Nanoparticles containing anti-inflammatory agents as chemotherapy adjuvants II: role of plasma esterases in drug release

Enhanced cardioprotective activity of ferulic acid-loaded solid lipid nanoparticle in an animal model of myocardial injury

Myocardial infarction results in an increased inflammatory and oxidative stress response in the heart, and reducing inflammation and oxidative stress after MI may offer protective effects to the heart. In the present study, we examined the cardioprotective effects of ferulic acid (FA) and ferulic acid nanostructured solid lipid nanoparticles (FA-SLNs) in an isoproterenol (ISO) induced MI model. Male Sprague Dawley rats were divided into five experimental groups to compare the effects of FA and FA-SLNs. The findings revealed that ISO led to extensive cardiomyopathy, characterized by increased infarction area, edema formation, pressure load, and energy deprivation. Additionally, ISO increased the levels of inflammatory markers (COX-2, NLRP3, and NF-кB) and apoptotic mediators such as p-JNK. However, treatment with FA and FA-SLNs mitigated the severity of the ISO-induced response, and elevated the levels of antioxidant enzymes while downregulating inflammatory pathways, along with upregulation of the mitochondrial bioenergetic factor PPAR-γ. Furthermore, virtual docking analysis of FA with various protein targets supported the in vivo results, confirming drug-protein interactions. Overall, the results demonstrated that FA-SLNs offer a promising strategy for protecting the heart from further injury following MI. This is attributed to the improved drug delivery and therapeutic outcomes compared to FA alone.

Simvastatin-loaded solid lipid nanoparticles for enhanced anti-hyperlipidemic activity in hyperlipidemia animal model

The objective of current study was to develop solid lipid nanoparticles-loaded with simvastatin (SIM-SLNs) and investigate their in vivo anti-hyperlipidemic activity in poloxamer-induced hyperlipidemia model. Nano-template engineering technique was used to prepare SIM-SLNs with palmityl alcohol as lipid core and a mixture of Tween 40/Span 40/Myrj 52 to stabilize the core. The prepared SIM-SLNs were evaluated for physicochemical parameters including particle diameter, surface charge, morphology, incorporation efficiency, thermal behaviour and crystallinity. In vitro release profile of SIM-SLNs in simulated gastric and intestinal fluids was evaluated by using dialysis bag technique and anti-hyperlipidemic activity was assessed in hyperlipidemia rat model. SIM-SLNs revealed uniform particle size with spherical morphology, zeta potential of -24.9 mV and high incorporation efficiency (∼85%). Thermal behaviour and crystallinity studies demonstrated successful incorporation of SIM in the lipid core and its conversion to amorphous form. SIM-SLNs demonstrated a sustained SIM release from the lipid core of nanoparticles. SIM-SLNs significantly reduced the elevated serum lipids as indicated by ∼3.9 and ∼1.5-times decreased total cholesterol compared to those of untreated control and SIM dispersion treated hyperlipidemic rats. In conclusion, SIM-SLNs showed a great promise for improving the therapeutic outcomes of SIM via its effective oral delivery.

Self-Assembled Nanostructured Lipid Systems: Is There a Link between Structure and Cytotoxicity?

Self-assembly of lipid-based liquid crystalline (LLC) nanoparticles is a formulation art arising from the hydrophilic-lipophilic qualities and the geometric packing of amphiphilic lipid molecules in an aqueous environment. The diversity of commercialized amphiphilic lipids and an increased understanding of the physicochemical factors dictating their membrane curvature has enabled versatile architectural design and engineering of LLC nanoparticles. While these exotic nanostructured materials are hypothesized to form the next generation of smart therapeutics for a broad field of biomedical applications, biological knowledge particularly on the systemic biocompatibility or cytotoxicity of LLC materials remains unclear. Here, an overview on the interactions between LLCs of different internal nanostructures and biological components (including soluble plasma constituents, blood cells, and isolated tissue cell lines) is provided. Factors affecting cell-nanoparticle tolerability such as the type of lipids, type of steric stabilizers, nanoparticle surface charges, and internal nanostructures (or lipid phase behaviors) are elucidated. The mechanisms of cellular uptake and lipid transfer between neighboring membrane domains are also reviewed. A critical analysis of these studies sheds light on future strategies to transform LLC materials into a viable therapeutic entity ideal for internal applications.

