Pharmacological activity of DTPA linked to protein-based drug carrier systems

Reversion of arterial calcification by elastin-targeted DTPA-HSA nanoparticles

Generalized arterial calcification of infancy (GACI) and pseudoxanthoma elasticum (PXE) are characterized by pathologic calcifications in the media of large- and medium sized arteries. GACI is associated with biallelic mutations in ENPP1 in the majority of cases, whereas mutations in ABCC6 are known to cause PXE. Different treatment approaches including bisphosphonates and orally administered pyrophosphate (PP_i) were investigated in recent years, but reversion of calcification could not be achieved. With this study, we pursued the idea of a combination of controlled drug delivery through nanoparticles and active targeting via antibody conjugation to develop a treatment for GACI and PXE. To establish a suitable drug delivery system, the chelating drug diethylenetriamine pentaacetic acid (DTPA) was conjugated to nanoparticles composed of human serum albumin (HSA) as biodegradable and non-toxic particle matrix. To accomplish an active targeting of the elastic fibers exposed through calcification of the affected areas, the nanoparticle surface was functionalized with an anti-elastin antibody. Cytotoxicity and cell interaction studies revealed favorable preconditions for the intended i.v. application. The chelating ability was evaluated in vitro and ex vivo on aortic ring culture isolated from two mouse models of GACI and PXE. The positive results led to the conclusion that the produced nanoparticles might be a promising therapy in the treatment of GACI and PXE.

The Thrombopoietin Receptor Agonist Eltrombopag Inhibits Human Cytomegalovirus Replication Via Iron Chelation

The thrombopoietin receptor agonist eltrombopag was successfully used against human cytomegalovirus (HCMV)-associated thrombocytopenia refractory to immunomodulatory and antiviral drugs. These effects were ascribed to the effects of eltrombopag on megakaryocytes. Here, we tested whether eltrombopag may also exert direct antiviral effects. Therapeutic eltrombopag concentrations inhibited HCMV replication in human fibroblasts and adult mesenchymal stem cells infected with six different virus strains and drug-resistant clinical isolates. Eltrombopag also synergistically increased the anti-HCMV activity of the mainstay drug ganciclovir. Time-of-addition experiments suggested that eltrombopag interfered with HCMV replication after virus entry. Eltrombopag was effective in thrombopoietin receptor-negative cells, and the addition of Fe³⁺ prevented the anti-HCMV effects, indicating that it inhibits HCMV replication via iron chelation. This may be of particular interest for the treatment of cytopenias after hematopoietic stem cell transplantation, as HCMV reactivation is a major reason for transplantation failure. Since therapeutic eltrombopag concentrations are effective against drug-resistant viruses, and synergistically increase the effects of ganciclovir, eltrombopag is also a drug-repurposing candidate for the treatment of therapy-refractory HCMV disease.

Optimization of the radiolabelling method for improved in vitro and in vivo stability of 90Y-albumin microspheres

Biologically stable ⁹⁰Y-labelled albumin microspheres (AMS) were developed by optimizing the process of their preparation. Three formulations of ⁹⁰Y-AMS were initially prepared with high radiolabelling yield but depending on the step when the radionuclide ⁹⁰Y and DTPA chelator were added, radiolabelled microspheres with different in vitro and in vivo stability were obtained. DTPA was proved as a useful chelating agent that tightly links radionuclide ⁹⁰Y to albumin. Also, AMS radiolabelled via DTPA during preparation and before microspheres stabilization, showed significant in vitro and in vivo stability ready for the potential use in selective internal radiation therapy.

