Biological Efficacy of Ionizing Radiation Sources on 3D Organotypic Tissue Slices Assessed by Fluorescence Microscopy

OBJECTIVE

Traditional cell-based radiobiological methods are inadequate for assessing the toxicity of ionizing radiation exposure in relation to the microstructure of the extracellular matrix. Organotypic tissue slices preserve the spatial organization observed in vivo, making the tissue easily accessible for visualization and staining. This study aims to explore the use of fluorescence microscopy of physiologically compatible 3D tissue cultures to assess the effects of ionizing radiation.

METHODS

Organotypic tissue slices were obtained by vibratome, and their mechanical properties were studied. Slices were exposed by two ionizing radiation sources; electron beams (80 Gy and 4 Gy), and soft gamma irradiation (80 Gy and 4 Gy). Two tissue culture protocols were used: the standard (37°C), and hypothermic (30°C) conditions. A qualitative analysis of cell viability in organotypic tissue slices was performed using fluorescent dyes and standard laser confocal microscopy.

RESULTS

Biological dosimetry is represented by differentially stained 200-µm thick organotypic tissue sections related to living and dead cells and cell metabolic activity.

CONCLUSION

Our results underscore the ability of fluorescence laser scanning confocal microscopy to rapidly assess the radiobiological effects of ionizing radiation in vitro on 3D organotypic tissue slices.

Molecular changes in the testes of COVID-19 patients

After the sudden outbreak of the COVID-19 pandemic, scientists and clinicians around the world have significantly expanded understanding of the pathogenesis of the disease as well as the impact of SARS-CoV-2 on various organs and tissues. To date, it is accepted to consider the new coronavirus infection as a multisystem disease, but the data on the effect on fertility remains unclear. Previous works by other authors have presented controversial results, and there is no evidence of a direct effect of the new coronavirus on the male gonads. Thus, further studies are needed to verify the hypothesis that the testicles are the target organ for SARS-CoV-2. Groups were formed: Group I (n = 109; age from 25 to 75 years, Median (IQR) - 60 (23) years), cause of death - new coronavirus infection; Group II (n = 21, age from 25 to 75 years, Median (IQR) - 55 (29.5) years) - autopsy testicular material obtained outside the pandemic. We used RT-PCR to detect the presence of viral RNA in testicular tissue. In addition, we investigated the levels of proteins that provide viral invasion, such as ACE-2 and Furin. In the present study, we detected genetic material of a new coronavirus and increased proteins required for viral invasion in testicular tissue of patients with COVID-19 by RT-PCR. Thus, based on our findings, we assume that testicular tissue is potentially vulnerable to SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Features of Appendix and the Characteristics of Appendicitis Development in Children with COVID-19

BACKGROUND

Research on the subject of the influence of SARS-CoV-2 mechanisms on human homeostasis remains an actual problem. Particular interest is the study of pathomorphological changes in the appendix in children with COVID-19.

OBJECTIVES

Aim of this study: morphological and molecular biological evaluation of the appendix in children of different age groups with COVID-19.

METHODS

Groups were formed on the basis of anamnestic, clinical, and morphological data: I (n = 42; aged 2 to 18 years, average age-10.8 ± 4.79)-with an established clinical diagnosis: coronavirus infection (COVID-19; PCR+); II (n = 55; aged 2 to 18 years, average age-9.7 ± 4.77)-with a confirmed clinical diagnosis of acute appendicitis; collected before the onset of the COVID-19 pandemic in 2017-2019; and III (n = 38; aged 2 to 18 years, average age-10.3 ± 4.62)-the control group. Histological and immunohistochemical studies were conducted using primary antibodies to CD3, CD4, CD68, CD163, CD20, and CD138 and to pro-inflammatory (IL-1, IL-6) and anti-inflammatory (IL-4, IL-10) cytokines.

RESULTS

In most samples of appendixes in children with COVID-19, signs of destructive phlegmonous-ulcerative and gangrenous appendicitis were discovered. An increase in CD3+, CD4+, CD68+, CD163+, and CD20+ CD138+ immunocompetent cells was found in the appendix of children with COVID-19. As well, there was an increase in pro-inflammatory (IL-1, IL-6) and anti-inflammatory (IL-4, IL-10) cytokines.

CONCLUSIONS

The aforementioned pathological and immunohistochemical changes were more pronounced in the group of children aged 6-12 years (childhood).