Intraorgan Targeting of Gold Conjugates for Precise Liver Cancer Treatment

Intraorgan targeting of chemical drugs at tumor tissues is essential in the treatment of solid tumors that express the same target receptor as normal tissues. Here, asialoglycoprotein receptor (ASGP-R)-targeting paclitaxel-conjugated gold nanoparticles (Gal/PTX-GNPs) are fabricated as a demonstration to realize the precise treatment of liver cancer. The enhanced biological specificity and therapeutic performance of drugs loaded on nanoparticles not only rely on the ligands on carriers for receptor recognition but are also determined by the performance of gold conjugates with designed structure. The tumor cell selectivity of the designed conjugates in liver tumor (HepG2) cells is close to six times of that incubated with control conjugates without galactose modification in liver normal (L02) cells. The drug level in tumor versus liver of Gal/PTX-GNPs is 121.0% at 8 h post injection, a 15.7-fold increase in the tumor specificity compared to that of GNPs conjugated with PTX only. This intraorgan-targeting strategy results in a considerable improvement of performance in treating both Heps heterotopic and orthotopic xenograft tumor models, which is expected to be used for the enhanced antitumor efficacy and reduced hepatotoxicity in liver cancer treatment.

Increased Body Exposure to New Anti-Trypanosomal Through Nanoencapsulation

Lychnopholide, a lipophilic sesquiterpene lactone, is efficacious in mice at the acute and chronic phases of Chagas disease. Conventional poly-ε-caprolactone (PCL) and long-circulating poly(D,L-lactide)-block-polyethylene glycol (PLA-PEG) nanocapsules containing lychnopholide were developed and characterized. Lychnopholide presented high association efficiency (>90%) with the nanocapsules. A new, fast and simple HPLC-UV-based bioanalytical method was developed, validated in mouse plasma and applied to lychnopholide quantification in in vitro release kinetics and pharmacokinetics. The nanocapsules had mean hydrodynamic diameters in the range of 100-250 nm, negative zeta potentials (-30 mV to -57 mV), with good physical stability under storage. Atomic force microscopy morphological analysis revealed spherical monodispersed particles and the absence of lychnopholide crystallization or aggregation. Association of lychnopholide to PLA-PEG nanocapsules resulted in a 16-fold increase in body exposure, a 26-fold increase in plasma half-life and a dramatic reduction of the lychnopholide plasma clearance (17-fold) in comparison with free lychnopholide. The improved pharmacokinetic profile of lychnopholide in long-circulating nanocapsules is in agreement with the previously reported improved efficacy observed in Trypanosoma cruzi-infected mice. The present lychnopholide intravenous dosage form showed great potential for further pre-clinical and clinical studies in Chagas disease and cancer therapies.

Sustained release docetaxel-incorporated lipid nanoparticles with improved pharmacokinetics for oral and parenteral administration

The aim of this study was to develop docetaxel-incorporated lipid nanoparticles (DTX-NPs) to improve the pharmacokinetic behaviour of docetaxel (DTX) after oral and parenteral administration via sustained release. DTX-NPs were prepared by nanotemplate engineering technique with palmityl alcohol as a solid lipid and Tween-40/Span-40/Myrj S40 as a surfactants mixture. Spherical DTX-NPs below 100 nm were successfully prepared with a narrow particle size distribution, 96% of incorporation efficiency and 686 times increase in DTX solubility. DTX-NPs showed a sustained release over 24 h in phosphate-buffered saline and simulated gastric and intestinal fluids, while DTX-micelles released DTX completely within 12 h. The half-maximal inhibitory concentration (IC₅₀) of DTX-NPs against human breast cancer MCF-7 cells was 1.9 times lower than that of DTX-micelles and DTX solution. DTX-NPs demonstrated 3.7- and 2.8-fold increase in the area under the plasma concentration-time curve compared with DTX-micelles after oral and parenteral administration, respectively.