Formulation and characterisation of antibody-conjugated soy protein nanoparticles--implications for neutralisation of snake venom with improved efficiency

The present study reports the formulation of soy protein nanoparticles and its conjugation to antivenom. The conditions for nanoparticle formation were optimised by considering particle size, count rate, stability and zeta potential. The smallest particle size of 70.9 ± 0.9 nm with a zeta potential of -28.0 ± 1.4 mV was obtained at pH 6.2, with NaOH 5.4 % and 28 μg/mg glutaraldehyde. The nanoparticle was conjugated with antisnake venom immunoglobulins (F(ab')2 fragments) using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide. TEM analysis indicated the increased size of particle to 600 nm after conjugation to antivenom. Further, in vitro studies indicated that conjugated antibodies inhibited the activity of protease, phospholipase and hyaluronidase enzymes of Bungarus caeruleus venom more efficiently than the free antivenom. This is the first report on the use of protein nanoparticles for conjugating snake venom antibodies and their implications for neutralising snake venom enzymes with increased efficiency.

Metal chelators coupled with nanoparticles as potential therapeutic agents for Alzheimer's disease

Alzheimer's disease (AD) is a devastating neuro-degenerative disorder characterized by the progressive and irreversible loss of memory followed by complete dementia. Despite the disease's high prevalence and great economic and social burden, an explicative etiology or viable cure is not available. Great effort has been made to better understand the disease's pathogenesis, and to develop more effective therapeutic agents. However, success is greatly hampered by the presence of the blood-brain barrier that limits a large number of potential therapeutics from entering the brain. Nanoparticle-mediated drug delivery is one of the few valuable tools for overcoming this impediment and its application as a potential AD treatment shows promise. In this review, the current studies on nanoparticle delivery of chelation agents as possible therapeutics for AD are discussed because several metals are found excessive in the AD brain and may play a role in the disease development. Specifically, a novel approach involving transport of iron chelation agents into and out of the brain by nanoparticles is highlighted. This approach may provide a safer and more effective means of simultaneously reducing several toxic metals in the AD brain. It may also provide insights into the mechanisms of AD pathophysiology, and prove useful in treating other iron-associated neurodegenerative diseases such as Friedreich's ataxia, Parkinson's disease, Huntington's disease and Hallervorden-Spatz Syndrome. It is important to note that the use of nanoparticle-mediated transport to facilitate toxicant excretion from diseased sites in the body may advance nanoparticle technology, which is currently focused on targeted drug delivery for disease prevention and treatment. The application of nanoparticle-mediated drug transport in the treatment of AD is at its very early stages of development and, therefore, more studies are warranted.

Cisplatin-resistant neuroblastoma cells express enhanced levels of epidermal growth factor receptor (EGFR) and are sensitive to treatment with EGFR-specific toxins

PURPOSE

Neuroblastomas frequently show expression of the epidermal growth factor receptor (EGFR) and may therefore be susceptible to EGFR-targeted therapies. Here, EGFR expression and functionality was investigated in parental chemosensitive neuroblastoma cell lines (UKF-NB-3, IMR-32, NLF, SH-SY5Y) and their cisplatin-resistant sublines (UKF-NB-3(r)CDDP(1000), IMR-32(r)CDDP(1000), NLF(r)CDDP(1000), and SH-SY5Y(r)CDDP(500)). Moreover, the EGFR antibody cetuximab, the EGFR tyrosine kinase inhibitor Tyrphostin B46, and recombinant EGFR-targeted toxins were investigated for their influence on the viability and growth of neuroblastoma cells.

EXPERIMENTAL DESIGN

EGFR expression and function was measured by flow cytometry or Western blot. Cell viability was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was examined by immunostaining for active caspase-3 or cleaved poly(ADP-ribose) polymerase. Cellular binding of FITC-labeled immunotoxins was studied by flow cytometry, and cellular uptake was studied by confocal laser scanning microscopy.

