Arsenic trioxide liposomes: encapsulation efficiency and in vitro stability

Composition, preparation methods, and applications of nanoniosomes as codelivery systems: a review of emerging therapies with emphasis on cancer

Nanoniosome-based drug codelivery systems have become popular therapeutic instruments, demonstrating tremendous promise in cancer therapy, infection treatment, and other therapeutic domains. An emerging form of vesicular nanocarriers, niosomes are self-assembling vesicles composed of nonionic surfactants, along with cholesterol or other amphiphilic molecules. This comprehensive review focuses on how nanosystems may aid in making anticancer and antibacterial pharmaceuticals more stable and soluble. As malleable nanodelivery instruments, the composition, types, preparation procedures, and variables affecting the structure and stability of niosomes are extensively investigated. In addition, the advantages of dual niosomes for combination therapy and the administration of multiple medications simultaneously are highlighted. Along with categorizing niosomal drug delivery systems, a comprehensive analysis of various preparation techniques, including thin-layer injection, ether injection, and microfluidization, is provided. Dual niosomes for cancer treatment are discussed in detail regarding the codelivery of two medications and the codelivery of a drug with organic, plant-based bioactive compounds or gene agents. In addition, niogelosomes and metallic niosomal carriers for targeted distribution are discussed. The review also investigates the simultaneous delivery of bioactive substances and gene agents, including siRNA, microRNA, shRNA, lncRNA, and DNA. Additional sections discuss the use of dual niosomes for cutaneous drug delivery and treating leishmanial infections, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. The study concludes by delineating the challenges and potential routes for nanoniosome-based pharmaceutical codelivery systems, which will be useful for nanomedicine practitioners and researchers.

Preparation of DRV Liposomes

Dried reconstituted vesicle (DRV) liposomes are formulated under mild conditions. The method has the capability to entrap substantially higher amounts of hydrophilic solutes, compared to other passive-loading liposome preparation methods. These characteristics make this liposome type ideal for entrapment of labile substances, such as peptides, proteins, or DNA's (or other nucleotides or oligonucleotides), or in general biopharmaceuticals and sensitive drugs. In this chapter, all possible types of DRV liposomes (in respect to the encapsulated molecule characteristics and/or their applications in therapeutics) are introduced, and preparation methodologies (for each type) are described in detail.

Current Advances of Nanomedicines Delivering Arsenic Trioxide for Enhanced Tumor Therapy

Arsenic trioxide (ATO) is one of the first-line chemotherapeutic drugs for acute promyelocytic leukemia. Its anti-cancer activities against various human neoplastic diseases have been extensively studied. However, the clinical use of ATO for solid tumors is limited, and these limitations are because of severe systemic toxicity, low bioavailability, and quick renal elimination before it reaches the target site. Although without much success, several efforts have been made to boost ATO bioavailability toward solid tumors without raising its dose. It has been found that nanomedicines have various advantages for drug delivery, including increased bioavailability, effectiveness, dose-response, targeting capabilities, and safety as compared to traditional drugs. Therefore, nanotechnology to deliver ATO to solid tumors is the main topic of this review, which outlines the previous and present medical applications of ATO. We also summarised ATO anti-cancer mechanisms, limitations, and outcomes of combinatorial treatment with chemo agents. As a result, we strongly recommend conducting pre-clinical and clinical studies of ATO, especially nano-system-based ones that might lead to a novel combination therapy for cancer treatment with high efficacy, bioavailability, and low toxicity for cancer patients.

Novel and efficient method for loading aptamer-conjugated liposomes with arsenic trioxide for targeting cancer cells

Although the therapeutic effect of liposomal arsenic trioxide arsenic trioxide (ATO) in the treatment of solid tumours has been confirmed, its dose-limiting loading is a challenging issue. To solve the problems in the preparation of liposomal ATO, different loading strategies were evaluated and compared. In addition, liposomes decorated with anti-nucleolin aptamers were developed as a novel formulation for targeted delivery with high loading efficiency and sustained releasing property in order to treat solid tumours. The liposomes were prepared by a thin-film method exploiting the passive loading strategy of Co(II) hydrogen arsenite (CHA). The structural characteristics of the liposomes were also investigated by Fourier transform infra-red spectroscopy (FT-IR), dynamic light scattering (DLS), zeta potentiometry, field emission scanning electron microscopy (FESEM), and Energy Dispersive X-ray Diffraction (EDX) techniques. To evaluate the potential cytotoxicity of this liposomal drug vehicle in vitro, MTT assay was performed on HT-29 cancer cell line. The results showed that the synthesised liposomes loaded with CHA exhibited high entrapment efficiency (77%). MTT assays showed a significant difference between the percentage of viable cells when HT -29 cells were treated with free ATO and liposomal formulation which can be corresponded to the sustained release of the drug from the liposomes. The results of this study may lead to a promising strategy for the effective treatment of solid tumours.

