Remote Drug Loading Research Articles

Multifunctional Lipid Bilayer Nanocarriers for Cancer Immunotherapy in Heterogeneous Tumor Microenvironments, Combining Immunogenic Cell Death Stimuli with Immune Modulatory Drugs.

In addition to the contribution of cancer cells, the solid tumor microenvironment (TME) has a critical role in determining tumor expansion, antitumor immunity, and the response to immunotherapy. Understanding the details of the complex interplay between cancer cells and components of the TME provides an unprecedented opportunity to explore combination therapy for intervening in the immune landscape to improve immunotherapy outcome. One approach is the introduction of multifunctional nanocarriers, capable of delivering drug combinations that provide immunogenic stimuli for improvement of tumor antigen presentation, contemporaneous with the delivery of coformulated drug or synthetic molecules that provide immune danger signals or interfere in immune-escape, immune-suppressive, and T-cell exclusion pathways. This forward-looking review will discuss the use of lipid-bilayer-encapsulated liposomes and mesoporous silica nanoparticles for combination immunotherapy of the heterogeneous immune landscapes in pancreatic ductal adenocarcinoma and triple-negative breast cancer. We describe how the combination of remote drug loading and lipid bilayer encapsulation is used for the synthesis of synergistic drug combinations that induce immunogenic cell death, interfere in the PD-1/PD-L1 axis, inhibit the indoleamine-pyrrole 2,3-dioxygenase (IDO-1) immune metabolic pathway, restore spatial access to activated T-cells to the cancer site, or reduce the impact of immunosuppressive stromal components. We show how an integration of current knowledge and future discovery can be used for a rational approach to nanoenabled cancer immunotherapy.

Liposomal drug delivery: Recent developments and challenges

The spherical vesicles known as liposomes may contain one or many phospholipid bilayers. The first liposomes were found in the 1960s. One of the many distinctive drug delivery methods is the liposome, which offers a complex way to transfer active molecules to the site of action. Clinical trials are now testing a variety of formulations. Long-lasting second-generation liposomes are created by altering the vesicle’s lipid composition, size, and charge. Superficial vesicles have given way to liposome growth. Glycolipids and other substances have been used to make liposomes for the modification of outer surfaces through various types of targeting ligands and detecting agents or moiety. Now, the liposomes developed for the different market and it is flooded with cosmetics and, more crucially, medications. Three of the main applications of liposome technology include steric and environmental stabilization of loaded molecules, remote drug loading through pH and ion gradients approach, and simultaneously lipoplexes which is the complexes forms of cationic liposomes with anionic nucleic acids or proteins for the gene delivery or siRNA technology. The scope of liposome research was expanded, allowing for the production of various goods. The present review focuses on the different aspects of liposomal drug delivery concerning types, preparation, pros, and cons.

Remote drug loading into liposomes via click reaction.

The development of liposome-based drugs was severely limited due to inefficient loading strategies. Herein, we developed a click reaction-mediated loading procedure by designing an enzyme-sensitive maleimide (MAL) tag for ferrying chemotherapeutics into preformed liposomes containing glutathione (GSH). Based on this strategy, various hydrophobic drugs could be encapsulated into liposomes within 5-30 min with encapsulation efficiency >95% and loading capacity of 10-30% (w/w). The entrapped cargo could be slowly released from the liposomes, followed by rapid enzyme-mediated conversion into active drugs to exert antitumor activity under physiological conditions. The resulting drug-loaded liposomes significantly prolonged the blood circulation of cargos and displayed more potent in vivo antitumor efficacy than free drugs at the equitoxic dose. More importantly, this method is a remote drug loading strategy in nature, which is suitable for industrial production. This is the first demonstration of active loading of MAL-tagged chemotherapeutics in liposomes for improved antitumor efficacies, which has the potential to serve as a universal drug loading strategy for the development of liposomal formulations of chemotherapeutics.

Lyoprotective Effects of Mannitol and Lactose Compared to Sucrose and Trehalose: Sildenafil Citrate Liposomes as a Case Study.

The lyoprotective effects of mannitol and lactose have been evaluated in the production of sildenafil citrate liposomes. Liposomes were prepared by mixing the components under ultrasonic agitation, followed by a transmembrane pH gradient for remote drug loading. Mannitol and lactose, as compared to sucrose and trehalose, were used as the stabilizing agents, and different freeze-drying cycles were assayed. The remaining moisture and the thermal characteristics of the lyophilized samples were analyzed. Size, entrapment efficiency, biocompatibility, and cell internalization of original and rehydrated liposomes were compared. The type of additive did not affect the biocompatibility or cell internalization, but did influence other liposome attributes, including the thermal characteristics and the remaining moisture of the lyophilized samples. A cut-off of 5% (w/w) remaining moisture was an indicator of primary drying completion—information useful for scaling up and transfer from laboratory to large-scale production. Lactose increased the glass transition temperature to over 70 °C, producing lyoprotective effects similar to those obtained with sucrose. Based on these results, formulations containing liposomes lyophilized with lactose meet the FDA’s requirements and can be used as a biocompatible and biodegradable vehicle for the pulmonary delivery of therapeutic doses of sildenafil citrate.