Performance of Doxorubicin-Conjugated Gold Nanoparticles: Regulation of Drug Location

Drug-conjugated gold nanoparticles (GNPs), which are generally constructed with many molecules of thiol-terminated polyethylene glycol (PEG)-drug decorated on their surfaces via a thiol-Au covalent bond, are promising and efficient nanoprodrugs. However, because of the exposure of the hydrophobic drug molecules on the surface of the conjugate, in vivo stability, opsonization, and subsequent inefficient therapy become the main issues of this system. To solve these problems without complicating the structures of gold conjugates, herein we propose a method to change the relative position of PEG and the drug. A novel gold conjugate (GNP-NHN═Dox-mPEG) with doxorubicin (Dox) shielded by PEGylation on the surface of GNPs is designed. It demonstrates improved solubility, stability, and dispersion and achieves a two-step stimulus-responsive drug release in response to an acidic environment in lysosomes and then esterase in the cytoplasm. This unique manner of release enables the cytoplasm to act as a reservoir for sustained drug delivery into the nucleus to improve antitumor efficacy in vivo. The intratumoral drug concentrations of the conjugate reach 14.4 ± 1.4 μg/g at 8 h, a two-fold increase in the drug concentration compared with that of the doxorubicin hydrochloride group. This molecular design and regulation approach is facile but important in modulating the in vivo performance of nanovehicles and demonstrates its vital potential in developing effective nanoparticle-based drug delivery agents.

Reduced in vivo toxicity of doxorubicin by encapsulation in cholesterol-containing self-assembled nanoparticles

We previously reported the development of an amphiphilic brush-like block copolymer composed of polynorbornene-cholesterol/polyethylene glycol (P(NBCh9-b-NBPEG)) that self-assembles in aqueous media to form long circulating nanostructures capable of encapsulating doxorubicin (DOX-NPs). Biodistribution studies showed that this formulation preferentially accumulates in tumor tissue with markedly reduced accumulation in the heart and other major organs. The aim of the current study was to evaluate the in vivo efficacy and toxicity of DOX containing self-assembled polymer nanoparticles in a mouse xenograft tumor model and compare its effects with the hydrochloride non-encapsulated form (free DOX). DOX-NPs significantly reduced the growth of tumors without inducing any apparent toxicity. Conversely, mice treated with free DOX exhibited significant weight loss, early toxic cardiomyopathy, acute toxic hepatopathy, reduced hematopoiesis and fatal toxicity. The improved safety profile of the polymeric DOX-NPs can be explained by the low circulating concentration of non-nanoparticle-associated drug as well as the reduced accumulation of DOX in non-target organs. These findings support the use of P(NBCh9-b-NBPEG) nanoparticles as delivery platforms for hydrophobic anticancer drugs intended to reduce the toxicity of conventional treatments.

Modulatory effect of human plasma on the internal nanostructure and size characteristics of liquid-crystalline nanocarriers

The inverted-type liquid-crystalline dispersions comprising cubosomes and hexosomes hold much potential for drug solubilization and site-specific targeting on intravenous administration. Limited information, however, is available on the influence of plasma components on nanostructural and morphological features of cubosome and hexosome dispersions, which may modulate their stability in the blood and their overall biological performance. Through an integrated approach involving SAXS, cryo-TEM, and nanoparticle tracking analysis (NTA) we have studied the time-dependent effect of human plasma (and the plasma complement system) on the integrity of the internal nanostructure, morphology, and fluctuation in size distribution of phytantriol (PHYT)-based nonlamellar crystalline dispersions. The results indicate that in the presence of plasma the internal nanostructure undergoes a transition from the biphasic phase (a bicontinuous cubic phase with symmetry Pn3m coexisting with an inverted-type hexagonal (H2) phase) to a neat hexagonal (H2) phase, which decreases the median particle size. These observations were independent of a direct effect by serum albumin and dispersion-mediated complement activation. The implication of these observations in relation to soft nanocarrier design for intravenous drug delivery is discussed.

