Liposome-based Formulations Research Articles

Interaction of MRI Contrast Agent [Gd(DOTA)]- with Lipid Membranes: A Molecular Dynamics Study.

Contrast agents are important imaging probes in clinical MRI, allowing the identification of anatomic changes that otherwise would not be possible. Intensive research on the development of new contrast agents is being made to image specific pathological markers or sense local biochemical changes. The most widely used MRI contrast agents are based on gadolinium(III) complexes. Due to their very high charge density, they have low permeability through tight biological barriers such as the blood-brain barrier, hampering their application in the diagnosis of neurological disorders. In this study, we explore the interaction between the widely used contrast agent [Gd(DOTA)]- (Dotarem) and POPC lipid bilayers by means of molecular dynamics simulations. This metal complex is a standard reference where several chemical modifications have been introduced to improve key properties such as bioavailability and targeting. The simulations unveil detailed insights into the agent's interaction with the lipid bilayer, offering perspectives beyond experimental methods. Various properties, including the impact on global and local bilayer properties, were analyzed. As expected, the results indicate a low partition coefficient (KP) and high permeation barrier for this reference compound. Nevertheless, favorable interactions are established with the membrane leading to moderately long residence times. While coordination of one inner-sphere water molecule is maintained for the membrane-associated chelate, the physical-chemical attributes of [Gd(DOTA)]- as a MRI contrast agent are affected. Namely, increases in the rotational correlation times and in the residence time of the inner-sphere water are observed, with the former expected to significantly increase the water proton relaxivity. This work establishes a reference framework for the use of simulations to guide the rational design of new contrast agents with improved relaxivity and bioavailability and for the development of liposome-based formulations for use as imaging probes or theranostic agents.

Effects of different immunomodulating liposome-based adjuvants and injection sites on immunogenicity in pigs

Vaccine adjuvants, such as liposome-based cationic adjuvant formulations (CAFs), are able to boost immune responses and, by incorporation of distinct immunomodulators, steer immunity towards a desired direction in mice, non-human primates and humans, while less studied in pigs. Here we used commercial pigs to investigate polarizing adjuvant effects of CAFs with immunomodulators: C-type lectin receptor ligands trehalose-6,6ʼ-dibehenate and monomycolyl glycerol, toll-like receptor 3 ligand Poly(I:C) or retinoic acid. Vaccines were formulated with a recombinant Chlamydia model protein antigen and administered via three injection routes. All adjuvants significantly increased antigen-specific IgG in serum, compared to non-adjuvanted antigen. Administering the vaccines through intramuscular and intraperitoneal routes induced significantly higher antigen-specific IgG and IgA serum antibodies, than the perirectal route. Although immunizations triggered cell-mediated immunity, no significant differences between adjuvants or injection sites were detected. Genes depicting T cell subtypes revealed only minor differences. Our findings suggest that specific signatures of the tested adjuvant immunomodulation do not translate well from mice to pigs in standard two-dose immunizations. This study provides new insights into immune responses to CAFs in pigs, and highlights that adjuvant development should ideally be carried out in the intended species of interest or in models with high predictive validity/translational value.

An updated review on liposomes

Liposomes, tiny bubbles made from the same material as a cell membrane, are considered the most successful nanocarriers for drug delivery. They are biocompatible and stable, encapsulating both hydrophilic and lipophilic drugs and protecting them from degradation. Liposomes are the most commonly used drug delivery vehicles due to their high drug trapping capacity and efficiency. These offer controlled release, targeted drug delivery, increased therapeutic efficacy, and reduced dosing frequency. Liposome-based drug formulations have been approved for clinical use and are the subject of extensive research. Recent liposomal formulations aim to reduce toxicity and increase target site accumulation. With numerous advantages, liposomes prove their uniqueness in safe drug delivery in various areas of pharmacy and medicine. We will keep an eye on overall updated review on liposomes classification, their structural components, mechanism of action, stability, method of preparation, their evaluation tests and applications.

