Three-dimensional apoptotic nuclear behavior analyzed by means of Field Emission in Lens Scanning Electron Microscope

Chondrocyte death involvement in osteoarthritis

Chondrocyte apoptosis is known to contribute to articular cartilage damage in osteoarthritis and is correlated to a number of cartilage disorders. Micromass cultures represent a convenient means for studying chondrocyte biology, and, in particular, their death. In this review, we focused the different kinds of chondrocyte death through a comparison between data reported in the literature. Chondrocytes show necrotic features and, occasionally, also apoptotic features, but usually undergo a new form of cell death called Chondroptosis, which occurs in a non-classical manner. Chondroptosis has some features in common with classical apoptosis, such as cell shrinkage, chromatin condensation, and involvement, not always, of caspases. The most crucial peculiarity of chondroptosis relates to the ultimate elimination of cellular remnants. Independent of phagocytosis, chondroptosis may serve to eliminate cells without inflammation in situations in which phagocytosis would be difficult. This particular death mechanism is probably due to the unusual condition chondrocytes both in vivo and in micromass culture. This review highlights on the morpho-fuctional alterations of articular cartilage and focus attention on various types of chondrocyte death involved in this degeneration. The death features have been detailed and discussed through in vitro studies based on tridimensional chondrocyte culture (micromasses culture). The study of this particular mechanism of cartilage death and the characterization of different biological and biochemical underlying mechanisms can lead to the identification of new potentially therapeutic targets in various joint diseases.

Holotomographic microscopy: A new approach to detect apoptotic cell features

Holotomographic (HT) microscopy, combines two techniques, holography and tomography, and, in this way, it allows to quantitatively and noninvasively investigate cells and thin tissue slices, by obtaining three-dimensional (3D) images and by monitoring inner morphological changes. HT has indeed two significant advantages: it is label-free and low-energy light passes through the specimen with minimal perturbation. Using quantitative phase imaging with optical diffraction tomography, it can produce 3D images by measuring the refraction index (RI). Therefore, based on RI values, HT can provide structural and chemical cell information, such as dry mass values, morphological changes, or cellular membrane dynamics. In this study, suspended and adherent culture cells have been processed for HT analyses. Some of them have been treated with known apoptotic drugs or pro-oxidant agents and cell response has been investigated both by conventional microscopic approaches and by HT. The ultrastructural and fluorescence images have been compared to those obtained by HT and their congruence has been discussed, with particular attention to apoptotic cell death and on correlated plasma membrane changes. HT appears a valid approach to further characterize well-known apoptotic features such as cell blebbing, chromatin condensation, micronuclei, and apoptotic bodies. Taken together, our data demonstrate that HT appears suitable to highlight suspended or adherent cell behavior under different conditions. In particular, this technique appears an important new tool to distinguish healthy cells from the apoptotic ones, as well as to monitor outer and inner cell changes in a rapid way and with a noninvasive, label-free, approach.

Ultrastructural changes in hepatocellular carcinoma cells induced by exponential pulses of nanosecond duration delivered via a transmission line

Clinical applications of high-intensity pulsed electric fields have proven useful in ablating solid tumors. However, novel ideas for the development of an effective tumor ablation device are urgently needed. Here, we studied cellular effects of the nanosecond exponential pulse, which is generated by a capacitor-discharging circuit and delivered via a transmission line. Pulses of peak voltage boosted by transmission line oscillation possess high capability to induce swelling and to cause loss of viability in cells. The appropriate parameter of the pulse was selected to investigate the ultrastructural changes in swollen cells, which present smoothened plasma membrane, loss of microvilli, and lowered cytoplasm electron density. We propose the equivalent force field hypothesis to understand the mechanism underlying cell swelling induced by pulsing. Wrinkles on the plasma membrane might indicate recovery from cell swelling, and this was verified by co-culture of pulsed PKH26-Cells with sham-treated PKH67-Cells. We concluded that the ultrastructural changes, such as irregular pores formed on the plasma membrane, were mainly induced by the effect of electric pulse applied on the charged molecules in the membrane.

