Liposomal Platform Research Articles

Pneumolysin-responsive liposomal platform for selective treatment of Streptococcus pneumoniae.

The bacterium Streptococcus pneumoniae has become a leading cause of meningitis, sepsis, and bacterial pneumonia worldwide, with increased prevalence of antibiotic-resistant serotypes serving to exacerbate the issue. The main factor responsible for colonization and immune response escape in pneumococcal infections is the secreted molecule pneumolysin, which is a subset within a family of related toxins that form transmembrane pores in biological membranes through cholesterol recognition and binding. The conserved activity and structure of pneumolysin between all observed S. pneumoniae serotypes, along with its requirement for pathogenicity, has made this molecule an attractive target for vaccination, diagnostic, and sequestration platforms, but not yet as a facilitative agent for therapeutic treatment. Consequently, the present work aimed to examine the impact of liposomal cholesterol content for pneumolysin-induced release of the encapsulated antimicrobial peptide nisin. It was determined that a cholesterol content above 45mol% was necessary to facilitate interactions with both purified pneumolysin toxin and S. pneumoniae culture, demonstrated through enhanced nisin release and a reduction in hemolytic rates upon exposure of the toxin with cholesterol-rich vesicles. Antibacterial testing highlighted the ability of the developed platform to elicit a potent and specific bactericidal response in vitro against cultured S. pneumoniae when compared to a control strain, Staphylococcus epidermidis. It further improved viability of a fibroblast cell line upon S. pneumoniae challenge, outperforming free nisin via the synergistic impact of simultaneous bacterial clearance and pneumolysin neutralization. These findings collectively indicate that cholesterol-rich liposomes hold promise as a selective treatment platform against pneumococcal infections.

Bacteria-responsive drug release platform for the local treatment of bacterial vaginosis

Bacterial vaginosis (BV) is a common vaginal infection affecting millions of women. Vaginal anaerobic dysbiosis occurs whenLactobacillusspp., the dominant flora in healthy vagina is replaced by certain overgrown anaerobes, resulting in unpleasant symptoms such as vaginal discharge and odor. With a high recurrence rate, BV also severely impacts the overall quality of life of childbearing women by inducing preterm delivery and increasing the risks of pelvic inflammatory disease and sexually transmitted infections. Among various BV-associated bacteria,Gardnerella vaginalis(G. vaginalis) has been identified as a primary pathogen since it has been isolated from almost all women carrying BV and exhibits higher virulence potential over other bacteria. When dealing with BV relapse, intravaginal drug delivery systems are superior to conventional oral antibiotic therapies in improving therapeutic efficacy owing to more effective drug dose, reduced drug resistance and minimized side effects such as stomach irritation. Traditional intravaginal drug administration generally involves solids, semi-solids and delivery devices inserted into the vaginal lumen to achieve sustained drug release. However, they are mostly designed for continuous drug release and are not preventative therapies, resulting in severe side effects caused by excess dosing. Stimuli-responsive systems that can release drug only when needed ('on-demand') can help diminish these negative side effects. Hence, we developed a bacteria-responsive liposomal platform for the prevention and treatment of BV. This platform demonstrated sustained drug release in the presence of vaginolysin, a toxin secreted specifically byG. vaginalis. We prepared four liposome formulations and evaluated their responsiveness toG. vaginalis. The results demonstrated that the liposome formulations could achieve cumulative drug release ranging from 46.7% to 51.8% over a 3-5 d period in response toG. vaginalisand hardly any drug release in the presence ofLactobacillus crispatus(L. crispatus), indicating the high specificity of the system. Overall, the bacteria-responsive drug release platform has great potential, since it will be the first time to realize sustained drug release stimulated by a specific pathogen for BV prevention and treatment. This on-demand therapy can potentially provide relief to the millions of women affected by BV.