Esterase-activatable β-lapachone prodrug micelles for NQO1-targeted lung cancer therapy

Lung cancer is one of the most lethal forms of cancer and current chemotherapeutic strategies lack broad specificity and efficacy. Recently, β-lapachone (β-lap) was shown to be highly efficacious in killing non-small cell lung cancer (NSCLC) cells regardless of their p53, cell cycle and caspase status. Pre-clinical and clinical use of β-lap (clinical form, ARQ501 or 761) is hampered by poor pharmacokinetics and toxicity due to hemolytic anemia. Here, we report the development and preclinical evaluation of β-lap prodrug nanotherapeutics consisting of diester derivatives of β-lap encapsulated in biocompatible and biodegradable poly(ethylene glycol)-b-poly(D,L-lactic acid) (PEG-b-PLA) micelles. Compared to the parent drug, diester derivatives of β-lap showed higher drug loading densities inside PEG-b-PLA micelles. After esterase treatment, micelle-delivered β-lap-dC3 and -dC6 prodrugs were converted to β-lap. Cytotoxicity assays using A549 and H596 lung cancer cells showed that both micelle formulations maintained

NAD(P)H

quinone oxidoreductase 1 (NQO1)-dependent cytotoxicity. However, antitumor efficacy study of β-lap-dC3 micelles against orthotopic A549 NSCLC xenograft-bearing mice showed significantly greater long-term survival over β-lap-dC6 micelles or β-lap-HPβCD complexes. Improved therapeutic efficacy of β-lap-dC3 micelles correlated with higher area under the concentration-time curves of β-lap in tumors, and enhanced pharmacodynamic endpoints (e.g., PARP1 hyperactivation, γH2AX, and ATP depletion). β-Lap-dC3 prodrug micelles provide a promising strategy for NQO1-targeted therapy of lung cancer with improved safety and antitumor efficacy.

Nanocarriers for vascular delivery of anti-inflammatory agents

There is a need for improved treatment of acute vascular inflammation in conditions such as ischemia-reperfusion injury, acute lung injury, sepsis, and stroke. The vascular endothelium represents an important therapeutic target in these conditions. Furthermore, some anti-inflammatory agents (AIAs) (e.g., biotherapeutics) require precise delivery into subcellular compartments. In theory, optimized delivery to the desired site of action may improve the effects and enable new mechanisms of action of these AIAs. Diverse nanocarriers (NCs) and strategies for targeting them to endothelial cells have been designed and explored for this purpose. Studies in animal models suggest that delivery of AIAs using NCs may provide potent and specific molecular interventions in inflammatory pathways. However, the industrial development and clinical translation of complex NC-AIA formulations are challenging. Rigorous analysis of therapeutic/side effect and benefit/cost ratios is necessary to identify and optimize the approaches that may find clinical utility in the management of acute inflammation.

Self-assembled nanoparticles from thiol functionalized liquid crystalline brush block copolymers for dual encapsulation of doxorubicin and gold nanoparticles

A facile approach to synthesize new thiol functionalized liquid crystalline brush block copolymers for dual encapsulation of an anticancer drug and inorganic nanoparticles.

High payload dual therapeutic-imaging nanocarriers for triggered tumor delivery

The in vitro and in vivo characterization of an optimized formulation of nanoparticles (NPs) loaded with a high content of dexamethasone palmitate (DEX-P), a chemotherapeutic adjuvant that decreases interstitial fluid pressure in tumors, and (111) In, a signaling agent, is described. These NPs are uniform in size and composition. Single photon emission computed tomography imaging demonstrates significant tumor uptake of (111) In-labeled DEX-P NPs in tumor-bearing mice. As with many nanoparticle-based drug delivery systems, significant liver accumulation is observed. Assessment of liver histology and blood tests show no apparent hepatic or renal toxicity of the DEX-P NPs. Conversion of DEX-P to DEX occurs when DEX-P NPs are incubated with mouse plasma, human tumor homogenate and ascites from tumor bearing mice, but not with human plasma. This conversion is slower in plasma from Es1(e) ((-/-)) /SCID mice, a potential alternative animal model that better mimics humans; however, plasma from these mice are not completely devoid of esterase activity. The difference between blood and tumor esterase activity in humans facilitates the delivery of DEX-P NPs to tumors and the release of dexamethasone by an esterase trigger.