Oxidative stress-mediated apoptotic cell death induced by camphor in sod1-deficient Schizosaccharomyces pombe

Camphor is one of the monoterpenes widely used in cosmetics, pharmaceutics and the food industry. In this study, we aimed to assess the oxidative, cytotoxic and apoptotic effects of camphor on the fission yeast (Schizosaccharomyces pombe), which is a promising unicellular model organism in mechanistic toxicology and cell biology. Since Sod1 is the main radical scavenger in the cell, we used sod1 mutants to understand whether camphor-induced ROS accumulation caused higher cytotoxicity and apoptosis. Camphor exposure (0-2000 mg L-1) caused significant cytotoxicity in yeast, particularly in sod1Δ cells. DCFDA (2,7-dichlorodihydrofluorescein diacetate) fluorescence and NBT (p-nitro-blue tetrazolium chloride) reduction increased (at least 2.5-3-fold in sod1Δ cells) in correlation with camphor concentrations (800-1200 mg L-1), showing higher ROS levels and oxidative stress. Moreover, cells, stained with acridine orange/ethidium bromide, showed an apoptotic morphology with nuclear fragmentation and condensation. DAPI (4',6-diamidino-2-phenylindole) staining was used to validate the apoptotic nuclear morphology. Dramatically increased mitochondrial impairment, which was higher in sod1Δ cells than in wild type cells, was shown by rhodamine 123 staining. In conclusion, camphor-induced excessive ROS production, which could not be prevented significantly in sod1 mutants, caused a dramatic increase in mortality rates due to intrinsic apoptosis revealed by mitochondrial impairment and apoptotic nuclear morphology. The potential effects of camphor on apoptotic cell death and the underlying mechanisms were clarified in the unicellular eukaryotic model, S. pombe.

Diet Modulation Restores Autophagic Flux in Damaged Skeletal Muscle Cells

OBJECTIVES

Autophagy is a physiological and highly regulated mechanism, crucial for cell homeostasis maintenance. Its impairment seems to be involved in the onset of several diseases, including muscular dystrophies, myopathies and sarcopenia. According to few papers, chemotherapeutic drug treatment is able to trigger side effects on skeletal muscle tissue and, among these, a defective autophagic activation, which leads to the persistence of abnormal organelles within cells and, finally, to myofiber degeneration. The aim of this work is to find a strategy, based on diet modulation, to prevent etoposide-induced damage, in a model of in vitro skeletal muscle cells.

METHODS

Glutamine supplementation and nutrient deprivation have been chosen as pre-treatments to counteract etoposide effect, a chemotherapeutic drug known to induce oxidative stress and cell death. Cell response has been evaluated by means of morpho-functional, cytofluorimetric and molecular analyses.

RESULTS

Etoposide treated cells, if compared to control, showed dysfunctional mitochondria presence, ER stress and lysosomal compartment damage, confirmed by molecular investigations.

CONCLUSIONS

Interestingly, both dietary approaches were able to rescue myofiber from etoposide-induced damage. Glutamine supplementation, in particular, seemed to be a good strategy to preserve cell ultrastructure and functionality, by preventing the autophagic impairment and partially restoring the normal lysosomal activity, thus maintaining skeletal muscle homeostasis.

Ultrastructural histochemistry in biomedical research: Alive and kicking

The high-resolution images provided by the electron microscopy has constituted a limitless source of information in any research field of life and materials science since the early Thirties of the last century. Browsing the scientific literature, electron microscopy was especially popular from the 1970’s to 80’s, whereas during the 90’s, with the advent of innovative molecular techniques, electron microscopy seemed to be downgraded to a subordinate role, as a merely descriptive technique. Ultra -structural histochemistry was crucial to promote the Renaissance of electron microscopy, when it became evident that a precise localization of molecules in the biological environment was necessary to fully understand their functional role. Nowadays, electron microscopy is still irreplaceable for ultrastructural morphology in basic and applied biomedical research, while the application of correlative light and electron microscopy and of refined ultrastructural histochemical techniques gives electron microscopy a central role in functional cell and tissue biology, as a really unique tool for high-resolution molecular biology in situ.

