Heterologous mRNA/MVA delivering trimeric-RBD as effective vaccination regimen against SARS-CoV-2: COVARNA Consortium.

Despite the high efficiency of current SARS-CoV-2 mRNA vaccines in reducing COVID-19 morbidity and mortality, waning immunity and the emergence of resistant variants underscore the need for novel vaccination strategies. This study explores a heterologous mRNA/Modified Vaccinia virus Ankara (MVA) prime/boost regimen employing a trimeric form of the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein compared to a homologous MVA/MVA regimen. In C57BL/6 mice, the RBD was delivered during priming via an mRNA vector encapsulated in nanoemulsions (NE) or lipid nanoparticles (LNP), followed by a booster with a replication-deficient MVA-based recombinant virus (MVA-RBD). This heterologous mRNA/MVA regimen elicited strong anti-RBD binding and neutralizing antibodies (BAbs and NAbs) against both the ancestral SARS-CoV-2 strain and different variants of concern (VoCs). Additionally, this protocol induced robust and polyfunctional RBD-specific CD4 and CD8 T cell responses, particularly in animals primed with mLNP-RBD. In K18-hACE2 transgenic mice, the LNP-RBD/MVA combination provided complete protection from morbidity and mortality following a live SARS-CoV-2 challenge compared with the partial protection observed with mNE-RBD/MVA or MVA/MVA regimens. Although the mNE-RBD/MVA regimen only protects half of the animals, it was able to induce antibodies with Fc-mediated effector functions besides NAbs. Moreover, viral replication and viral load in the respiratory tract were markedly reduced and decreased pro-inflammatory cytokine levels were observed. These results support the efficacy of heterologous mRNA/MVA vaccine combinations over homologous MVA/MVA regimen, using alternative nanocarriers that circumvent intellectual property restrictions of current mRNA vaccine formulations.

Nanoemulsions and nanocapsules as carriers for the development of intranasal mRNA vaccines.

The global emergency of coronavirus disease 2019 (COVID-19) has spurred extensive worldwide efforts to develop vaccines for protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our contribution to this global endeavor involved the development of a diverse library of nanocarriers, as alternatives to lipid nanoparticles (LNPs), including nanoemulsions (NEs) and nanocapsules (NCs), with the aim of protecting and delivering messenger ribonucleic acid (mRNA) for nasal vaccination purposes. A wide range of prototypes underwent rigorous screening through a series of in vitro and in vivo experiments, encompassing assessments of cellular transfection, cytotoxicity, and intramuscular administration of a model mRNA for protein translation. As a result, two promising candidates were identified for nasal administration. One of them was a NE incorporating a combination of an ionizable lipid (C12-200) and cationic lipid (DOTAP), both intended to condense mRNA, along with DOPE, which is known to facilitate endosomal escape. This NE exhibited a size of 120 nm and a highly positive surface charge (+ 50 mV). Another candidate was an NC formulation comprising the same components and endowed with a dextran sulfate shell. This formulation showed a size of 130 nm and a moderate negative surface charge (-16 mV). Upon intranasal administration of mRNA encoding for ovalbumin (mOVA) associated with optimized versions of the said NE and NCs, a robust antigen-specific CD8 + T cell response was observed. These findings underscore the potential of NEs and polymeric NCs in advancing mRNA vaccine development for combating infectious diseases.

Modulating the immune response to SARS-CoV-2 by different nanocarriers delivering an mRNA expressing trimeric RBD of the spike protein: COVARNA Consortium.

Vaccines based on mRNA technology have revolutionized the field. In fact, lipid nanoparticles (LNP) formulated with mRNA are the preferential vaccine platform used in the fight against SARS-CoV-2 infection, with wider application against other diseases. The high demand and property right protection of the most potent cationic/ionizable lipids used for LNP formulation of COVID-19 mRNA vaccines have promoted the design of alternative nanocarriers for nucleic acid delivery. In this study we have evaluated the immunogenicity and efficacy of different rationally designed lipid and polymeric-based nanoparticle prototypes against SARS-CoV-2 infection. An mRNA coding for a trimeric soluble form of the receptor binding domain (RBD) of the spike (S) protein from SARS-CoV-2 was encapsulated using different components to form nanoemulsions (NE), nanocapsules (NC) and lipid nanoparticles (LNP). The toxicity and biological activity of these prototypes were evaluated in cultured cells after transfection and in mice following homologous prime/boost immunization. Our findings reveal good levels of RBD protein expression with most of the formulations. In C57BL/6 mice immunized intramuscularly with two doses of formulated RBD-mRNA, the modified lipid nanoparticle (mLNP) and the classical lipid nanoparticle (LNP-1) were the most effective delivery nanocarriers at inducing binding and neutralizing antibodies against SARS-CoV-2. Both prototypes fully protected susceptible K18-hACE2 transgenic mice from morbidity and mortality following a SARS-CoV-2 challenge. These results highlight that modulation of mRNAs immunogenicity can be achieved by using alternative nanocarriers and support further assessment of mLNP and LNP-1 prototypes as delivery vehicles for mRNA vaccines.

