Search Results (30)

Objectives: Membrane-enveloped virus-like particles (VLPs) constitute a versatile vaccine platform allowing for the display of heterologous viral surface antigens. The density of displayed antigens is paramount for the efficient elicitation of a strong cellular and humoral immune response. SARS-CoV-2 spike protein variants with engineered cytoplasmic tails (CTs) were generated to enhance decoration efficiency on the surface of VLPs formed by the HIV core protein Gag. These HIV (SARS-CoV-2) chimeric particles serve as a vaccine component prototype. Methods: Spike variants were first analyzed for cellular and surface expression as well as incorporation into extracellular vesicles (EVs) and VLPs using flow cytometric analysis and Western blot analysis. Receptor binding, fusogenicity, i.e., mediating the fusion of spike-positive with receptor-containing membranes, and the proteins’ potential to mediate lentiviral vector gene transduction into susceptible target cells was examined by employing syncytia-formation assays and vector titration experiments. The display of a neutralization-sensitive epitope was examined utilizing immuno-precipitation using a neutralizing antibody. Results: All four variants were shown to be cell-surface expressed, to recruit the cognate receptor, to mediate membrane fusion and cell entry of lentiviral pseudotype vector particles and to decorate VLPs and EVs. However, the spike variant encompassing a truncated CT derived from the gibbon ape leukemia virus (GaLV) transmembrane (TM) envelope protein was most efficiently incorporated into HIV Gag-formed VLPs. All variants exposed a neutralization-sensitive epitope in the receptor binding domain. Conclusions: Engineering of the CTs of viral surface antigens can enhance VLP decoration, while required functionality of the ecto-domain such as receptor recognition, fusogenicity and neutralization-sensitive epitope presentation are not abrogated. This indicates the preservation of the structural integrity of the antigen required to elicit a neutralizing humoral immunity upon vaccination. The identified truncated CT of GaLV TM may be of utility to improve the incorporation of other viral surface antigens into a variety of membrane-enveloped VLPs derived from a range of different parental viruses. Full article

The emergence of membrane boundaries represents a decisive transition in the origin of life, yet the molecular nature of the earliest abiotic membranes remains uncertain. Existing models based on simple fatty acids, while experimentally tractable, often lack the environmental robustness required under fluctuating prebiotic conditions. Furthermore, the absence of clear pathways linking primitive amphiphiles to later phospholipid systems highlights the need for chemically continuous intermediate frameworks. Here, we explore borate-bridged amphiphile–carbohydrate conjugates as plausible intermediates between simple prebiotic surfactants and modern lipid bilayers. These conjugates arise from low-molecular-weight polyols—including glycerol, butane-1,2,3,4-tetraol, pentane-1,2,3,4,5-pentaol, and hexane-1,2,3,4,5,6-hexitol—reacting with long-chain alkyl ethers and borate species under alkaline conditions, enabling reversible coupling to ribose and other vicinal diol-containing sugars. This chemistry integrates three essential properties for early compartmentalization: hydrolytically robust ether-linked hydrophobic domains, multivalent and highly hydrated headgroups, and environmentally responsive borate coordination. Comparative physicochemical analysis suggests that single-tail alkylglycerol derivatives preferentially form micelles and interfacial films, while di- and tri-tail tetritol and pentitol conjugates favor lamellar assemblies and vesicle formation across realistic prebiotic pH and salinity ranges. Hexitol-based systems, particularly those bearing three hydrophobic chains, may act as membrane-stabilizing components that enhance rigidity and reduce permeability under extreme conditions. We propose that heterogeneous mixtures dominated by two-tail polyol diethers, supplemented by tri-tail stabilizers and surface-active alkylglycerols, could provide mechanically robust, pH-tunable, and sugar-decorated abiotic membranes. Such borate-mediated amphiphiles offer a chemically coherent framework linking carbohydrate stabilization, ether lipid persistence, and dynamic self-assembly, potentially representing a transitional stage in the evolutionary pathway from primitive amphiphilic films to biologically encoded membranes. Full article

