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

Synthesis of Novel Arsonolipids and Development of Novel Arsonoliposome Types

Arsonolipids represent a class of arsenic-containing compounds with interesting biological properties either as monomers or as nanostructure forming components, such as arsonoliposomes that possess selective anticancer activity as proven by in vitro and in vivo studies. In this work, we describe, for the first time, the synthesis of novel arsono-containing lipids where the alkyl groups are connected through stable ether bonds. It is expected that this class of arsonolipids, compared with the corresponding ester linked, will have higher chemical stability. To accomplish this task, a new methodology of general application was developed, where a small arsono compound, 2-hydroxyethylarsonic acid, when protected with thiophenol, can be used in an efficient and simple way as a building block for the synthesis of arsono-containing lipids as well as other arsono-containing biomolecules. Thus, besides the above-mentioned arsonolipid, an arsono cholesterol derivative was also obtained. Both ether arsonolipid and arsono cholesterol were able to form liposomes having similar physicochemical properties and integrity to conventional arsonoliposomes. Furthermore, a preliminary in vitro anticancer potential assessment of the novel ether arsonolipid containing liposomes against human prostate cancer (PC-3) and Lewis lung carcinoma (LLC) cells showed significant activity (dose- and time-dependent), which was similar to that of the conventional arsonoliposomes (studied before). Given the fact that novel arsonolipids may be more stable compared to the ones used in conventional arsonoliposomes, the current results justify further exploitation of the novel compounds by in vitro and in vivo studies.

Arsenic exposure via drinking water during pregnancy and lactation induces autism-like behaviors in male offspring mice

Exposure to arsenic (As), an environmental toxicant, causes damages to the central nervous system (CNS) structure and function. Emerging epidemiological studies support that exposure to As, especially during the critical periods of the CNS development, may act as an environmental risk factor of autism spectrum disorders (ASD), which is characterized by behavioral changes, including abnormal social behaviors, restricted interests and repetitive behaviors. However, direct evidence supporting the cause-effect relationship between As exposure and the risk of ASD is still missing. Thus, we aimed to investigate whether As exposure during pregnancy and lactation led to autism-like behaviors in offspring mice in the present study. We established a mice model of exposure to As via drinking water during pregnancy and lactation and conducted a battery of behavioral tests to evaluate social behaviors, repetitive behaviors, anxiety behaviors and learning and memory ability in offspring mice. We found that perinatal exposure to As caused autism-like behaviors in male offspring, which demonstrated by abnormal social behaviors and repetitive behaviors. Anxiety-like behaviors, and learning and memory impairments, known as concomitant behavioral phenotypes in mice with autism-like behaviors, were also observed. Decreases of synaptic density, especially in cortex, hippocampus and cerebellum, are extensively observed in both ASD patients and animal models of ASD. Thus, immunofluorescence staining and western blotting were used to observe the expression of PSD-95 and SYP, well-known markers for presynaptic and postsynaptic membranes, to assess the synaptic density in offspring cortex, hippocampus and cerebellum. We found perinatal exposure to As decreased the expression of PSD-95 and SYP in these brain regions. This indicated that perinatal exposure to As caused decreases of synaptic density, a typical autism-like cellular alteration in brains, which may contribute to autism-like behaviors in offspring.

Preparation, Physicochemical Properties, and In Vitro Toxicity towards Cancer Cells of Novel Types of Arsonoliposomes

Arsonoliposomes (ARSL) are liposomes that incorporate arsonolipids (ARS) in their membranes. They have demonstrated significant toxicity towards cancer cells, while being less toxic towards normal cells. In this study, we sought to investigate the possibility to prepare novel types of arsonoliposomes (ARSL) by incorporating a lipidic derivative of curcumin (TREG) in their membrane, and/or by loading the vesicles with doxorubicin (DOX). The final aim of our studies is to develop novel types of ARSL with improved pharmacokinetics/targeting potential and anticancer activity. TREG was incorporated in ARSL and their integrity during incubation in buffer and serum proteins was studied by monitoring calcein latency. After evaluation of TREG-ARSL stability, the potential to load DOX into ARSL and TREG-ARSL, using the active loading protocol, was studied. Loading was performed at two temperatures (40 °C and 60 °C) and different time periods of co-incubation (of empty vesicles with DOX). Calculation of DOX entrapment efficiency (%) was based on initial and final drug/lipid ratios. The cytotoxic activity of DOX-ARSL was tested towards B16F10 cells (mouse melanoma cells), LLC (Lewis Lung carcinoma cells), and HEK-293 (Human embryonic kidney cells). Results show that TREG-ARSL have slightly larger size but similar surface charge with ARSL and that they are both highly stable during storage at 4 °C for 56 d. Interestingly, the inclusion of TREG in ARSL conferred increased stability to the vesicles towards disruptive effects of serum proteins. The active-loading protocol succeeded to encapsulate high amounts of DOX into ARSL as well as TREG-LIP and TREG-ARSL, while the release profile of DOX from the novel liposome types was similar to that demonstrated by DOX-LIP. The cytotoxicity study results are particularly encouraging, since DOX-ARSL were less toxic towards the (normal) HEK cells compared to the two cancer cell-types. Furthermore, DOX-ARSL demonstrated lower toxicities (at all concentrations tested) for HEK cells, compared to that of the corresponding mixtures of free DOX and empty ARSL, while the opposite was true for the cancer cells (in most cases). The current results justify further in vivo exploitation of DOX-ARSL, as well as TREGARSL as anticancer therapeutic systems.

