Progress and promise of alternative animal and non-animal methods in biomedical research

New insights into the cytotoxic mechanism of marine-fungus-derived citrinin in three-dimensional Hepa1-6 cell model

Although recent studies have demonstrated that Marine-fungus-derived citrinin (MFDC) has a significant cytotoxic effect in traditional two-dimensional (2D) monolayer cell culture and animal models, its precise cytotoxic mechanism, particularly in a three-dimensional (3D) cell culture model remains unclear. In this study, a 3D Hepa1-6 cell model based on Matrigel was used to investigate the potential cytotoxic mechanism of MFDC (0-100 μg/mL). The results revealed that, after treatment of 60-100 μg/mL MFDC, the increases of reactive oxygen species (ROS), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in 2D cell model were more significant than those in 3D cell model. In addition, the metabolomic results revealed that the significantly altered metabolic pathways were pyrimidine metabolism and vitamin B6 metabolism, which might be related to the interference of MFDC in the pyrimidine synthesis pathway, as well as the upregulation of pyridoxine 5'phosphate oxidase and pyridoxal kinase activities. This study was the first to compare the cytotoxicology of 2D and Matrigel-based 3D cell models after MFDC induction, and to detect differences in cell metabolites after MFDC induction in 3D cell models, providing a new scientific basis for the use of a 3D cell model and a novel research idea for the cellular damage caused by MFDC.

Developmental toxicity: artificial intelligence-powered assessments

Regulatory agencies require comprehensive toxicity testing for prenatal drug exposure, including new drugs in development, to reduce concerns about developmental toxicity, that is, drug-induced toxicity and adverse effects in pregnant women and fetuses. However, defining developmental toxicity endpoints and optimal analysis of associated public big data remain challenging. Recently, artificial intelligence (AI) approaches have had a critical role in analyzing complex, high-dimensional data, uncovering subtle relationships between chemical exposures and associated developmental risks. Here, we present an overview of major big data resources and data-driven models that focus on predicting various toxicity endpoints. We also highlight emerging, interpretable AI models that integrate multimodal data and domain knowledge to reveal toxic mechanisms underlying complex endpoints, and outline a potential framework that leverages multiple interpretable models to comprehensively evaluate chemical-induced developmental toxicity.

A novel free fatty acid receptor agonist improving metabolic health in Drosophila models

The development of synthetic modulators for human free fatty acid receptors (FFARs) has gained attention for addressing diabetes, metabolic syndrome, and dyslipidaemia. A new dual FFAR1 (GPR40) and FFAR4 (GPR120) agonist, DFL23916, was recently identified to improve glucose homeostasis, prompting investigations into its effects on metabolic disorders. This study assessed the selectivity and toxicity of DFL23916 in vitro and evaluated its effects in vivo using Drosophila melanogaster models of high-sugar (HSD) and high-fat diets (HFD). DFL23916 showed no off-target activities with no toxicity/hepatotoxicity in cultured cells. In adult HSD-fed flies with defective mobility, the oral administration of DFL23916 enhanced climbing speed in a concentration-dependent manner and reduced the high content of glucose and triglyceride levels alongside markers of insulin resistance. The compound did not affect viability and food intake of flies exposed to chronic overcaloric conditions but it inhibited the progressive weight gain. Similarly, larvae development remained unaffected by DFL23916, while it counteracted glucose and triglyceride elevation and reduced lipid droplet size caused by HSD and HFD. Finally, in silico analysis highlighted the relevance of evolutionary conserved Drosophila receptors in fatty acid sensing, suggesting putative candidates for DFL23916 binding. Collectively, these findings indicated the safe profile of DFL23916 and its efficacy in ameliorating hyperglycaemic and hyperlipidaemic features in overcaloric fed flies. Our results not only suggest that DFL23916 could be a potential candidate for further investigation in the context of metabolic disorders but also reinforce D. melanogaster as a valuable model for the preclinical evaluation of metabolic interventions, including FFAR-targeting strategies.

Chromosome-level genome assembly of the doctor fish (Garra rufa)

Garra rufa, or doctor fish, is a small cyprinid known for its high-temperature tolerance and its use in ichthyotherapy. Recently, this trait has gained interest as a model for human diseases, including infections and cancer xenografts, though limited genomic resources hinder experimental use. In this study, we have generated a high-quality, chromosome-level genome assembly of G. rufa using PacBio HiFi long-read sequencing and Hi-C technology. The genome is 1.38 Gb in size, with 25 chromosomes and a scaffold N50 of 49.3 Mb. Approximately 59% of the genome consists of repetitive elements, while 27,352 protein-coding genes were annotated, with 98.3% being functionally characterized. BUSCO analysis revealed 94.5% and 94.7% completeness for the genome assembly and annotated protein sequences, respectively. Notably, we identified two heat shock transcription factor (HSF) genes, 239 heat shock protein (HSP)-related genes, and 1,036 heat shock elements (HSEs) in regulatory regions. Phylogenetic analysis supports the placement of G. rufa within the Labeoninae subfamily. This genome assembly provides a valuable resource for advancing G. rufa as a model organism.