Neutrophil-targeted liposomal platform: A shift in novel approach for early detection and treatment of cancer metastasis

Tumor metastasis is responsible for 90 % of cancer-associated deaths, and its early detection may decrease the likelihood of mortality. Studies have demonstrated that metastasis results from the interaction between “seeds” (tumor cells) and “soil” (pre-metastatic niche, PMN). As the first and most abundant immune cells to be recruited to PMN, neutrophils play a key role in the ultimate formation of metastatic foci through mechanisms such as supporting tumor cell growth, promoting angiogenesis, and shaping an immune-suppressive microenvironment. In this study, two distinct types of sialic acid (SA)-modified liposomes were prepared to target and regulate pro-metastatic neutrophils through the l-selectin receptor. One of these liposomes, named ICG@SAL, was used to encapsulate indocyanine green (ICG) and was specifically designed for the early detection of cancer metastasis. The other liposome, referred to as ABE/Cur@SAL, co-loaded abemaciclib (ABE) and curcumin (Cur), with the intention of suppressing the progression of metastatic tumor. Fluorescence imaging results from the mouse spontaneous metastasis model indicated that ICG@SAL demonstrated faster targeting and stronger accumulation in the metastatic organs than unmodified ICG liposomes (ICG@CL). This suggested that ICG@SAL could detect tumor metastasis at an early stage. The therapy with co-loaded liposomes in the mouse experimental lung metastasis model indicated that ABE/Cur@SAL could inhibit regulatory T (Treg) cell proliferation, enhance effector T cell activity and reduce tumorigenic factor release, implying that ABE/Cur@SAL could inhibit tumor metastasis. Overall, our work provided a sensitive and convenient approach to early diagnosis and treatment of tumor metastasis. ICG@SAL could be employed for the early detection of tumor metastasis, while ABE/Cur@SAL could be used to inhibit the development of tumor metastasis when early metastasis was identified.

Nanoparticles in liposomes: a platform for increased antibiotic selectivity in multidrug resistant bacteria in respiratory tract infections.

Antibiotic resistance is a cause of serious illness and death, originating often from insufficient permeability into gram-negative bacteria. Nanoparticles (NP) can increase antibiotic delivery in bacterial cells, however, may as well increase internalization in mammalian cells and toxicity. In this work, NP in liposome (NP-Lip) formulations were used to enhance the selectivity of the antibiotics (3C and tobramycin) and quorum sensing inhibitor (HIPS-1635) towards Pseudomonas aeruginosa by fusing with bacterial outer membranes and reducing uptake in mammalian cells due to their larger size. Poly (lactic-co-glycolic) acid NPs were prepared using emulsion solvent evaporation and incorporated in larger liposomes. Cytotoxicity and uptake studies were conducted on two lung cell lines, Calu-3 and H460. NP-Lip showed lower toxicity and uptake in both cell lines. Then formulations were investigated for suitability for oral inhalation. The deposition of NP and NP-Lip in the lungs was assessed by next generation impactor and corresponded to 75% and 45% deposition in the terminal bronchi and the alveoli respectively. Colloidal stability and mucus-interaction studies were conducted. NP-Lip showed higher diffusion through mucus compared to NPs with the use of nanoparticle tracking analyzer. Moreover, the permeation of delivery systems across a liquid-liquid interface epithelial barrier model of Calu-3 cells indicated that NP-Lip could cause less systemic toxicity upon in-vivo like administration by aerosol deposition. Monoculture and Pseudomonas aeruginosa biofilm with Calu-3 cells co-culture experiments were conducted, NP-Lip achieved highest toxicity towards bacterial biofilms and least toxicity % of the Calu-3 cells. Therefore, the NP- liposomal platform offers a promising approach for enhancing antibiotic selectivity and treating pulmonary infections.

Long circulating liposomal platform utilizing hydrophilic polymer-based surface modification: preparation, characterisation, and biological evaluation

Liposomes are one of the most important drug delivery vectors, nowadays used in clinics. In general, polyethylene glycol (PEG) is used to ensure the stealth properties of the liposomes. Here, we have employed hydrophilic, biocompatible and highly non-fouling N-(2-hydroxypropyl) methacrylamide (HPMA)-based copolymers containing hydrophobic cholesterol anchors for the surface modification of liposomes, which were prepared by the method of lipid film hydration and extrusion through 100 nm polycarbonate filters. Efficient surface modification of liposomes was confirmed by transmission electron microscopy, atomic force microscopy, and gradient ultracentrifugation. The ability of long-term circulation in the vascular bed was demonstrated in rabbits after i.v. application of fluorescently labelled liposomes. Compared to PEGylated liposomes, HPMA-based copolymer-modified liposomes did not induce specific antibody formation and did not activate murine and human complement. Compared with PEGylated liposomes, HPMA-based copolymer-modified liposomes showed a better long-circulating effect after repeated administration. HPMA-based copolymer-modified liposomes thus represent suitable new candidates for a generation of safer and improved liposomal drug delivery platforms.

