in the Spikevax group (fever: p=0.006). However, all side effects were short-term and resolved on their own.

INTERPRETATION

Both vaccines induce neutralizing antibody to XBB1.5, JN.1 and KP.2. Specifically, Spikevax induces higher cellular and humoral immune responses than Comirnaty in the elderly, but it is also associated with a higher incidence of fever. These findings can guide public health strategies for vaccinating the elderly population.

Harnessing nanoengineered CAR-T cell strategies to advance solid tumor immunotherapy

The efficacy and safety of chimeric antigen receptor (CAR) T cell therapy is still inconclusive in solid tumor treatment. Recently, nanotechnology has emerged as a potent strategy to reshape CAR-T cell therapy with promising outcomes. This review aims to discuss the significant potential of nano-engineered CAR-T cell therapy in addressing existing challenges, including CAR-T cell engineering evolution, tumor microenvironment (TME) modulation, and precise CAR-T cell therapy (precise targeting, monitoring, and activation), under the main consideration of clinical translation. It also focuses on the growing trend of technological convergence within this domain, such as mRNA therapeutics, organoids, neoantigen, and artificial intelligence. Moreover, safety management of nanomedicine is seriously emphasized to facilitate clinical translation.

Effect of Lipid Nanoparticle Physico-Chemical Properties and Composition on Their Interaction with the Immune System

Lipid nanoparticles (LNPs) have shown promise as a delivery system for nucleic acid-based therapeutics, including DNA, siRNA, and mRNA vaccines. The immune system plays a critical role in the response to these nanocarriers, with innate immune cells initiating an early response and adaptive immune cells mediating a more specific reaction, sometimes leading to potential adverse effects. Recent studies have shown that the innate immune response to LNPs is mediated by Toll-like receptors (TLRs) and other pattern recognition receptors (PRRs), which recognize the lipid components of the nanoparticles. This recognition can trigger the activation of inflammatory pathways and the production of cytokines and chemokines, leading to potential adverse effects such as fever, inflammation, and pain at the injection site. On the other hand, the adaptive immune response to LNPs appears to be primarily directed against the protein encoded by the mRNA cargo, with little evidence of an ongoing adaptive immune response to the components of the LNP itself. Understanding the relationship between LNPs and the immune system is critical for the development of safe and effective nucleic acid-based delivery systems. In fact, targeting the immune system is essential to develop effective vaccines, as well as therapies against cancer or infections. There is a lack of research in the literature that has systematically studied the factors that influence the interaction between LNPs and the immune system and further research is needed to better elucidate the mechanisms underlying the immune response to LNPs. In this review, we discuss LNPs' composition, physico-chemical properties, such as size, shape, and surface charge, and the protein corona formation which can affect the reactivity of the immune system, thus providing a guide for the research on new formulations that could gain a favorable efficacy/safety profile.

New insights for the development of efficient DNA vaccines

Despite the great potential of DNA vaccines for a broad range of applications, ranging from prevention of infections, over treatment of autoimmune and allergic diseases to cancer immunotherapies, the implementation of such therapies for clinical treatment is far behind the expectations up to now. The main reason is the poor immunogenicity of DNA vaccines in humans. Consequently, the improvement of the performance of DNA vaccines in vivo is required. This mini-review provides an overview of the current state of DNA vaccines and the various strategies to enhance the immunogenic potential of DNA vaccines, including (i) the optimization of the DNA construct itself regarding size, nuclear transfer and transcriptional regulation; (ii) the use of appropriate adjuvants; and (iii) improved delivery, for example, by careful choice of the administration route, physical methods such as electroporation and nanomaterials that may allow cell type-specific targeting. Moreover, combining nanoformulated DNA vaccines with other immunotherapies and prime-boost strategies may help to enhance success of treatment.

mRNA vaccines for infectious diseases - advances, challenges and opportunities

The concept of mRNA-based vaccines emerged more than three decades ago. Groundbreaking discoveries and technological advancements over the past 20 years have resolved the major roadblocks that initially delayed application of this new vaccine modality. The rapid development of nucleoside-modified COVID-19 mRNA vaccines demonstrated that this immunization platform is easy to develop, has an acceptable safety profile and can be produced at a large scale. The flexibility and ease of antigen design have enabled mRNA vaccines to enter development for a wide range of viruses as well as for various bacteria and parasites. However, gaps in our knowledge limit the development of next-generation mRNA vaccines with increased potency and safety. A deeper understanding of the mechanisms of action of mRNA vaccines, application of novel technologies enabling rational antigen design, and innovative vaccine delivery strategies and vaccination regimens will likely yield potent novel vaccines against a wide range of pathogens.