Alginate-based microcapsules loaded with Brazilian green propolis decrease reactive oxygen species production, reduce inflammatory cytokines, and mitigate intestinal inflammation

Ulcerative colitis causes intestinal inflammation, with treatments often limited in efficacy and safety. New technologies enable the controlled release of bioactive compounds, and Brazilian green propolis could benefit in managing inflammation. This study proposed developing alginate-based microcapsules loaded with ethanolic extract of green propolis (EEGP-MC), evaluating their effects on inflammatory cytokines, reactive oxygen species, and experimental colitis. The results demonstrated that the EEGP-MC reached peak release of phenolic compounds in the intestinal phase (IP) at 4 h (76.9 %) and 6 h (75.0 %). Similarly, Artepillin C peaked at 22.3 ± 1.2 mg/g at 4 h and 22.5 ± 1.1 mg/g at 6 h in the IP. In THP-1 cell cultures, pretreatment with EEGP-MC (1000 μg/mL) and IP (300 and 1000 μg/mL) reduced TNF-α and IL-6 levels and ROS production. Additionally, oral administration of EEGP-MC at 300 mg/kg demonstrated superior protective activity in the colonic mucosa, reducing lesions by 86.1 % compared to 54.9 % with EEGP alone. Finally, the treatment with EEGP-MC suppressed TNF-α, IL-6, and IL-1β cytokines in the intestinal tissue. No toxicity was observed for the EEGP-MC. These findings highlight EEGP-MC as an innovative technology with promising applications for managing chronic inflammation in the food and pharmaceutical industries.

Synthesis, antimicrobial activity, and toxicological evaluation of a p-coumaric acid derivative as a potential new antibacterial agent

AIMS

Bacterial infections have a profound impact on human health and require continuous development of medical treatments. They remain an important area of research due to their ability to adapt and develop resistance to available therapies. This research aims to identify an additional molecule as a potential future option for the treatment of bacterial infections.

METHODS AND RESULTS

4-Chlorobenzyl p-coumarate was tested to evaluate its activity against bacterial strains in both planktonic and biofilm forms, its possible mode of action, and its toxicity through in silico, in vitro, and in vivo approaches. The molecule exhibited significant activity against Gram-positive bacteria leading to their elimination within 24 h. It induced morphological alterations on the surface and within the cells, ultimately causing cell lysis. The compound reduced bacterial biofilm, penetrated the extracellular matrix, and reached cells within the biofilm, disrupting its architecture. Toxicological assessments in predictive models were promising, showing low cytotoxic effects on human cells and no systemic toxicity.

CONCLUSIONS

4-Chlorobenzyl p-coumarate proved to be a promising compound for proposing new investigative hypotheses considering its effect on multidrug-resistant and non-resistant Gram-positive bacteria.

Past, Current and Future Techniques for Monitoring Paralytic Shellfish Toxins in Bivalve Molluscs

Paralytic shellfish poisoning is a threat to human health caused by the consumption of shellfish contaminated with toxins of the saxitoxin class. Human health is protected by the setting of regulatory limits and the analysis of shellfish prior to sale. Both robust toxicity data, generated from experiments fitting into the ethical 3R framework, and appropriate analysis methods are required to ensure the success of this approach. A literature review of in vivo animal bioassays and in vitro and analytical methods showed that in vitro methods are the best option to screen shellfish for non-regulatory purposes. However, since neither the receptor nor antibody binding of paralytic shellfish toxin analogues correlate with toxicity, these assays cannot accurately quantify toxicity in shellfish nor be used to calculate toxicity equivalence factors. Fully replacing animals in testing is rightfully the ultimate goal, but this cannot be at a cost to human health. More modern technology, such as organ-on-a-chip, represent an exciting development, but animal bioassays cannot currently be replaced in the determination of toxicity. Analytical methods that employ toxicity equivalence factors calculated using oral animal toxicity data result in an accurate assessment of the food safety risk posed by paralytic shellfish toxin contamination in bivalve molluscs.

