Ultrastructural pathology and interorganelle cross talk in hepatotoxicity

Microscopy based methods for characterization, drug delivery, and understanding the dynamics of nanoparticles

Nanomedicine is an emerging field that exploits nanotechnology for the development of novel therapeutic and diagnostic modalities. Researches are been focussed in nanoimaging to develop noninvasive, highly sensitive, and reliable tools for diagnosis and visualization in nanomedical field. The application of nanomedicine in healthcare requires in-depth understanding of their structural, physical and morphological properties, internalization inside living system, biodistribution and localization, stability, mode of action and possible toxic health effects. Microscopic techniques including fluorescence-based confocal laser scanning microscopy, super-resolution fluorescence microscopy and multiphoton microscopy; optical-based Raman microscopy, photoacoustic microscopy and optical coherence tomography; photothermal microscopy; electron microscopy (transmission electron microscope and scanning electron microscope); atomic force microscopy; X-ray microscopy and, correlative multimodal imaging are recognized as an indispensable tool in material research and aided in numerous discoveries. Microscopy holds great promise in detecting the fundamental structures of nanoparticles (NPs) that determines their performance and applications. Moreover, the intricate details that allows assessment of chemical composition, surface topology and interfacial properties, molecular, microstructure, and micromechanical properties are also elucidated. With plethora of applications, microscopy-based techniques have been used to characterize novel NPs alongwith their proficient designing and adoption of safe strategies to be exploited in nanomedicine. Consequently, microscopic techniques have been extensively used in the characterization of fabricated NPs, and their biomedical application in diagnostics and therapeutics. The present review provides an overview of the microscopy-based techniques for in vitro and in vivo application in nanomedical investigation alongwith their challenges and advancement to meet the limitations of conventional methods.

Comparative Histological Study of Therapeutic Effect of Mesenchymal Stem Cells versus Mesenchymal Stem Cells Co-Cultured with Liver Tissue on Carbon Tetrachloride-Induced Hepatotoxicity in Adult Male Albino Rats

Context

Liver diseases are major causes of morbidity and mortality. Mesenchymal stem cells (MSCs) have immunomodulatory, anti-inflammatory, and antifibrotic effects, so they can be used in the treatment of liver diseases. MSCs co-cultured with diseased liver tissue improve the homing capacity, survival rate, and paracrine effects of the MSCs, as well as the ability to enhance liver function.

Aims

This work aimed to study the therapeutic effect of MSCs versus MSCs co-cultured with liver tissue on carbon tetrachloride (CCl4)-induced hepatotoxicity in adult male albino rats.

Settings and Design

Twenty adult male albino rats were divided into four equal groups; Group I (control group), Group II received CCl4 intraperitoneally (i.p.), Group III received CCl4 i.p. and then injected with MSCs intravenously (i.v.), and Group IV received CCl4 i.p. and then injected with co-cultured MSCs i.v.

Materials and Methods

Finally, liver specimens were processed for light microscopy (LM) and electron microscopy (EM). Statistical analysis was carried out to assess histological scoring, area percentage of collagen fibers, number of glial fibrillary acidic protein-positive cells, and biochemical analysis of alanine aminotransferase and aspartate aminotransferase.

Statistical Analysis Used

Statistical analysis of (histological scoring, area % of collagen fibers, and biochemical analysis) was done by using one-way analysis of variance (ANOVA) test using graphpad software (SanDiego, CA, USA). The means ± standard deviations were used for statistical analysis.

Results

LM of Group II revealed loss of hepatic architecture and diffuse fibrosis with dilated congested blood vessels, bile ductular proliferation, and cellular infiltrations. Vacuolated cytoplasm with or without pyknotic nuclei was observed in addition to micro- and macro-steatosis. EM demonstrated disfigured hepatocytes with abnormal organelles surrounding atypical nucleus. Group III showed restoration of the normal liver architecture with greater extent in Group IV. Statistical analysis confirmed the microscopic findings.

Conclusions

Co-cultured MSCs with diseased liver tissue augmented the therapeutic effects of MSCs in treating hepatotoxicity induced by CCl4 in adult male albino rats.