Comparative Characterisation of Proliferation and Apoptosis of Colonic Epithelium after Electron Irradiation with 2 GY and 25 GY

Development of new techniques for multimodal treatment and diagnostics of various neoplasms and the improvement of current techniques can significantly increase the life expectancy of patients with carcinomas of the colon and abdominal-cavity organs, since prevention of various side effects of radiation therapy is one of the main problems of oncological care. Electron irradiation is one of the most promising types of radiation therapy. There are no data on proliferation and apoptosis of the colon epithelium after irradiation with electrons, especially in different modes (single and summary). Morphological evaluation of apoptosis and proliferation of colonic epithelium after local irradiation with electrons were conducted at doses of 2 Gy (Gray) and 25 Gy. Colon fragments from sexually mature Wistar rats (n = 50, body weight 200 ± 10 g) were divided into three groups: I-control (n = 10); II-experimental group (n = 20; local single electron irradiation at a dose of 2 Gy); III-experimental group (n = 30) with local fractional irradiation with electrons at a total dose of 25 Gy. They were studied using light microscopy using hematoxylin and eosin staining and immunohistochemical reactions with antibodies to Ki-67 and caspase-3 (Cas3). Morphological disorders were accompanied by increased expression of pro-apoptotic molecules (caspase-3), and the period of regeneration by proliferative marker (Ki-67). Colon electron irradiation led to disturbances in the histoarchitecture of varying severity, and an increase in cell apoptosis was observed (increased expression of caspase-3 and decrease in Ki-67). In addition, modulation of the PI3K/AKT and MAPK/ERK signalling pathways was detected. The most pronounced destructive changes were observed in the group of 25 Gy fractionated electron irradiation.

Immunohistochemical and histochemical analysis of the rat skin after local electron irradiation

Background

Skin cancer is the most frequently diagnosed type of cancer among all malignant neoplasms. The decrease in mitotic activity and the death of intact keratinocytes arise due to the constantly renewing epithelium being highly sensitive to ionizing radiation.

Aim

The aim of the study is immunohistochemical evaluation of the proliferative-apoptotic balance of keratinocytes, the fibrous component of the skin, and the expression of pro-inflammatory and anti-inflammatory cytokines after single or fractional local electron irradiation.

Methods

Wistar rats (n = 80) were taken from the ITM&B Vivarium (Sechenov University) and divided into groups: I-control, which were injected with saline; and experimental groups, local electron irradiation at doses: II-8 Gy (single), III-40 Gy (single), IV-summary dose 78 Gy (fractional; 13 Gy per day for 6 days). We performed histological analysis, histochemical analysis using Masson, safranine, and picrosirius red staining, immunohistochemical (Ki-67, caspase-3, p53, types I and III collagens, IL-1, IL-6, IL-4, and IL-10) and morphometric analysis of skin fragments of the outer surface of the thigh, irradiated in accordance with the design of the experiment. The early and delayed effects of local electron irradiation at different doses were studied.

Results

After local electron irradiation, dose-dependent morphological changes in the skin of the experimental groups were observed: violation of the histoarchitectonics of the skin confirmed by morphological and morphometric analysis, the proliferation of connective tissue according to the results of histochemical and immunohistochemical studies with signs of the radiation-induced skin fibrosis development, an increase in the levels of pro- and anti-inflammatory cytokines. We observed the most pronounced signs of radiation-induced skin damage in the group of fractional irradiation after 3 months.

Conclusion

8 Gy and 40 Gy single local electron irradiation leads to a shift in the proliferative-apoptotic balance of keratinocytes toward their apoptosis, which activity is directly correlated with the dose of ionizing radiation, and 78 Gy in fractions leads to partial desquamation of the epithelium and inflammatory infiltration. In addition, after 3 months a significant increase in the expression of type I and III collagen fibers and the development of radiation-induced skin fibrosis takes place against the background of 78 Gy fractional local electron irradiation.

Morphofunctional characteristics of proliferation and apoptosis of germinal epithelium: pathogenesis of temporary azoospermia after local electron irradiation

Background

At present, the violation of male reproductive function caused by electron irradiation, leading to a decrease in the proliferative activity of germ cells, as well as the development of methods for its correction are relevant. The effect of leukocyte-poor platelet-rich plasma (LP-PRP) growth factors, which have a high regenerative capacity for the restoration of spermatogenesis, remains poorly understood. Objective of the study: immunohistochemical (IHC) assessment of the proliferation of germinal epithelium after electron irradiation with a dose of 2 Gy.

Methods

Wistar rats (n=60) were divided into groups (conventional names): (I) control (n=30), which were injected with saline; (II) single local irradiation of the testes with electrons at a dose of 2 Gy (n=30). Animals were gradually withdrawn from the experiment over 11 weeks: 5 animals one week after irradiation, and then 5 animals once every 2 weeks. The testes were studied by histological and IHC methods using antibodies to Ki-67, Bcl-2, and p53. Terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) method was used to study DNA fragmentation in germ cells, which were stained with TdT solution (Thermo Fisher, USA) and incubated for 60 minutes. The nuclei were counterstained with 4',6-diamidino-2-phenylindole (DAPI) (blue spectrum) (Thermo Fisher), and the luminescence intensity was controlled in a fluorescent microscope with a set of fluorescein isothiocyanate (FITC) filters (green spectrum).

