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Human Merkel cells (MCs) were first described by Friedrich S. Merkel in 1875 and named "Tastzellen" (touch cells). Merkel cells are mainly located in the basal layer of the epidermis and are concentrated in touch-sensitive areas. Their density varies among different anatomical sites. Increased concentration was observed in the palms of hands with a predominance in the finger pads and also in the soles and toes. They can be classified according to the function as mechanoreceptive, endocrine, and chemo-sensitive cells. In the development of primary ridges which establish the future fingerprint patterns is assumed that Merkel cells have a significant importance in this process. At about the 7th week EGA, they first time appear in the volar skin and start to occupy the place of future primary ridges at 10 weeks EGA. It will be interesting to study their presence or absence in individuals suffering with abnormal dermatoglyphics and also to study whether the skin diseases associated with altered dermatoglyphics display some deviation regarding the distribution and density of MCs in primary ridges (Fig. 2, Ref. 40). Text in PDF www.elis.sk Keywords: Merkel cells, development, primary ridges, fingerprints, CK-20.

Recently, several scaffolds have been introduced for urethral tissue engineering. However, acellular human urethral scaffold harvested from deceased donors may provide significant advantages compared to synthetic, composite, or other biological scaffolds. This study aims to develop the protocol for decellularization of the human urethra that preserves substantial extracellular matrix (ECM) components, which are essential for subsequent recellularization mimicking the natural environment of the native ECM. A total of 12 human urethras were harvested from deceased donors. An equal part of every harvested urethra was used as a control sample for analyses. The protocol design was based on the enzyme-detergent-enzyme method. Trypsin and Triton X-100 were used to remove cells, followed by DNase treatment to remove DNA residues. Subsequently, the specimens were continually rinsed in deionized water for seven days. The efficiency of decellularization was determined by histochemistry, immunohistochemical staining, scanning electron microscopy (SEM), and DNA quantification. Histological analysis confirmed cell removal and preservation of urethral structure after decellularization. The preservation of collagen IV and fibronectin was confirmed by histologic examination and immunohistochemical staining. SEM confirmed the maintenance of the ultrastructural architecture of ECM and fibers. DNA content in decellularized urethra was significantly lower compared to the native sample ( P

Iron is critically important and highly regulated trace metal in the human body. However, in its free ion form, it is known to be cytotoxic; therefore, it is bound to iron storing protein, ferritin. Ferritin is a key regulator of body iron homeostasis able to form various types of minerals depending on the tissue environment. Each mineral, e.g. magnetite, maghemite, goethite, akaganeite or hematite, present in the ferritin core carry different characteristics possibly affecting cells in the tissue. In specific cases, it can lead to disease development. Widely studied connection with neurodegenerative conditions is widely studied, including Alzheimer disease. Although the exact ferritin structure and its distribution throughout a human body are still not fully known, many studies have attempted to elucidate the mechanisms involved in its regulation and pathogenesis. In this review, we try to summarize the iron uptake into the body. Next, we discuss the known occurrence of ferritin in human tissues. Lastly, we also examine the formation of iron oxides and their involvement in brain functions.

Oral and craniofacial bone defects caused by congenital disease or trauma are widespread. In the case of severe alveolar bone defect, autologous bone grafting has been considered a “gold standard”; however, the procedure has several disadvantages, including limited supply, resorption, donor site morbidity, deformity, infection, and bone graft rejection. In the last few decades, bone tissue engineering combined with stem cell-based therapy may represent a possible alternative to current bone augmentation techniques. The number of studies investigating different cell-based bone tissue engineering methods to reconstruct alveolar bone damage is rapidly rising. As an interdisciplinary field, bone tissue engineering combines the use of osteogenic cells (stem cells/progenitor cells), bioactive molecules, and biocompatible scaffolds, whereas stem cells play a pivotal role. Therefore, our work highlights the osteogenic potential of various dental tissue-derived stem cells and induced pluripotent stem cells (iPSCs), the progress in differentiation techniques of iPSCs into osteoprogenitor cells, and the efforts that have been made to fabricate the most suitable and biocompatible scaffold material with osteoinductive properties for successful bone graft generation. Moreover, we discuss the application of stem cell-derived exosomes as a compelling new form of “stem-cell free” therapy.

The ependymal lining of the walls of the human brain third ventricle (3v), fourth ventricle (4v) and aqueductus cerebri (A) was studied. For a better localization of different ependymal areas, they were labelled by periventricular structures that represent a basic and stable part of brain nerve tissue and they are localized most closely to ventricle walls. Labelling of individual ependymal areas of the ventricle walls was composed of the number of a brain ventricle, letters: E – ependyma and abbreviation of a Latin name of the periventricular structure, e.g., the corpus mammillare is “CM“. Labelling of ependyma over the corpus mammillare is” 3vE – CM “Results of labelling of ependymal areas were arranged in the form of tables called “ependymal table “(ET), i.e., ET for 3v; ET for 4v; ET for A. It is believed that labelling of individual ependymal areas according to periventricular structures could be useful for unambiguous labelling of ependyma of the ventricle walls and will help to a mutual comparison of the same types of ependymal areas studied by various authors.