The Impact of COVID-19 on RNA Therapeutics: A Surge in Lipid Nanoparticles and Alternative Delivery Systems

The COVID-19 pandemic has significantly accelerated progress in RNA-based therapeutics, particularly through the successful development and global rollout of mRNA vaccines. This review delves into the transformative impact of the pandemic on RNA therapeutics, with a strong focus on lipid nanoparticles (LNPs) as a pivotal delivery platform. LNPs have proven to be critical in enhancing the stability, bioavailability, and targeted delivery of mRNA, facilitating the unprecedented success of vaccines like those developed by Pfizer-BioNTech and Moderna. Beyond vaccines, LNP technology is being explored for broader therapeutic applications, including treatments for cancer, rare genetic disorders, and infectious diseases. This review also discusses emerging RNA delivery systems, such as polymeric nanoparticles and viral vectors, which offer alternative strategies to overcome existing challenges related to stability, immune responses, and tissue-specific targeting. Additionally, we examine the pandemic's influence on regulatory processes, including the fast-tracked approvals for RNA therapies, and the surge in research funding that has spurred further innovation in the field. Public acceptance of RNA-based treatments has also grown, laying the groundwork for future developments in personalized medicine. By providing an in-depth analysis of these advancements, this review highlights the long-term impact of COVID-19 on the evolution of RNA therapeutics and the future of precision drug delivery technologies.

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.

The future of genetic medicines delivered via targeted lipid nanoparticles to leukocytes

Genetic medicines hold vast therapeutic potential, offering the ability to silence or induce gene expression, knock out genes, and even edit DNA fragments. Applying these therapeutic modalities to leukocytes offers a promising path for treating various conditions yet overcoming the obstacles of specific and efficient delivery to leukocytes remains a major bottleneck in their clinical translation. Lipid nanoparticles (LNPs) have emerged as the leading delivery system for nucleic acids due to their remarkable versatility and ability to improve their in vivo stability, pharmacokinetics, and therapeutic benefits. Equipping LNPs with targeting moieties can promote their specific cellular uptake and internalization to leukocytes, making targeted LNPs (tLNPs) an inseparable part of developing leukocyte-targeted gene therapy. However, despite the significant advancements in research, genetic medicines for leukocytes using targeted delivery approaches have not been translated into the clinic yet. Herein, we discuss the important aspects of designing tLNPs and highlight the considerations for choosing an appropriate bioconjugation strategy and targeting moiety. Furthermore, we provide our insights on limiting challenges and identify key areas for further research to advance these exciting therapies for patient care.

Immunity to fungi and vaccine considerations

Fungal disease poses a growing threat to public health that our current antifungal therapies are not well equipped to meet. As the population of immunocompromised hosts expands, and ecological changes favor the emergence of fungal pathogens, the development of new antifungal agents, including vaccines, becomes a global priority. Here, we summarize recent advancements in the understanding of fungal pathogenesis, key features of the host antifungal immune response, and how these findings could be leveraged to design novel approaches to deadly fungal disease.

Evaluating the breadth of nucleic acid-based payloads delivered in lipid nanoparticles to establish fundamental differences in development

INTRODUCTION

Nucleic acid (NA)-based therapeutics have shown great potential for downregulating or augmenting gene expression, and for promising applications, e.g., protein-replacement therapy and vaccination, a comprehensive understanding of the requirements for their targeted delivery to specific tissues or cells is needed.

AREAS COVERED

In this review, we discuss clinical applications of four representative types of NA-based therapeutics, i.e. antisense oligonucleotides, small interfering RNA, messenger RNA, and circular RNA, with a focus on the lipid nanoparticle (LNP) technology used for intracellular delivery. The in vivo fate of LNPs is discussed to improve the understanding of trafficking of nanomedicines at the systemic and cellular levels. In addition, NA-based vaccines are discussed, focusing on targeting antigen-presenting cells and immune activation.

