Journal of Controlled Release

Targeted mRNA transport plays a crucial role in enhancing the therapeutic efficacy of the molecule, reducing its side effects, and minimizing off-target effects. Systemic administration of mRNA through lipid nanoparticles (LNPs) or extracellular vesicles (EVs) predominantly results in mRNA accumulation in the liver. We hypothesized that cardiac-specific EVs could more effectively target the transport of mRNA to the heart, in comparison to non-cardiac-specific EVs or LNPs. In mice, after intravenous administration, EVs from cardiac progenitor cells (CPC-EVs) were the most efficient to transport the modified mRNA, encoding vascular endothelial growth factor A (VEGF-A), to mouse heart, with minimal liver accumulation compared to non-cardiac-specific EVs or LNPs. Additionally, intracardiac injections of CPC-EVs not only demonstrate that they are the most adapted vehicle for interacting with heart tissue, delivering the mRNA to cells, and inducing maximal VEGF-A protein production, but RNA-seq analyses also revealed their minimal impact on overall gene expression, compared to LNPs or non-cardiac-specific EVs. Furthermore, immunofluorescence staining of CD31 and -SMA, markers of microvascular density, showed increased vessel density in mouse aortic rings following the delivery of VEGF-A mRNA via CPC-EVs. These findings suggest that CPC-EVs are superior in mRNA targeting to heart, communication with cardiac cells, and causing minimal transcriptomic changes during VEGF-A mRNA delivery. Therefore, CPC-EVs could be promising vectors for heart-targeted mRNA delivery, potentially reducing liver accumulation.

Monoclonal antibodies (mAbs) are an emerging class of therapeutics for the prevention and treatment of viral infections. Recent advances in mRNA/lipid nanoparticle (LNP) technology provide a potential new modality for the expression of mAbs in vivo, potentially bypassing the need for recombinant manufacturing of mAb proteins. In this study, we compared traditional infusion of neutralising mAbs targeting SARS-CoV-2 or influenza to mRNA-based induction of de novo mAb expression in treated mice. High serum concentrations of mAbs were achieved upon delivery of a single mRNA encoding both heavy and light chains via intravenous or intramuscular routes using prototypic LNP formulations. However, pharmacokinetics were heavily influenced by the induction of anti-drug antibody responses directed against the encoded mAbs, driving reductions in in vivo half-life and compromising protective capacity against SARS-CoV-2 Omicron BA.1 infection. Overall, mRNA/LNP delivery comprises a feasible and attractive pathway to speed the development and deployment of antiviral antibodies, however optimisation of LNP formulation, dosing and administration routes is required to maximise protective potential.

Angiopoietin ligands Ang1 and Ang2 and the Tie2 receptor tyrosine kinases form an endothelial signaling pathway regulating vascular homeostasis and controlling vessel permeability, inflammation and angiogenic responses. Whereas Ang1-mediated Tie2 activation reduces inflammation and endothelial permeability, its antagonist, Ang2 increases it. Increased plasma Ang2 levels are associated with poor outcomes in patients with acute lung injury (ALI), as well as in acute respiratory distress syndrome (ARDS). In the study presented here we tested the effect of a novel synthetic, nucleoside-modified mRNA-76 encoding for a hyperactive Ang1 derived fusion protein (COMP-Ang1) on attenuating post-inflammation vascular leakage. COMP-Ang1 mRNA was formulated into a cationic lipid nanoparticle (cLNP) using an optimized mixture of three different lipids and a microfluidic mixing technology. After intravenous injection, the respective mRNA-loaded LNPs were found to be delivered predominantly to the endothelial cells of the lung, while sparing other vascular beds. Also, the specific multimeric folding of the COMP-Ang1 protein complex appeared to be pivotal for its activity in preventing vascular leakage and in restoring the alveolar-endothelial barrier function in the inflamed and injured pulmonary vasculature. The mode of action of mRNA-76, such as its activation of the Tie2 signal transduction pathway, was tested by pharmacological studies in vitro and in vivo by systemic administration in respective mouse models. mRNA-76 was found to prevent lung vascular leakage/lung edema as well as neutrophil infiltration in an LPS-challenging model.