Current status and future prospects of nanomedicine for arsenic trioxide delivery to solid tumors

Despite having a rich history as a poison, arsenic and its compounds have also gained a great reputation as promising anticancer drugs. As a pioneer, arsenic trioxide has been approved for the treatment of acute promyelocytic leukemia. Many in vitro studies suggested that arsenic trioxide could also be used in the treatment of solid tumors. However, the transition from bench to bedside turned out to be challenging, especially in terms of the drug bioavailability and concentration reaching tumor tissues. To address these issues, nanomedicine tools have been proposed. As nanocarriers of arsenic trioxide, various materials have been examined including liposomes, polymer, and inorganic nanoparticles, and many other materials. This review gives an overview of the existing strategies of delivery of arsenic trioxide in cancer treatment with a focus on the drug encapsulation approaches and medicinal impact in the treatment of solid tumors. It focuses on the progress in the last years and gives an outlook and suggestions for further improvements including theragnostic approaches and targeted delivery.

Niosomal Drug Delivery Systems for Ocular Disease-Recent Advances and Future Prospects

The eye is a complex organ consisting of several protective barriers and particular defense mechanisms. Since this organ is exposed to various infections, genetic disorders, and visual impairments it is essential to provide necessary drugs through the appropriate delivery routes and vehicles. The topical route of administration, as the most commonly used approach, maybe inefficient due to low drug bioavailability. New generation safe, effective, and targeted drug delivery systems based on nanocarriers have the capability to circumvent limitations associated with the complex anatomy of the eye. Nanotechnology, through various nanoparticles like niosomes, liposomes, micelles, dendrimers, and different polymeric vesicles play an active role in ophthalmology and ocular drug delivery systems. Niosomes, which are nano-vesicles composed of non-ionic surfactants, are emerging nanocarriers in drug delivery applications due to their solution/storage stability and cost-effectiveness. Additionally, they are biocompatible, biodegradable, flexible in structure, and suitable for loading both hydrophobic and hydrophilic drugs. These characteristics make niosomes promising nanocarriers in the treatment of ocular diseases. Hereby, we review niosome based drug delivery approaches in ophthalmology starting with different preparation methods of niosomes, drug loading/release mechanisms, characterization techniques of niosome nanocarriers and eventually successful applications in the treatment of ocular disorders.

Construction of arsenic-metal complexes loaded nanodrugs for solid tumor therapy: A mini review

Arsenic trioxide (As₂O₃), a front-line therapeutic agent against acute promyelocytic leukemia, has a broad spectrum against malignancies. Unfortunately, the clinical application of As₂O₃ in treating hematological cancers has not been transformed to solid tumors, for its dose-limited toxicity and undesirable pharmacokinetics. The ordinary As₂O₃ loaded nanodrugs (such as liposomes, polymer micelles, albumin-based nanodrugs, and silica-based nanodrugs, etc.) still could not fuel up pharmaceuticals and eradicate toxicity for low delivery efficiency caused by the instability and severe drug leakage of formulations during circulation. Recently, the approach of forming and delivering arsenic-metal complexes which will dissociate in the tumoral environment caught our mind. This is the most effective strategy to reduce drug leakage in circulation and accumulate arsenite ions in tumor sites, therefore promote the anti-tumor effect and lighten the toxicity of the drug. This review aims to explain the formation mechanism of arsenic-metal nanocomposites and summarize the constructing strategies of the arsenic-metal nanocomplexes (arsenic-nickel, arsenic-manganese, arsenic-platinum, arsenic-gadolinium, arsenic-zinc, and arsenic-iron nanobins) loaded nanodrugs for solid tumor therapy. Furthermore, the expectations and challenges of arsenic-metal complexes containing nanodrugs for cancer therapy in the future were discussed.