EXPERT OPINION

Optimization of delivery systems for NA-based therapeutics is mainly focused on the standard requirements of prolonged systemic circulation and enhancing endosomal escape. Depending on the final destination in specific target tissues or cells, strategies should be adjusted to achieve the desired biodistribution of NA-based payloads. More studies relating to the pharmacokinetics of both cargo and carrier are encouraged, because their in vivo fates may differ, considering the possibility of premature cargo release before reaching the target.

The transformative potential of mRNA vaccines for glioblastoma and human cancer: technological advances and translation to clinical trials

Originally devised for cancer control, mRNA vaccines have risen to the forefront of medicine as effective instruments for control of infectious disease, notably their pivotal role in combating the COVID-19 pandemic. This review focuses on fundamental aspects of the development of mRNA vaccines, e.g., tumor antigens, vector design, and precise delivery methodologies, - highlighting key technological advances. The recent, promising success of personalized mRNA vaccines against pancreatic cancer and melanoma illustrates the potential value for other intractable, immunologically resistant, solid tumors, such as glioblastoma, as well as the potential for synergies with a combinatorial, immunotherapeutic approach. The impact and progress in human cancer, including pancreatic cancer, head and neck cancer, bladder cancer are reviewed, as are lessons learned from first-in-human CAR-T cell, DNA and dendritic cell vaccines targeting glioblastoma. Going forward, a roadmap is provided for the transformative potential of mRNA vaccines to advance cancer immunotherapy, with a particular focus on the opportunities and challenges of glioblastoma. The current landscape of glioblastoma immunotherapy and gene therapy is reviewed with an eye to combinatorial approaches harnessing RNA science. Preliminary preclinical and clinical data supports the concept that mRNA vaccines could be a viable, novel approach to prolong survival in patients with glioblastoma.

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.

Physicochemical and structural insights into lyophilized mRNA-LNP from lyoprotectant and buffer screenings

The surge in RNA therapeutics has revolutionized treatments for infectious diseases like COVID-19 and shows the potential to expand into other therapeutic areas. However, the typical requirement for ultra-cold storage of mRNA-LNP formulations poses significant logistical challenges for global distribution. Lyophilization serves as a potential strategy to extend mRNA-LNP stability while eliminating the need for ultra-cold supply chain logistics. Although recent advancements have demonstrated the promise of lyophilization, the choice of lyoprotectant is predominately focused on sucrose, and there remains a gap in comprehensive evaluation and comparison of lyoprotectants and buffers. Here, we aim to systematically investigate the impact of a diverse range of excipients including oligosaccharides, polymers, amino acids, and various buffers, on the quality and performance of lyophilized mRNA-LNPs. From the screening of 45 mRNA-LNP formulations under various lyoprotectant and buffer conditions for lyophilization, we identified previously unexplored formulation compositions, e.g., polyvinylpyrrolidone (PVP) in Tris or acetate buffers, as promising alternatives to the commonly used oligosaccharides to maintain the physicochemical stability of lyophilized mRNA-LNPs. Further, we delved into how physicochemical and structural properties influence the functionality of lyophilized mRNA-LNPs. Leveraging high-throughput small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM), we showed that there is complex interplay between mRNA-LNP structural features and cellular translation efficacy. We also assessed innate immune responses of the screened mRNA-LNPs in human peripheral blood mononuclear cells (PBMCs), and showed minimal alterations of cytokine secretion profiles induced by lyophilized formulations. Our results provide valuable insights into the structure-activity relationship of lyophilized formulations of mRNA-LNP therapeutics, paving the way for rational design of these formulations. This work creates a foundation for a comprehensive understanding of mRNA-LNP properties and in vitro performance change resulting from lyophilization.