Background/Objectives: Extracellular Vesicles (EVs) have shown great promise as diagnostic and therapeutic tools, as well as pharmacological nanocarriers. Various strategies are being explored to develop EVs for monitoring, imaging, loading with pharmacological agents, and surface decoration with tissue-specific ligands. EVs derived from Mesenchymal Stromal Cells (MSC-EVs) are of particular interest both as therapeutics per se and as natural nanocarriers for the targeted delivery of biotherapeutics. Methods: In this study, we investigated the ability of different tags to deliver a reporter protein into canine MSC-EVs with the aim of identifying the most effective endogenous loading mechanism. To this aim, canine MSCs were engineered to express the Green Fluorescent Protein (GFP) fused to CD63, Syntenin-1, TSG101, and the palmitoylation signal of Lck, which were expected to promote GFP incorporation into EVs. Overexpression of tagged GFP in canine MSCs was confirmed by Western blotting and examined by confocal microscopy and transmission electron microscopy to map intracellular localization. Results: All tags were able to deliver GFP into EVs. Syntenin-1 showed relatively high loading efficiency and secretion index but exhibited a diffuse localization pattern in the transfected cells. The palmitoylation signal showed low loading efficiency and localization specificity. TSG101 displayed a morphological pattern consistent with specific localization in endosomal structures, but its low expression level prevented further evaluations. Finally, CD63 showed the highest expression efficiency, as GFP-CD63 levels were approximately 5-fold higher than untagged GFP. Conclusions: In conclusion, CD63 emerged as the most suitable tag for canine MSC-EV engineering. Indeed, even if the secretion index favours Syntenin-1, CD63’s higher abundance in the lysate suggests its substantial post-secretion uptake. Further studies aimed at elucidating CD63’s specific contribution and identifying the domains involved in vesicle trafficking could provide valuable insights into EV bioengineering. Full article

Autophagy is a conserved catabolic pathway that degrades intracellular cargo through the lysosomal system. Canonically, this process is orchestrated by the autophagy-related (Atg)5-Atg7 conjugation system, which facilitates the formation of microtubule-associated protein 1 light chain 3 (LC3)-decorated double-membrane vesicles known as autophagosomes. However, accumulating evidence has revealed the existence of an Atg5-Atg7-independent, alternative autophagy pathway that still relies on upstream regulators such as the unc-51 like autophagy activating kinase 1 (Ulk1) kinase and the Beclin1 complex. In this review, we provide a comprehensive overview of the role of the Beclin1 complex in canonical autophagy and highlight its emerging importance in alternative autophagy. Notably, the recent identification of transmembrane protein 9 (TMEM9) as a lysosomal protein that interacts with Beclin1 to promote member RAS oncogene family 9 (Rab9)-dependent autophagosome formation has significantly advanced our understanding of alternative autophagy regulation. Furthermore, this Ulk1-Rab9-Beclin1-dependent mitophagy has been shown to mediate to mitochondrial quality control in the heart, thereby contributing to cardioprotection under ischemic and metabolic stress conditions. We further examine how the Beclin1 complex functions as a central scaffold in both canonical and alternative autophagy, with a focus on its modulation by novel factors such as TMEM9 and the potential therapeutic implications of these regulatory mechanisms. Full article

Background/Objectives: Extracellular vesicles (EVs) are involved in cell-to-cell communication and delivery of signaling molecules and represent an interesting approach in targeted therapy. This project focused on EV-mediated facilitation and cell-specific delivery of effector antimiR molecules carried by biologically produced gold nanoparticles (AuNPs). Methods: First, we loaded EVs derived from cancer cells 4T1 with AuNPs-antimiR. The AuNPs were also decorated with or without transferrin (Tf) molecules. We examined parental cell-specific delivery of the AuNPs-Tf-antimiR within monocultures as well as co-cultures in vitro. Subsequently, we used autologous EVs containing AuNPs-Tf-antimiR to target tumor cells in a xenograft tumor model in vivo. Efficacy of the antimir transfer was assessed by qPCR and apoptosis assessment. Results: In vitro, EVs loaded with AuNPs-antimiR were internalized only by the parental cells and the AuNPs-antimiR transfer was successful and effective only in EVs that were decorated with Tf. We achieved effective delivery of the antimiR molecule into cancer cells in vivo, which was proved by specific silencing of the target oncogenic miRNA as well as induction of cancer cells apoptosis. Conclusions: EVs represent an interesting and potent way for targeted cargo delivery and personalized medicine. On the other hand, there are various safety and efficacy challenges that remain to be addressed. Full article