An updated review on liposomes- a modified dosage form

The first Nano medication to be approved for clinical usage was liposomes. Liposomes are being utilized more frequently for targeted drug delivery because of their incredible capacity to prevent drug deterioration and minimize unwanted side effects. In Liposomes, the drug can either be integrated inside the aqueous space (hydrophilic drugs) or inside the phospholipid's bilayer (hydrophobic drugs). The classification of liposomes, production of liposomes, applications, their advantages and drawbacks are the main topics covered in this review. Today, most researchers are becoming more and more interested in liposomes. As they are effective against a certain condition, and are simple to make, and have several additional benefits than others. This review covered liposomes as a modified dosage form, covering their present status, drawbacks, and applications. Numerous liposome-based formulations with higher drug concentrations have been developed as liposomes are effective as therapeutic agents.

Emulsion and liposome-based adjuvanted R21 vaccine formulations mediate protection against malaria through distinct immune mechanisms

Adjuvanted protein vaccines offer high efficacy, yet most potent adjuvants remain proprietary. Several adjuvant compounds are being developed by the Vaccine Formulation Institute in Switzerland for global open access clinical use. In the context of the R21 malaria vaccine, in a mouse challenge model, we characterize the efficacy and mechanism of action of four Vaccine Formulation Institute adjuvants: two liposomal (LQ and LMQ) and two squalene emulsion-based adjuvants (SQ and SMQ), containing QS-21 saponin (Q)and optionally a synthetic TLR4 agonist (M). Two R21 vaccine formulations, R21/LMQ and R21/SQ, offer the highest protection (81%-100%), yet they trigger different innate sensing mechanisms in macrophages with LMQ, but not SQ, activating the NLRP3 inflammasome. The resulting invivo adaptive responses have a different TH1/TH2 balance and engage divergent innate pathways while retaining high protective efficacy. We describe how modular changes in vaccine formulation allow for the dissection of the underlying immune pathways, enabling future mechanistically informed vaccine design.

Liposomes in Cancer Therapy: How Did We Start and Where Are We Now

Since their first discovery in the 1960s by Alec Bangham, liposomes have been shown to be effective drug delivery systems for treating various cancers. Several liposome-based formulations received approval by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA), with many others in clinical trials. Liposomes have several advantages, including improved pharmacokinetic properties of the encapsulated drug, reduced systemic toxicity, extended circulation time, and targeted disposition in tumor sites due to the enhanced permeability and retention (EPR) mechanism. However, it is worth noting that despite their efficacy in treating various cancers, liposomes still have some potential toxicity and lack specific targeting and disposition. This explains, in part, why their translation into the clinic has progressed only incrementally, which poses the need for more research to focus on addressing such translational limitations. This review summarizes the main properties of liposomes, their current status in cancer therapy, and their limitations and challenges to achieving maximal therapeutic efficacy.

Liposome-based diagnostic and therapeutic applications for pancreatic cancer.

Pancreatic cancer is one of the harshest and most challenging cancers to treat, often labeled as incurable. Chemotherapy continues to be the most popular treatment yet yields a very poor prognosis. The main barriers such as inefficient drug penetration and drug resistance, have led to the development of drug carrier systems. The benefits, ease of fabrication and modification of liposomes render them as ideal future drug delivery systems. This review delves into the versatility of liposomes to achieve various mechanisms of treatment for pancreatic cancer. Not only are there benefits of loading chemotherapy drugs and targeting agents onto liposomes, as well as mRNA combined therapy, but liposomes have also been exploited for immunotherapy and can be programmed to respond to photothermal therapy. Multifunctional liposomal formulations have demonstrated significant pre-clinical success. Functionalising drug-encapsulated liposomes has resulted in triggered drug release, specific targeting, and remodeling of the tumor environment. Suppressing tumor progression has been achieved, due to their ability to more efficiently and precisely deliver chemotherapy. Currently, no multifunctional surface-modified liposomes are clinically approved for pancreatic cancer thus we aim to shed light on the trials and tribulations and progress so far, with the hope for liposomal therapy in the future and improved patient outcomes. STATEMENT OF SIGNIFICANCE: Considering that conventional treatments for pancreatic cancer are highly associated with sub-optimal performance and systemic toxicity, the development of novel therapeutic strategies holds outmost relevance for pancreatic cancer management. Liposomes are being increasingly considered as promising nanocarriers for providing not only an early diagnosis but also effective, highly specific, and safer treatment, improving overall patient outcome. This manuscript is the first in the last 10 years that revises the advances in the application of liposome-based formulations in bioimaging, chemotherapy, phototherapy, immunotherapy, combination therapies, and emergent therapies for pancreatic cancer management. Prospective insights are provided regarding several advantages resulting from the use of liposome technology in precision strategies, fostering new ideas for next-generation diagnosis and targeted therapies of pancreatic cancer.