Arsenic trioxide encapsulated liposomes prepared via copper acetate gradient loading method and its antitumor efficiency

In this study, arsenic trioxide (ATO) was encapsulated in liposomes via copper acetate (Cu(OAc)₂) gradients and high entrapment efficiency of over 80% was obtained. The average particle size and the zeta-potential of the liposomes were detected to be 115.1 ± 29.1 nm and −21.97 ± 0.6 mV, respectively. The TEM images showed rod-like precipitates in the inner aqueous phase, which was supposed be due to the formation of insoluble ATO—Cu complex. The in vitro drug release of ATO—Cu liposomes exhibited a sustained release over 72 h, and the release rates decreased with the increase of the pH of release media. Pharmacokinetic and tissue distribution studies of ATO liposomes showed significantly reduced plasma clearance rate, increased AUC_0–12h and T_1/2, and improved tumor distribution of As compared to iv administration of ATO solution. The anti-tumor effect of ATO loaded liposomes to S180 tumor-bearing mice was significantly improved with a tumor inhibition rate of 61.2%, meanwhile the toxicity of encapsulated ATO was greatly decreased. In conclusion, ATO can be effectively encapsulated into liposomes by remote loading method via Cu(OAc)₂ gradients; the co-administration of ATO and Cu(II) via liposomal formulation may find wide applications in the treatment of various tumors.

Bone-targeting nanoparticle to co-deliver decitabine and arsenic trioxide for effective therapy of myelodysplastic syndrome with low systemic toxicity

Myelodysplastic syndromes (MDS) are a diverse group of bone marrow disorders and clonal hematopoietic stem cell disorders characterized by abnormal blood cells, or reduced peripheral blood cell count. Recent clinical studies on combination therapy of decitabine (DAC) and arsenic trioxide (ATO) have demonstrated synergy on MDS treatment, but the treatment can cause significant side effects to patients. In addition, both drugs have to be administered on a daily basis due to their short half-lives. In addressing key issues of reducing toxic side effects and improving pharmacokinetic profiles of the therapeutic agents, we have developed a new formulation by co-packaging DAC and ATO into alendronate-conjugated bone-targeting nanoparticles (BTNPs). Our pharmacokinetic studies revealed that intravenously administered BTNPs increased circulation time up to 3days. Biodistribution analysis showed that the BTNP facilitated DAC and ATO accumulation in the bone, which is 6.7 and 7.9 times more than untargeted NP. Finally, MDS mouse model treated with BTNPs showed better restoration of complete blood count to normal level, and significantly longer median survival as compared to free drugs or untargeted NPs treatment. Our results support bone-targeted co-delivery of DAC and ATO for effective treatment of MDS.

Preparation of DRV Liposomes

Dried reconstituted vesicles (DRV) are liposomes that are formulated under mild conditions and have the capability to entrap substantially high amounts of hydrophilic solutes (compared to other types of liposomes). These characteristics make this liposome type ideal for entrapment of labile substances, as peptide, protein, or DNA vaccines, or in general biopharmaceuticals and sensitive drugs. In this chapter, all possible types of DRV liposomes (with respect to the encapsulated molecule characteristics and/or their applications in therapeutics) are introduced, and preparation methodologies (for each type) are described in detail.

Anticancer activity of small-molecule and nanoparticulate arsenic(III) complexes

Starting in ancient China and Greece, arsenic-containing compounds have been used in the treatment of disease for over 3000 years. They were used for a variety of diseases in the 20th century, including parasitic and sexually transmitted illnesses. A resurgence of interest in the therapeutic application of arsenicals has been driven by the discovery that low doses of a 1% aqueous solution of arsenic trioxide (i.e., arsenous acid) lead to complete remission of certain types of leukemia. Since Food and Drug Administration (FDA) approval of arsenic trioxide (As2O3) for treatment of acute promyelocytic leukemia in 2000, it has become a front-line therapy in this indication. There are currently over 100 active clinical trials involving inorganic arsenic or organoarsenic compounds registered with the FDA for the treatment of cancers. New generations of inorganic and organometallic arsenic compounds with enhanced activity or targeted cytotoxicity are being developed to overcome some of the shortcomings of arsenic therapeutics, namely, short plasma half-lives and a narrow therapeutic window.

A novel nanoparticulate formulation of arsenic trioxide with enhanced therapeutic efficacy in a murine model of breast cancer

PURPOSE

The clinical success of arsenic trioxide (As(2)O(3)) in hematologic malignancies has not been replicated in solid tumors due to poor pharmacokinetics and dose-limiting toxicity. We have developed a novel nanoparticulate formulation of As(2)O(3) encapsulated in liposomal vesicles or "nanobins" [(NB(Ni,As)] to overcome these hurdles. We postulated that nanobin encapsulation of As(2)O(3) would improve its therapeutic index against clinically aggressive solid tumors, such as triple-negative breast carcinomas.

EXPERIMENTAL DESIGN

The cytotoxicity of NB(Ni,As), the empty nanobin, and free As(2)O(3) was evaluated against a panel of human breast cancer cell lines. The plasma pharmacokinetics of NB(Ni,As) and free As(2)O(3) were compared in rats to measure drug exposure. In addition, the antitumor activity of these agents was evaluated in an orthotopic model of human triple-negative breast cancer.