As1411-modified liposomes to enhance drug utilization and augment the anti-tumor efficacy

BackgroundThe utilization of liposomes in drug delivery has garnered significant attention due to their efficient drug loading capacity and excellent biocompatibility, rendering them a promising platform for tumor therapy. However, the average size of liposomes ~ 100 nm leads to liposomes being susceptible to hepatic and renal metabolism to excretion outside the body leading to poor drug delivery efficiency with a total utilization rate of less than 0.7%, resulting in unfavorable treatment outcomes.ResultsWe have developed a novel liposome platform equipped with tumor surface nucleolin-targeting capacity to enhance drug accumulation at the tumor in vivo. The encapsulation of doxorubicin through thin film hydration has resulted in the formation of D@L-AS1411. Through in vivo experiments, we have demonstrated the effective accumulation of D@L-AS1411 at the tumor site and its ability to improve doxorubicin utilization rates by 40%. Additionally, D@L-AS1411 induces immunogenic death of tumor cells, release of tumor-associated antigens, upregulation of calreticulin expression, and recruitment of active T cell infiltration, and ultimately improves the therapeutic efficacy against tumors (70%).ConclusionsBased on the nucleic acid aptamer AS1411, D@L-1411 is developed to specifically enhance the accumulation of Dox at tumor sites, thereby inhibiting and enhancing the anti-tumor effect. In summary, this study not only provides an efficient tumor-targeting delivery platform but also contributes to the improvement of chemotherapy–immunotherapy combination for tumor treatment strategy in the clinic.

Far-red light-triggered cargo release from liposomes bound to a photosensitizer-cellulose nanofiber hydrogel

In our research we used the anionic nanofibrillar cellulose (ANFC) as a platform for far-red light-induced release of cargo from liposomes. In contrast to previous works, where photosensitizers are usually in the liposomal bilayers, we used a cellulose-binding dye. Our phthalocyanine derivative has been shown to bind very strongly to cellulose and cellulose nanofiber hydrogels, allowing us to place it outside of the liposomes. Both the sensitizer and cationic liposomes bind strongly to the ANFC after mixing, making the system easy to fabricate. Upon light activation, the photosensitizer generates reactive oxygen species (ROS) within the ANFC hydrogel, where the reactive oxygen species oxidize unsaturated lipids in the liposomal membrane, which makes the liposomes more permeable, resulting in on-demand cargo release. We were able to achieve ca. 70 % release of model hydrophilic cargo molecule calcein from the hydrogels with a relatively low dose of light (262 J/cm2) while employing the straightforward fabrication techniques. Our system was remarkably responsive to the far-red light (730 nm), enabling deep tissue penetration. Therefore, this very promising novel cellulose-immobilized photosensitizer liposomal platform could be used as a controlled drug delivery system, which can have applications in externally activated coatings or implants.

Abstract 5743: Liposome platform enables X-ray induced photodynamic therapy treatment against human triple negative breast cancer cells

Abstract In this study, we employed X-ray induced photodynamic therapy (X-PDT) for the treatment on triple negative breast cancer (TNBC) cells. To do this, we rationally developed a liposome delivery system co-loaded with protoporphyrin IX (PPIX) and perfluorooctyl bromide (PFOB). Low-dose X-ray at 2Gy was employed to activate PPIX for reactive oxygen species (ROS) generation, and the co-loading of PFOB provided additional oxygen to augment ROS production. The highly toxic ROS triggered TNBC cell death. In vitro X-PDT effects including intracellular ROS generation, cytotoxicity, cell viability and apoptosis/necrosis assay in TNBC cells were studied. Our results indicate that the nanocarriers effectively induced X-PDT effect with very low dose radiation, which makes it possible to damage cancer cells. Our strategy may offer a paradigm-shifting treatment alternative for TNBC patients who need neoadjuvant radiotherapy but wish to avoid long term detrimental effect on functional outcome by undergoing X-PDT using only a fraction of the conventional radiotherapy. Citation Format: Biyao Yang, Rui Sang, Yi Li, Ewa Goldys, Wei Deng. Liposome platform enables X-ray induced photodynamic therapy treatment against human triple negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5743.