Novel Liposomal Formulation of Baicalein for the Treatment of Pancreatic Ductal Adenocarcinoma: Design, Characterization, and Evaluation.

Pancreatic cancer (PC) is one of the deadliest cancers so there is an urgent need to develop new drugs and therapies to treat it. Liposome-based formulations of naturally-derived bioactive compounds are promising anticancer candidates due to their potential for passive accumulation in tumor tissues, protection against payload degradation, and prevention of non-specific toxicity. We chose the naturally-derived flavonoid baicalein (BAI) due to its promising effect against pancreatic ductal adenocarcinoma (PDAC) and encapsulated it into a liposomal bilayer using the passive loading method, with an almost 90% efficiency. We performed a morphological and stability analysis of the obtained BAI liposomal formulation and evaluated its activity on two-dimensional and three-dimensional pancreatic cell models. As the result, we obtained a stable BAI-encapsulated liposomal suspension with a size of 100.9 nm ± 2.7 and homogeneity PDI = 0.124 ± 0.02, suitable for intravenous administration. Furthermore, this formulation showed high cytotoxic activity towards AsPC-1 and BxPC-3 PDAC cell lines (IC50 values ranging from 21 ± 3.6 µM to 27.6 ± 4.1 µM), with limited toxicity towards normal NHDF cells and a lack of hemolytic activity. Based on these results, this new BAI liposomal formulation is an excellent candidate for potential anti-PDAC therapy.

Lipid Nanoparticles as a Promising Drug Delivery Carrier for Topical Ocular Therapy-An Overview on Recent Advances.

Due to complicated anatomical and physical properties, targeted drug delivery to ocular tissues continues to be a key challenge for formulation scientists. Various attempts are currently being made to improve the in vivo performance of therapeutic molecules by encapsulating them in various nanocarrier systems or devices and administering them via invasive/non-invasive or minimally invasive drug administration methods. Biocompatible and biodegradable lipid nanoparticles have emerged as a potential alternative to conventional ocular drug delivery systems to overcome various ocular barriers. Lipid-based nanocarrier systems led to major technological advancements and therapeutic advantages during the last few decades of ocular therapy, such as high precorneal residence time, sustained drug release profile, minimum dosing frequency, decreased drug toxicity, targeted site delivery, and, therefore, an improvement in ocular bioavailability. In addition, such formulations can be given as fine dispersion in patient-friendly droppable preparation without causing blurred vision and ocular sensitivity reactions. The unique advantages of lipid nanoparticles, namely, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, and liposomes in intraocular targeted administration of various therapeutic drugs are extensively discussed. Ongoing and completed clinical trials of various liposome-based formulations and various characterization techniques designed for nanoemulsion in ocular delivery are tabulated. This review also describes diverse solid lipid nanoparticle preparation methods, procedures, advantages, and limitations. Functionalization approaches to overcome the drawbacks of lipid nanoparticles, as well as the exploration of new functional additives with the potential to improve the penetration of macromolecular pharmaceuticals, would quickly progress the challenging field of ocular drug delivery systems.

Liposomal-Based Formulations: A Path from Basic Research to Temozolomide Delivery Inside Glioblastoma Tissue.

