Lipid nanoparticles (LNP) can provide a clinically effective method for delivering small interfering RNA (siRNA) to silence pathological genes in hepatocytes. The gene silencing potency of these ...LNP-siRNA systems has been shown to depend on a variety of factors including association with serum factors such as ApoE and the pKa of component ionizable lipids. Here we investigate the influence of LNP size, an important parameter affecting tissue penetration of LNP systems, on the pharmacokinetics, biodistribution, and hepatic gene silencing potency of LNP-siRNA systems following intravenous administration. For LNP systems stabilized by a polyethylene glycol (PEG)-lipid that can dissociate from the LNP following injection, it is shown that small (diameter≤30nm) systems are considerably less potent than their larger counterparts. This is attributed in part to the ability of other lipid components, particularly the ionizable amino-lipid, to dissociate from the LNP following dissociation of the PEG-lipid. Small LNP stabilized by PEG-lipids with slow dissociation rates exhibited much reduced amino-lipid dissociation rates, however such systems are relatively impotent due to the continued presence of the PEG coating. These results demonstrate the delicate balance between the in vivo potency of LNP-siRNA systems and the residence times of component lipids in the LNP particle itself and suggest new directions to optimize the in vivo gene silencing potency of small LNP-siRNA systems.
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The regulatory approval of Onpattro, a lipid nanoparticle-based short interfering RNA drug for the treatment of polyneuropathies induced by hereditary transthyretin amyloidosis, paves the way for ...clinical development of many nucleic acid-based therapies enabled by nanoparticle delivery.
The spread of the SARS-CoV-2 into a global pandemic within a few months of onset motivates the development of a rapidly scalable vaccine. Here, we present a self-amplifying RNA encoding the ...SARS-CoV-2 spike protein encapsulated within a lipid nanoparticle (LNP) as a vaccine. We observe remarkably high and dose-dependent SARS-CoV-2 specific antibody titers in mouse sera, as well as robust neutralization of both a pseudo-virus and wild-type virus. Upon further characterization we find that the neutralization is proportional to the quantity of specific IgG and of higher magnitude than recovered COVID-19 patients. saRNA LNP immunizations induce a Th1-biased response in mice, and there is no antibody-dependent enhancement (ADE) observed. Finally, we observe high cellular responses, as characterized by IFN-γ production, upon re-stimulation with SARS-CoV-2 peptides. These data provide insight into the vaccine design and evaluation of immunogenicity to enable rapid translation to the clinic.
In recent years, in vitro transcribed messenger RNA (mRNA) has emerged as a potential therapeutic platform. To fulfill its promise, effective delivery of mRNA to specific cell types and tissues needs ...to be achieved. Lipid nanoparticles (LNPs) are efficient carriers for short-interfering RNAs and have entered clinical trials. However, little is known about the potential of LNPs to deliver mRNA. Here, we generated mRNA-LNPs by incorporating HPLC purified, 1-methylpseudouridine-containing mRNA comprising codon-optimized firefly luciferase into stable LNPs. Mice were injected with 0.005-0.250mg/kg doses of mRNA-LNPs by 6 different routes and high levels of protein translation could be measured using in vivo imaging. Subcutaneous, intramuscular and intradermal injection of the LNP-encapsulated mRNA translated locally at the site of injection for up to 10days. For several days, high levels of protein production could be achieved in the lung from the intratracheal administration of mRNA. Intravenous and intraperitoneal and to a lesser extent intramuscular and intratracheal deliveries led to trafficking of mRNA-LNPs systemically resulting in active translation of the mRNA in the liver for 1–4 days. Our results demonstrate that LNPs are appropriate carriers for mRNA in vivo and have the potential to become valuable tools for delivering mRNA encoding therapeutic proteins.
Graphical representation of experimental approaches and data acquisition. Methods for the delivery and analysis of data are described in the Materials and methods and Results sections. Display omitted
Recently developed lipid nanoparticle (LNP) formulations of siRNA have proven to be effective agents for hepatocyte gene silencing following intravenous administration with at least three LNP–siRNA ...formulations in clinical trials. The aim of this work was to develop LNP–siRNA systems for hepatocyte gene silencing that can be administered subcutaneously (s.c.). Three parameters were investigated, namely LNP size, residence time of the polyethylene glycol (PEG)-lipid coating and the influence of hepatocyte-specific targeting ligands. LNP sizes were varied over the range of 30 to 115nm in diameter and PEG-lipid that dissociates rapidly (PEG-DMG) and slowly (PEG-DSG) were employed. In mice, results show that large (~80nm) LNP exhibited limited accumulation in the liver and poor Factor VII (FVII) gene silencing at 1mg siRNA/kg body weight. Conversely, small (~30nm) LNP systems showed maximal liver accumulation yet still had minimal activity. Interestingly, intermediate size (~45nm) LNP containing PEG-DSG exhibited nearly equivalent liver accumulation as the smaller systems following s.c. administration but reduced FVII levels by 80% at 1mg siRNA/kg body weight. Smaller systems (~35nm diameter) containing either PEG-DMG or PEG-DSG were less active; however addition of 0.5mol.% of a GalNAc-PEG lipid to these smaller systems improved activity to levels similar to that observed for the ~45nm diameter systems. In summary, this work shows that appropriately designed LNP–siRNA systems can result in effective hepatocyte gene silencing following s.c administration.