RESULTS

The NB(Ni,As) agent was much less cytotoxic in vitro than free As(2)O(3) against a panel of human breast cancer cell lines. In contrast, NB(Ni,As) dramatically potentiated the therapeutic efficacy of As(2)O(3) in vivo in an orthotopic model of triple-negative breast cancer. Reduced plasma clearance, enhanced tumor uptake, and induction of tumor cell apoptosis were observed for NB(Ni,As).

CONCLUSIONS

Nanobin encapsulation of As(2)O(3) improves the pharmacokinetics and antitumor efficacy of this cytotoxic agent in vivo. Our findings demonstrate the therapeutic potential of this nanoscale agent and provide a foundation for future clinical studies in breast cancer and other solid tumors.

Preparation of DRV liposomes

Dried reconstituted vesicles (DRV) are liposomes that are formulated under mild conditions and have the capability to entrap substantially high amounts of hydrophilic solutes (compared with other types of liposomes). These characteristics make this liposome type ideal for entrapment of labile substances, as peptide, protein or DNA vaccines and sensitive drugs. In this chapter, we initially introduce all possible types of DRV liposomes (in respect to the encapsulated molecule characteristics and/or their applications in therapeutics) and discuss in detail the preparation methodologies for each type.

Folate-mediated intracellular drug delivery increases the anticancer efficacy of nanoparticulate formulation of arsenic trioxide

Arsenic trioxide (As(2)O(3)) is a frontline drug for treatment of acute promyelocytic leukemia and is in clinical trials for treatment of other malignancies, including multiple myeloma; however, efforts to expand clinical utility to solid tumors have been limited by toxicity. Nanoparticulate forms of As(2)O(3) encapsulated in 100-nm-scale, folate-targeted liposomes have been developed to lower systematic toxicity and provide a platform for targeting this agent. The resultant arsenic "nanobins" are stable under physiologic conditions but undergo triggered drug release when the pH is lowered to endosomal/lysosomal levels. Cellular uptake and antitumor efficacy of these arsenic liposomes have been evaluated in folate receptor (FR)-positive human nasopharyngeal (KB) and cervix (HeLa) cells, as well as FR-negative human breast (MCF-7) tumor cells through confocal microscopy, inductively coupled plasma mass spectroscopy, and cytotoxicity studies. Uptake of folate-targeted liposomal arsenic by KB cells was three to six times higher than that of free As(2)O(3) or nontargeted liposomal arsenic; the enhanced uptake occurs through folate-mediated endocytosis, leading to a 28-fold increase in cytotoxicity. In contrast, tumor cells with lower FR density on the surface (HeLa and MCF-7) showed much less uptake of the folate-targeted drug and lower efficacy. In cocultures of KB and MCF-7 cells, the folate-targeted arsenic liposomes were exclusively internalized by KB cells, showing high targeting specificity. Our studies further indicate that folate-targeted delivery of As(2)O(3) with coencapsulated nickel(II) ions (as a nontoxic adjuvant) potentiates the As(2)O(3) efficacy in relatively insensitive solid tumor-derived cells and holds the promise of improving drug therapeutic index.

Stability of Protein-Encapsulating DRV Liposomes After Freeze-Drying: A Study with BSA and t-PA

Stability of protein-encapsulating DRV (dried-rehydrated vesicle) liposomes is evaluated after freeze-drying vesicles in presence (or not) of trehalose. Two proteins, bovine serum albumin (BSA) and tissue-type plasminogen activator (t-PA), are used, and protein-encapsulating liposomes with different lipid compositions are prepared by DRV technique. Encapsulation efficiencies are calculated, after measuring BSA with a fluorescence technique and t-PA's amidolytic activity toward a chromogenic substrate. Experimental results show that encapsulation of BSA in vesicles ranges between 35 and 53% of the protein and is only slightly affected by lipid composition. For t-PA, entrapment efficiencies are lower, ranging between 2 and 16%, while lipid composition has substantial effect on entrapment (cholesterol inclusion is very important). After freeze-drying, some lipid compositions remain stable, retaining most of initially entrapped proteins, while others do not, but they may be stabilized by trehalose. In the case of BSA, liposome behavior cannot be explained based on lipid membrane rigidity (more rigid = more stable). This may be connected with previously demonstrated interactions of BSA with membranes. Oppositely, t-PA behavior is more predictable, meaning that the lipid composition selected for the specific therapeutic application determines the need for cryoprotectant addition before freeze-drying t-PA containing DRV liposomes, perhaps due to the fact that under conditions applying minimum or no interactions between t-PA and lipid membranes occur.Thereby, interactions between proteins and membranes determine not only the encapsulation efficiency but also the need for cryopreservation of liposomal protein formulations.