The role of nanoparticle format and route of administration on self-amplifying mRNA vaccine potency.

The efficacy of RNA-based vaccines has been recently demonstrated, leading to the use of mRNA-based COVID-19 vaccines. The application of self-amplifying mRNA within these formulations may offer further enhancement to these vaccines, as self-amplifying mRNA replicons enable longer expression kinetics and more potent immune responses compared to non-amplifying mRNAs. To investigate the impact of administration route on RNA-vaccine potency, we investigated the immunogenicity of a self-amplifying mRNA encoding the rabies virus glycoprotein encapsulated in different nanoparticle platforms (solid lipid nanoparticles (SLNs), polymeric nanoparticles (PNPs) and lipid nanoparticles (LNPs)). These were administered via three different routes: intramuscular, intradermal and intranasal. Our studies in a mouse model show that the immunogenicity of our 4 different saRNA vaccine formulations after intramuscular or intradermal administration was initially comparable; however, ionizable LNPs gave higher long-term IgG responses. The clearance of all 4 of the nanoparticle formulations from the intramuscular or intradermal administration site was similar. In contrast, immune responses generated after intranasal was low and coupled with rapid clearance for the administration site, irrespective of the formulation. These results demonstrate that both the administration route and delivery system format dictate self-amplifying RNA vaccine efficacy.

Manufacturing Considerations for the Development of Lipid Nanoparticles Using Microfluidics.

In the recent of years, the use of lipid nanoparticles (LNPs) for RNA delivery has gained considerable attention, with a large number in the clinical pipeline as vaccine candidates or to treat a wide range of diseases. Microfluidics offers considerable advantages for their manufacture due to its scalability, reproducibility and fast preparation. Thus, in this study, we have evaluated operating and formulation parameters to be considered when developing LNPs. Among them, the flow rate ratio (FRR) and the total flow rate (TFR) have been shown to significantly influence the physicochemical characteristics of the produced particles. In particular, increasing the TFR or increasing the FRR decreased the particle size. The amino lipid choice (cationic-DOTAP and DDAB; ionisable-MC3), buffer choice (citrate buffer pH 6 or TRIS pH 7.4) and type of nucleic acid payload (PolyA, ssDNA or mRNA) have also been shown to have an impact on the characteristics of these LNPs. LNPs were shown to have a high (>90%) loading in all cases and were below 100 nm with a low polydispersity index (≤0.25). The results within this paper could be used as a guide for the development and scalable manufacture of LNP systems using microfluidics.

Delivery of self-amplifying mRNA vaccines by cationic lipid nanoparticles: The impact of cationic lipid selection.

Self-amplifying RNA (SAM) represents a versatile tool that can be used to develop potent vaccines, potentially able to elicit strong antigen-specific humoral and cellular-mediated immune responses to virtually any infectious disease. To protect the SAM from degradation and achieve efficient delivery, lipid nanoparticles (LNPs), particularly those based on ionizable amino-lipids, are commonly adopted. Herein, we compared commonly available cationic lipids, which have been broadly used in clinical investigations, as an alternative to ionizable lipids. To this end, a SAM vaccine encoding the rabies virus glycoprotein (RVG) was used. The cationic lipids investigated included 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol), dimethyldioctadecylammonium (DDA), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), 1,2-dimyristoyl-3-trimethylammonium-propane (DMTAP), 1,2-stearoyl-3-trimethylammonium-propane (DSTAP) and N-(4-carboxybenzyl)-N,N-dimethyl-2,3-bis(oleoyloxy)propan-1-aminium (DOBAQ). Whilst all cationic LNP (cLNP) formulations promoted high association with cells in vitro, those formulations containing the fusogenic lipid 1,2-dioleoyl-sn-3-phosphoethanolamine (DOPE) in combination with DOTAP or DDA were the most efficient at inducing antigen expression. Therefore, DOTAP and DDA formulations were selected for further in vivo studies and were compared to benchmark ionizable LNPs (iLNPs). Biodistribution studies revealed that DDA-cLNPs remained longer at the injection site compared to DOTAP-cLNPs and iLNPs when administered intramuscularly in mice. Both the cLNP formulations and the iLNPs induced strong humoral and cellular-mediated immune responses in mice that were not significantly different at a 1.5 µg SAM dose. In summary, cLNPs based on DOTAP and DDA are an efficient alternative to iLNPs to deliver SAM vaccines.