Exposure to nanoparticles (NPs) is frequently associated with adverse cardiovascular effects. In contrast, NPs in nanomedicine hold great promise for precise lung-specific drug delivery, especially considering the extensive pulmonary capillary network that facilitates interactions with bloodstream-suspended particles. Therefore, exact knowledge about interactions and effects of engineered NPs with the pulmonary microcirculation are instrumental for future application of this technology in patients. To unravel the real-time dynamics of intravenously delivered NPs and their effects in the pulmonary microvasculature, we employed intravital microscopy of the mouse lung. PEG amine-modified quantum dots (aQDs) with a low potential for biomolecule and cell interactions and carboxyl-modified quantum dots (cQDs) with a high interaction potential were used, representing two different NP subtypes. Only aQDs triggered rapid neutrophil recruitment in microvessels and their subsequent recruitment to the alveolar space. Application of specific inhibitors revealed that the aQDs induced neutrophil recruitment was linked to cellular degranulation, TNF-, and DAMP release into the circulation, particularly extracellular ATP (eATP). Stimulation of the ATP-gated P2X7R induced the expression of E-selectin on microvascular endothelium with the subsequent E-selectin depended neutrophilic immune response. Leukocyte integrins (LFA-1 and MAC-1) mediated adhesion and reduction in neutrophil crawling velocity on the vascular surface. In summary, this study unravels the complex cascade of neutrophil recruitment during NP-induced sterile inflammation. Thereby we demonstrate novel adverse effects for NPs in the pulmonary microcirculation and provide critical insights for optimizing NP-based drug delivery and therapeutic intervention strategies, to ensure their efficacy and safety in clinical applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/584398v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@d10acborg.highwire.dtl.DTLVardef@1bbfe7org.highwire.dtl.DTLVardef@1d3e415org.highwire.dtl.DTLVardef@2328de_HPS_FORMAT_FIGEXP M_FIG C_FIG

Ultrasound-activatable drug-loaded nanocarriers enable noninvasive and spatiotemporally-precise on-demand drug delivery throughout the body. However, most systems for ultrasonic drug uncaging utilize cavitation or heating as the drug release mechanism and often incorporate relatively exotic excipients into the formulation that together limit the drug-loading potential, stability, and clinical translatability and applicability of these systems. Here we describe an alternate strategy for the design of such systems in which the acoustic impedance and osmolarity of the internal liquid phase of a drug-loaded particle is tuned to maximize ultrasound-induced drug release. No gas phase, cavitation, or medium heating is necessary for the drug release mechanism. Instead, a non-cavitation-based mechanical response to ultrasound mediates the drug release. Importantly, this strategy can be implemented with relatively common pharmaceutical excipients, as we demonstrate here by implementing this mechanism with the inclusion of a few percent sucrose into the internal buffer of a liposome. Further, the ultrasound protocols sufficient for in vivo drug uncaging with this system are achievable with current clinical therapeutic ultrasound systems and with intensities that are within FDA and society guidelines for safe transcranial ultrasound application. Finally, this current implementation of this mechanism should be versatile and effective for the loading and uncaging of any therapeutic that may be loaded into a liposome, as we demonstrate for four different drugs in vitro, and two in vivo. These acoustomechanically activatable liposomes formulated with common pharmaceutical excipients promise a system with high clinical translational potential for ultrasonic drug uncaging of myriad drugs of clinical interest. One Sentence SummaryIncorporating a few percent sucrose into a liposome transforms it into an immediately translatable vehicle for noninvasive, on-demand ultrasound-targeted drug delivery.

Messenger RNA (mRNA) vaccines using lipid nanoparticles (LNPs) are well-established and globally approved with acceptable safety profiles for preventing respiratory disease. Other mRNA-LNP product concepts are also emerging as novel treatments for broader clinical use. Here, we describe mRNA-LNP vaccine tissue distribution and kinetics after intramuscular dosing using three products formulated with same LNP matrix: mRNA-1273 (Spikevax), mRNA-1647 (a candidate cytomegalovirus [CMV] vaccine), and a reporter mRNA (nascent peptide-luciferase) drug product. Consistent biodistribution patterns were observed across studies: tissues with highest exposures were the injection site, draining lymph nodes, and spleen, with minimal distribution to non-lymphoid tissues. Vaccine components cleared rapidly from circulation and tissues, with complete elimination simulated to occur by [~]2 weeks. Following mRNA-1273 vaccination, Spike protein levels were transiently observed (elimination <5 days) and did not accumulate with repeated dosing. The ionizable lipid in the LNP matrix, Lipid H, underwent biotransformation and was excreted renally and hepatically, with no human-specific metabolites. Collectively, these results indicate that the LNP composition, not mRNA cargo, governs biodistribution. Furthermore, in a SARS-CoV-2 infection-free model, there was no evidence of Spike protein persistence. Overall, the data establish a framework that justifies leveraging biodistribution data across products and supports eliminating redundant animal studies.