Samples taken from the human brain (Globus Pallidus) have been investigated by physical techniques such as light microscopy, scanning electron microscopy, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. SEM-EDX/TEM investigation reveals multielemental composition of hematite and magnetite nanocrystals with sizes ranging from 40 nm to 100 nm and hematite microcrystals from 3 μm to 7 μm. Room temperature Mössbauer spectra show quadrupole doublets assigning to hematite and ferrihydrite. SQUID measurements of temperature dependence of the mass magnetic susceptibility between T = 2 – 300 K at DC field B 0 = 0.1 T, the field dependence of the mass magnetization taken at the fixed temperature T 0 = 2.0 and 4.6 K and the zero-field cooled and field cooled magnetization experiments (ZFCM/FCM) confirm a presence of ferrimagnetic phases such as maghemite and/or magnetite with hysteresis loops surviving until the room temperature. Differences between these measurements from the point of view of iron oxides detected can indicate important processes in human brain and interactions between ferritin as a physiological source of iron and surrounding environment.

Iron is very important element for functioning of the brain. Its concentration changes with aging the brain or during disease. The aim of our work was the histological examination of content of ferritin and free iron (unbound) in brain cortex in association with Aβ plaques from their earliest stages of accumulation in amyloid plaque forming APP/PS1 transgenic mice. Light microscopy revealed the onset of plaques formation at 8-monthage. Detectable traces of free iron and no ferritin were found around plaques at this age, while the rate of their accumulation in and around Aβ plaques was elevated at 13 months of age. Ferritin accumulated mainly on the edge of Aβ plaques, while the smaller amount of free iron was observed in the plaque-free tissue, as well as in and around Aβ plaques. We conclude that free iron and ferritin accumulation follows the amyloid plaques formation. Quantification of cortical iron and ferritin content can be an important marker in the diagnosis of Alzheimer’s disease.

Osteoarthritis (OA) belongs to chronic degenerative disorders and is often a leading cause of disability in elderly patients. Typically, OA is manifested by articular cartilage erosion, pain, stiffness, and crepitus. Currently, the treatment options are limited, relying mostly on pharmacological therapy, which is often related to numerous complications. The proper management of the disease is challenging because of the poor regenerative capacity of articular cartilage. During the last decade, cell-based approaches such as implantation of autologous chondrocytes or mesenchymal stem cells (MSCs) have shown promising results. However, the mentioned techniques face their hurdles (cell harvesting, low proliferation capacity). The invention of induced pluripotent stem cells (iPSCs) has created new opportunities to increase the efficacy of the cartilage healing process. iPSCs may represent an unlimited source of chondrocytes derived from a patient’s somatic cells, circumventing ethical and immunological issues. Aside from the regenerative potential of iPSCs, stem cell-derived cartilage tissue models could be a useful tool for studying the pathological process of OA. In our recent article, we reviewed the progress in chondrocyte differentiation techniques, disease modeling, and the current status of iPSC-based regenerative therapy of OA.

The recent Coronavirus 2019 outbreak took the world by surprise and called for global drastic measures. At this early point in the timeline of the pandemic, several questions remain open until the results of large scale studies become available. This article offers few insights on scattered issues; including the clinical characteristics, pathology and diagnosis, as well as treatment perspectives and public health approach. Focusing healthcare resources on necessary treatment and prevention and combining efforts for developing feasible solutions will be decisive for time needed to achieve worldwide containment (Tab. 1, Ref. 23). Keywords: COVID-19, Coronavirus 2019, pandemic, public health.

Objectives The ependymal lining of the human brain ventricular system displays distinct structural differences and functional heterogeneity among individual ependymal cells (ECs). To date, multi-ciliated ECs (E1 cells), bi-ciliated ECs (E2 cells), uni-ciliated ECs (E3 cells), ECs without cilia, and ECs with cytoplasmic protrusions have been described in human brain ventricles. Method Using scanning electron microscopy (SEM), we evaluated ependymal samples from 6 defined regions of the third ventricle from 9 human brains. These regions were strictly defined according to the periventricular structures they neighbour with. Results We observed different structures on the apical surface of the ECs. Various ECs differed from each other by the presence of microvilli, secretory bodies, and a variable number of cilia, which led us to divide the ECs into several exactly specified types according to their apical morphology. Conclusion We found all types of ECs in every examined region with a predominance of particular types of apical surface of ECs in the individual areas (Tab. 4, Fig. 7, Ref. 22).

Huntington’s disease (HD) is an inherited, autosomal dominant, degenerative disease characterized by involuntary movements, cognitive decline, and behavioral impairment ending in death. HD is caused by an expansion in the number of CAG repeats in the huntingtin gene on chromosome 4. To date, no effective therapy for preventing the onset or progression of the disease has been found, and many symptoms do not respond to pharmacologic treatment. However, recent results of pre-clinical trials suggest a beneficial effect of stem-cell-based therapy. Induced pluripotent stem cells (iPSCs) represent an unlimited cell source and are the most suitable among the various types of autologous stem cells due to their patient specificity and ability to differentiate into a variety of cell types both in vitro and in vivo. Furthermore, the cultivation of iPSC-derived neural cells offers the possibility of studying the etiopathology of neurodegenerative diseases, such as HD. Moreover, differentiated neural cells can organize into three-dimensional (3D) organoids, mimicking the complex architecture of the brain. In this article, we present a comprehensive review of recent HD models, the methods for differentiating HD–iPSCs into the desired neural cell types, and the progress in gene editing techniques leading toward stem-cell-based therapy.

