Combining Cytotoxicity Assessment and Xenopus laevis Phenotypic Abnormality Assay as a Predictor of Nanomaterial Safety

In Vivo Assessment of Drug-Induced Hepatotoxicity Using Xenopus Embryos

Failure to predict drug-induced toxicity reactions is a major problem contributing to a high attrition rate and tremendous cost in drug development. Drug screening in X. laevis embryos is high-throughput relative to screening in rodents, potentially making them ideal for this use. Xenopus embryos have been used as a toxicity model in the frog embryo teratogenesis assay on Xenopus (FETAX) for the early stages of drug safety evaluation. We previously developed compound-screening methods using Xenopus embryos and believe they could be used for in vitro drug-induced toxicity safety assessment before expensive preclinical trials in mammals. Specifically, Xenopus embryos could help predict drug-induced hepatotoxicity and consequently aid lead candidate prioritization. Here we present methods, which we have modified for use on Xenopus embryos, to help measure the potential for a drug to induce liver toxicity. One such method examines the release of the liver-specific microRNA (miRNA) miR-122 from the liver into the vasculature as a result of hepatocellular damage, which could be due to drug-induced acute liver injury. Paracetamol, a known hepatotoxin at high doses, can be used as a positive control. We previously showed that some of the phenotypes of mammalian paracetamol overdose are reflected in Xenopus embryos. Consequently, we have also included here a method that measures the concentration of free glutathione (GSH), which is an indicator of paracetamol-induced liver injury. These methods can be used as part of a panel of protocols to help predict the hepatoxicity of a drug at an early stage in drug development.

Solid lipid nanoparticles for the delivery of anti-microbial oligonucleotides

Novel alternatives to antibiotics are urgently needed for the successful treatment of antimicrobial resistant (AMR) infections. Experimental antibacterial oligonucleotide therapeutics, such as transcription factor decoys (TFD), are a promising approach to circumvent AMR. However, the therapeutic potential of TFD is contingent upon the development of carriers that afford efficient DNA protection against nucleases and delivery of DNA to the target infection site. As a carrier for TFD, here we present three prototypes of anionic solid lipid nanoparticles that were coated with either the cationic bolaamphiphile 12-bis-tetrahydroacridinium or with protamine. Both compounds switched particles zeta potential to positive values, showing efficient complexation with TFD and demonstrable protection from deoxyribonuclease. The effective delivery of TFD into bacteria was confirmed by confocal microscopy while SLN-bacteria interactions were studied by flow cytometry. Antibacterial efficacy was confirmed using a model TFD targeting the Fur iron uptake pathway in E. coli under microaerobic conditions. Biocompatibility of TFD-SLN was assessed using in vitro epithelial cell and in vivo Xenopus laevis embryo models. Taken together these results indicate that TFD-SLN complex can offer preferential accumulation of TFD in bacteria and represent a promising class of carriers for this experimental approach to tackling the worldwide AMR crisis.