Writers, readers, and erasers RNA modifications and drug resistance in cancer

Drug resistance in cancer cells significantly diminishes treatment efficacy, leading to recurrence and metastasis. A critical factor contributing to this resistance is the epigenetic alteration of gene expression via RNA modifications, such as N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), 7-methylguanosine (m7G), pseudouridine (Ψ), and adenosine-to-inosine (A-to-I) editing. These modifications are pivotal in regulating RNA splicing, translation, transport, degradation, and stability. Governed by "writers," "readers," and "erasers," RNA modifications impact numerous biological processes and cancer progression, including cell proliferation, stemness, autophagy, invasion, and apoptosis. Aberrant RNA modifications can lead to drug resistance and adverse outcomes in various cancers. Thus, targeting RNA modification regulators offers a promising strategy for overcoming drug resistance and enhancing treatment efficacy. This review consolidates recent research on the role of prevalent RNA modifications in cancer drug resistance, with a focus on m6A, m1A, m5C, m7G, Ψ, and A-to-I editing. Additionally, it examines the regulatory mechanisms of RNA modifications linked to drug resistance in cancer and underscores the existing limitations in this field.

Delivery of nucleic acid based genome editing platforms via lipid nanoparticles: Clinical applications

CRISPR/Cas technology presents a promising approach for treating a wide range of diseases, including cancer and genetic disorders. Despite its potential, the translation of CRISPR/Cas into effective in-vivo gene therapy encounters challenges, primarily due to the need for safe and efficient delivery mechanisms. Lipid nanoparticles (LNPs), FDA-approved for RNA delivery, show potential for delivering also CRISPR/Cas, offering the capability to efficiently encapsulate large mRNA molecules with single guide RNAs. However, achieving precise targeting in-vivo remains a significant obstacle, necessitating further research into optimizing LNP formulations. Strategies to enhance specificity, such as modifying LNP structures and incorporating targeting ligands, are explored to improve organ and cell type targeting. Furthermore, the development of base and prime editing technology presents a potential breakthrough, offering precise modifications without generating double-strand breaks (DSBs). Prime editing, particularly when delivered via targeted LNPs, holds promise for treating diverse diseases safely and precisely. This review assesses both the progress made and the persistent challenges faced in using LNP-encapsulated CRISPR-based technologies for therapeutic purposes, with a particular focus on clinical translation.

A Physiochemical, In Vitro, and In Vivo Comparative Analysis of Verteporfin-Lipid Conjugate Formulations: Solid Lipid Nanoparticles and Liposomes

VisudyneⓇ, a liposomal formulation of verteporfin (benzoporphyrin derivative; BPD), is the only nanomedicine approved to date for photodynamic therapy (PDT). We have previously demonstrated that BPD conjugated to the lysophospholipid 1-arachidoyl-2-hydroxy-sn-glycero-3-phosphocholine (BPD-PC) exhibits the greatest physical stability in liposomes, while maintaining cancer cell phototoxicity, from a panel of BPD lipid conjugates evaluated. In this study, we prepared 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-based solid lipid nanoparticles (LNPs) that stably entrap BPD-PC, which resemble the composition of the SpikevaxⓇ Moderna COVID-19 vaccine, and compared them to a DPPC based liposomal formulation (Lipo BPD-PC). We evaluated the photochemical, optical, and phototherapeutic properties of both formulations. We also investigated the in vivo distribution and tumor microdistribution of both formulations. Our results demonstrated that Lipo BPD-PC is able to generate 17% more singlet oxygen than LNP BPD-PC, while interestingly, LNP BPD-PC is able to produce 76% more hydroxyl radicals and/or peroxynitrite anion. Importantly, only 28% of BPD-PC leaches out of the LNP BPD-PC formulation during 7 days of incubation in serum at 37 °C, while 100% of BPD-PC leaches out of the Lipo BPD-PC formulation under the same conditions. Despite these differences, there was no significant difference in cellular uptake of BPD-PC or phototoxicity in CT1BA5 murine pancreatic cancer cells (derived from a genetically engineered mouse model). Interestingly, PDT using LNP BPD-PC was more efficient at inducing immunogenic cell death (calreticulin membrane translocation) than Lipo BPD-PC when using IC25 and IC50 PDT doses. In vivo studies revealed that CT1BA5 tumor fluorescence signals from BPD-PC were 2.41-fold higher with Lipo BPD-PC than with LNP BPD-PC; however, no significant difference was observed in tumor tissue selectivity or tumor penetration. As such, we present LNP BPD-PC as a unique and more stable nanoplatform to carry BPD lipid conjugates, such as BPD-PC, with a potential for future photodynamic immune priming studies and multiagent drug delivery.