The widespread use of Covid-19 mRNA vaccines has highlighted the need to address rare but concerning side effects. Systemic off-target gene expression has been identified as a primary cause of acute adverse reactions and side effects associated with nucleoside-modified mRNA vaccines. In this study, we incorporated the permanent cationic lipid Dotap component into the mRNA-LNP formula associated with the FDA-approved mRNA vaccine Comirnaty to create a novel positively charged LNP carrier for mRNA vaccine delivery. Using the optimized LNP formula to prepare SARS-Cov-2 Spike mRNA vaccines for immunogenicity testing, Balb/c mice exhibited improved immunogenicity kinetics with initial antibody titers being lower but showing a continuous upward trend, ultimately reaching levels comparable to those of control mRNA vaccines 8 weeks after boost immunization. The mRNA vaccines encapsulated in the modified LNPs have demonstrated a superior safety profile in respect to systemic delivery of LNP constituents, off-target gene expression, and the systemic pro-inflammatory stimulation. Consequently, it may represent a safer alternative of conventional mRNA-LNP vaccines.

Niemann-Pick Disease Type C (NPC) is a severe neurovisceral disorder that is pathophysiologically characterized by intracellular transport abnormalities leading to cytoplasmic accumulation of lipids such as cholesterol and multiple sphingolipids, including sphingosine. The compound 2-hydroxypropyl-{beta}-cyclodextrin (HP{beta}CD) is a compound with high cholesterol complexation capacity and is currently under clinical investigation for the treatment of NPC. However, due to its short blood half-life, high doses are required to produce a therapeutic effect. It has been reported in mice that HP{beta}CDs circulation time and efficacy can be improved by increasing its size via polymerization, but the biodegradable nature of these systems did not allow the contribution of the macromolecule to the activity to be determined. In this work, stable forms of polymerized HP{beta}CD were generated (via epichlorohydrin crosslinking) to investigate their in vitro mechanisms of action and in vivo effects. Crosslinked CDs (8-312 kDa) displayed a 10-fold greater complexation capacity towards cholesterol than monomeric HP{beta}CD but were taken up by cells to a lower extent (in a size-dependent fashion), resulting in an overall comparable in vitro effect on intracellular cholesterol accumulation that was dependent on cholesterol complexation. When tested in vivo, the crosslinked 19.3 kDa HP{beta}CD exhibited a longer terminal half-life than the monomeric HP{beta}CD. However, it did not increase the life span of Npc1 mice, possibly due to reduced organ penetration and brain diffusion consequence of its large molecular weight. This could be circumvented by the application of magnetic resonance imaging-guided low intensity-pulsed focused ultrasound (MRIg-FUS), which increased the brain penetration of the CD. In conclusion, stable forms of polymerized HP{beta}CD constitute valuable tools to elucidate CDs mechanism of action. Moreover, the use of MRIg-FUS to maximize CDs tissue penetration warrants further investigation, as it may be key to harnessing CDs full therapeutic potential in the treatment of NPC. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/230136v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@3dbaf1org.highwire.dtl.DTLVardef@bc255dorg.highwire.dtl.DTLVardef@390e7borg.highwire.dtl.DTLVardef@1e5e5c5_HPS_FORMAT_FIGEXP M_FIG C_FIG The 2-hydroxypropyl-{beta}-cyclodextrin (HP{beta}CD) is a well-established pharmaceutical excipient that can complex cholesterol and is currently under clinical investigation to treat Niemann-Pick Disease Type C (NPC). However, high doses of the drug are needed to achieve a therapeutic effect. Using stable and long circulating crosslinked HP{beta}CDs, this study attempts to further understand the mechanisms behind CDs activity.