RESULTS

The EGFR-targeted antibody and growth factor toxins scFv(14E1)- Pseudomonas exotoxin A (ETA) and TGF-alpha-ETA exerted anti-cancer effects in neuroblastoma cell lines that were insensitive to cetuximab or EGFR tyrosine kinase inhibitors. Furthermore, adaptation of chemosensitive neuroblastoma cells to cisplatin increased EGFR expression and sensitivity to both recombinant toxins. Treatment of chemosensitive neuroblastoma cells with cisplatin reversibly increased EGFR expression, whereas cisplatin-resistant cells showed enhanced EGFR expression independent of the presence of cisplatin. Combination treatment with scFv(14E1)-ETA or TGF-alpha-ETA and cisplatin exerted significantly improved anticancer effects compared with either single treatment in parental neuroblastoma cells, cisplatin-resistant sublines, and primary cultures.

CONCLUSIONS

EGFR-targeted cytotoxic reagents such as scFv(14E1)-ETA and TGF-alpha-ETA represent promising candidates for further development as antineuroblastoma agents, especially in combination with cisplatin.

5-Fluorouracil-loaded BSA nanoparticles: formulation optimization and in vitro release study

Over the past few decades, there has been considerable interest in developing protein nanoparticles as drug delivery devices. The underlying rationale is their exceptional characteristics, namely biodegradability and nonantigenicity. Herein, phase separation method was used to prepare 5-fluorouracil-loaded bovine serum albumin (BSA) nanoparticles. Drug release was tracked by continuous flow dialysis technique. Effect of process variables on loading efficiency of 5-fluorouracil was investigated and optimized through Taguchi's M16 design with the amount of entrapped drug as response. Optimum condition was found to be 2 mg/mL of 5-fluorouracil, 3.7 mL of added ethanol, 176 microL of glutaraldehyde, drug-protein incubation time of 30 min, and pH of 8.4 for 200 mg of BSA in 2 mL drug solution. pH had the most noticeable effect on the amount of entrapped drug, but glutaraldehyde had the least. Mean diameter and zeta potential of fabricated nanoparticles under these conditions were 210 nm and -31.7 mV, respectively. Drug-loaded BSA nanoparticles suspension maintained constant release of drug for 20 h under experimental conditions, so this colloidal drug carrier is capable of releasing drug in a sustained manner.

Recent developments in nanoparticle-based drug delivery and targeting systems with emphasis on protein-based nanoparticles

BACKGROUND

Drug delivery systems with nm dimensions (nanoparticles [NPs]) are attracting increasing attention because they can sequester drugs in systemic circulation, prevent non-specific biodistribution, and target to specific tissues.

OBJECTIVE

We reviewed the recent literature pertinent to NP-based drug delivery, primarily emphasizing NPs fabricated from proteins.

METHODS

A summary of common NP fabrication techniques is provided along with the range of sizes and functional properties obtained. The NP properties critical for injectable drug delivery are reviewed, as well as the attempts to design 'tissue-specific' NPs.

RESULTS/CONCLUSIONS

It has been possible to design > 100 nm NPs from different biomaterials, and further understanding of in vivo stability and interactions with physiologic systems will lead to improved drug delivery systems.

Final Report on the Safety Assessment of Pentasodium Pentetate and Pentetic Acid as Used in Cosmetics