During sexual reproduction, the freshwater ciliate Tetrahymena thermophila sheds membrane-bound vesicles into the extracellular environment (cEMVs: ciliary extracellular micro-vesicles). We provide evidence that 100 nm vesicles shed from the cilia of starved cells promote mating between cells of complementary mating types. A proteomic analysis revealed that these EMVs are decorated with mating-type proteins expressed from the MAT locus, proteins that define a cell’s sex (one of seven). Once the mating junction is established between cells, smaller 60 nm vesicles (junction vesicles) appear within the extracellular gap that separates mating partners. Junction vesicles (jEMVs) may play a role in remodeling the mating junction through which gametic pronuclei are exchanged. Evidence is presented demonstrating that cells must be able to internalize extracellular signals via some form of endocytosis in order to trigger conjugation. Finally, an evolutionarily conserved fusogen (Hap2) implicated in pore formation also appears necessary for jEMV processing. This system offers an excellent opportunity for studies on ectosome shedding, intercellular signaling and shed vesicle uptake by macro-pinocytosis, as they relate to sexual reproduction in the ciliate Tetrahymena thermophila. Full article

Lung cancer is one of the major cancer types and poses challenges in its treatment, including lack of specificity and harm to healthy cells. Nanoparticle-based drug delivery systems (NDDSs) show promise in overcoming these challenges. While conventional NDDSs have drawbacks, such as immune response and capture by the reticuloendothelial system (RES), extracellular vesicles (EVs) present a potential solution. EVs, which are naturally released from cells, can evade the RES without surface modification and with minimal toxicity to healthy cells. This makes them a promising candidate for developing a lung-cancer-targeting drug delivery system. EVs isolated from vascular endothelial cells, such as human umbilical endothelial-cell-derived EVs (HUVEC-EVs), have shown anti-angiogenic activity in a lung cancer mouse model; therefore, in this study, HUVEC-EVs were chosen as a carrier for drug delivery. To achieve lung-cancer-specific targeting, HUVEC-EVs were engineered to be decorated with GE11 peptides (GE11-HUVEC-EVs) via a postinsertional technique to target the epidermal growth factor receptor (EGFR) that is overexpressed on the surface of lung cancer cells. The GE11-HUVEC-EVs were loaded with vinorelbine (GE11-HUVEC-EVs-Vin), and then characterized and evaluated in in vitro and in vivo lung cancer models. Further, we examined the binding affinity of ABCB1, encoding P-glycoprotein, which plays a crucial role in chemoresistance via the efflux of the drug. Our results indicate that GE11-HUVEC-EVs-Vin effectively showed tumoricidal effects against cell and mouse models of lung cancer. Full article

Outer membrane vesicles (OMVs) produced by Gram-negative bacteria have emerged as a novel and flexible vaccine platform. OMVs can be decorated with foreign antigens and carry potent immunostimulatory components. Therefore, after their purification from the culture supernatant, they are ready to be formulated for vaccine use. It has been extensively demonstrated that immunization with engineered OMVs can elicit excellent antibody responses against the heterologous antigens. However, the definition of the conditions necessary to reach the optimal antibody titers still needs to be investigated. Here, we defined the protein concentrations required to induce antigen-specific antibodies, and the amount of antigen and OMVs necessary and sufficient to elicit saturating levels of antigen-specific antibodies. Since not all antigens can be expressed in OMVs, we also investigated the effectiveness of vaccines in which OMVs and purified antigens are mixed together without using any procedure for their physical association. Our data show that in most of the cases OMV–antigen mixtures are very effective in eliciting antigen-specific antibodies. This is probably due to the capacity of OMVs to “absorb” antigens, establishing sufficiently stable interactions that allow antigen–OMV co-presentation to the same antigen presenting cell. In those cases when antigen–OMV interaction is not sufficiently stable, the addition of alum to the formulation guarantees the elicitation of high titers of antigen-specific antibodies. Full article