The human clavicle provides the bony connection between the upper extremity and the axial skeleton and it is reported to be among the first bones ossified and the last bone to fuse. Clavicle development of the studied mammals shows a combination of intramembranous and endochondrial ossification. The covering of its joints in adult humans differs from other joints of long bones. The rat clavicle pattern morphologically appears to be partly different in comparison with the human one. These differences partially restrict the use of the rat as a model for the study of human articular cartilage but on the other hand they can provide some valuable possibilities for application in medical research and practice.

Diabetes type 1 (T1D) is a common autoimmune disease characterized by permanent destruction of the insulin-secreting β-cells in pancreatic islets, resulting in a deficiency of the glucose-lowering hormone insulin and persisting high blood glucose levels. Insulin has to be replaced by regular subcutaneous injections, and blood glucose level must be monitored due to the risk of hyperglycemia. Recently, transplantation of new pancreatic β-cells into T1D patients has come to be considered one of the most potentially effective treatments for this disease. Therefore, much effort has focused on understanding the regulation of β-cells. Induced pluripotent stem cells (iPSCs) represent a valuable source for T1D modelling and cell replacement therapy because of their ability to differentiate into all cell types in vitro. Recent advances in stem cell-based therapy and gene-editing tools have enabled the generation of functionally adult pancreatic β-cells derived from iPSCs. Although animal and human pancreatic development and β-cell physiology have significant differences, animal models represent an important tool in evaluating the therapeutic potential of iPSC-derived β-cells on type 1 diabetes treatment. This review outlines the recent progress in iPSC-derived β-cell differentiation methods, disease modelling, and future perspectives.

Aim Morphological description of milky spots (MSs) in the human greater omentum. Method Samples of the greater omentum collected during surgical procedures were subjected to further histological analysis. Two groups of patients were studied. Group A consisted of patients with colon cancer and peritonitis (stimulated MSs), group B consisted of patients without colon cancer and without peritonitis (unstimulated MSs). In the research, we focused on the cellular composition and differences between stimulated and unstimulated MSs. Results MSs detected in the study were predominantly oval (67 %), round (12 %) or irregular in shape (21 %). The average number of immune cells found in one milky spot (MS) in the group A was 454 (209-694), consisted of T cells in 44.7 % (27-55 %), B cells in 26.8 % (16-34 %), macrophages in 18.3 % (12-27 %) and other immune cells in 10.2 % (6-18 %). The average number of immune cells found in one MS in the group B was 58 (42-100 %), consisted of T cells in 21.1 % (16-22 %), B cells in 18.7 % (13-22 %), macrophages in 46.9 % (33-60 %) and other immune cells in 13.3 % (1-22 %). The average size of MSs in the group A was significantly higher than in the group B: 768 μm (313-1075) to 293 μm (197-421). The results showed that there were significant differences in terms of strong predominance of macrophages in unstimulated milky spots and strong predominance of T cells in stimulated milky spots. Conclusion MSs are specific immune active lymphatic structures on the greater omentum. They play a key role in defense mechanism, especially in peritonitis. Their function is not completely clear in cancer, some authors suggest they might play a significant role in omental metastasis. Further analysing of the morphology and cells interactions of MSs is needed (Tab. 2, Fig. 6, Ref. 20).

Heart failure is the end stage of cardiovascular abnormalities. Studies have primarily focused on the functional changes of cardiomyocytes in the failing heart from different animal models with very little information in the human condition. In addition little is known about the ultrastructural changes that proceed in cardiomyocytes in route to failure. The aim of this study was to examine the ultrastructural changes in the myocardium of human with end-stage heart failure. Left ventricular myocardial tissue samples from 7 patients with end-stage heart failure were examined with transmission and scanning electron microscopy. All heart failure patients were of New York Heart Association (NYHA) class III-IV. The data indicated normal three-dimensional arrangement of cardiac muscle cells in failing myocardium. The various organelles in cardiomyocytes including the nucleus, mitochondria, myofibrils, T-tubules and intercalated discs did not exhibit any remarkable morphological changes. We did observe the appearance of small membrane bound vesicles which appear to be associated with the intercalated discs. The nearly normal ultrastructure and arrangement of cardiomyocytes was remarkable in contrast to the dramatic clinical status of these patients in heart failure. These observations support the hypothesis, that there are no dramatic changes in the ultrastructure or three-dimensional architecture of cardiomyocytes in end-stage failing human myocardium.

Different types of ependymal areas were studied and labelled in the human brain lateral ventricle. Periventricular structures were included in coining the names of the ependymal areas because they represent a basic and stable part of brain nerve structures suitable for the sake of clarity of localization of the ependyma. The labelling of individual ependymal areas was composed from letters: "Lv" (lateral ventricle); "E" (ependymal area) and letters for abbreviations of the closest periventricular structure, e.g. the septum pellucidum is "sp". The labelling for ependymal area over the septum pellucidum is thus "LvE-sp". The studied types of ependymal areas were arranged in so‑called ependymal tables for cornu anterius, pars centralis, cornu inferius and cornu posterius of the human lateral ventricle. Labelling of individual ependymal areas allows for better localization and characterisation of these areas in future studies carried out by various methods (e.g. morphological, biological, molecular) and will prevent from using misnomers with different types of ependymal areas in norm as well as in pathology (Tab. 5, Fig. 6, Ref. 22). Text in PDF www.elis.sk.