Oxidative stress and mitochondrial impairment mediated apoptotic cell death induced by terpinolene in Schizosaccharomyces pombe

Terpinolene is one of the most abundant monoterpenes used as a food supplement or odorant in cosmetics and the pharmaceutical industry. In this study, we aimed to assess apoptotic, oxidative and cytotoxic effects of terpinolene. We used the fission yeast (Schizosaccharomyces pombe) as a promising uni-cellular model organism in molecular toxicology and cell death research, due to its resemblance to mammalian cells at the molecular level. After terpinolene exposure (200-800 mg L-1), the IC50 and LC50 were calculated as 349.17 mg L-1 and 593.87 mg L-1. Cells, stained with acridine orange/ethidium bromide and DAPI, showed apoptotic nuclear morphology, chromatin condensation and fragmentation. 2,7-Dichlorodihydrofluorescein diacetate (DCFDA) fluorescence gradually increased (1.5-2-fold increase) in correlation with increasing concentrations of terpinolene (200-800 mg L-1). Mitochondrial impairment at higher concentrations of terpinolene (400-800 mg L-1) was shown by Rhodamine 123 staining. Real-time PCR experiments showed significant increases (1.5-3-fold) in SOD1 and GPx1 levels (p < 0.05) as well as 2-2.5-fold increases (p < 0.05) in pro-apoptotic factors, Pca1 and Sprad9. The potential effects of terpinolene on programmed cell death and the underlying mechanisms were clarified in unicellular model fungi, Schizosaccharomyces pombe.

Marine bisindole alkaloid: A potential apoptotic inducer in human cancer cells

Marine organisms such as corals, sponges and tunicates produce active molecules which could represent a valid starting point for new drug development processes. Among the various structural classes, the attention has been focused on 2,2-bis(6-bromo-3-indolyl) ethylamine, a marine alkaloid which showed a good anticancer activity against several tumor cell lines. Here, for the first time, the mechanisms of action of 2,2-bis(6-bromo-3-indolyl) ethylamine have been evaluated in a U937 tumor cell model. Morpho-functional and molecular analyses, highlighting its preferred signaling pathway, demonstrated that apoptosis is the major death response induced by this marine compund. Chromatin condensation, micronuclei formation, blebbing and in situ DNA fragmentation, occurring through caspase activation (extrinsic and intrinsic pathways), were observed. In particular, the bisindole alkaloid induces a mitochondrial involvement in apoptosis machinery activation with Blc-2/Bcl-x down-regulation and Bax up-regulation. These findings demonstrated that 2,2-bis(6-bromo-3-indolyl) ethylamine alkaloid-induced apoptosis is regulated by the Bcl-2 protein family upstream of caspase activation.

Is there still room for novelty, in histochemical papers?

Histochemistry continues to be widely applied in biomedical research, being nowadays mostly addressed to detect and locate single molecules or molecular complexes inside cells and tissues, and to relate structural organization and function at the high resolution of the more advanced microscopical techniques. In the attempt to see whether histochemical novelties may be found in the recent literature, the articles published in the European Journal of Histochemistry in the period 2014-2016 have been reviewed. In the majority of the published papers, standardized methods have been preferred by scientists to make their results reliably comparable with the data in the literature, but several papers (approximately one fourth of the published articles) described novel histochemical methods and procedures. It is worth noting that there is a growing interest for minimally-invasive in vivo techniques (magnetic resonance imaging, autofluorescence spectroscopy), which may parallel conventional histochemical analyses to acquire evidence not only on the morphological features of living organs and tissues, but also on their functional, biophysical and molecular characteristics. Thanks to this unceasing methodological refinement, histochemistry will continue to provide innovative applications in the biomedical field.