DMEM and EMEM are suitable surrogate media to mimic host environment and expand leptospiral pathogenesis studies using in vitro tools

Pathogenic Leptospira species can survive and thrive in a wide range of environments. Distinct environments expose the bacteria to different temperatures, osmolarities, and amounts and sources of nutrition. However, leptospires are mostly cultured, in a laboratory setting under in vitro conditions that do not reflect natural environments. This constraint on laboratory cultures limits the applicability of in vitro studies to the understanding of even simple pathogenic processes. Here we report, investigate, and identify a medium and conditions that mimic the host environment during leptospirosis infection, expanding the available in vitro tools to evaluate leptospiral pathogenesis. We quantified genome-wide gene expression of pathogenic Leptospira interrogans cultured in different in vitro media compositions (EMJH, DMEM, EMEM, and HAN). Using EMJH as standard, we compared gene expression in these compositions to genome-wide gene expression gathered in a host environment: whole blood (WB) of hamsters after infection with pathogenic leptospires. Leptospires cultured in DMEM and EMEM media shared 40% and 47% of all differentially expressed genes (DEGs) of leptospires present within WB (FDR<0.01), while leptospires cultured in HAN media only shared 20% of DEGs with those from WB. Furthermore, gene and pathway expression of leptospires cultured on DMEM and EMEM media exhibited a better correlation with leptospires grown in WB, including promoting expression of a similar leptospiral lipid A profile to the one identified directly in host tissues. Taken together, these results indicate that commercial cell-culture media EMEM or DMEM are better surrogates for in vivo pathogenic studies than EMJH or HAN media in Leptospira. These alternative culture conditions, using media that are a standard supply worldwide, provide a reproducible and cost-effective approach that can accelerate research investigation and reduce the number of animal infections necessary for basic research of leptospirosis.

The Imidazacridine Derivative LPSF/AC-05 Induces Apoptosis, Cell Cycle Arrest, and Topoisomerase II Inhibition in Breast Cancer, Leukemia, and Lymphoma

INTRODUCTION

Cancer is one of the major causes of morbidity and mortality worldwide. Current treatments for both solid and hematological tumors are associated with severe adverse effects and drug resistance, necessitating the development of novel selective antineoplastic drugs.

METHODS

The present study describes the antitumor activity of the imidazacridine derivative 5- acridin-9-ylmethylidene-2-thioxoimidazolidin-4-one (LPSF/AC05) in breast cancer, leukemia, and lymphoma cells. Cytotoxicity assays were performed in PBMC and in breast cancer, leukemia, and lymphoma cell lines using the MTT method. Changes in cell cycle progression and apoptosis were assessed using flow cytometry. Moreover, topoisomerase II inhibition assays were performed. LPSF/AC05 exhibited cytotoxicity in six of the nine cell lines tested.

RESULTS

The best results for leukemia and lymphoma were observed in the Toledo, Jurkat, and Raji cell lines (IC50 = 27.18, 31.04, and 33.36 µM, respectively). For breast cancer, the best results were observed in the triple-negative cell line MDA-MB-231 (IC50 = 27.54 μM). The compound showed good selectivity, with no toxicity to normal human cells (IC50 > 100µM; selectivity index > 3). Cell death was primarily induced by apoptosis in all cell lines. Furthermore, LPSF/AC05 treatment induced cell cycle arrest at the G0/G1 phase in leukemia/lymphoma and at the G2/M phase in breast cancer. Finally, topoisomerase II was inhibited.

CONCLUSION

These results indicate the potential application of LPSF/AC05 in cancer therapy.

Phthalocyanine derivative attenuates TNF-α production in macrophage culture and prevents alveolar bone loss in experimental periodontitis

AIM

This study investigated the activity and mechanism of action of the iron tetracarboxyphthalocyanine (FeTcPc) on tumor necrosis factor alpha (TNF-α) production and its impact on experimental periodontitis.

METHODS

RAW 264.7 macrophages were treated with FeTcPc, activated with lipopolysaccharide (LPS) at 10 ng/mL, and the TNF-α levels were measured, as well as the nuclear factor kappa B (NF-κB) activation. Subsequently, a mouth gel containing 1% FeTcPc was topically administered to the gingival tissue of mice with periodontitis-induced ligatures. Bone loss and the gene expression of Tnfα, p65 (NF-κB), and receptor-activating nuclear factor kappa B ligand (Rankl) were quantified in gingival tissue. Finally, the systemic toxicity of FeTcPc was estimated in Galleria mellonella larvae.

RESULTS

In an activated RAW 264.7 macrophage culture, 100 μM FeTcPc reduced TNF-α release and NF-κB activation. Regarding experimental periodontitis, topical application of mouth gel containing 1% FeTcPc blocked alveolar bone loss. Additionally, 1% FeTcPc reduced the expression of Tnfα, p65 (NF-κB), and Rankl in gingival tissue. Finally, administration FeTcPc at doses ranging from 1 to 1000 mg/kg did not cause acute systemic toxicity in G. mellonella.