Results

IHC analysis of testes after irradiation showed a shift in the proliferative-apoptotic balance towards apoptosis of germ cells: a decrease in the expression levels of Ki-67 (16.3%±1.1%, P<0.05) and Bcl-2 (9.1%±1.1%, P<0.05), an increase in p53-positive cells (74.8%±1.2%, P<0.05) by the end of the experiment.

Conclusions

In the experimental model, local irradiation of the testes with electrons at a dose of 2 Gy causes the development of focal hypospermatogenesis, affecting up to 1/8 of the sections of the tubules (in the first week) with a subsequent increase to 1/4 (in the second month), with a tendency to recovery in the third month (temporary azoospermia). The basis of focal hypospermatogenesis is the irradiation-induced proliferative-apoptotic imbalance towards the dominance of apoptosis, which is most pronounced in the pool of spermatogonia.

Assessment of Proliferation and Apoptosis in Testes of Rats after Experimental Localized Electron Irradiation

BACKGROUND AND PURPOSE

With the emergence of linear accelerators in radiotherapy, it becomes necessary to accurately select new dosing regimens. The purpose of this study was to assess the morphological changes of spermatogenesis after radiation exposure.

MATERIALS AND METHODS

Male Wistar rats (n = 40) were subjected to targeted ionizing radiation on a pulsed electron accelerator "NOVAC-11" with doses of 2, 8 and 12 Gy. Spermatogenesis was assessed a week later using light microscopy and immunohistochemical method (antibodies to Ki-67, Bcl-2, p53, Caspase 3).

RESULTS

A decrease in the number of normal germ cells was seen in all experimental groups, while radioresistant Sertoli and Leydig cells were barely affected. The most serious damage to the tubules and germ cells was observed in 8 and 12 Gy irradiation groups. IHC analysis of testes after irradiation showed a shift in the proliferative-apoptotic balance toward apoptosis of germ cells: a decrease in the expression levels of Ki-67 and Bcl-2, an increase in p53-positive and caspase 3-positive cells by the end of the experiment.

CONCLUSION

Dose-dependent progressive pathomorphological changes in histoarchitectonics of the testes are traced, and a decrease in the number of germ cells is seen on the seventh day after irradiation with a pulsed electron accelerator "NOVAC-11".

Angiotensin-Converting Enzyme 2 and Furin Expression in the Appendix of Children with COVID-19

Background: The sudden outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has resulted in more than 261 million infections and an estimated 5.1 million deaths. Some vital organs such as the kidneys, heart, intestines, and lungs could be damaged by SARS-CoV-2. Questions remain regarding the effect of SARS-CoV-2 on the mucous membrane of the appendix in children. The aim of this study was to evaluate the knowledge of cytologic processes in appendix tissue in children with coronavirus disease 2019 (COVID-19). Patients and Methods: Fragments of the appendices of children with confirmed COVID-19 (n = 42) were studied by real-time polymerase chain reaction (PCR) to determine the expression of SARS-CoV-2 RNA and genes encoding protein complexes: ACE-2 and Furin. Results: We found traces of coronavirus genetic material in the appendices of children with COVID-19. We also found increased expression of ACE-2 and Furin in the tissue, which indicates favorable conditions for coronavirus infection. Conclusions: Viral load in the appendices of children can be reported based on the results of real-time PCR for SARS-CoV-2 and the expression of ACE-2 and Furin.

Peliosis hepatis complicated by portal hypertension following renal transplantation

Peliosis hepatis is a rare benign disease, but in last years the number of identified cases has increased. This disease is known to be sometimes accompanied by hepatocellular carcinoma. In the recent article, Yu et al describe a case of liver peliosis, characterized by an increased proliferative index. Therefore, additional diagnosis of patients should include analyzing other tumor markers expression in order to assess the risk of malignant cell transformation in peliosis hepatis.

Immunohistochemical and morphological characteristics of tissues response to polylactic acid membranes with silver nanoparticles

Background

The aim of this research was to study anti-microbial and anti-inflammatory characteristics of silver nanoparticles helping bone structures to recover during late stage of parodontitis, which afterwards will increase the effect of bone regeneration operations.

Material and Methods

We assessed colloid solution-derived silver nanoparticles coating of polylactic acid membrane regarding tissue foreign body response. Thirty eight polylactic acid membranes were implanted intracranially in rabbits – ten unmodified (control group) and twenty eight with silver nanoparticles coating (experimental group). In controls, penicillin was used for infection prophylaxis. Tissue response was assessed by light microscopy and immunohistochemistry (CD3, CD15, CD30) 2 weeks after implantation.

Results

inflammation markers in experimental group were significantly lower than in control group, there were no signs of forming a fibrosis capsule nor infectious signs.

Conclusions

colloid silver solution can be used as a source of nanoparticles for anti-microbial and anti-inflammatory biodegradable membranes’ coating.

Key words:Guided bone regeneration, polylactic acid membrane, silver nanoparticles.