Jaundice, the clinical hallmark of infection-associated liver dysfunction, reflects altered membrane organization of the canalicular pole of hepatocytes and portends poor outcomes. Mice lacking phosphoinositide 3-kinase-{gamma} (PI3K{gamma}) are protected against membrane disintegration and hepatic excretory dysfunction. However, they exhibit a severe immune defect that hinders neutrophil recruitment to sites of infection. To exploit the therapeutic potential of PI3K{gamma} inhibition in sepsis, a targeted approach to deliver drugs to hepatic parenchymal cells without compromising other cells, in particular immune cells, seems warranted. Here we demonstrate that nanocarriers functionalized through DY-635, a fluorescent polymethine dye and a ligand of organic anion transporters can selectively deliver therapeutics to hepatic parenchymal cells. Applying this strategy to a murine model of sepsis, we observed PI3K{gamma}-dependent restoration of biliary canalicular architecture, maintained excretory liver function, and improved survival without impairing host defense mechanisms. This strategy carries the potential to expand targeted nanomedicines to disease entities with systemic inflammation and concomitantly impaired barrier functionality. One-Sentence SummaryDye-functionalized liposomes allow delivery of a PI3K{gamma} inhibitor to hepatocytes to resolve sepsis-related liver failure without off-target effects on immunity. Graphical AbstractTargeting PI3K{gamma} in hepatocytes by dye-functionalized liposomes to resolve sepsis-related liver failure without off-target effects on immunity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/427305v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@d52fdeorg.highwire.dtl.DTLVardef@39bf3aorg.highwire.dtl.DTLVardef@13999c7org.highwire.dtl.DTLVardef@9edfa0_HPS_FORMAT_FIGEXP M_FIG C_FIG

Chronic inflammation, characterized by the infiltration of macrophages and the heightened release of pro-inflammatory cytokines, is the underlying cause of the pathogenesis of many critical diseases. Therapeutic interventions for controlling inflammation via gene knockdown of inflammatory mediators have emerged as a promising approach for regulating uncontrolled inflammation. This study explores the potential of siIL-1{beta}-anti-CD44-Liposomes (SIL) as a potent anti-inflammatory therapy against pro-inflammatory RAW264.7 macrophages via gene specific knockdown of IL-1{beta} mRNA through RNAi, and the subsequent down-regulation of the pro-inflammatory cytokine loop. The designed SIL exhibited a uniform size of 131.1 {+/-} 0.5 nm with a quasi-spherical morphology and sustained release of siIL-1{beta} within 24 hours. The reduction in pro-inflammatory cytokines like IL-1{beta}, TNF-, and IL-6 and inflammatory enzymes iNOS and COX-2; and the simultaneous increase in the anti-inflammatory cytokine IL-4, is indicative of the formulations therapeutic efficacy in reducing inflammation at a cellular level. The effects of SIL on the Macrophage-T cell crosstalk also uncovers the liposomes efficacy in reducing cytokine-mediated T cell effector functions. The nuanced effects of siIL-1{beta}-anti-CD44-Liposomes on in-vivo model of chronic inflammation underscore their potential for precise therapeutic interventions in inflammatory conditions, with multifaceted anti-inflammatory effects on tissue levels and cytokine levels. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/683015v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@f4d0f9org.highwire.dtl.DTLVardef@c3c24aorg.highwire.dtl.DTLVardef@8c115org.highwire.dtl.DTLVardef@bc863d_HPS_FORMAT_FIGEXP M_FIG Schematic representation of the study: CD44 receptors are elevated in LPS activated macrophages, which can be targeted by using anti-CD44 Liposomes, for RNA therapy. IL-1 knockdown via siRNA leads to lower inflammatory nature of macrophages, compromising its the antigen presentation and T-cell activation. This lowers the cytokine storm in inflammatory milieu and lower tissue damage can be achieved. Created with BioRender.com. C_FIG

Treatment of neurological disorders is partly impeded by the size of large pharmacological agents which are thereby unable to bypass the blood-brain barrier (BBB). Focused ultrasound (FUS) in conjunction with systemically administered microbubbles has been shown to safely, non-invasively and transiently open the BBB, allowing the passage of large biomolecules to the brain parenchyma through the otherwise impermeable barrier. This pilot study assessed the feasibility of FUS-mediated delivery of an anti-alpha-synuclein (-syn) monoclonal antibody (mAb) in Parkinsons disease (PD) mouse models that exhibit -syn aggregates. Mice (n=21) underwent FUS on a weekly basis over the course of 2-3 weeks, followed by a one-month survival period. MRI and microscopy were performed to confirm BBB opening with FUS and visualize antibody delivery. Safety was assessed in vivo using passive cavitation detection and immunohistochemistry to evaluate microglial and astrocyte activity ex vivo. It was found that treatment sessions for multiple FUS sessions of targeted antibody delivery was feasible in alpha-synuclein models facilitating immunotherapeutics for PD.