A potent bioreducible ionizable lipid nanoparticle enables siRNA delivery for retinal neovascularization inhibition

Small interfering RNA (siRNA) is emerging as a promising treatment for retinal neovascularization due to its specific inhibition of the expression of target genes. However, the clinical translation of siRNA drugs is hindered by the efficiency and safety of delivery vectors. Here, we describe the properties of a new bioreducible ionizable lipid nanoparticle (LNP) 2N12H, which is based on a rationally designed novel ionizable lipid called 2N12B. 2N12H exhibited degradation in response to the mimic cytoplasmic glutathione condition and ionization with a pKa value of 6.5, which remaining neutral at pH 7.4. At a nitrogen to phosphorus ratio of 5, 2N12H efficiently encapsulated and protected siRNA from degradation. Compared to the commercial vehicle Lipofectamine 2000, 2N12H demonstrated similar silencing efficiency and improved safety in the in vitro cell experiments. 2N12H/siVEGFA reduced the expression of VEGFA in retinal pigment epithelium cells and mouse retina, consequently suppressing cell migration and retinal neovascularization. In the mouse model, the therapeutic effect of 2N12H/siVEGFA was comparable to that of the clinical drug ranibizumab. Together, these results suggest the potential of this novel ionizable LNP to facilitate the development of nonviral ocular gene delivery systems.

Organ- and Cell-Selective Delivery of mRNA In Vivo Using Guanidinylated Serinol Charge-Altering Releasable Transporters

Selective RNA delivery is required for the broad implementation of RNA clinical applications, including prophylactic and therapeutic vaccinations, immunotherapies for cancer, and genome editing. Current polyanion delivery relies heavily on cationic amines, while cationic guanidinium systems have received limited attention due in part to their strong polyanion association, which impedes intracellular polyanion release. Here, we disclose a general solution to this problem in which cationic guanidinium groups are used to form stable RNA complexes upon formulation but at physiological pH undergo a novel charge-neutralization process, resulting in RNA release. This new delivery system consists of guanidinylated serinol moieties incorporated into a charge-altering releasable transporter (GSer-CARTs). Significantly, systematic variations in structure and formulation resulted in GSer-CARTs that exhibit highly selective mRNA delivery to the lung (∼97%) and spleen (∼98%) without targeting ligands. Illustrative of their breadth and translational potential, GSer-CARTs deliver circRNA, providing the basis for a cancer vaccination strategy, which in a murine model resulted in antigen-specific immune responses and effective suppression of established tumors.

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.

Effect of Micromixer Design on Lipid Nanocarriers Manufacturing for the Delivery of Proteins and Nucleic Acids

Lipid-based nanocarriers have emerged as helpful tools to deliver sensible biomolecules such as proteins and oligonucleotides. To have a fast and robust microfluidic-based nanoparticle synthesis method, the setup of versatile equipment should allow for the rapid transfer to scale cost-effectively while ensuring tunable, precise and reproducible nanoparticle attributes. The present work aims to assess the effect of different micromixer geometries on the manufacturing of lipid nanocarriers taking into account the influence on the mixing efficiency by changing the fluid-fluid interface and indeed the mass transfer. Since the geometry of the adopted micromixer varies from those already published, a Design of Experiment (DoE) was necessary to identify the operating (total flow, flow rate ratio) and formulation (lipid concentration, lipid molar ratios) parameters affecting the nanocarrier quality. The suitable application of the platform was investigated by producing neutral, stealth and cationic liposomes, using DaunoXome®, Myocet®, Onivyde® and Onpattro® as the benchmark. The effect of condensing lipid (DOTAP, 3-10-20 mol%), coating lipids (DSPE-PEG550 and DSPE-PEG2000), as well as structural lipids (DSPC, eggPC) was pointed out. A very satisfactory encapsulation efficiency, always higher than 70%, was successfully obtained for model biomolecules (myoglobin, short and long nucleic acids).