Pentasodium Pentetate and Pentetic Acid function as chelating agents in cosmetics. Pentasodium Pentetate is readily soluble in water, but the corresponding free acid is not. Pentasodium Pentetate is used in almost 400 cosmetic products over a wide range of product categories, although it is mostly used in hair dyes and colors at use concentrations of 0.1% to 1.0%. Pentetic Acid is used in 150 cosmetic products, mostly in hair dyes and colors. Chelating agents are used in cosmetics to remove calcium and magnesium cations, which impede foaming and cleansing performance and which can cause a haze in clear liquids. The acute oral LD50 of Pentasodium Pentetate in rats was >5 g/kg. The acute dermal LD50 of Pentapotassium Pentetate using rats was reported to be >2 g/kg. The intraperitonal LD50 of Pentetic Acid was reported to be 585 mg/kg. Short-term studies of the calcium and sodium salts of Pentetic Acid in male mice demonstrated no dose-related toxicity over the dose range of 10, 100, and 250 mg/kg. In a 4-week dermal toxicity study, daily topical application of 0.05% Pentasodium Pentetate to shaved and abraded rabbit skin produced moderate erythema after the first week and throughout the study, but no systemic tox-icity. Pentasodium Pentetate or Pentapotassium Pentetate applied to intact albino rabbit skin were not irritating. A 40% solution of Pentapotassium Pentetate was not sensitizing in a guinea pig maximization test. The no observed adverse effect level (NOAEL) for rats given 40% Pentapotassium Pentetate by oral gavage was reported to be 83 mg/kg day-1. Subchronic inhalation evaluation of a bath freshener containing 0.05% or 0.09% Pentasodium Pentetate using albino rats determined that there was no cumulative systemic toxicity attributable to the ingredient at either concentration. The no observed effect level (NOEL) for maternal toxicity in pregnant rats was 400 mg/kg body weight and for fetal toxicity was 100 mg/kg body weight. Another reproductive toxicity study evaluated Pentetic Acid–Zn with and without sodium chloride in pregnant C57/B1 Dougherty mice. No toxicity was found without added sodium chloride. Pentapotassium Pentetate was not muta-genic in an Ames test, with or without metabolic activation. The same material tested in Chinese hamster ovary cells was not clas-togenic. Calcium Pentetate at 1.351 µg/ml produced a statistically significant increase in the number of sister-chromatid exchanges. Pentasodium Pentetate is nonirritating to moderately irritating, but not a sensitizer in clinical tests. A human comedogenicity (acne promotion) test using Pentasodium Pentetate found no effect. Although data are lacking on the dermal penetration of these two ingredients, other chelating agents such as EDTA do not penetrate the skin, so it is likely that Pentasodium Pentetate and Pentetic Acid also would not penetrate. The high water solubility of Pentasodium Pentetate and the low water solubility of Pentetic Acid also support that their dermal penetration will be low. Other chelating agents, including EDTA and its salts, have been determined to be safe in the current practices of use in cosmetics. Meta-, Tri-, and Hexam-etaphosphate salts are chelating agents determined to be safe in the current practices of use in cosmetics. Metasilicate salts were found to be safe as chelating agents in cosmetics when formulated to avoid irritation. Overall, these data were considered sufficient to support the safety of Pentesodium Pentetate and Pentetic Acid as used in cosmetics.

Protein nanospheres for gene delivery

INTRODUCTIONNanoparticles have been widely used to overcome the barriers for drug delivery. Those prepared from natural polymers have a significant advantage over others prepared from synthetic polymers. This article outlines the advantages of gelatin for the preparation of nanoparticles and a method for preparing them. The uses of nanoparticles are also discussed. Cell trafficking can be studied using nanoparticles encapsulated with electron-dense material (e.g., gold); such particles are then visualized by transmission electron microscopy (TEM). DNA-encapsulated nanoparticles can be used for transfection and other methods of gene delivery. The qualitative and quantitative analysis of transfection studies is outlined briefly.

Convenient Synthesis of Multifunctional EDTA-Based Chiral Metal Chelates Substituted with anS-Mesylcysteine

We describe the synthetic route to ethylenediaminetetraacetic acid (EDTA) derivatives that can be attached to surface-exposed thiol functional groups of cysteine residues in proteins, via a methylthiosulfonate moiety that is connected in a stereochemically unique way to the C-1 carbon atom of EDTA. Such compounds can be used to align proteins in solution without the need to add liquid crystalline media, and are, therefore, of great interest for the NMR spectroscopic analysis of biomolecules. The binding constant for the paramagnetic tag to lanthanide ions was determined by measuring luminescence. For the Tb(+3)-ligand complex, a K(b) value of 6.5 x 10(17) M(-1) was obtained. This value is in excellent agreement with literature values for the related EDTA compound. In addition, it could be shown that there is no significant reduction in the luminescence intensity upon addition of a 10(4) excess of Ca2+ ions, indicating that this paramagnetic tag is compatible with buffers containing high concentrations of divalent alkaline earth ions.