Lung surfactant dysfunction has a critical role in the pathophysiology of acute respiratory distress syndrome (ARDS). Yet, efforts to treat ARDS patients with liquid instillations of exogenous surfactant have so far failed. One of the ongoing challenges in surfactant therapy is obtaining a homogeneous distribution of surfactant within the lungs despite an inherent tendency to non-uniform spreading, owing amongst others to the influence of gravity. Here, we show that liquid foam therapy (LiFT), where surfactant is foamed prior to intratracheal administration, may improve notably surfactant distribution while maintaining safety and efficacy. We first show quantitatively that a foamed surrogate surfactant solution distributes more uniformly in ex vivo pig lungs compared to endotracheal instillations of the liquid solution, while maintaining pulmonary airway pressures within a safe range. Next, we demonstrate that a foamed commercial surfactant preparation (Infasurf) is effective in an established in vivo rat lung lavage model of ARDS. Our results suggest that LiFT may be more effective than liquid instillations for treating ARDS and serve as a proof-of-principle towards large animal and clinical trials.

RNA-based medicines are ideally suited for precise modulation of T cell phenotypes in anti-cancer immunity, in autoimmune diseases and for ex vivo modulation of T-cell-based therapies. Therefore, understanding productive siRNA uptake to T cells is of particular importance. Most studies used unmodified siRNAs or commercially available siRNA with undisclosed chemical modifications patterns to show functionality in T cells. Despite being an active field of research, robust siRNA delivery to T cells still represents a formidable challenge. Therefore, a systematic approach is needed to further optimize and understand productive siRNA uptake pathways to T cells. Here we compared conjugate-mediated and nanoparticle-mediated delivery of siRNAs to T cells in the context of fully chemically modified RNA constructs. We showed that lipid-conjugate-mediated delivery outperforms lipid-nanoparticle-mediated and extracellular-vesicle-mediated delivery in activated T cells ex vivo. Yet, ex vivo manipulation of T cells without the need of activation is of great therapeutic interest for CAR-T, engineered TCR-T and allogeneic donor lymphocyte applications. We are first to report productive siRNA uptake into resting T cells using lipid-conjugate mediated delivery. Interestingly, we observed strong dependence of silencing activity on lipid-conjugate-identity in resting T cells but not in activated T cells. This phenomenon is consistent with our early uptake kinetics data. Lipid-conjugates also enabled delivery of siRNA to all mononuclear immune cell types, including both lymphoid and myeloid lineages. These findings are expected to be broadly applicable for ex vivo modulation of immune cell therapies.

Polyethylene glycol (PEG) has been extensively utilized in food, cosmetics, and pharmaceutical fields, especially in the realm of nanomedicines, where it serves as a pivotal excipient for extending the nanoparticles circulation half-life. Contrary to its historical perception as non-immunogenic, pre-existing anti-PEG antibodies have been widely detected in human who even have never been exposed to PEGylated therapeutics, which considered to be associated with serious side effects of PEGylated nanomedicines including infusion reactions and other hypersensitive reactions. Herein, we elucidated the prevalence and distribution characteristics of pre-existing anti-PEG antibodies in 2074 human blood samples, and investigated its binding with PEG. Pre-existing anti-PEG antibodies were found to primarily recognize the PEG terminus, especially methoxy, which is the only PEG terminus contained in currently marketed PEGylated nanomedicines. While hydroxy PEG (OH-PEG) significantly evaded binding with pre-existing anti-PEG antibodies among most clinical samples. Noteworthily, substituting OH-PEG for MeO-PEG significantly mitigated complement activation of lipid nanoparticle (LNP) caused by pre-existing anti-PEG antibodies, thereby markedly enhancing stability and reducing mRNA leakage in human serum. Additionally, LNP modified with OH-PEG exhibited reduced immunogenicity, which was crucial for repeated drug administrations. The present work elucidated the crucial role of OH-PEG in evading human pre-existing anti-PEG antibodies, and discovered that the current pre-clinical studies inadequately simulated the biological effects of clinical pre-existing anti-PEG antibodies on such formulations through interspecies study, which had a profound impact on clinical translation of PEGylated nanomedicines.