Investigating the Impact of Delivery System Design on the Efficacy of Self-Amplifying RNA Vaccines.

messenger RNA (mRNA)-based vaccines combine the positive attributes of both live-attenuated and subunit vaccines. In order for these to be applied for clinical use, they require to be formulated with delivery systems. However, there are limited in vivo studies which compare different delivery platforms. Therefore, we have compared four different cationic platforms: (1) liposomes, (2) solid lipid nanoparticles (SLNs), (3) polymeric nanoparticles (NPs) and (4) emulsions, to deliver a self-amplifying mRNA (SAM) vaccine. All formulations contained either the non-ionizable cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or dimethyldioctadecylammonium bromide (DDA) and they were characterized in terms of physico-chemical attributes, in vitro transfection efficiency and in vivo vaccine potency. Our results showed that SAM encapsulating DOTAP polymeric nanoparticles, DOTAP liposomes and DDA liposomes induced the highest antigen expression in vitro and, from these, DOTAP polymeric nanoparticles were the most potent in triggering humoral and cellular immunity among candidates in vivo.

Using microfluidics for scalable manufacturing of nanomedicines from bench to GMP: A case study using protein-loaded liposomes.

Nanomedicines are well recognised for their ability to improve therapeutic outcomes. Yet, due to their complexity, nanomedicines are challenging and costly to produce using traditional manufacturing methods. For nanomedicines to be widely exploited, new manufacturing technologies must be adopted to reduce development costs and provide a consistent product. Within this study, we investigate microfluidic manufacture of nanomedicines. Using protein-loaded liposomes as a case study, we manufacture liposomes with tightly defined physico-chemical attributes (size, PDI, protein loading and release) from small-scale (1 mL) through to GMP volume production (200 mL/min). To achieve this, we investigate two different laminar flow microfluidic cartridge designs (based on a staggered herringbone design and a novel toroidal mixer design); for the first time we demonstrate the use of a new microfluidic cartridge design which delivers seamless scale-up production from bench-scale (12 mL/min) through GMP production requirements of over 20 L/h using the same standardised normal operating parameters. We also outline the application of tangential flow filtration for down-stream processing and high product yield. This work confirms that defined liposome products can be manufactured rapidly and reproducibly using a scale-independent production process, thereby de-risking the journey from bench to approved product.

Scalable Manufacturing Processes for Solid Lipid Nanoparticles.

BACKGROUND: Solid lipid nanoparticles offer a range of advantages as delivery systems but they are limited by effective manufacturing processes. OBJECTIVE: In this study, we outline a high-throughput and scalable manufacturing process for solid lipid nanoparticles. METHODS: The solid lipid nanoparticles were formulated from a combination of tristearin and 1,2-Distearoyl-phosphatidylethanolamine-methyl-polyethyleneglycol conjugate-2000 and manufactured using the M-110P Microfluidizer processor (Microfluidics Inc, Westwood, Massachusetts, US). RESULTS: The manufacturing process was optimized in terms of the number of process cycles (1 to 5) and operating pressure (20,000 to 30,000 psi). The solid lipid nanoparticles were purified using tangential flow filtration and they were characterized in terms of their size, PDI, Z-potential and protein loading. At-line particle size monitoring was also incorporated within the process. Our results demonstrate that solid lipid nanoparticles can be effectively manufactured using this process at pressures of 20,000 psi with as little as 2 process passes, with purification and removal of non-entrapped protein achieved after 12 diafiltration cycles. Furthermore, the size could be effectively monitored at-line to allow rapid process control monitoring and product validation. CONCLUSION: Using this method, protein-loaded solid lipid nanoparticles containing a low (1%) and high (16%) Pegylation were manufactured, purified and monitored for particle size using an at-line system demonstrating a scalable process for the manufacture of these nanoparticles.

A novel microfluidic-based approach to formulate size-tuneable large unilamellar cationic liposomes: Formulation, cellular uptake and biodistribution investigations.