Organic Arsenicals as Functional Motifs in Polymer and Biomaterials Science

Arsenic (As) exhibits diverse (bio)chemical reactivity and biological activity depending upon its oxidation state. However, this distinctive reactivity has been largely overlooked across many fields owing to concerns regarding the toxicity of arsenic. Recently, a clinical renaissance in the use of arsenicals, including organic arsenicals that are known to be less toxic than inorganic arsenicals, alludes to the possibility of broader acceptance and application in the field of polymer and biomaterials science. Here, current examples of polymeric/macromolecular arsenicals are reported to stimulate interest and highlight their potential as a novel platform for functional, responsive, and bioactive materials.

Novel Arsenic Nanoparticles Are More Effective and Less Toxic than As (III) to Inhibit Extracellular and Intracellular Proliferation of Leishmania donovani

Visceral leishmaniasis, a vector-borne tropical disease that is threatening about 350 million people worldwide, is caused by the protozoan parasite Leishmania donovani. Metalloids like arsenic and antimony have been used to treat diseases like leishmaniasis caused by the kinetoplastid parasites. Arsenic (III) at a relatively higher concentration (30 μg/mL) has been shown to have antileishmanial activity, but this concentration is reported to be toxic in several experimental mammalian systems. Nanosized metal (0) particles have been shown to be more effective than their higher oxidation state forms. There is no information so far regarding arsenic nanoparticles (As-NPs) as an antileishmanial agent. We have tested the antileishmanial properties of the As-NPs, developed for the first time in our laboratory. As-NPs inhibited the in vitro growth, oxygen consumption, infectivity, and intramacrophage proliferation of L. donovani parasites at a concentration which is about several fold lower than that of As (III). Moreover, this antileishmanial activity has comparatively less cytotoxic effect on the mouse macrophage cell line. It is evident from our findings that As-NPs have more potential than As (III) to be used as an antileishmanial agent.

Aquaglyceroporins are involved in uptake of arsenite into murine gastrointestinal tissues

Aquaglyceroporins (AQGPs) are members of aquaporin (AQP) family and belong to a subgroup of this water channel family; they are transmembrane proteins that transport water as well as glycerol and other solutes of small molecules. Recent studies have also identified that AQGPs are important transporters of trivalent metalloid in some mammalian cells. However, the uptake routes of arsenite in mammals are still less defined. In this study, to understand the routes of arsenite intake in mammals, mice were treated with Hg(II), glycerol, and As(III) and uptake of As(III) into the gastrointestinal tissues was measured. The level of inorganic arsenic (iAs) in gastrointestinal tissues after As(III) stimulation was much higher than Hg(II) +As(III) or glycerol+As(III) group. RT-PCR results showed that AQGPs were extensively expressed in gastrointestinal tissues of mice. We also treated Caco-2 cells with Hg(II) and As(III); the level of iAs in a group treated with Hg(II)+As(III) decreased compared with As(III)-treated group. Our results suggested that AQGPs could be important transporters in arsenite uptake into gastrointestinal tissues of mice, but more data are need to prove if AQGPs is the only pathway involved in As transport in mammals or just one of them.

Arsonoliposomes: preparation and physicochemical characterization

Arsonoliposomes (ARSL) which are liposomes that contain arsonolipids in their membranes have shown interesting anticancer and antiparasitic activity in vitro. Their lipid composition (the specific arsonolipids and/or phospholipids used for their preparation, and the relative amounts of each lipid type) highly influences their physicochemical properties as well as their in vivo kinetics and antiparasitic activity; however, their cytotoxicity towards cancer cells is minimally--if at all--modified. ARSL are prepared by a modification of the "one step" method followed or not by sonication (for formation of sonicated or non-sonicated ARSL, respectively). Arsonoliposomes may be composed only of arsonolipids (containing or not cholesterol) [plain ARSL], or they may contain mixtures of arsonolipids with phospholipids (with or without Chol) [mixed ARSL]. Herein, we describe in detail the preparation and physicochemical characterization of ARSL.