Zeolitic Imidazolate Framework-8 (ZIF-8) is becoming popular in research for its potential in antigen protection and for providing a thermally stable, slow-release platform. While papers applying these materials for immunological applications are aplenty in literature, studies that explore the biosafety of ZIF-8 in mammals--especially when administered intranasally--are not well represented. We checked the body clearance of uncoated and ZIF-coated liposomes and observed that the release slowed as ZIF-8 is easily degraded by mucosal fluid in the nasal cavity. We delivered varying doses of ZIF-8, checked their short- and long-term effects on diagnostic proteins found in blood serum, and found no noticeable differences from the saline control group. We also studied their lung diffusing capacity and tissue morphology; neither showed significant changes in morphology or function. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/523104v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@c2c72forg.highwire.dtl.DTLVardef@1a2ee70org.highwire.dtl.DTLVardef@1d3fdf4org.highwire.dtl.DTLVardef@c5a43d_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO General overview of the investigation C_FIG

The blood-brain barrier (BBB) limits drug delivery to the brain and the movement of neurological biomarkers between the brain and blood. Focused ultrasound-mediated blood-brain barrier opening (FUS-BBBO) noninvasively opens the BBB, allowing increased molecular transport to and from the brain parenchyma. Despite being initially developed as a drug delivery method, FUS-BBBO has shown promise both as a neuroimmunotherapeutic modality, and as a way of improving neurological disease diagnosis via amplification of disease biomarker circulation. Recently, the role of extracellular vesicles (EVs) in modulating the neuroimmune system and in improving biomarker detection has sparked research interest. However, despite their potential role in modulating FUS-BBBO-induced neuroimmunotherapy and their ability to improve biomarker specificity after treatment, the EV response to FUS-BBBO had not been extensively characterized prior to this study. In this study, we investigated the effect of FUS-BBBO on EV concentration and content in the serum of mice and Alzheimers Disease (AD) patients. We observed a 164% increase in murine EV concentration one hour after treatment, as well as an increase in EV RNA associated with FUS-BBBO neuroimmunotherapy. Patient EV concentration also increased one hour after treatment and was dependent on the volume of BBB opening three days post-treatment. Furthermore, EV isolation was found to significantly enhance the amplification of AD biomarker detection by FUS-BBBO. Overall, we present the first evidence of altered murine and AD patient EV concentration and content in response to FUS-BBBO, providing evidence of EVs role within FUS-BBBO neuroimmunotherapy as well as their utility in improving FUS-BBBO biomarker amplification.

Improving siRNA delivery to the central nervous system (CNS) is a major focus for treating the numerous debilitating neurological conditions which have a genetic basis. Here, we present an albumin-binding siRNA based on an amphiphilic dendrimer conjugate (D-siRNA). We demonstrate that D-siRNA achieves effective and homogeneous delivery throughout the CNS following administration into the cerebrospinal fluid (CSF). In mice, a single CSF administration of D-siRNA resulted in potent and durable gene silencing across various brain regions, with effects lasting six months without detectable toxicity. We validate its utility in larger rodents (rats) using intrathecal administration--a clinically relevant route--showing effective and broad delivery and robust silencing. Benchmarking against other clinically relevant siRNA delivery scaffolds revealed that D-siRNA provides comparable delivery and efficacy, with more efficient conversion of gross uptake to functional uptake. These findings support the use of albumin-binding conjugates for brain delivery, and position D-siRNA as a safe, effective, and durable platform for gene silencing in the CNS.

The exploration and identification of safe and effective vaccines for the SARS-CoV-2 pandemic has captured the worlds attention and remains an ongoing issue in order to protect against emerging variants of concern (VoCs) while generating long lasting immunity. Here, we report the synthesis of a novel messenger ribonucleic acid (mRNA) encoding the spike protein in a lipid nanoparticle formulation (LNP) (STI-7264) that generates robust humoral and cellular immunity following immunization of C57Bl6 mice. In efforts to continually improve immunity, a lymphatic drug delivery device (MuVaxx) was engineered and tested to modulate immune cells at the injection site (epidermis and dermis) and draining lymph node (LN) to elicit adaptive immunity. Using MuVaxx, immune responses were elicited and maintained at a 10-fold dose reduction compared to traditional intramuscular (IM) administration as measured by anti-spike antibodies, cytokine producing CD8 T cells, and neutralizing antibodies against the Washington (Wild Type, WT) and South African (beta) variants. Remarkably, a 4-fold elevated T cell response was observed in MuVaxx administered vaccination as compared to that of IM administered vaccination. Thus, these data support further investigation into STI-7264 and lymphatic mediated delivery using MuVaxx for SARS-CoV-2 and VoCs vaccines.