Uterine telocytes are interstitial cells characterized by a very long cytoplasmic prolongations, which form a 3D network, functionally integrating a wide variety of different cells. Leiomyomas (uterine fibroids) are benign tumors, which pose a huge threat concerning various health problems in women affected by this condition. The exact cause of leiomyomas development is, however, still largely unknown. Therefore, in an attempt to clarify their etiology, we performed an immunohistochemical characterization of telocytes in leiomyomas as well as in normal myometrium. Tissue samples of intramural leiomyomas from 26 women (age 46.26 ± 11.07) were immunohistochemically stained for the expression of c-kit (CD117) antigen, one of the markers of telocytes. C-kit (CD117) antigen is useful for a routine immunohistochemical identification of uterine telocytes in histological sections of myometrium. In normal, healthy myometrium the c-kit positive telocytes occupy approximately 2.2% of the area of a tissue slide, contrasting with no detectable c-kit positive cells within leiomyomas. As telocytes are thought to be key players in the regulation of tissue homoeostasis, our data suggest that uterine telocyte loss may have important implications in the pathogenesis of leiomyomas. In addition, we supposed to summarize three hypotheses on the association of the cells telocytes loss within the myometrium and formation of leiomyomas. These hypotheses include the loss of telocytes’ functions as “sex hormone sensors” and regulators of smooth muscle cells cycle; the role of telocytes as progenitor cells for the development of leiomyomas; and the hypothesis of decreased angiogenesis after telocytes’ loss with subsequent hypoxia (as a key factor for leiomyomas development).

Gonadotropin-releasing hormone agonists were described as anti-angiogenic factors in tumors. Simultaneously they were associated with increased cardiovascular risk in patients treated for prostate cancer, especially in those with preexisting cardiac disease. Studies aiming to elucidate the mechanisms by which androgen deprivation therapy causes cardiovascular effects are rare. We believe that gonadotropin-releasing hormone agonists can impair myocardial angiogenesis. That, in patients with myocardial disease can deepen hypoxia, significantly worsen the condition of the myocardium, and therefore increase the risk of cardiac failure. Careful assessment of the myocardial status and consequent timing and typing of therapy can minimalize the adverse effects. Ideally through close cooperation between cardiologists and oncologists (Fig. 1, Ref. 25). Keywords: angiogenesis, cardiovascular risk, follicle stimulating hormone, GnRH agonist, testosterone.

Iron, an essential element for most living organism, participates in a wide variety of physiological processes. Disturbance in iron homeostasis has been associated with numerous pathologies, particularly in the heart and brain, which are the most susceptible organs. Under iron-overload conditions, the generation of reactive oxygen species leads to impairment in Ca2+ signaling, fundamentally implicated in cardiac and neuronal physiology. Since iron excess is accompanied by increased expression of iron-storage protein, ferritin, we examined whether ferritin has an effect on the ryanodine receptor - isoform 2 (RYR2), which is one of the major components of Ca2+ signaling. Using the method of planar lipid membranes, we show that ferritin induced an abrupt, permanent blockage of the RYR2 channel. The ferritin effect was strongly voltage dependent and competitively antagonized by cytosolic TEA+, an impermeant RYR2 blocker. Our results collectively indicate that monomeric ferritin highly likely blocks the RYR2 channel by a direct electrostatic interaction within the wider region of the channel permeation pathway.

Knowledge about the three-dimensional fine structure of human heart, as a crucial vital organ of the body, is not only fascinating from the scientific or educational points of view, but has a very important clinical impact. Therefore, we decided to create a three-dimensional atlas of fine structure of the human heart. Tissue samples from ten human hearts were rinsed in phosphate-buffer solution, fixed by glutaraldehyde buffered solution, and post-fixed in osmium tetroxide solution. A gentle dehydration with ethanol in different concentration and drying at the critical point of CO2 were applied as next procedures. Non-conductive specimens were galvanized with thin gold layer and observed in scanning electron microscope. In this study, we present the three-dimensional ultrastructural architecture of the human heart from patients after myocardial infarction, end-stage failing heart as well as without apparent cardiac abnormalities at the time of autopsy. The results are presented as a histological atlas. Its images illustratively describe the fine structure of endocardium including the morphology of Purkyně (Purkinje) fibres, spatial arrangements of cardiac muscle cells inside myocardium or the arrangements of adipose tissue of epicardium. We present also figures of the ultrastructure of papillary muscles, intercalated discs as well as the connective tissue scars after myocardial infarction. The scanning electron microscopy could be a reliable technique to perform a more complete morphological data and to improve our knowledge of some pathological changes of tissues and cells, not always detected by conventional morphological examinations.

Over the last few years, researchers have been studying telocytes, recently described interstitial cells, voraciously. This morphological study focused on the immunohistochemical identification of telocytes and the study of their topographical relations in the wall of the human uterine body and cervix. This study attempted to find the most specific and therefore, the most suitable monoclonal antibody for the study of telocytes via the immunohistochemical methods. Tissue specimens from human uteruses were stained with eight different primary antibodies, to detect the expression of c-kit (CD117), CD34 antigen, vimentin, α-smooth muscle actin, progesterone receptor, desmin, estrogen receptor and S 100 protein. The presence of telocytes was studied in four different histological regions of the uterus: the endometrium and myometrium of the corpus, endocervical mucosa and exocervical mucosa. This study shows that c-kit is the most suitable marker for identification of telocytes in human uterine body and cervix. C-kit positive telocytes within the endometrium, myometrium, as well as the mucosa of the endocervix and exocervix exhibited an assorted variety of shapes from spindle-shaped, triangular to star-shaped. The greatest abundance of c-kit positive telocytes is found within the myometrium. The connective tissue of endocervical mucosa also contains a considerable number of these cells, while the lowest count of c-kit positive telocytes is found within the endometrium and exocervical mucosa.