Overcoming neutrophil-induced immunosuppression in postoperative cancer therapy: Combined sialic acid-modified liposomes with scaffold-based vaccines

Immunotherapy is a promising approach for preventing postoperative tumor recurrence and metastasis. However, inflammatory neutrophils, recruited to the postoperative tumor site, have been shown to exacerbate tumor regeneration and limit the efficacy of cancer vaccines. Consequently, addressing postoperative immunosuppression caused by neutrophils is crucial for improving treatment outcomes. This study presents a combined chemoimmunotherapeutic strategy that employs a biocompatible macroporous scaffold-based cancer vaccine (S-CV) and a sialic acid (SA)-modified, doxorubicin (DOX)-loaded liposomal platform (DOX@SAL). The S-CV contains whole tumor lysates as antigens and imiquimod (R837, Toll-like receptor 7 activator)-loaded PLGA nanoparticles as immune adjuvants for cancer, which enhance dendritic cell activation and cytotoxic T cell proliferation upon localized implantation. When administered intravenously, DOX@SAL specifically targets and delivers drugs to activated neutrophils in vivo, mitigating neutrophil infiltration and suppressing postoperative inflammatory responses. In vivo and vitro experiments have demonstrated that S-CV plus DOX@SAL, a combined chemo-immunotherapeutic strategy, has a remarkable potential to inhibit postoperative local tumor recurrence and distant tumor progression, with minimal systemic toxicity, providing a new concept for postoperative treatment of tumors.

Construction Strategy of Functionalized Liposomes and Multidimensional Application.

Liposomes are widely used in the biological field due to their good biocompatibility and surface modification properties. With the development of biochemistry and material science, many liposome structures and their surface functional components have been modified and optimized one by one, pushing the liposome platform from traditional to functionalized and intelligent, which will better satisfy and expand the needs of scientific research. However, a main limiting factor effecting the efficiency of liposomes is the complicated environmental conditions in the living body. Currently, in order to overcome the above problem, functionalized liposomes have become a very promising strategy. In this paper, binding strategies of liposomes with four main functional elements, namely nucleic acids, antibodies, peptides, and stimuli-responsive motif have been summarized for the first time. In addition, based on the construction characteristics of functionalized liposomes, such as drug-carrying, targeting, long-circulating, and stimulus-responsive properties, a comprehensive overview of their features and respective research progress are presented. Finally, the paper critically presents the limitations of these functionalized liposomes in the current applications and also prospectively suggests the future development directions, aiming to accelerate realization of their industrialization.

Tissue and Cell Dual‐Penetrating Dendritic Lipopeptide Liposomes for Hypertrophic Scar Treatment

AbstractHypertrophic scar is a complex global disease, which can lead to remarkable functional impairment, pruritus, and pain. Treating local skin diseases needs a transdermal drug delivery system that can simultaneously promote cell and tissue penetration within the hypertrophic scar. Herein, a tissue and cell dual‐penetrating liposomal delivery platform consisting of arginine‐based dendritic lipopeptide mimicking the pivotal amino acid sequence in viral protein transduction domains and virion‐like nanostructure to enhance hypertrophic scar tissue deep penetration and cellular internalization is reported. This dendritic lipopeptide liposomal delivery platform can overcome corneum barriers to the punch on hypertrophic scar fibroblast membranes, as are natural viruses. It also can deeply deliver drugs to promote hypertrophic scar fibroblast apoptosis and collagen fiber remodeling within thickened dermis and epidermis, and finally remove the raised scars.

Caspase-1 Responsive Nanoreporter for In Vivo Monitoring of Inflammasome Immunotherapy.

Inflammasomes are multimeric protein signaling complexes that are assembled in innate immune cells in response to a multitude of pathogen and damage-associated signals. They are essential for generating robust inflammatory responses to prevent pathogenic insults. However, inflammasome dysregulation can induce cascading immune responses, resulting in systemic toxicities and inflammatory disease. In this sense, there is a strong need to develop potent inflammasome inhibiting therapies as well as technologies to monitor their efficacy, yet current systems lack the ability to effectively image inflammasome activation and track therapy response early. To overcome these limitations, we report a novel nanoparticle system delivering both a caspase-1 cleavable inflammasome detecting probe and the NLRP3 inhibitor drug MCC-950, providing dual capabilities of monitoring and regulation of inflammasome activation in a biocompatible, tissue penetrating, and sustained release liposomal formulation. We observed this liposomal nanoreporter's ability to reduce and detect inflammasome activation both in vitro in immortalized bone marrow-derived macrophages and in vivo in a DSS-induced ulcerative colitis mouse model. Our results exhibited the nanoreporter's ability to penetrate inflammatory tissues and detect inflammasome activation early and in real-time for multiple days while alleviating inflammation in the groups coencapsulating imaging reporter and inflammasome inhibitor. Overall, the developed liposomal nanoreporter platform enables spatiotemporal delivery of imaging probe and inhibitor, captures early and sustained inflammasome detection, and induces inflammasome amelioration, thus establishing a novel tool for the real-time monitoring and treatment of inflammasome-mediated disease with high potential for clinical application.