ObjectiveThe current study aims to fill a gap in knowledge on the effects of focused ultrasound (FUS)-mediated blood-brain-barrier (BBB) modulation on the proliferation and development of oligodendrocyte progenitor cells (OPCs). Researchers established that FUS combined with intravenous microbubbles can modulate the BBB in a controlled, reversible, localized, and non-invasive manner to facilitate the delivery of intravenous therapeutics to the brain. Over a decade ago, we discovered that, even without intravenous therapeutics, FUS-BBB modulation stimulates elements of brain repair, including hippocampal neurogenesis. MethodsIn adult mice, FUS-BBB modulation was targeted unilaterally to the hippocampus and proliferation of OPCs was quantified at 1, 4, 7, and 10 days post-FUS. Mature oligodendrocytes were quantified at 30 days post-FUS. OPC proliferation was assessed at 7 days post-FUS, and mature oligodendrocytes at 30 days. ResultsThe proliferation of hippocampal OPCs was increased by 6.8-fold and 2.3-fold between 1 and 4 days post-sonication, respectively, resulting in a 5.3-fold increase in mature oligodendrocytes one month later. To test the robustness of oligodendrogenesis following FUS-BBB modulation, the striatum was targeted as a second brain region with an independent experimental design. In line with hippocampal results, striatal FUS-BBB modulation promoted the generation of OPCs by 3.9-fold during the first week, leading to a 5.2-fold increase in oligodendrogenesis 30 days post-treatment. InterpretationWe conclude that FUS-BBB modulation in the hippocampus and striatum promotes oligodendrogenesis by stimulating the proliferation of OPCs and being permissive to their maturation. HighlightsO_LIBeyond the potential for the delivery of therapeutics to the brain, the modulation of the BBB by FUS can stimulate regenerative effects, including oligodendrogenesis. C_LIO_LIFUS-BBB modulation induced a significant proliferation of OPCs which resulted in increases in oligodendrogenesis of 5.3-fold in the hippocampus and 6.7-fold in the striatum C_LI

Neuroinflammation is a pathological process mediated through immune cell activation and pro-inflammatory cytokine release, resulting in neuronal cell death. In the central nervous system (CNS), neuroinflammation is a characteristic feature underlying the onset and progression of retinal and neurodegenerative diseases. Targeting neuroinflammation to reduce neuronal cell death and protect against visual and cognitive declines is therefore a key therapeutic strategy. However, due to the complex and multi-faceted nature of these diseases, to date there has been little therapeutic success with single target approaches insufficient to tackle widespread and multi-pathway inflammatory cascades. Furthermore, as the retina and brain reside within immune-privileged environments, a major challenge in treating these diseases is producing and delivering a therapeutic that, in itself, does not exacerbate inflammation. Extracellular vesicles (EV), derived from red blood cells (RBC EV), present a promising solution to overcome these hurdles, due to their innate ability to cross blood-tissue barriers, biocompatible nature, and their broad anti-inflammatory properties to modulate complex neuroinflammatory pathways. This study therefore investigated the therapeutic potential of RBC EV in mediating neuroinflammation using an in-vivo photo-oxidative damage model of retinal degeneration as a model for CNS neuroinflammation. In this work, we developed a novel incubation pipeline using N1 medium supplement and superoxide dismutase (SOD) supplementation to promote the production of safe, neuroprotective, and anti-inflammatory RBC EV. Delivery of RBC EV in vivo, was shown to be safe with strong penetration across all retinal layers. Further, therapeutic administration of RBC EV via local intravitreal injection significantly reduced inflammation and cell death and preserved retinal function. Notably, strong safety and therapeutic efficacy was also demonstrated in the retina following systemic (intraperitoneal) administration, highlighting a potential game-changing approach for less-invasive therapeutic delivery to the CNS. Finally, multi-omic analyses and in vitro findings supported an anti-inflammatory mechanism-of-action, with RBC EV modulating pro-inflammatory cytokine release, including those known to be involved in the pathogenesis of retinal and neurodegenerative diseases. Taken together, these findings highlight the broad applicability of RBC EV in treating neuroinflammation in the CNS, presenting a scalable and effective treatment approach for these currently untreatable diseases.