Impacts of iron on ultrastructural features of NCI-H295R cell line related to steroidogenesis

The current study was intended to evaluate impacts of both iron (Fe) enrichment and overload (in the form of ferrous sulphate heptahydrate, FeSO4.7H2O) on ultrastructural characteristics of human adrenocarcinoma NCI-H295R cell line. Here, the NCI-H295R cells were treated with 0, 3.90, and 1000 µM FeSO4.7H2O, and consequently proceeded for purposes of ultrastructural studies. Micrographs taken under transmission electron microscope (TEM) were investigated from the qualitative and quantitative (unbiased stereological approaches) aspects, and obtained findings were compared among the three groups of the cells. The ultrastructural features related to the steroidogenic process were found to be similar between the untreated and both Fe-exposed cell populations, with conspicuous mitochondria with well-defined lamellar cristae (creating clusters of varying sizes in the regions of increased energy demands) and concentric whorls of smooth endoplasmic reticulum (SER) being the most noticeable characteristics. The precise estimates of the component (volume, surface) fractions of the nucleus, mitochondria, and lipid droplets (LDs), as well as of the nucleus/cytoplasm (N/C) ratio have revealed close similarities (P > 0.05) in all cell groups investigated. Nonetheless, the low concentration of FeSO4.7H2O exhibited beneficial action on ultrastructural organization of the NCI-H295R cells. In effect, these cells were distinguished by mitochondria with smoother surfaces and clearer outlines, higher density of thin, parallel lamellar cristae (deeply extending into the mitochondrial matrix), and more widespread distribution of fine SER tubules as compared to the control ones, all of them suggesting higher level of energy requirements and metabolic activity, and more intensive rate of steroidogenesis. Interestingly, no obvious ultrastructural modifications were observed in the NCI-H295R cells treated with high FeSO4.7H2O concentration. This finding can be linked to either an adaptive ultrastructural machinery of these cells to cope with the adverse effect of the element or to insufficient dose of FeSO4.7H2O (1000 µM) to induce ultrastructural signs of cytotoxicity. Purposefully, the results of the current study complement our previous paper dealing with impacts of FeSO4.7H2O on the NCI-H295R cell viability and steroidogenesis at the molecular level. Hence, they fill a knowledge gap considering structure-function coupling in this cellular model system upon the metal exposure. This integrated approach can enhance our understanding of the cellular responses to Fe enrichment and overload which can be helpful for individuals with reproductive health concerns.

Transmission Electron Microscopy as a Powerful Tool to Investigate the Interaction of Nanoparticles with Subcellular Structures

Nanomedical research necessarily involves the study of the interactions between nanoparticulates and the biological environment. Transmission electron microscopy has proven to be a powerful tool in providing information about nanoparticle uptake, biodistribution and relationships with cell and tissue components, thanks to its high resolution. This article aims to overview the transmission electron microscopy techniques used to explore the impact of nanoconstructs on biological systems, highlighting the functional value of ultrastructural morphology, histochemistry and microanalysis as well as their fundamental contribution to the advancement of nanomedicine.

Hepatoprotective activity of chrysin is mediated through TNF-α in chemically-induced acute liver damage: An in vivo study and molecular modeling

Chrysin (5,7-dihydroxyflavone) is a naturally occurring flavonoid present at high levels in honey, propolis and numerous plant extracts. Chrysin is known to have hepatoprotective activity, however, the mechanisms by which it exerts this effect remain unclear. In the present study, the effects of chrysin in carbon tetrachloride (CCl₄)-induced acute liver damage were investigated and the results used to infer a possible mechanism behind chrysin's hepatoprotective activity. Prior to an intraperitoneal injection of CCl4 (1 ml/kg) to induce acute liver damage, chrysin (50 mg/kg) was administered orally to mice for 7 days. The positive control group was given 50 mg/kg standardized silymarin, a well-studied hepatoprotective flavonoid. Twenty-four h following CCl4 administration, an increase in the activity levels of serum aspartate-amino-transferase and alanine-amino-transferase was found. This was accompanied by extended centrilobular necrosis, steatosis and an altered hepatocyte ultrastructure. In addition, CCl4-induced acute hepatotoxicity was associated with an increase in hepatic tumor necrosis factor-α (TNF-α) and α-smooth muscle actin (α-SMA) protein expression, which was significantly decreased in the livers of mice pre-treated with chrysin (P<0.001), similar to the results of the silymarin pre-treated group (P<0.001). Treatment with chrysin prior to CCl4 exposure significantly reduced the activity of enzymes used as biochemical markers of poor liver function compared with the group which did not receive pre-treatment (P<0.001). In addition, the results of histopathological and electron microscopy liver examination showed chrysin pre-treatment reduced the effects of CCl4 treatment. Molecular modeling results demonstrated that the hepatoprotective activity of chrysin is mediated through TNF-α, as it reduces soluble TNF-α generation via blocking TNF-α-converting enzyme activity. In conclusion, the results of the present study suggest that inflammatory pathways are activated in CCl4-induced acute liver damage, which are ameliorated by chrysin pre-treatment. This indicates that chrysin is a potent hepatoprotective agent, similarly to silymarin at the same dose, which has the potential to be a viable alternative to conventional hepatoprotective treatments.