Glioblastoma (GBM) is a lethal brain cancer with a very difficult therapeutic approach and ultimately frustrating results. Currently, therapeutic success is mainly limited by the high degree of genetic and phenotypic heterogeneity, the blood brain barrier (BBB), as well as increased drug resistance. Temozolomide (TMZ), a monofunctional alkylating agent, is the first line chemotherapeutic drug for GBM treatment. Yet, the therapeutic efficacy of TMZ suffers from its inability to cross the BBB and very short half-life (~2 h), which requires high doses of this drug for a proper therapeutic effect. Encapsulation in a (nano)carrier is a promising strategy to effectively improve the therapeutic effect of TMZ against GBM. Although research on liposomes as carriers for therapeutic agents is still at an early stage, their integration in GBM treatment has a great potential to advance understanding and treating this disease. In this review, we provide a critical discussion on the preparation methods and physico-chemical properties of liposomes, with a particular emphasis on TMZ-liposomal formulations targeting GBM developed within the last decade. Furthermore, an overview on liposome-based formulations applied to translational oncology and clinical trials formulations in GBM treatment is provided. We emphasize that despite many years of intense research, more careful investigations are still needed to solve the main issues related to the manufacture of reproducible liposomal TMZ formulations for guaranteed translation to the market.

A Recent Overview on Dermatological Applications of Liposomes.

In dermatology, the topical application of liposomes has proven to be of therapeutic value. Many drugs encapsulated into liposomes have shown enhanced skin penetration. Liposomes are lipid based spherical vesicles. In structure and composition, they resemble cell membrane. Because of their amphipathic nature, they can be used as carriers for hydrophilic as well as lipophilic therapeutic agents. These liposomal systems can easily get integrated with the skin lipids and maintain the desired hydration conditions to improve drug penetration and localization in the skin layers. Considering the need for topical delivery and the promising potential of liposomes, an attempt has been made to explore the recent advances of liposome-based formulations in dermatological applications. This patent summarizes the recent findings of liposome-based formulations for dermal delivery of drugs.

Solubilization Methods for Paclitaxel and Docetaxel: An Overview

Cancer is still a serious disease with high incidence over the past decades. Many anticancer drugs are discovered and used to treat cancer, among them, taxanes such as paclitaxel and docetaxel have high lipophilicity and low aqueous solubility which is further magnified considering the strong need for administering them by intravenous infusion. Currently, the poor water-solubility of taxanes is improved by prodrug formation, conjugation, inclusion complexation, micellar solubilization and liposome-based formulations. Recent achievement for solubilization of taxanes are reviewed and critically discussed regarding their pharmaceutical and chemical applications.

Nanocrystal-loaded liposome for targeted delivery of poorly water-soluble antitumor drugs with high drug loading and stability towards efficient cancer therapy

Nanocrystals (NCs) enable the delivery of poorly water-soluble drugs with improved dissolution and bioavailability. However, their uncontrolled release and instability make targeted delivery challenging. Herein, a nano-in-nano delivery system composed of a drug nanocrystal core and liposome shell (NC@Lipo) is presented, which merges the advantages of drug nanocrystals (high drug loading) and liposomes (easy surface functionalization and high stability) for targeted delivery of hydrophobic drugs to tumors. CHMFL-ABL-053 (053), a hydrophobic drug candidate discovered by our group, was employed as a model drug to demonstrate the performance of NC@Lipo delivery system. Surface PEGylated (053-NC@PEG-Lipo) and folic acid-functionalized (053-NC@FA-Lipo) formulations were fabricated by wet ball milling combined with probe sonication. 053-NC@Lipo enabled high drug loading (up to 19.51%), considerably better colloidal stability, and longer circulation in vivo than 053-NC. Compared with free 053, 053-NC@PEG-Lipo and 053-NC@FA-Lipo exhibited higher tumor accumulation and considerably better in vivo antitumor efficacy in K562 xenograft mice with tumor growth inhibition rate (TGI) of up to 98%. Additionally, more effective tumor cell targeting in vitro and higher TGI in vivo were achieved with 053-NC@FA-Lipo. The NC@Lipo strategy may contribute to the targeted delivery of poorly water-soluble drugs with high drug loading, high stability, and tailorable surface, and has potential for the development of more efficient nanocrystal- and liposome-based formulations for commercial and clinical applications. It may also provide new opportunities for potential clinical application of candidate 053.

Liposome Formulations as Adjuvants for Vaccines.