Carboxylesterase-triggered hydrolysis of nanoparticle PEGylating agents

Despite the importance of PEGylation in achieving long nanoparticle circulation times, many nanoparticles are coated with PEGylating agents susceptible to enzymatic degradation. In this study, solid lipid nanoparticles (SLNs) prepared with ester-containing compounds were evaluated for their stability in the presence of carboxylesterase. SLN suspensions became turbid within 30 min of enzymatic exposure, indicating possible disassociation of a portion of the nanoparticles. The particle size of SLNs incubated with the enzyme was smaller than the size of controls, although their morphologies appeared similar in transmission electron microscopy images. Although SLNs offered some protection over micelles, PEG6000 monostearate was rapidly degraded within 15 min. Hydrolysis of polysorbate 60 was much slower, reaching only 36% in 2 h. These studies reveal the importance of confirming the stability of PEG surface coatings prior to undertaking in vivo experiments in small animal models, which can have considerably higher plasma esterase activity than humans.

Physicochemical characterization of nanotemplate engineered solid lipid nanoparticles

As the physicochemical characteristics of solid lipid nanoparticles (SLNs) play a critical role in their success, it is important to understand how the materials and process used in their preparation affect these properties. In this study, two stearyl alcohol-based formulations were prepared using nanotemplate engineering technology and characterized. Both formulations were of a small particle size (<100 nm), ellipsoidal shape, and low polydispersity. (1)H NMR spectroscopy confirmed that the SLNs have the expected solid core structure and PEGylated surface. Analysis of the bulk materials indicated that a number of complex interactions are present among the SLN components, including a eutectic between stearyl alcohol and Brij 78. The decreased crystallinity resulting from these interactions may allow for enhanced drug loading. Physiological stability was identified and confirmed as a potential problem due to the low melting point of the eutectic. However, it is expected that with appropriate formulation modifications nanotemplate engineered SLNs will possess the properties necessary for a successful drug delivery system.

Uniformity of drug payload and its effect on stability of solid lipid nanoparticles containing an ester prodrug

Nanocarrier systems are frequently characterized by their size distribution, while drug encapsulation in nanocarriers is generally characterized in terms of an entire population, assuming that drug distribution is uniform. Careful characterization of nanocarriers and assessment of their behavior in biological environments are essential for adequate prediction of the fate of the nanoparticles in vivo. Solid lipid nanoparticles containing [(3)H]-dexamethasone palmitate (an ester prodrug) and [(14)C]-stearyl alcohol (a component of the nanoparticle matrix) were prepared using the nanotemplate engineering method for bioresponsive tumor delivery to overcome interstitial fluid pressure gradients, a physiological barrier to tumor uptake of chemotherapeutic agents. While particle size analysis indicated a uniform size distribution of 93.2 ± 0.5 nm, gel filtration chromatography (GFC) revealed two nanoparticle populations. Drug encapsulation efficiency was 97%, but it distributed differently in the two populations, with average drug/lipid ratios of 0.04 and 0.25, respectively. The difference in surface properties resulted in distinguishing protein adsorption features of the two populations. GFC and HPLC profiles of the mixture of nanoparticles and human serum albumin (HSA) showed that no HSA was adsorbed to the first population of nanoparticles, but minor amounts were adsorbed to the second population. After 24 h incubation in 50% human plasma, ≥80% of the [(3)H]-dexamethasone palmitate was associated with nanoparticles. Thus, characterization of solid lipid nanoparticles produced by this method may be challenging from a regulatory perspective, but the strong association of the drug with the nanoparticles in plasma indicates that this nanocarrier system has the potential for in vivo application.