Impact of Chromogranin A deficiency on catecholamine storage, catecholamine granule morphology and chromaffin cell energy metabolism in vivo

Chromogranin A (CgA) is a prohormone and granulogenic factor in neuroendocrine tissues with a regulated secretory pathway. The impact of CgA depletion on secretory granule formation has been previously demonstrated in cell culture. However, studies linking the structural effects of CgA deficiency with secretory performance and cell metabolism in the adrenomedullary chromaffin cells in vivo have not previously been reported. Adrenomedullary content of the secreted adrenal catecholamines norepinephrine (NE) and epinephrine (EPI) was decreased 30-40 % in Chga-KO mice. Quantification of NE and EPI-storing dense core (DC) vesicles (DCV) revealed decreased DCV numbers in chromaffin cells in Chga-KO mice. For both cell types, the DCV diameter in Chga-KO mice was less (100-200 nm) than in WT mice (200-350 nm). The volume density of the vesicle and vesicle number was also lower in Chga-KO mice. Chga-KO mice showed an ~47 % increase in DCV/DC ratio, implying vesicle swelling due to increased osmotically active free catecholamines. Upon challenge with 2 U/kg insulin, there was a diminution in adrenomedullary EPI, no change in NE and a very large increase in the EPI and NE precursor dopamine (DA), consistent with increased catecholamine biosynthesis during prolonged secretion. We found dilated mitochondrial cristae, endoplasmic reticulum and Golgi complex, as well as increased synaptic mitochondria, synaptic vesicles and glycogen granules in Chga-KO mice compared to WT mice, suggesting that decreased granulogenesis and catecholamine storage in CgA-deficient mouse adrenal medulla is compensated by increased VMAT-dependent catecholamine update into storage vesicles, at the expense of enhanced energy expenditure by the chromaffin cell.

Hepatic Mitochondrial Alteration in CD-1 Mice Associated with Prenatal Exposures to Low Doses of Perfluorooctanoic Acid (PFOA)

Perfluorooctanoic acid (PFOA) is a perfluoroalkyl acid primarily used as an industrial surfactant. It persists in the environment and has been linked to potentially toxic and/or carcinogenic effects in animals and people. As a known activator of peroxisome proliferator-activated receptors (PPARs), PFOA exposure can induce defects in fatty acid oxidation, lipid transport, and inflammation. Here, pregnant CD-1 mice were orally gavaged with 0, 0.01, 0.1, 0.3, and 1 mg/kg of PFOA from gestation days (GD) 1 through 17. On postnatal day (PND) 21, histopathologic changes in the livers of offspring included hepatocellular hypertrophy and periportal inflammation that increased in severity by PND 91 in an apparent dose-dependent response. Transmission electron microscopy (TEM) of selected liver sections from PND 91 mice revealed PFOA-induced cellular damage and mitochondrial abnormalities with no evidence of peroxisome proliferation. Within hypertrophied hepatocytes, mitochondria were not only increased in number but also exhibited altered morphologies suggestive of increased and/or uncontrolled fission and fusion reactions. These findings suggest that peroxisome proliferation is not a component of PFOA-induced hepatic toxicity in animals that are prenatally exposed to low doses of PFOA.