A high yield procedure for the preparation of arsonolipids (2,3-diacyloxypropylarsonic acids)

The crucial step in the preparation of the title arsonolipids starting from the dichloromethane-soluble dithioarsonite CH(2)(OH)CH(OH)CH(2)-As(SPh)(2) is to avoid an internal cyclization during the acylation which protects the primary -OH group from being acylated. This was to a large extent accomplished by using fatty acyl chloride in the presence of the weak base pyridine and controlling the temperature and rate of the acyl chloride addition, giving approximately 70% yields of arsonolipids. The presence of catalytic amounts of 4-dimethylaminopyridine boosted the yields to 82-85%. This yield is a great improvement over the yields (20-55%) previously achieved. The acylating systems (RCO)(2)O or RCOCl and BF(3).Et(2)O gave only moderate yields (25-60%) of arsonolipids.

Bioavailability and bioaccessibility of arsenic in a soil amended with drinking-water treatment residuals

Earlier incubation and greenhouse studies in our laboratory confirmed the effectiveness of drinking-water treatment residual (WTR) in decreasing soil arsenic (As) bioaccessibility as determined with in vitro tests, which led us to hypothesize a similar outcome if animal studies were to be conducted. Our objective was to evaluate the potential of WTR in lowering soil As bioavailability by conducting in vivo experiments and compare the in vitro to the in vivo As data. This study was performed using 6-week-old male BALB/c mice that were fed with an As-contaminated soil slurry using the gavage method. Blood and stomach contents were collected at 1 and 24 h after feeding. Urine and excreta were collected at time 0 (before feeding) and 24 h after feeding. Relative As bioavailability (RBA) values calculated from the blood samples of mice fed with WTR and WTR-amended soil samples ranged from 13% to 24% and from 25% to 29%, respectively; both were significantly (p < 0.001) lower than that of the unamended (no-WTR) soil (approximately 100% RBA). Absolute As bioavailability (ABA) in the gastric phase was significantly (p < 0.001) lowered, to 7-16%, in the WTR-amended soil compared with that of the unamended control (26%). A significant (p < 0.001) linear correlation (r = 0.94) was observed between the in vitro (stomach-phase) and the in vivo RBA data. Percentage recovery of As obtained from four mice tissue compartments (i.e., blood, stomach, urine, and fecal matter) after oral and intramuscular administrations was 63-80%. Results illustrate the effectiveness of in situ WTR amendment in decreasing in vivo soil As bioavailability, thereby lowering the potential cancer risk via an oral ingestion pathway.

In vivo distribution of arsonoliposomes: Effect of vesicle lipid composition

Sonicated arsonoliposomes were prepared using arsonolipid with palmitic acid acyl chain (C16), mixed with 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC-based), and cholesterol (Chol) with a molar ratio C16/DSPC/Chol 8:12:10. PEG-lipid (1,2-distearoyl-sn-glycero-3-phosphoethanolamine conjugated to polyethylenoglycol 2000) containing vesicles (Pegylated-arsonoliposomes) were also prepared. DSPC-based and Pegylated-arsonoliposomes, were administered by intraperitoneal injection in balb/c mice (15 mg arsenic/kg) 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 30-40% of the dose was detected cumulatively in animal tissues. After this, the whole body elimination of arsenic was a slow process with a half-life of 27.6 h for Pegylated-arsonoliposomes, and 83 h, for the DSPC-based ones. For both arsonoliposomes, arsenic distribution was greater in intestines, followed by liver, carcass+skin stomach, spleen, kidney, lung and heart. Different arsenic kinetics in blood between the two liposome types were observed. Compared to the results obtained previously with PC-based arsonoliposomes, both the DSPC-based and Pegylated-arsonoliposomes have better bioavailability. This proves that arsonoliposome lipid composition (and consequently their integrity) influences their pharmacokinetic profile. Thus, the proper arsonoliposome composition should be used according to the intended application.