Human in vitro modeling of adjuvant formulations demonstrates enhancement of immune responses to SARS-CoV-2 antigen

Adjuvants can enhance vaccine immunogenicity, but their mechanism of action is often incompletely understood, hampering rapid applicability for pandemic vaccines. Herein, we characterized the cellular and molecular activity of adjuvant formulations available for pre-clinical evaluation, including several developed for global open access. We applied four complementary human in vitro platforms to assess individual and combined adjuvants in unformulated, oil-in-water, and liposomal delivery platforms. Liposomal co-formulation of MPLA and QS-21 was most potent in promoting dendritic cell maturation, selective production of Th1-polarizing cytokines, and activation of SARS-CoV-2 Spike-specific CD4+ and CD8+ T cells in a co-culture assay. Select formulations also significantly enhanced Spike antigen-specific humoral immunity in vivo. This study confirms the utility of the cumulative use of human in vitro tools to predict adjuvanticity potential. Thus, human in vitro modeling may advance public health by accelerating the development of affordable and scalable adjuvants for vaccines tailored to vulnerable populations.

Use of Stromal Intervention and Exogenous Neoantigen Vaccination to Boost Pancreatic Cancer Chemo-Immunotherapy by Nanocarriers.

Despite the formidable treatment challenges of pancreatic ductal adenocarcinoma (PDAC), considerable progress has been made in improving drug delivery via pioneering nanocarriers. These innovations are geared towards overcoming the obstacles presented by dysplastic stroma and fostering anti-PDAC immune reactions. We are currently conducting research aimed at enhancing chemotherapy to stimulate anti-tumor immunity by inducing immunogenic cell death (ICD). This is accomplished using lipid bilayer-coated nanocarriers, which enable the attainment of synergistic results. Noteworthy examples include liposomes and lipid-coated mesoporous silica nanoparticles known as "silicasomes". These nanocarriers facilitate remote chemotherapy loading, as well as the seamless integration of immunomodulators into the lipid bilayer. In this communication, we elucidate innovative ways for further improving chemo-immunotherapy. The first is the development of a liposome platform engineered by the remote loading of irinotecan while incorporating a pro-resolving lipoxin in the lipid bilayer. This carrier interfered in stromal collagen deposition, as well as boosting the irinotecan-induced ICD response. The second approach was to synthesize polymer nanoparticles for the delivery of mutated KRAS peptides in conjunction with a TLR7/8 agonist. The dual delivery vaccine particle boosted the generation of antigen-specific cytotoxic T-cells that are recruited to lymphoid structures at the cancer site, with a view to strengthening the endogenous vaccination response achieved by chemo-immunotherapy.

A liposomal platform for the delivery of ion channel proteins for treatment of channelopathies — Application in therapy of cystic fibrosis

Channelopathies arise from ion channel dysfunction. Successful treatment entails delivery of functional ion channels to replace dysfunctional ones. Glycine receptor (GlyR)-rich cell membrane fragments (CMF) were previously delivered to target cell membranes using fusogenic liposomes. Here, cystic fibrosis transmembrane conductance regulator (CFTR)-bearing CMF were similarly delivered to target cells. We studied the effect of lipid composition on liposomes' ability to incorporate CMF and fuse with target cell membranes to deliver functional CFTR. Four formulations were prepared using thin-film hydration out of different lecithin sources, egg and soy lecithin (EL and SL), in the presence and absence of cholesterol (CHOL): EL + CHOL, EL-CHOL, SL + CHOL, and SL-CHOL. EL liposomes incorporated more CMF than SL liposomes, with CHOL only increasing CMF incorporation in SL liposomes. SL + CHOL fused better with target cell membranes than EL + CHOL. SL + CHOL and EL + CHOL equally delivered CFTR to target cell membranes, owing to the former's superior fusogenic capacity and the latter's superior CMF-incorporation capacity. SL-CHOL and EL-CHOL delivered CFTR to a lesser extent, indicating the importance of CHOL for fusion. Patch-clamp electrophysiology and confocal laser scanning microscopy (CLSM) confirmed CFTR delivery to target cell membranes by SL + CHOL. Therefore, CMF-bearing fusogenic liposomes offer a promising universal platform for the treatment of channelopathies.