L-cysteine encapsulation in liposomes: effect of phospholipids nature on entrapment efficiency and stability

Liposomal entrapment of L-cysteine (L-CySH) could be a solution to enhance its oxidative stability and its intracellular bioavailability for glutathione (GSH) synthesis. This study addresses the influence of different factors (i.e. pH value (6.3 vs 7.4), antioxidant agents (EDTA or tocopherol (TO and nature of phosphatidylcholine (PC) (Soybean PC (SPC) vs hydrogenated SPC (HSPC)) to formulate and optimize Large Unilamellar Vesicles (LUVs) of L-CySH composed of PC/Cholesterol/ Phosphatidylglycerol (6:3:1). pH decrease (p = 0.0002) and substitution of SPC by HSPC (p < 0.001) reduced L-CySH oxidation. EE% (entrapment efficiency) varied from 0.98% +/- 0.54 (SPC, pH 7.4) to 6.46% +/- 1.37 (HSPC, pH 6.3) and was improved by decreasing pH (p = 0.011) and using HSPC (p < 0.0001). An immediate release of L-CySH was observed with SPC. On the contrary, with HSPC at pH 6.3, 42.0% +/- 1.2 and 73.0% +/- 1.7 remained encapsulated after 24h at 25 degrees C and 4 degrees C, respectively. In conclusion, HSPC offering both stronger rigidity and lesser propensity for peroxidation led to optimize L-CySH liposomal stability.

Lipid Encapsulation of Arsenic Trioxide Attenuates Cytotoxicity and Allows for Controlled Anticancer Drug Release

Arsenic trioxide (ATO, As2O3) is emerging as a front line agent for treatment of acute promyelocytic leukemia with giving a complete remission rate of 83-95%. ATO also shows significant activity in relapsed/refactory multiple myeloma; however, efforts to expand clinical utility to other cancers have been limited by its toxicity profile at higher doses. New bioavailable, liposome encapsulated As(III) materials exhibit a significantly attenuated cytotoxicity that undergoes pH-triggered release of an active drug. The arsenic drugs are loaded into 100-nm-scale liposomes at high concentration (>270 mM) and excellent retention (shelf life > 6 months at 4 degrees C), as determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) diffraction. In the loading mechanism, arsenous acid crosses the bilayer membrane in exchange for acetic acid and an insoluble transitional metal (e.g., Ni2+, Co2+) arsenite salt is formed. The resultant liposomal arsenic nanoparticles appear to be stable in physiological situations but release the drug cargo in a lower pH environment, as encountered in intracellular endosomes. These drugs exhibit attenuated cytotoxicities against human lymphoma tumor cells compared with that of free As2O3. Controlled release of arsenic drugs, and hence control of toxicity, is feasible with this system. The results demonstrate that cytotoxicity can be controlled via transitions of the inorganic drug between solid and solution phases and suggest a mechanism for further improvement of the risk/benefit ratio of As2O3 in treatment of a variety of cancers.

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In vivo distribution of arsenic after i.p. injection of arsonoliposomes in balb-c mice

We recently showed that arsonoliposomes (novel arsenic containg liposomes) demonstrate differential toxicity towards various types of cancer and normal cells, in cell culture studies, as well as anti-parasitic activity. In this study, the in-vivo distribution of the active moiety of these vesicles, As, is evaluated. Sonicated arsonoliposomes were prepared using the arsonolipid with palmitic acid acyl chain (C16) mixed with egg-phosphatidyl choline (PC) and cholesterol (Chol) [C16/PC/Chol at 8:12:10 mol/mol/mol]. A dose of arsonoliposomes, corresponding to 5 mg arsenate/kg was administered by intraperitoneal injection in balb-c mice. At various time points post-injection the mice were sacrificed and the distribution of As in the organs was measured, by atomic absorption spectroscopy. Results demonstrate that a high portion of the dose administered is rapidly excreted; since 1-h post-injection only about 30% of the dose administered was detected cumulatively in the animal tissues. After this the elimination of arsenic was a slow process with a total body elimination rate constant of 0.023 h(-1), corresponding to a half-life of 30 h. Tissues with the highest arsenic concentration during the study period are: spleen-kidneys-stomach, followed by lung, liver, intestines-heart, carcass+skin and finally blood. No acute toxicity, or effect on the body or organ weight of the mice was observed.