Trypanocidal activity of arsonoliposomes: Effect of vesicle lipid composition

Sonicated arsonoliposomes were prepared using an arsonolipid with palmitic acid acyl chain (C16), mixed with phosphatidylcholine (PC-based) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC-based), and cholesterol (Chol) with a molar ratio C16 /PC or DSPC/ Chol 8:12:10. PEG-lipid (1,2-distearoyl-sn-glycero-3-phosphoethanolamine conjugated to polyethylenoglycol 2000) containing vesicles (pegylated-arsonoliposomes) were also prepared. The in vitro and in vivo trypanocidal activity of the various types of arsonoliposomes was evaluated. Although PC-based arsonoliposomes exhibited in vivo activity on an acute trypanosomiasis animal model, no evidence of activity was demonstrated for DSPC-based or pegylated-arsonoliposomes on a chronic model. Despite the fact that DSPC-based and pegylated-arsonoliposomes have better bioavailability compared to PC-based ones, their in vitro activity is lower than that of PC-based arsonoliposomes, indicating the importance of arsonoliposome lipid composition on their trypanocidal activity and suggesting that further arsonoliposome structure design is required to overcome these disadvantages.

Incorporation of PEG-lipids in arsonoliposomes results in formation of highly stable arsenic-containing vesicles

We investigated the effect of pegylation on the physical stability, morphology and membrane integrity of arsonoliposomes. Arsonoliposomes composed of distearoylglycerophosphocholine (DSPC), cholesterol (Chol) and the palmitoyl side chain arsonolipid (with concentrations ranging from 0 mol% [DSPC/Chol vesicles] to 53 mol% of total lipid) containing either 4 or 8 mol% DPPE-PEG2000 or DSPE-PEG2000, were prepared by sonication. Arsonoliposome membrane integrity was evaluated by measuring the retention of encapsulated calcein in vesicles (during incubation in buffer or fetal calf serum [FCS]) while physical stability was evaluated by measuring vesicle dispersion turbidity (during incubation in water or CaCl(2)). Vesicle morphology was studied by cryo-electron microscopy. Experimental results show that: (i) PEG-lipids are incorporated in arsonoliposomes (as confirmed by the vesicle zeta potential modulation), (ii) pegylation of arsonoliposomes prevents their aggregation and fusion in the presence of calcium ions and (iii) when 8 mol% of PEG-DSPE is incorporated in arsonoliposomes based on their arsonolipid content, two groups of pegylated vesicles are formed: low content arsonoliposomes (<20 mol% arsonolipid) which are highly leaky and high content arsonoliposomes (>27 mol% arsonolipid) which are highly stable (70% calcein retention after 24h incubation in fetal calf serum [FCS]). In addition to high membrane integrity, the high content pegylated arsonoliposomes are morphologically perfect round-shaped vesicles without the sharp edges typically observed with non-pegylated DSPC-containing arsonoliposomes.

Development of stealth liposome formulation of 2'-deoxyinosine as 5-fluorouracil modulator: in vitro and in vivo study

PURPOSE

The aims of this study were to develop a stealth, pegylated liposomal formulation of 2'-deoxyinosine (d-Ino), a 5-fluorouracil (5-FU) modulator, to evaluate its efficacy in vitro and in tumor-bearing mice, and to study its pharmacokinetics in rats.

METHOD

After designing a pegylated liposome encapsulating d-Ino (L-d-Ino), we evaluated its efficacy as 5-FU modulator in vitro. Antiproliferative assays, thymidylate synthase (TS) inhibition, and apoptosis studies were carried out to check whether an optimization of 5-FU action was achieved on the 5-FU-resistant SW620 cell line. Animal pharmacokinetic and ex vivo studies were next performed to confirm that L-d-Ino displayed a slower plasma elimination pattern than free d-Ino. Finally, effects on tumor growth of L-d-Ino + 5-FU combination was evaluated in xenografted mice.

RESULTS

We developed a stable, sterile, and homogenous 100-nm population of pegylated liposomes encapsulating 30% of d-Ino. Liposomal d-Ino exhibited a strong potential as 5-FU modulator in vitro by enhancing TS inhibition and subsequent apoptosis induction, while displaying a better pharmacokinetic profile in animals, with a near seven times clearance reduction as compared with the free form. When used in tumor-bearing mice in combination with 5-FU, our results showed next that the association led to 70% of tumor reduction with a doubling median survival time as compared with untreated animals, whereas 5-FU alone was ineffective.

CONCLUSION

Our data show that liposomal d-Ino, through an optimized pharmacokinetic profile, displays a potent effect as fluoropyrimidines modulator, both in vitro and in xenografted mice. Besides, we showed here that it is possible to reverse a resistant phenotype to 5-FU, a major drug extensively described in clinical oncology.