Human cardiac muscle cells are the most physically energetic cells in the body, and according to various researchers they contain two nuclei in 25240%. In humans, the heart during prenatal development consists mainly of cardiomyocytes with one nucleus. Just before birth, binucleation begins and can extend into early neonatal life. The physiological importance of binucleation is still poorly understood. In this critical review, we provide a summary of the latest research on binucleation of cardiac muscle cells, with special emphasis on the potential application of such knowledge to the fields of regenerative medicine. We summed up and discussed about ten possible biological arguments why binucleation may be beneficial for cardiac muscle cells as well as for the whole myocardium. These arguments include increase of gene expression, purposeful cell shaping, increase of metabolic activity, energysaving growth and function, need for organ growth despite of telomere depletion, adaptation to stress (tissue regeneration), prevention of overgrowth — organ shaping, prevention of aneuploidy, terminally differentiated state (cardiomyocytes exit the cell cycle, end of proliferation activity); or, we hypothesize, binucleation is just an unwanted side product.

The present study deals with histological descriptions of clinically healthy human gingivae through the methods of light, electron microscopy and immunohistochemistry. Even clinically healthy human gingivae are subject to constant bacterial and mechanical influences present in the oral cavity; therefore, the term “normal gingiva” is misleading. The aim of this study was to identify, in clinically healthy gingiva, all active cells through immunohistochemical markers and light and electron microscope examination. In tissue samples from clinically healthy gingivae of nine patients, we observed the presence of different cells (e.g., T- and B-lymphocytes, macrophages, Merkel cells, Langerhans cells, proliferating cells) and some components of their extracellular matrix that use antibodies against S-100 protein, CD68, CD20, CD45RO, CD20, and Ki67. The presence of immunologically active cells and the ultrastructural characteristics of gingivae were also confirmed. The stratified squamous epithelium of human gingiva contains a population of Langerhans cells and intraepithelial T-lymphocytes. The underlying dense connective tissue contains primarily fibroblasts, but also T-lymphocytes, occasionally B-lymphocytes, plasma cells, and macrophages can be seen. As a border between the oral cavity and the internal environment of the human body, the gingivae are an important part of the immune system. Such findings show that, in healthy gingival tissue, there are constantly ongoing anti-inflammatory, immunological, and regenerative reactions and processes.

Regeneration of injuries occurring in the central nervous system, particularly spinal cord injuries (SCIs), is extremely difficult. The complex pathological events following a SCI often restrict regeneration of nervous tissue at the injury site and frequently lead to irreversible loss of motor and sensory function. Neural stem/progenitor cells (NSCs/NPCs) possess neuroregenerative and neuroprotective features, and transplantation of such cells into the site of damaged tissue is a promising stem cell-based therapy for SCI. However, NSC/NPCs have mostly been induced from embryonic stem cells or fetal tissue, leading to ethical concerns. The pioneering work of Yamanaka and colleagues gave rise to the technology to induce pluripotent stem cells (iPSCs) from somatic cells, overcoming these ethical issues. The advent of iPSCs technology has meant significant progress in the therapy of neurodegenerative disease and nerve tissue damage. A number of published studies have described the successful differentiation of NSCs/NPCs from iPSCs and their subsequent engraftment into SCI animal models, followed by functional recovery of injury. The aim of this present review is to summarize various iPSC- NPCs differentiation methods, SCI modelling, and the current status of possible iPSC- NPCs- based therapy of SCI.

Nowadays, breast cancer is the leading oncological diagnosis in women worldwide. On the other hand, breast cancer treatment can be considered one of the most progressive therapeutic approach in the medical field of oncology. The invasive types of breast cancer have a tendency to spread via lymphatic route, what brings in the issue of sentinel lymph node - the first node into which the lymph drains from a given anatomical location. This review paper discusses the historical background of the concept of sentinel lymph node and focuses on clinical significance of the positivity of sentinel lymph node(s) as well. Modern-day conservative therapeutic surgery of breast cancer should be in accordance with diagnostic and preventive interventions in the axilla, whose rate of invasiveness and morbidity must be also attenuated without worsening the patient´s prognosis and survival rate. Formerly, a complete axillary lymph node dissection was routinely performed for prophylactic and cancer staging purposes. The indiscriminate application of this approach was replaced by sentinel lymph node biopsy. Along with common histopathological examination, immunohistochemistry, as well as modern techniques of molecular biology are often employed. These state-of-the-art methods enabled the identification of micrometastases, or even nanometastases, though their real prognostic value is yet to be concluded (Ref. 52). Keywords: sentinel node, breast cancer, biopsy, historical background.