CONCLUSION

Overall, we demonstrated the potential of mouth gel containing FeTcPc as a therapeutic strategy for managing osteolytic inflammatory disorders, such as periodontitis.

Azobenzenesulfonamide Carbonic Anhydrase Inhibitors as New Weapons to Fight Helicobacter pylori: Synthesis, Bioactivity Evaluation, In Vivo Toxicity, and Computational Studies

Research into novel anti-Helicobacter pylori agents represents an important approach for the identification of new treatments for chronic gastritis and peptic ulcers, which are associated with a high risk of developing gastric carcinoma. In this respect, two series of azobenzenesulfonamides were designed, synthesized, and tested against a large panel of human and bacterial CAs to evaluate their inhibitory activity. In addition, computational studies of the novel primary benzenesulfonamides (4a-j) were performed to predict the putative binding mode to both HpCAs. Then, the antimicrobial activity versus H. pylori of the two series was also studied. The best-in-class compounds were found to be 4c and 4e among the primary azobenzenesulfonamides and 5c and 5f belonging to the secondary azobenzenesulfonamides series, showing themselves to exert a promising anti-H. pylori activity, with MIC values of 4-8 μg/mL and MBCs between 4 and 16 μg/mL. Moreover, the evaluation of their toxicity on a G. mellonella larva in vivo model indicated a safe profile for 4c,e and 5c,f. The collected results warrant considering these azobenzenesulfonamides as an interesting starting point for the development of a new class of anti-H. pylori agents.

Pathological Defects in a Drosophila Model of Alzheimer's Disease and Beneficial Effects of the Natural Product Lisosan G

Alzheimer's disease (AD) brains are histologically marked by the presence of intracellular and extracellular amyloid deposits, which characterize the onset of the disease pathogenesis. Increasing evidence suggests that certain nutrients exert a direct or indirect effect on amyloid β (Aβ)-peptide production and accumulation and, consequently, on AD pathogenesis. We exploited the fruit fly Drosophila melanogaster model of AD to evaluate in vivo the beneficial properties of Lisosan G, a fermented powder obtained from organic whole grains, on the intracellular Aβ-42 peptide accumulation and related pathological phenotypes of AD. Our data showed that the Lisosan G-enriched diet attenuates the production of neurotoxic Aβ peptides in fly brains and reduces neuronal apoptosis. Notably, Lisosan G exerted anti-oxidant effects, lowering brain levels of reactive oxygen species and enhancing mitochondrial activity. These aspects paralleled the increase in autophagy turnover and the inhibition of nucleolar stress. Our results give support to the use of the Drosophila model not only to investigate the molecular genetic bases of neurodegenerative disease but also to rapidly and reliably test the efficiency of potential therapeutic agents and diet regimens.

Assessment of the Artemia salina toxicity assay as a substitute of the mouse lethality assay in the determination of venom-induced toxicity and preclinical efficacy of antivenom

Mice are routinely used in snake venom research but are costly and subject to pain and suffering. The crustacean Artemia salina could be an alternative to mice, but data to support its adoption in snake venom research is limited. The aim of the present study was to evaluate the suitability of A. salina as a surrogate of mice in assessing the toxicity of venoms and the preclinical efficacy of antivenoms. The toxicity of venoms from 22 snakes of medical importance in sub-Saharan Africa was evaluated in mice (intraperitoneally; i.p. and intravenously; i.v.) and in A. salina. Subsequently, the capacity of a commercial antivenom to neutralize the toxicity of these venoms in mice and A. salina was investigated. There was a positive correlation between the i.v. median lethal doses (LD50s) and the i.p. LD50s in mice (r = 0.804; p < 0.0001), a moderate correlation between the i.v. LD50s in mice and the median lethal concentrations (LC50s) in A. salina (r = 0.606; p = 0.003), and a moderate correlation between the i.p. LD50s in mice and the LC50s in A. salina (r = 0.426; p = 0.048). Moreover, there was a strong correlation between the i.p. median effective doses (ED50s) and the i.v. ED50s in mice (r = 0.941, p < 0.0001), between the i.p. ED50s in mice and the ED50s in A. salina (r = 0.818, p < 0.0001), and between the i.v. ED50s in mice and the ED50s in A. salina (r = 0.972, p < 0.0001). These findings present A. salina as a promising candidate for reducing reliance on mice in snake venom research. Future investigations should build upon these findings, addressing potential limitations and expanding the scope of A. salina in venom research and antivenom development.