RGD-expressed bacterial membrane-derived nanovesicles enhance cancer therapy via multiple tumorous targeting.

Background: A tumor microenvironment is a complicated multicellular system comprised of tumor cells, immune cells and blood vessels. Blood vessels are the barriers for drug tissue penetration. Effectively treating a cancer requires drug delivery systems to overcome biological barriers present in tumor microenvironments (TMEs).Methods: We designed a drug delivery system made of bacterial (Escherichia coli) double layer membrane-derived nanovesicles (DMVs) with the expression of RGD peptides and endogenous targeting ligands of bacteria. The physical and biological characteristics of DMVs were assessed by cryogenic transmission electron microscopy, western blotting, flow cytometry and confocal microscopy. Doxorubicin (DOX) was loaded in DMVs via a pH gradient driven drug loading method. Therapeutical effects of DOX-loaded DMVs were studied in a melanoma xenograft mouse model.Results: In vitro and in vivo experiments showed that DMVs can target neutrophils and monocytes that mediated the transport of DMVs across blood vessel barriers and they can also directly target tumor vasculature and tumor cells, resulting in enhanced delivery of therapeutics to TMEs. Furthermore, we developed a remote drug loading approach to efficiently encapsulate DOX inside DMVs, and the drug loading was 12% (w/w). In the B16-F10 melanoma mouse model, we showed that DOX-RGD-DMVs significantly inhibited the tumor growth compared to several controls.Conclusion: Our studies reveal that DMVs are a powerful tool to simultaneously target multiple cells in TMEs, thus increasing drug delivery for improved cancer therapies.

Preparation and Evaluation of Cubic Nanoparticles for Improved Transdermal Delivery of Propranolol Hydrochloride

Transdermal drug delivery of propranolol hydrochloride (PRH) is promising for the treatment of infantile hemangioma (IH). Clinically used PRH hydrogel fails to reach the deep IH for complete recovery. In this study, the PRH-loaded cubic nanoparticles (CNPs) were prepared to promote the transdermal effect of PRH. A remote drug loading method was developed to prepare the PRH-CNPs. For the traditional passive drug loading method, the largest encapsulation efficiency (EE%) was around 50%. The remote drug loading was performed by increasing the pH of the mixture of blank CNPs and PRH solution. The optimal PRH-CNPs showed an EE% of 90.15 ± 2.44% at pH8.5. The permeation of the PRH solution was poor while the PRH-CNPs showed greatly enhanced skin permeation. It was found that smaller-sized PRH-CNPs contributed to increased skin permeation and retention. In addition, the PRH-CNPs had higher cytotoxicity towards the EOMA cells when compared with the PRH solution. During storage for 1month, the PRH-CNPs kept stable size distribution, pH, and EE%. In conclusion, results of this study suggested that the PRH-CNPs could be a potential candidate for the treatment of the IH by transdermal delivery.

A facile and universal method to achieve liposomal remote loading of non-ionizable drugs with outstanding safety profiles and therapeutic effect

Liposomes have made remarkable achievements as drug delivery vehicles in the clinic. Liposomal products mostly benefited from remote drug loading techniques that succeeded in amphipathic and/or ionizable drugs, but seemed impracticable for nonionizable and poorly water-soluble therapeutic agents, thereby impeding extensive promising drugs to hitchhike liposomal vehicles for disease therapy. In this study, a series of weak acid drug derivatives were designed by a simplistic one step synthesis, which could be remotely loaded into liposomes by pH gradient method. Cabazitaxel (CTX) weak acid derivatives were selected to evaluate regarding its safety profiles, pharmacodynamics, and pharmacokinetics. CTX weak acid derivative liposomes were superior to Jevtana® in terms of safety profiles, including systemic toxicity, hematological toxicity, and potential central nerve toxicity. Specifically, it was demonstrated that liposomes had capacity to weaken potential toxicity of CTX on cortex and hippocampus neurons. Significant advantages of CTX weak acid derivative-loaded liposomes were achieved in prostate cancer and metastatic cancer therapy resulting from higher safety and elevated tolerated doses.

Liposomes: Current Approaches for Development and Evaluation

Liposomes (50-1000nm) are the part of a specific type of drug delivery system which is non-toxic and biodegradable in nature. That having ability to reduce the toxicity also enhances the therapeutic efficiency and protects the drug which is encapsulated, from the degradation and immediate dilution. These can be prepared by using various techniques like lipid hydration method, sonication method and solvent injecting method etc. But the selection of technique is depended upon the size of liposome which we want. The main disadvantage of this dosage form is it is very much costly and also having time consuming process. But it has major applications in the form of extrusion for homogeneous size, long circulating liposomes, triggered release liposome, remote drug loading, ligand targeted liposomes and containing combination of drugs. These applications are helpful for advanced drug delivery of anticancer, antifungal and anti-inflammatory drug, the delivery of gene medicine, delivery of anaesthetic and antibiotic drug. The newer researches in this field include hybrid liposomes, phototrigerable liposomes which are fabricated to have the improved functionality. These serves as the upcoming novel nanomedicinal chemotherapy technique.