Human papillomaviruses (HPVs) are a large family of viruses with a capsid composed of the L1 and L2 proteins, which bind to receptors of the basal epithelial cells and promote virus entry. The majority of sexually active people become exposed to HPV and the virus is the most common cause of cervical cancer. Vaccines are available based on the L1 protein, which self-assembles and forms virus-like particles (VLPs) when expressed in yeast and insect cells. Although very effective, these vaccines are HPV type-restricted and their costs limit broad vaccination campaigns. Recently, vaccine candidates based on the conserved L2 epitope from serotypes 16, 18, 31, 33, 35, 6, 51, and 59 were shown to elicit broadly neutralizing anti-HPV antibodies. In this study, we tested whether E. coli outer membrane vesicles (OMVs) could be successfully decorated with L2 polytopes and whether the engineered OMVs could induce neutralizing antibodies. OMVs represent an attractive vaccine platform owing to their intrinsic adjuvanticity and their low production costs. We show that strings of L2 epitopes could be efficiently expressed on the surface of the OMVs and a polypeptide composed of the L2 epitopes from serotypes 18, 33, 35, and 59 provided a broad cross-protective activity against a large panel of HPV serotypes as determined using pseudovirus neutralization assay. Considering the simplicity of the OMV production process, our work provides a highly effective and inexpensive solution to produce universal anti-HPV vaccines. Full article

The vaccination campaign against SARS-CoV-2 relies on the world-wide availability of effective vaccines, with a potential need of 20 billion vaccine doses to fully vaccinate the world population. To reach this goal, the manufacturing and logistic processes should be affordable to all countries, irrespective of economical and climatic conditions. Outer membrane vesicles (OMVs) are bacterial-derived vesicles that can be engineered to incorporate heterologous antigens. Given the inherent adjuvanticity, such modified OMVs can be used as vaccines to induce potent immune responses against the associated proteins. Here, we show that OMVs engineered to incorporate peptides derived from the receptor binding motif (RBM) of the spike protein from SARS-CoV-2 elicit an effective immune response in vaccinated mice, resulting in the production of neutralizing antibodies (nAbs) with a titre higher than 1:300. The immunity induced by the vaccine is sufficient to protect the animals from intranasal challenge with SARS-CoV-2, preventing both virus replication in the lungs and the pathology associated with virus infection. Furthermore, we show that OMVs can be effectively decorated with the RBM of the Omicron BA.1 variant and that such engineered OMVs induce nAbs against Omicron BA.1 and BA.5, as measured using the pseudovirus neutralization infectivity assay. Importantly, we show that the RBM_438–509 ancestral-OMVs elicited antibodies which efficiently neutralize in vitro both the homologous ancestral strain, the Omicron BA.1 and BA.5 variants with a neutralization titre ranging from 1:100 to 1:1500, suggesting its potential use as a vaccine targeting diverse SARS-CoV-2 variants. Altogether, given the convenience associated with the ease of engineering, production and distribution, our results demonstrate that OMV-based SARS-CoV-2 vaccines can be a crucial addition to the vaccines currently available. Full article

The severe course of COVID-19 leads to the long-terming pulmonary diseases, such as bacterial pneumonia and post-COVID-19 pulmonary fibrosis. Thus, the essential task of biomedicine is a design of new effective drug formulations, including those for inhalation administration. In this work, we propose an approach to the creation of lipid–polymer delivery systems for fluoroquinolones and pirfenidone based on liposomes of various compositions decorated with mucoadhesive mannosylated chitosan. A generalizing study on the physicochemical patterns of the interactions of drugs with bilayers of various compositions was carried out, and the main binding sites were identified. The role of the polymer shell in the stabilization of vesicles and the delayed release of the contents has been demonstrated. For the liquid–polymer formulation of moxifloxacin, a prolonged accumulation of the drug in lung tissues was found after a single endotracheal administration to mice, significantly exceeding the control intravenous and endotracheal administration of the drug. Full article

Chlamydia trachomatis is the bacterial pathogen that causes most cases of sexually transmitted diseases annually. To combat the global spread of asymptomatic infection, development of effective (mucosal) vaccines that offer both systemic and local immune responses is considered a high priority. In this study, we explored the expression of C. trachomatis full-length (FL) PmpD, as well as truncated PmpD passenger constructs fused to a “display” autotransporter (AT) hemoglobin protease (HbpD) and studied their inclusion into outer membrane vesicles (OMVs) of Escherichia coli and Salmonella Typhimurium. OMVs are considered safe vaccine vectors well-suited for mucosal delivery. By using E. coli AT HbpD-fusions of chimeric constructs we improved surface display and successfully generated Salmonella OMVs decorated with a secreted and immunogenic PmpD passenger fragment (aa68-629) to 13% of the total protein content. Next, we investigated whether a similar chimeric surface display strategy could be applied to other AT antigens, i.e., secreted fragments of Prn (aa35-350) of Bordetella pertussis and VacA (aa65-377) of Helicobacter pylori. The data provided information on the complexity of heterologous expression of AT antigens at the OMV surface and suggested that optimal expression strategies should be developed on an antigen-to-antigen basis. Full article