Delineating three-dimensional behavior of uveal melanoma cells under anchorage independent or dependent conditions

BACKGROUND

Although rare, uveal melanoma (UM) is a life-threatening malignancy. Understanding its biology is necessary to improve disease outcome. Three-dimensional (3D) in vitro culture methods have emerged as tools that incorporate physical and spatial cues that better mimic tumor biology and in turn deliver more predictive preclinical data. Herein, we comprehensively characterize UM cells under different 3D culture settings as a suitable model to study tumor cell behavior and therapeutic intervention.

METHODS

Six UM cell lines were tested in two-dimensional (2D) and 3D-culture conditions. For 3D cultures, we used anchorage-dependent (AD) methods where cells were embedded or seeded on top of basement membrane extracts and anchorage-free (AF) methods where cells were seeded on agarose pre-coated plates, ultra-low attachment plates, and on hanging drops, with or without methylcellulose. Cultures were analyzed for multicellular tumor structures (MCTs) development by phase contrast and confocal imaging, and cell wellbeing was assessed based on viability, membrane integrity, vitality, apoptotic features, and DNA synthesis. Vascular endothelial growth factor (VEGF) production was evaluated under hypoxic conditions for cell function analysis.

RESULTS

UM cells cultured following anchorage-free methods developed MCTs shaped as spheres. Regardless of their sizes and degree of compaction, these spheres displayed an outer ring of viable and proliferating cells, and a core with less proliferating and apoptotic cells. In contrast, UM cells maintained under anchorage-dependent conditions established several morphological adaptations. Some remained isolated and rounded, formed multi-size irregular aggregates, or adopted a 2D-like flat appearance. These cells invariably conserved their metabolic activity and conserved melanocytic markers (i.e., expression of Melan A/Mart-1 and HMB45). Notably, under hypoxia, cells maintained under 3D conditions secrete more VEGF compared to cells cultured under 2D conditions.

CONCLUSIONS

Under an anchorage-free environment, UM cells form sphere-like MCTs that acquire attributes reminiscent of abnormal vascularized solid tumors. UM cells behavior in anchorage-dependent manner exposed diverse cells populations in response to cues from an enriched extracellular matrix proteins (ECM) environment, highlighting the plasticity of UM cells. This study provides a 3D cell culture platform that is more predictive of the biology of UM. The integration of such platforms to explore mechanisms of ECM-mediated tumor resistance, metastatic abilities, and to test novel therapeutics (i.e., anti-angiogenics and immunomodulators) would benefit UM care.

Exposure to the Natural Compound Climacostol Induces Cell Damage and Oxidative Stress in the Fruit Fly Drosophila melanogaster

The ciliate Climacostomum virens produces the metabolite climacostol that displays antimicrobial activity and cytotoxicity on human and rodent tumor cells. Given its potential as a backbone in pharmacological studies, we used the fruit fly Drosophila melanogaster to evaluate how the xenobiotic climacostol affects biological systems in vivo at the organismal level. Food administration with climacostol demonstrated its harmful role during larvae developmental stages but not pupation. The midgut of eclosed larvae showed apoptosis and increased generation of reactive oxygen species (ROS), thus demonstrating gastrointestinal toxicity. Climacostol did not affect enteroendocrine cell proliferation, suggesting moderate damage that does not initiate the repairing program. The fact that climacostol increased brain ROS and inhibited the proliferation of neural cells revealed a systemic (neurotoxic) role of this harmful substance. In this line, we found lower expression of relevant antioxidant enzymes in the larvae and impaired mitochondrial activity. Adult offsprings presented no major alterations in survival and mobility, as well the absence of abnormal phenotypes. However, mitochondrial activity and oviposition behavior was somewhat affected, indicating the chronic toxicity of climacostol, which continues moderately until adult stages. These results revealed for the first time the detrimental role of ingested climacostol in a non-target multicellular organism.

Carbon Nanotubes and Graphene Materials as Xenobiotics in Living Systems: Is There a Consensus on Their Safety?

Carbon nanotubes and graphene are two types of nanomaterials that have unique properties and potential applications in various fields, including biomedicine, energy storage, and gas sensing. However, there is still a debate about the safety of these materials, and there is yet to be a complete consensus on their potential risks to human health and the environment. While some studies have provided recommendations for occupational exposure limits, more research is needed to fully understand the potential risks of these materials to human health and the environment. In this review, we will try to summarize the advantages and disadvantages of using carbon nanotubes and graphene as well as composites containing them in the context of their biocompatibility and toxicity to living systems. In addition, we overview current policy guidelines and technical regulations regarding the safety of carbon-based nanomaterials.