Magnetic-Responsive Liposomal Hydrogel Membranes for Controlled Release of Small Bioactive Molecules-An Insight into the Release Kinetics.

This work explores the unique features of magnetic-responsive hydrogels to obtain liposomal hydrogel delivery platforms capable of precise magnetically modulated drug release based on the mechanical responses of these hydrogels when exposed to an external magnetic field. Magnetic-responsive liposomal hydrogel delivery systems were prepared by encapsulation of 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) multilayered vesicles (MLVs) loaded with ferulic acid (FA), i.e., DPPC:FA liposomes, into gelatin hydrogel membranes containing dispersed iron oxide nanoparticles (MNPs), i.e., magnetic-responsive gelatin. The FA release mechanisms and kinetics from magnetic-responsive liposomal gelatin were studied and compared with those obtained with conventional drug delivery systems, e.g., free liposomal suspensions and hydrogel matrices, to access the effect of liposome entrapment and magnetic field on FA delivery. FA release from liposomal gelatin membranes was well described by the Korsmeyer-Peppas model, indicating that FA release occurred under a controlled diffusional regime, with or without magnetic stimulation. DPPC:FA liposomal gelatin systems provided smoother controlled FA release, relative to that obtained with the liposome suspensions and with the hydrogel platforms, suggesting the promising application of liposomal hydrogel systems in longer-term therapeutics. The magnetic field, with low intensity (0.08 T), was found to stimulate the FA release from magnetic-responsive liposomal gelatin systems, increasing the release rates while shifting the FA release to a quasi-Fickian mechanism. The magnetic-responsive liposomal hydrogels developed in this work offer the possibility to magnetically activate drug release from these liposomal platforms based on a non-thermal related delivery strategy, paving the way for the development of novel and more efficient applications of MLVs and liposomal delivery systems in biomedicine.

Co-Delivery of Therapeutics and Bioactive Gas Using a Novel Liposomal Platform for Enhanced Treatment of Acute Arterial Injury.

Atherosclerosis is a complex, multi-stage disease characterized by pathological changes across the vascular wall. Endothelial dysfunction, inflammation, hypoxia, and vascular smooth muscle cell proliferation contribute to its progression. An effective strategy capable of delivering pleiotropic treatment to the vascular wall is essential to limit neointimal formation. Echogenic liposomes (ELIP), which can encapsulate bioactive gases and therapeutic agents, have the potential to deliver enhanced penetration and treatment efficacy for atherosclerosis. In this study, liposomes loaded with nitric oxide (NO) and rosiglitazone, a peroxisome proliferator-activated receptor agonist, were prepared using hydration, sonication, freeze-thawing, and pressurization. The efficacy of this delivery system was evaluated in a rabbit model of acute arterial injury induced by balloon injury to the common carotid artery. Intra-arterial administration of rosiglitazone/NO co-encapsulated liposomes (R/NO-ELIP) immediately following injury resulted in reduced intimal thickening after 14 days. The anti-inflammatory and anti-proliferative effects of the co-delivery system were investigated. These liposomes were echogenic, enabling ultrasound imaging to assess their distribution and delivery. R/NO-ELIP delivery exhibited a greater attenuation (88 ± 15%) of intimal proliferation when compared to NO-ELIP (75 ± 13%) or R-ELIP (51 ± 6%) delivery alone. The study demonstrates the potential of echogenic liposomes as a promising platform for ultrasound imaging and therapeutic delivery.

A pH-responsive liposomal nanoplatform for co-delivery of a Pt(IV) prodrug and cinnamaldehyde for effective tumor therapy.