Chitosan-decorated liposomes were proposed for the first time for the intranasal delivery of acetylcholinesterase (AChE) reactivator pralidoxime chloride (2-PAM) to the brain as a therapy for organophosphorus compounds (OPs) poisoning. Firstly, the chitosome composition based on phospholipids, cholesterol, chitosans (Cs) of different molecular weights, and its arginine derivative was developed and optimized. The use of the polymer modification led to an increase in the encapsulation efficiency toward rhodamine B (RhB; ~85%) and 2-PAM (~60%) by 20% compared to conventional liposomes. The formation of monodispersed and stable nanosized particles with a hydrodynamic diameter of up to 130 nm was shown using dynamic light scattering. The addition of the polymers recharged the liposome surface (from −15 mV to +20 mV), which demonstrates the successful deposition of Cs on the vesicles. In vitro spectrophotometric analysis showed a slow release of substrates (RhB and 2-PAM) from the nanocontainers, while the concentration and Cs type did not significantly affect the chitosome permeability. Flow cytometry and fluorescence microscopy qualitatively and quantitatively demonstrated the penetration of the developed chitosomes into normal Chang liver and M-HeLa cervical cancer cells. At the final stage, the ability of the formulated 2-PAM to reactivate brain AChE was assessed in a model of paraoxon-induced poisoning in an in vivo test. Intranasal administration of 2-PAM-containing chitosomes allows it to reach the degree of enzyme reactivation up to 35 ± 4%. Full article

The formation of gas vesicles has been investigated in bacteria and haloarchaea for more than 50 years. These air-filled nanostructures allow cells to stay at a certain height optimal for growth in their watery environment. Several gvp genes are involved and have been studied in Halobacterium salinarum, cyanobacteria, Bacillus megaterium, and Serratia sp. ATCC39006 in more detail. GvpA and GvpC form the gas vesicle shell, and additional Gvp are required as minor structural proteins, chaperones, an ATP-hydrolyzing enzyme, or as gene regulators. We analyzed the Gvp proteins of Hbt. salinarum with respect to their protein–protein interactions, and developed a model for the formation of these nanostructures. Gas vesicles are also used in biomedical research. Since they scatter waves and produce ultrasound contrast, they could serve as novel contrast agent for ultrasound or magnetic resonance imaging. Additionally, gas vesicles were engineered as acoustic biosensors to determine enzyme activities in cells. These applications are based on modifications of the surface protein GvpC that alter the mechanical properties of the gas vesicles. In addition, gas vesicles have been decorated with GvpC proteins fused to peptides of bacterial or viral pathogens and are used as tools for vaccine development. Full article

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been demonstrated to deliver therapeutic drugs in preclinical studies. However, their use is limited, as they lack the ability to specifically deliver drugs to tumor tissues in vivo. In the present study, we propose the use of a targeting peptide, IL-4R-binding peptide (IL4RPep-1), to specifically deliver intravenously (i.v.) infused EVs to thyroid tumors. In vivo, a xenograft tumor model was treated with either the control peptide (NSSSVDK) or IL4RPep-1-Flamma; mice were fluorescently imaged (FLI) using an in vivo imaging system at 0–3 h post-treatment. EVs (labeled with DiD dye) were conjugated with IL4RPep-1 through a DOPE-NHS linker and administered to mice intravenously. FLI was performed 0–24 h post-injection, and the animals were sacrificed for further experiments. The morphology and size of EVs, the presence of EV markers such as CD63 and ALIX, and the absence of the markers GM130 and Cyto-C were confirmed. In vivo, FLI indicated an accumulation of i.v. injected IL4RPep-1-Flamma at the tumor site 90 min post-injection. No accumulation of NSSSVDK-Flamma was detected. In vivo, IL4RPep-1-EVs targeted the Cal-62 tumor 2 h post-injection. NSSSVDK-EVs were not even detected in the tumor 24 h post-injection. The quantification of FLI showed a significant accumulation of MSC-EVs in the tumor 2 h, 3 h, and 24 h post-injection. Furthermore, ex vivo imaging and an IF analysis confirmed the in vivo findings. Our results demonstrate the use of the IL4RPep-1 peptide as a targeting moiety of EVs for IL-4R-expressing anaplastic thyroid tumors. Full article