Development of liposome-based formulations as vaccine adjuvants has been intimately associated with, and dependent on, and informed by, a fundamental understanding of biochemical and biophysical properties of liposomes themselves. The Walter Reed Army Institute of Research (WRAIR) has a fifty-year history of experience of basic research on liposomes; and development of liposomes as drug carriers; and development of liposomes as adjuvant formulations for vaccines. Uptake of liposomes by phagocytic cells in vitro has served as an excellent model for studying the intracellular trafficking patterns of liposomal antigen. Differential fluorescent labeling of proteins and liposomal lipids, together with the use of inhibitors, has enabled the visualization of physical locations of antigens, peptides, and lipids to elucidate mechanisms underlying the MHC class I and class II pathways in phagocytic APCs. Army Liposome Formulation (ALF) family of vaccine adjuvants, which have been developed and improved since 1986, and which range from nanosize to microsize, are currently being employed in phase 1 studies with different types of candidate vaccines.

Liposome-Based Bioassays.

This review highlights the potential of using liposomes in bioassays. Liposomes consist of nano- or micro-sized, synthetically constructed phospholipid vesicles. Liposomes can be loaded with a number of reporting molecules that allow a dramatic amplification of the detection threshold in bioassays. Liposome-based sensors bind or react with the biological components of targets through the introduction of properly tailored vectors anchored on their external surface. The use of liposome-based formulations allows the set-up of bioassays that are rapid, sensitive, and often suitable for in-field applications. Selected applications in the field of immunoassays, as well as recognition/assessment of corona proteins, nucleic acids, exosomes, bacteria, and viruses are surveyed. The role of magnetoliposomes is also highlighted as an additional tool in the armory of liposome-based systems for bioassays.

Long-acting liposomal corneal anesthetics

Eye drops producing long-acting ocular anesthesia would be desirable for corneal pain management. Here we present liposome-based formulations to achieve very long ocular anesthetic effect after a single eye drop instillation. The liposomes were functionalized with succinyl-Concanavalin A (sConA-Lip), which can bind corneal glycan moieties, to significantly prolong the dwell time of liposomes on the cornea. sConA-Lip were loaded with tetrodotoxin and dexmedetomidine (sConA-Lip/TD), and provided sustained release for both. A single topical instillation of sConA-Lip/TD on the cornea could achieve 105 min of complete analgesia and 608 min of partial analgesia, which was significantly longer than analgesia with proparacaine, tetrodotoxin/dexmedetomidine solution or unmodified liposomes containing tetrodotoxin and dexmedetomidine. sConA-Lip/TD were not cytotoxic in vitro to human corneal limbal epithelial cells or corneal keratocytes. Topical administration of sConA-Lip/TD provided prolonged corneal anesthesia without delaying corneal wound healing. Such a formulation may be useful for the management of acute surgical and nonsurgical corneal pain, or for treatment of other ocular surface diseases.

Antileishmanial Activity of Amphotericin B-loaded-PLGA Nanoparticles: An Overview.

In recent decades, nanotechnology has made phenomenal strides in the pharmaceutical field, favouring the improvement of the biopharmaceutical properties of many active compounds. Many liposome-based formulations containing antitumor, antioxidant and antifungal compounds are presently on the market and are used daily (for example Doxil®/Caelyx® and Ambisome®). Polymeric nanoparticles have also been used to entrap many active compounds with the aim of improving their pharmacological activity, bioavailability and plasmatic half-life while decreasing their side effects. The modulation of the structural/morphological properties of nanoparticles allows us to influence various technological parameters, such as the loading capacity and/or the release profile of the encapsulated drug(s). Amongst the biocompatible polymers, poly(D,L-lactide) (PLA), poly(D,L-glycolide) (PLG) and their co-polymers poly(lactide-co-glycolide) (PLGA) are the most frequently employed due to their approval by the FDA for human use. The aim of this review is to provide a description of the foremost recent investigations based on the encapsulation of amphotericin B in PLGA nanoparticles, in order to furnish an overview of the technological properties of novel colloidal formulations useful in the treatment of Leishmaniasis. The pharmacological efficacy of the drug after nanoencapsulation will be compared to the commercial formulations of the drug (i.e., Fungizone®, Ambisome®, Amphocil® and Abelcet®).