Introduction: The tumor microenvironment (TME) is mainly characterized by abnormally elevated intracellular redox levels and excessive oxidative stress. However, the balance of the TME is also very fragile and susceptible to be disturbed by external factors. Therefore, several researchers are now focusing on intervening in redox processes as a therapeutic strategy to treat tumors. Here, we have developed a liposomal drug delivery platform that can load a Pt(IV) prodrug (DSCP) and cinnamaldehyde (CA) into a pH-responsive liposome to enrich more drugs in the tumor region for better therapeutic efficacy through enhanced permeability and retention effect. Methods: Using the glutathione-depleting properties of DSCP together with the ROS-generating properties of cisplatin and CA, we synergistically altered ROS levels in the tumor microenvironment to damage tumor cells and achieve anti-tumor effects in vitro. Results: A liposome loaded with DSCP and CA was successfully established, and this liposome effectively increased the level of ROS in the tumor microenvironment and achieved effective killing of tumor cells in vitro. Conclusion: In this study, novel liposomal nanodrugs loaded with DSCP and CA provided a synergistic strategy between conventional chemotherapy and disruption of TME redox homeostasis, leading to a significant increase in antitumor effects in vitro.

Synthesis and Evaluation of a Self-Adjuvanting Pseudomonal Vaccine Based on Major Outer Membrane Porin OprF Epitopes Formulated with Low-Toxicity QS-21-Containing Liposomes.

Pseudomonas aeruginosa (PA) is a Gram-negative pathogen that the World Health Organization has ranked as a priority 1 (critical) threat. One potential prophylactic approach to preventing or reducing the incidence of PA would be development of a long sought-after vaccine. Both antibody and CD4+ T-cell responses have been noted as playing key roles in protection against infection. In these studies, we have designed a prototype vaccine consisting of several known linear B-cell epitopes derived from an outer membrane porin F (OprF). The resulting thiol-containing protein was conjugated to a version of the lipopeptide-based Toll-like receptor agonist Pam3CysSK4Mal (10) containing a maleimide moiety and formulated into dipalmitoylphosphatidylcholine (DPPC)/cholesterol (Chol) liposomes. Mice immunized with the resulting vaccine generated antibodies that bound PA14 (serotype O10) in vitro and induced opsonization in the presence of rabbit complement and murine macrophage RAW264.7 cells. The liposome was optimized to contain 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG), Chol, Pam3CysSK4-OprF (12) and the Quillaja saponaria-derived saponin adjuvant QS-21. The resulting vaccine formulation produced significantly higher antibody titers, increased the IgG2a antibody isotype, and increased the number of IgG-producing B-cells as well as splenic primed T-cells. In summary, the liposomal vaccine platform was found highly useful for the generation of a robust and balanced TH1/TH2 response.

A liposomal vaccine promotes strong adaptive immune responses via dendritic cell activation in draining lymph nodes.

Subunit proteins provide a safe source of antigens for vaccine development especially for intracellular infections which require the induction of strong cellular immune responses. However, those antigens are often limited by their low immunogenicity. In order to achieve effective immune responses, they should be encapsulated into a stable antigen delivery system combined with an appropriate adjuvant. As such cationic liposomes provide an efficient platform for antigen delivery. In the present study, we describe a liposomal vaccine platform for co-delivery of antigens and adjuvants able to elicit strong antigen-specific adaptive immune responses. Liposomes are composed of the cationic lipid dimethyl dioctadecylammonium bromide (DDAB), cholesterol (CHOL) and oleic acid (OA). Physicochemical characterization of the formulations showed that their size was in the range of ∼250 nm with a positive zeta potential which was affected in some cases by the enviromental pH facilitating endosomal escape of potential vaccine cargo. In vitro, liposomes were effectively taken up by bone marrow dendritic cells (BMDCs) and when encapsulated IMQ they promoted BMDCs maturation and activation. Upon in vivo intramuscular administration, liposomes' active drainage to lymph nodes was mediated by DCs, B cells and macrophages. Thus, mice immunization with liposomes having encapsulated LiChimera, a previously characterized anti-leishmanial antigen, and IMQ elicited infiltration of CD11blow DCs populations in draining LNs followed by increased antigen-specific IgG, IgG2a and IgG1 levels production as well as indcution of antigen-specific CD4+ and CD8+ T cells. Collectively, the present work provides a proof-of-concept that cationic liposomes composed of DDAB, CHOL and OA adjuvanted with IMQ provide an efficient delivery platform for protein antigens able to induce strong adaptive immune responses via DCs targeting and induction of maturation.