Extensive research has been undertaken to investigate the effect of liposome size in vitro and in vivo. However, it is often difficult to generate liposomes in different size ranges that offer similar low polydispersity and lamellarity. Conventional methods used in the preparation of liposomes, such as lipid film hydration or reverse phase evaporation, generally give rise to liposomal suspensions displaying broad, multimodal size distribution combined with uncontrolled degree of lamellarity. In contrast, microfluidics allows highly homogeneous liposome dispersions to be produced and adjustment of microfluidic operating parameters (flow rate ratio (FRR) and total flow rate (TFR)) can offer size-tuning of liposomes (up to 300 nm, depending on the formulation). Herein, we demonstrate a novel method which allows the production of highly monodisperse, cationic liposomes over a wide particle size range (up to 750 nm in size). This is achieved through controlling the concentration of the aqueous buffer during production. Using this method, liposomes composed of 1,2-dioleoyl-sn-3-phosphoethanolamine (DOPE) and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or dimethyldioctadecylammonium (DDA) - DOPE:DOTAP and DOPE:DDA liposomes - of up to 750 nm were prepared and investigated. These investigations demonstrate that the in vitro cellular uptake of small (40 nm) and large (>500 nm) liposomes in bone marrow-derived macrophages (BMDM) is similar terms of percentage of liposome+ cells and mean fluorescence intensity (MFI). However, significant differences are observed in BMDM uptake when represented in terms of number of liposomes, liposome surface area or liposome internal volume. In vivo biodistribution studies in mice show that by creating small (<50 nm) liposomes we can modify the clearance rates of these liposomes from the injection site and increase accumulation to the draining lymphatics.

Mannosylation of LNP Results in Improved Potency for Self-Amplifying RNA (SAM) Vaccines.

Mannosylation of Lipid Nanoparticles (LNP) can potentially enhance uptake by Antigen Presenting Cells, which are highly abundant in dermal tissues, to improve the potency of Self Amplifying mRNA (SAM) vaccines in comparison to the established unmodified LNP delivery system. In the current studies, we evaluated mannosylated LNP (MLNP), which were obtained by incorporation of a stable Mannose-cholesterol amine conjugate, for the delivery of an influenza (hemagglutinin) encoded SAM vaccine in mice, by both intramuscular and intradermal routes of administration. SAM MLNP exhibited in vitro enhanced uptake in comparison to unglycosylated LNP from bone marrow-derived dendritic cells, and in vivo more rapid onset of the antibody response, independent of the route. The increased binding antibody levels also translated into higher functional hemagglutinin inhibition titers, particularly following intradermal administration. T cell assay on splenocytes from immunized mice also showed an increase in antigen specific CD8+ T responses, following intradermal administration of MLNP SAM vaccines. Induction of enhanced antigen specific CD4+ T cells, correlating with higher IgG2a antibody responses, was also observed. Hence, the present work illustrates the benefit of mannosylation of LNPs to achieve a faster immune response with SAM vaccines and these observations could contribute to the development of novel skin delivery systems for SAM vaccines.

PEG-copolymer-coated iron oxide nanoparticles that avoid the reticuloendothelial system and act as kidney MRI contrast agents.

In vitro experiments have shown the great potential of magnetic nanocarriers for multimodal imaging diagnosis and non-invasive therapies. However, their extensive clinical application is still jeopardized by a fast retention in the reticuloendothelial system (RES). The other issue that restrains their potential performance is slow degradation and excretion, which increases their risks of toxicity. We report a promising case in which multicore iron oxide nanoparticles coated with a poly(4-vinylpyridine) polyethylene glycol copolymer show low RES retention and high urinary excretion, as confirmed by single photon emission computerized tomography (SPECT), gamma counting, magnetic resonance imaging (MRI) and electron microscopy (EM) biodistribution studies. These iron oxide-copolymer nanoparticles have a high PEG density in their coating which may be responsible for this effect. Moreover, they show a clear negative contrast in the MR imaging of the kidneys. These nanoparticles with an average hydrodynamic diameter of approximately 20 nm were nevertheless able to cross the glomerulus wall which has an effective pore size of approximately 6 nm. A transmission electron microscopy inspection of kidney tissue revealed the presence of iron containing nanoparticle clusters in proximal tubule cells. This therefore makes them exceptionally useful as magnetic nanocarriers and as new MRI contrast agents for the kidneys.

Functional insights into the cellular response triggered by a bile-acid platinum compound conjugated to biocompatible ferric nanoparticles using quantitative proteomic approaches.

At present, bioferrofluids are employed as powerful multifunctional tools for biomedical applications such as drug delivery, among others. The present study explores the cellular response evoked when bile-acid platinum derivatives are conjugated with bioferrofluids by testing the biological activity in osteosarcoma (MG-63) and T-cell leukemia (Jurkat) cells. The aim of this work is to evaluate the biocompatibility of a bile-acid platinum derivative conjugated with multi-functional polymer coated bioferrofluids by observing the effects on the protein expression profiles and in intracellular pathways of nanoparticle-stimulated cells. To this end, a mass spectrometry-based approach termed SILAC has been applied to determine in a high-throughput manner the key proteins involved in the cellular response process (including specific quantitatively identified proteins related to the vesicular transport, cellular structure, cell cycle, biosynthetic process, apoptosis and regulation of the cell cycle). Finally, biocompatibility was evaluated and validated by conventional strategies also (such as flow cytometry, MTT, etc.).