Evaluation of pharmacokinetic and pharmacodynamic profiles of liposomes for the cell type-specific delivery of small molecule drugs

Liposome-based drug formulations represent an exciting avenue of research as they increase efficacy to toxicity ratios. Current formulations rely on passive accumulation to the disease site where drug is taken up by the cells. Ligand mediated targeting increases the net accumulation of liposomes, however, an unexplored benefit is to potentially refine pharmacodynamics (PD) of a drug specifically to different cell types within diseased tissue. As a model system, we engineered cardiomyocyte- (I-1) and endothelial-targeted (B-40) liposomes to carry a VEGFR2 inhibitor (PTK787), and examined the effect of cell type-specific delivery on both pharmacokinetics (PK) and PD. Neovascularization in post-myocardial infarction was significantly reduced by B-40 liposomes loaded with PTK787 as compared to animals injected with I-1 liposomes, and profoundly more as compared to free PTK787. This study thus shows that the intraorgan targeting of drugs through cell type-specific delivery holds substantial promise towards lowering the minimal efficacious dose administered systemically.

Alternatives to mineral oil adjuvants in vaccines against Aeromonas salmonicida subsp. salmonicida in rainbow trout offer reductions in adverse effects

In an effort to reduce the frequency and severity of adverse reactions seen from the use of mineral oil adjuvants in salmonid fish, the effects of two alternative adjuvants were assessed, focusing on the induction of adverse effects as well as protection. Using rainbow trout (Oncorhynchus mykiss) as recipients, injection vaccines based on formalin-inactivated Aeromonas salmonicida subspecies salmonicida were formulated with CpG oligodeoxynucleotides, the liposomal cationic adjuvant formulation 01 (CAF01) or with Freund’s incomplete adjuvant and administered intraperitoneally. Control groups of unvaccinated, Tris-buffered saline-injected or bacterin-injected individuals were included, and each group included in the study held a total number of 240 individuals. Subsequently, individuals from each group were examined for differences in Fulton’s condition factor, macro- and microscopic pathological changes, as well as protection against experimental infection with A. salmonicida. While adverse effects were not eliminated, reductions in microscopic and macroscopic adverse effects, in particular, were seen for both the nucleotide- and liposome-based vaccine formulations. Furthermore, the induced protection appears similar to that of the benchmark formulation, thus introducing viable, potential alternative types of adjuvants for use in future fish vaccines.

Novel anti-inflammatory liposomal formulation for the pre-ocular tear film: In vitro and ex vivo functionality studies in corneal epithelial cells

In ocular surface inflammatory diseases, such as dry eye disease, long-term symptom relief requires targeting the inflammation itself rather than treating only the surface-associated dryness with artificial tears. Therefore, we included an anti-inflammatory agent in an unpreserved liposome-based (LP) formulation used as artificial tears. Our aim was to characterize and study its in vitro and ex vivo cell uptake and functionality. Human corneal epithelial (HCE) cells were used to study MPA-LP-induced effects after 60 min of exposure, using blank LP and non-LP MPA formulations as controls. A fluorescent labeled LP formulation was used to determine uptake by HCE cells and localization in ex vivo porcine corneas. The LP formulation complied with the required physicochemical properties and had no cytotoxicity on HCE cells after 60 min of exposure. HCE cells showed LP-associated fluorescence at 24, 48, and 72 h after 60 min of exposure, and the LP-associated fluorescence was uniformly distributed throughout the porcine corneal epithelium immediately after 5 min of exposure. MPA-LP increased protein expression and nuclear translocation of progesterone receptor in comparison with controls as determined by Western blotting and immunofluorescence. Moreover, MPA-LP significantly reduced the cell proliferation rate and IL-6 and IL-8 production 48 h after the exposure period, as determined by the alamarBlue assay and ELISA, respectively. None of these effects were evident in blank LP-exposed cells and non-LP MPA formulation reduced only IL-6 production. Our results suggest that the LP-based formulation, used to replenish the lipids of the tear film, can be loaded with anti-inflammatory agents that can be delivered into the cells and activate specific drug receptors. These agents can reduce inflammatory cytokine production and may be effective in the treatment of inflammatory processes associated with ocular surface diseases.