The race to make the dream of artificial intelligence a reality comes parallel with the increasing struggle of health care systems to cope with information overload and translational pressure. It is clear that a shift in the way data is generated requires a shift in the way they are processed. This is where AI comes with great promises to solve the problem of volume versus applicability of information in science. In medicine, AI is showing exponential progress in the fields of predictive analysis and image recognition. These promises however, come with an intricate package of ethico-social, scientific and economic implications, towards which a reductionist approach leads to distorted and dramatic predictions. All this, in a time when the growing pressure on healthcare systems towards defensive medicine begs the question of the true need for AI for good medical practice.This article examines the concept and achievements of AI and attempts to offer a complex view on the realistic expectations from it in medicine, in the context of current practice (Ref. 38). Keywords: algorithms, artificial intelligence, image recognition, neural networks, predictive analysis.

In recent years, the interstitial cells telocytes, formerly known as interstitial Cajal-like cells, have been described in almost all organs of the human body. Although telocytes were previously thought to be localized predominantly in the organs of the digestive system, as of 2018 they have also been described in the lymphoid tissue, skin, respiratory system, urinary system, meninges and the organs of the male and female genital tracts. Since the time of eminent German pathologist Rudolf Virchow, we have known that many pathological processes originate directly from cellular changes. Even though telocytes are not widely accepted by all scientists as an individual and morphologically and functionally distinct cell population, several articles regarding telocytes have already been published in such prestigious journals as Nature and Annals of the New York Academy of Sciences. The telocyte diversity extends beyond their morphology and functions, as they have a potential role in the etiopathogenesis of different diseases. The most commonly described telocyte-associated diseases (which may be best termed “telocytopathies„ in the future) are summarized in this critical review. It is difficult to imagine that a single cell population could be involved in the pathogenesis of such a wide spectrum of pathological conditions as extragastrointestinal stromal tumors (“telocytomas„), liver fibrosis, preeclampsia during pregnancy, tubal infertility, heart failure and psoriasis. In any case, future functional studies of telocytes in vivo will help to understand the mechanism by which telocytes contribute to tissue homeostasis in health and disease.

A novel approach for stem cell generation is the attempt to induce conversion of the adult somatic cells into pluripotent stem cells so called induced pluripotent stem cells (iPSCs) by introducing specific transcription factors. iPSCs have two essential cell characteristics, they are pluripotent and posses long term cell-renewal capacity. Additionally, iPSCs can be derived from patient-specific somatic cells, thus bypassing ethical and immunological issues. The aim of our study was to reprogram long-term cryopreserved human neonatal fibroblasts by new method using lipid nano-particle technology (Lipofectamine 3000 reagent transfection system) in combination with Epi 5 reprogramming vectors. Obtained iPSCs were characterized by several sophisticated methods of molecular biology and microscopy. Distinct colonies of iPSCs started to appear by day 20 after reprogramming. The presence of iPSCs colonies was proved by alkaline phosphatase (AP) live staining. After manual picking the colonies and their subsequent passaging, they did not lose ability to form embryoid bodies, they were positive for AP, Tra-1-60, and SSEA-5. Moreover, obtained iPSCs expressed pluripotency markers Oct4, Sox2 and Nanog, and the expression levels of chondrogenic, osteogenic and adipogenic markers were significantly higher in comparison to control (p

The lack of effective therapies for different neurodegenerative disorders has placed huge burdens on society. To overcome the restricted capacity of the central nervous system for regeneration, the promising alternative would be to use stem cells for more effective treatment of chronic degenerative and inflammatory neurological conditions and also of acute neuronal damage and from injuries or cerebrovascular diseases. The generation of induced pluripotent stem cells from somatic cells by the ectopic expression of specific transcription factors has provided the regenerative medicine field with a new tool for investigating and treating neurodegenerative diseases, including Alzheimer’s disease (AD). This technology provides an alternative to traditional approaches, such as nuclear transfer and somatic cell fusion using embryonic stem cells. However, due to a problem in standardization of certain reprogramming techniques and systems research, the induced pluripotent stem cell-based technology is still in its infancy. The present paper is aimed at a brief review of the current status in modeling and cell-based therapies for AD.

Unexpected toxicity in areas such as cardiotoxicity, hepatotoxicity, and neurotoxicity is a serious complication of clinical therapy and one of the key causes for failure of promising drug candidates in development. Animal studies have been widely used for toxicology research to provide preclinical security evaluation of various therapeutic agents under development. Species differences in drug penetration of the blood–brain barrier, drug metabolism, and related toxicity contribute to failure of drug trials from animal models to human. The existing system for drug discovery has relied on immortalized cell lines, animal models of human disease, and clinical trials in humans. Moreover, drug candidates that are passed as being safe in the preclinical stage often show toxic effects during the clinical stage. Only around 16% drugs are approved for human use. Research on induced pluripotent stem cells (iPSCs) promises to enhance drug discovery and development by providing simple, reproducible, and economically effective tools for drug toxicity screening under development and, on the other hand, for studying the disease mechanism and pathways. In this review, we provide an overview of basic information about iPSCs, and discuss efforts aimed at the use of iPSC-derived hepatocytes, cardiomyocytes, and neural cells in drug discovery and toxicity testing.