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Currently available influenza virus vaccines have inadequate effectiveness and are reformulated annually due to viral antigenic drift. Thus, development of a vaccine that confers long-term protective ...immunity against antigenically distant influenza virus strains is urgently needed. The highly conserved influenza virus hemagglutinin (HA) stalk represents one of the potential targets of broadly protective/universal influenza virus vaccines. Here, we evaluate a potent broadly protective influenza virus vaccine candidate that uses nucleoside-modified and purified mRNA encoding full-length influenza virus HA formulated in lipid nanoparticles (LNPs). We demonstrate that immunization with HA mRNA-LNPs induces antibody responses against the HA stalk domain of influenza virus in mice, rabbits, and ferrets. The HA stalk-specific antibody response is associated with protection from homologous, heterologous, and heterosubtypic influenza virus infection in mice.
Monoclonal antibodies are one of the fastest growing classes of pharmaceutical products, however, their potential is limited by the high cost of development and manufacturing. Here we present a safe ...and cost-effective platform for in vivo expression of therapeutic antibodies using nucleoside-modified mRNA. To demonstrate feasibility and protective efficacy, nucleoside-modified mRNAs encoding the light and heavy chains of the broadly neutralizing anti-HIV-1 antibody VRC01 are generated and encapsulated into lipid nanoparticles. Systemic administration of 1.4 mg kg
of mRNA into mice results in ∼170 μg ml
VRC01 antibody concentrations in the plasma 24 h post injection. Weekly injections of 1 mg kg
of mRNA into immunodeficient mice maintain trough VRC01 levels above 40 μg ml
. Most importantly, the translated antibody from a single injection of VRC01 mRNA protects humanized mice from intravenous HIV-1 challenge, demonstrating that nucleoside-modified mRNA represents a viable delivery platform for passive immunotherapy against HIV-1 with expansion to a variety of diseases.
Special (lipid) delivery: The role of the ionizable lipid pKa in the in vivo delivery of siRNA by lipid nanoparticles has been studied with a large number of head group modifications to the lipids. A ...tight correlation between the lipid pKa value and silencing of the mouse FVII gene (FVII ED50) was found, with an optimal pKa range of 6.2–6.5 (see graph). The most potent cationic lipid from this study has ED50 levels around 0.005 mg kg−1 in mice and less than 0.03 mg kg−1 in non‐human primates.
The protective efficacy of serum antibodies results from the interplay of antigen-specific B cell clones of different affinities and specificities. These cellular dynamics underlie serum-level ...phenomena such as original antigenic sin (OAS)-a proposed propensity of the immune system to rely repeatedly on the first cohort of B cells engaged by an antigenic stimulus when encountering related antigens, in detriment to the induction of de novo responses
. OAS-type suppression of new, variant-specific antibodies may pose a barrier to vaccination against rapidly evolving viruses such as influenza and SARS-CoV-2
. Precise measurement of OAS-type suppression is challenging because cellular and temporal origins cannot readily be ascribed to antibodies in circulation; its effect on subsequent antibody responses therefore remains unclear
. Here we introduce a molecular fate-mapping approach with which serum antibodies derived from specific cohorts of B cells can be differentially detected. We show that serum responses to sequential homologous boosting derive overwhelmingly from primary cohort B cells, while later induction of new antibody responses from naive B cells is strongly suppressed. Such 'primary addiction' decreases sharply as a function of antigenic distance, allowing reimmunization with divergent viral glycoproteins to produce de novo antibody responses targeting epitopes that are absent from the priming variant. Our findings have implications for the understanding of OAS and for the design and testing of vaccines against evolving pathogens.
Fibrosis affects millions of people with cardiac disease. We developed a therapeutic approach to generate transient antifibrotic chimeric antigen receptor (CAR) T cells in vivo by delivering modified ...messenger RNA (mRNA) in T cell–targeted lipid nanoparticles (LNPs). The efficacy of these in vivo–reprogrammed CAR T cells was evaluated by injecting CD5-targeted LNPs into a mouse model of heart failure. Efficient delivery of modified mRNA encoding the CAR to T lymphocytes was observed, which produced transient, effective CAR T cells in vivo. Antifibrotic CAR T cells exhibited trogocytosis and retained the target antigen as they accumulated in the spleen. Treatment with modified mRNA-targeted LNPs reduced fibrosis and restored cardiac function after injury. In vivo generation of CAR T cells may hold promise as a therapeutic platform to treat various diseases.
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