Liposomes as colloidal nanovehicles: on the road to success in intravenous drug delivery

Abstract The advancement of research in colloidal systems has led to the increased application of this technology in more effective and targeted drug delivery. Nanotechnology enables control over functionality parameters and allows innovations in biodegradable, biocompatible, and stimuli-responsive delivery systems. The first closed bilayer phospholipid system, the liposome system, has been making steady progress over five decades of extensive research and has been efficient in achieving many desirable parameters such as remote drug loading, size-controlling measures, longer circulation half-lives, and triggered release. Liposome-mediated drug delivery has been successful in overcoming obstacles to cellular and tissue uptake of drugs with improved biodistribution in vitro and in vivo. These colloidal nanovehicles have moved on from a mere concept to clinical applications in various drug delivery systems for antifungal, antibiotic, and anticancer drugs.

New drug candidates for liposomal delivery identified by computer modeling of liposomes' remote loading and leakage

Remote drug loading into nano-liposomes is in most cases the best method for achieving high concentrations of active pharmaceutical ingredients (API) per nano-liposome that enable therapeutically viable API-loaded nano-liposomes, referred to as nano-drugs. This approach also enables controlled drug release. Recently, we constructed computational models to identify APIs that can achieve the desired high concentrations in nano-liposomes by remote loading. While those previous models included a broad spectrum of experimental conditions and dealt only with loading, here we reduced the scope to the molecular characteristics alone. We model and predict API suitability for nano-liposomal delivery by fixing the main experimental conditions: liposome lipid composition and size to be similar to those of Doxil® liposomes. On that basis, we add a prediction of drug leakage from the nano-liposomes during storage. The latter is critical for having pharmaceutically viable nano-drugs. The “load and leak” models were used to screen two large molecular databases in search of candidate APIs for delivery by nano-liposomes. The distribution of positive instances in both loading and leakage models was similar in the two databases screened. The screening process identified 667 molecules that were positives by both loading and leakage models (i.e., both high-loading and stable). Among them, 318 molecules received a high score in both properties and of these, 67 are FDA-approved drugs. This group of molecules, having diverse pharmacological activities, may be the basis for future liposomal drug development.

Liposomal Delivery Systems: Design Optimization and Current Applications.

The liposome, a closed phospholipid bilayered vesicular system, has received considerable attention as a pharmaceutical carrier of great potential over the past 30 years. The ability of liposomes to encapsulate both hydrophilic and hydrophobic drugs, coupled with their biocompatibility and biodegradability, make liposomes attractive vehicles in the field of drug delivery. In addition, great technical advances such as remote drug loading, triggered release liposomes, ligand-targeted liposomes, liposomes containing combinations of drugs, and so on, have led to the widespread use of liposomes in diverse areas as delivery vehicles for anti-cancer, bio-active molecules, diagnostics, and therapeutic agents. In this review, we summarize design optimization of liposomal systems and invaluable applications of liposomes as effective delivery systems.

Microfluidic remote loading for rapid single-step liposomal drug preparation.

Microfluidic-directed formation of liposomes is combined with in-line sample purification and remote drug loading for single step, continuous-flow synthesis of nanoscale vesicles containing high concentrations of stably loaded drug compounds. Using an on-chip microdialysis element, the system enables rapid formation of large transmembrane pH and ion gradients, followed by immediate introduction of amphipathic drug for real-time remote loading into the liposomes. The microfluidic process enables in-line formation of drug-laden liposomes with drug : lipid molar ratios of up to 1.3, and a total on-chip residence time of approximately 3 min, representing a significant improvement over conventional bulk-scale methods which require hours to days for combined liposome synthesis and remote drug loading. The microfluidic platform may be further optimized to support real-time generation of purified liposomal drug formulations with high concentrations of drugs and minimal reagent waste for effective liposomal drug preparation at or near the point of care.

The encapsulation of idarubicin within liposomes using the novel EDTA ion gradient method ensures improved drug retention in vitro and in vivo

The purpose of this study was to design a new stable liposomal formulation for the anticancer drug idarubicin. Idarubicin is a relatively hydrophobic member of the anthracycline family. It exhibits pronounced bilayer interactions leading to rapid in vivo drug release from liposomes. This rapid drug leakage is due to the presence of cholesterol and charged lipids in the liposomal bilayer. Therefore, a novel method of remote drug loading was developed to prevent rapid drug release from PEGylated cholesterol-containing liposomes. This method uses EDTA disodium or diammonium salt as an agent to form low solubility complexes between the drug and EDTA molecules inside the liposomes, thus yielding improved drug retention. The efficiency of idarubicin encapsulation is close to 98% at a drug to lipid molar ratio of 1:5. An in vitro long-term storage experiment confirmed the high stability of the liposomes. The in vivo studies also showed the superiority of the new idarubicin formulation over the recently used remote loading methods. The plasma level of idarubicin was much higher when EDTA liposomes were used. The presented results fully demonstrate the superiority of the proposed method of idarubicin encapsulation over existing methods. The method offers the possibility of encapsulating not only all the anthracyclines, but also other weakly amphiphilic bases within the liposomes.