The proliferative activity of tumour cells represents an important prognostic marker in the diagnosis of cancer. One of the methods for assessing the proliferative activity of cells is the immunohistochemical detection of cell cycle-specific antigens. For example, Ki67, proliferating cell nuclear antigen (PCNA), and minichromosome maintenance (MCM) proteins are standard markers of proliferation that are commonly used to assess the growth fraction of a cell population. The function of Ki67, the widely used marker of proliferation, still remains unclear. In contrast, PCNA and MCM proteins have been identified as important participants of DNA replication. All three proteins only manifest their expression during the cell division of normal and neoplastic cells. Since the expression of these proliferative markers was confirmed in several malignant tumours, their prognostic and predictive values have been evaluated to determine their significance in the diagnosis of cancer. This review offers insight into the discovery of the abovementioned proteins, as well as their current molecular and biological importance. In addition, the functions and properties of all three proteins and their use as markers of proliferation in the diagnosis of breast cancer are described. This work also reveals new findings about the role of Ki67 during the mitotic phase of the cell cycle. Finally, information is provided about the advantages and disadvantages of using all three antigens in the diagnosis of cancer.

Somatic stem cells posses an exclusive property of self regeneration and plasticity which makes them promising candidates for use in tissue engineering and regenerative medicine. In the case of stem cell therapy it is crucial to obtain them in sufficient amount. That's why they have to be cultured under in vitro conditions. Long term culture provides adequate number of cells, but on the other hand it is associated with increased risk of spontaneous cell transformation. In this study we analyzed the effect of serial passaging (up to 10th passage) on the morphological and selected biological characteristics of human stem cells isolated from adipose tissue in respect to potential malignant transformation. Obtained results showed that human adipose tissue-derived stem cells maintained their morphological and biological properties during 10 passages and after performing further tests mainly addressed the cytogenetic stability and expression of regulators of cell cycle, senescence and apoptosis, they should be safely used in clinical practice.

We studied the influence of etching time in hydrofluoric acid and methanol solution on the structure and morphology of n-type porous silicon (PSi). Dissolution of Si in the solution of hydrofluoric acid with methanol with surface oxidation occurs. All investigated samples reveal pores with increasing average size proportional to the etching time. Areic density and RMS roughness observed by scanning electron and atomic force microscopies have maximum for 10 min etching time. Additional etching time leads to slight increase in the pore size diameter and decreasing the RMS roughness of layers. All amorphous PSi samples are covered with the SiO2 layer containing probably HySiOx and SiFxHy complexes. The presence of SiH complexes leads probably to the growth of PSi layers with pores. The thickness of this layer depends on etching time and probably contains HySiOx and SiFxOy complexes.

Human Merkel cells (MCs) were first described by Friedrich S. Merkel in 1875 and named “Tastzellen” (touch cells). Merkel cells are primarily localized in the basal layer of the epidermis and concentrated in touch-sensitive areas. In our previous work, we reported on the distribution of MCs in the human esophagus, so therefore we chose other parts of the human body to study them. We selected the human vagina, because it has a similar epithelium as the esophagus and plays very important roles in reproduction and sexual pleasure. Due to the fact that there are very few research studies focusing on the innervation of this region, we decided to investigate the occurrence of MCs in the anterior wall of the vagina. The aim of our research was to identify MCs in the stratified squamous non-keratinized epithelium of the human vagina in 20 patients. For the identification of Merkel cells by light microscopy, we used antibodies against simple-epithelial cytokeratins (especially anti-cytokeratin 20). We also tried to identify them using transmission electron microscopy. Our investigation confirmed that 10 (50 %) of 20 patients had increased number of predominantly intraepithelial CK20 positive “Merkel-like” cells (MLCs) in the human vaginal epithelium. Subepithelial CK20 positive MLCs were observed in only one patient (5%). We tried to identify them also using transmission electron microscopy. Our investigation detected some unique cells that may be MCs. The purpose of vaginal innervation is still unclear. There are no data available concerning the distribution of MCs in the human vagina, so it would be interesting to study the role of MCs in the vaginal epithelium, in the context of innervation and epithelial biology.

The mammary gland is a dynamic organ that undergoes structural and functional changes associated with growth, reproduction, and post-menopausal regression. The postnatal transformations of the epithelium and stromal cells of the mammary gland may contribute to its susceptibility to carcinogenesis. The increased cancer incidence in mammary glands of humans and similarly of rodents in association with their development is believed to be partly explained by proliferative activity together with lesser degree of differentiation, but it is not completely understood how the virgin gland retains its higher susceptibility to carcinogenesis. During its developmental cycle, the mammary gland displays many of the properties associated with breast cancer. An early first full-term pregnancy may have a protective effect. Rodent models are useful for investigating potential breast carcinogens. The purpose of this review is to help recognizing histological appearance of the epithelium and the stroma of the normal mammary gland in rats, and throughout its development in relation to tumorigenic potential.

BACKGROUND Mobile phone application may cause structural, functional changes and accumulation of toxic elements in brain. OBJECTIVES The aim of this study was to investigate iron accumulation in rabbit cerebellum after exposure to RF EMF with light and scanning electron microscopy. MATERIALS AND METHODS Histochemical analysis of iron distribution by light and electron microscopy with energy-dispersive microanalysis was used. RESULTS Light microscopy revealed dystrophic changes of Purkinje cells in irradiated groups and iron deposits located in various parts of cerebellum. Deposits consists of C, O, Na, Mg, Al, Si, P, S, Cl, Ca and Fe. CONCLUSION Our experiment revealed structural changes of Purkinje cells and iron and aluminium accumulations in stratum granulosum of rabbit's cerebellum after exposure to RF EMF (Fig. 6, Ref. 33).

Acellular dermal matrix (ADM) is a tissue graft of allogeneic origin from post-mortem tissue donors prepared by an innovative decellularization process. The newly developed non-toxic and low cost decellularization process of cadaver origin dermis included ADM in breast reconstruction procedures proved to help coverage of the lower-pole of breast expanders or implants. As the results have shown, it did help to eliminate autologous dermis donor site morbidity along with shortening the operation time by avoiding elevation of additional muscle or fascia during the operation. Main aims of this article include histology evaluation of allogeneic acellular dermal matrix prepared by a new decellularization method and presentation of clinical results of its use. A total of 22 patients underwent 26 ADM based breast reconstructions. The mean patient’s follow up was 12.6 months. Average total size of ADM used for one breast was 273 cm2. Post-operative complications occurred in 3 patients including one expander infection, one expander extrusion and one expander pocket disfiguration. Microscopic analysis of tissue samples has confirmed incorporation of the acellular dermal matrices into the surrounding connective tissue without any noticeable immune reaction. In a majority of the ADM samples we found pseudocapsullar formation on implant side of samples without acute or chronic inflammatory cells. The use of ADM prepared by new preparation method in expansive post mastectomy breast reconstruction was associated by a relatively low complication rate resulting in good outcomes.

Hassall's corpuscles are the most prominent structures in the human thymus. However, relatively few analyses have been performed to determine their function and cellular origins during development. In this study, we evaluated the cellular microenvironment of human thymic Hassall's corpuscles using histochemistry, immunohistochemistry, and transmission electron microscopy. We examined 95 human thymic tissue samples, which were perioperatively obtained from children undergoing cardiac surgery. To characterize the complex cellular microenvironment of human thymic corpuscles, we used a panel of 14 different antibodies to identify discrete cell types. We also utilized various histochemical methods (PAS reaction, alcian blue staining, alkaline phosphatase and acid phosphatase activity staining, von Kossa staining of calcified particles) and transmission electron microscopy to visualize these structures. Considerable variation in the sizes, shapes, and numbers of Hassall's corpuscles was observed, even amongst children of the same age. Inside the largest Hassall's corpuscles, cystic dilatation with an accumulation of cellular debris was found. These morphological observations might be associated with disruptions in the formation, migration, or differentiation of cardiac neural crest cells, which are essential for heart and thymus development. Immunohistochemical staining and electron microscopy revealed that Hassall's corpuscles resemble other types of stratified squamous epithelia. Most Hassall's corpuscles are heterocellular, consisting of thymic epithelial cells, macrophages, interdigitating dendritic cells, myoid cells, and, occasionally, mast cells and lymphocytes. To explore the potential functions of Hassall's corpuscles, we found that the concentrations of B-lymphocytes and BCL2-positive lymphocytes suggested a role in regulation of lymphopoiesis. We also found that these structures do not originate from the perivascular epithelium as previously proposed, nor could we identify blood or lymph endothelial cells in close proximity. This leaves the origins of Hassall's corpuscles an open question.

Adipose tissue seems to be a rich and safe source of mesenchymal stem cells (MSCs). The present study was aimed to investigate the biological and morphological characteristics of human adipose tissue-derived stem cells (ATSCs). Light and transmission electron microscopy were used. Course of proliferation was analyzed by growth curve. Expression of surface antigens was assessed by flow cytometry. Chondrogenic potential was assessed by immunohistochemistry. Obtained results showed morphology typical of fibroblastoid cells. TEM analysis proved ultrastructural morphology similar to MSCs from other sources. ATSCs reflected their proteosynthetic and metabolic activity. Each cell had irregular shape of nucleus with noticeable nucleoli. Abundant cisterns of rough endoplasmic reticulum were present in their cytoplasm. Karyotype mapping showed normal count of human chromosomes (46,XX). The growth curve revealed high capability for proliferation and population doubling time was 27.36 hours. ATSCs were positive for CD13, CD29, CD44, CD73, CD90, CD105 and CD106, but did not express CD14, CD34, CD45 and HLA-DR. It was also proved that ATSCs underwent chondrogenic differentiation in vitro. On the basis of obtained results it should be emphasized that ATSCs are typical MSCs and after further investigations they may be used in tissue engineering and regenerative medicine.

The aim of our research was to identify Merkel cells in stratified squamous nonkeratinized epithelium of the human oesophagus. We chose the middle and lower part of the oesophagus. For identification of Merkel cells we used antibodies against simple-epithelial cytokeratines, especially anti CK 20, because it is providing the highest degree of specificity. Our investigation showed increased number of CK 20- positive Merkel cells in lower (distal) part of the oesophagus, approximately 60%. In the middle part of the oesophagus there were 30% of CK20-positive Merkel cells.

The groundbreaking discovery, that somatic mammalian cells can be epigenetically reprogrammed to a pluripotent state through the exogenous expression of the transcription factors Oct4, Sox2, Klf4 and c -myc, has yielded a new cell type for potential applicati on in regenerative medicine, the induced Pluripoten t Stem Cells (iPSCs). Since the first demonstration of cre ating iPSCs in 2006 great efforts have been made in to improving iPS cell generation methods and understanding the reprogramming mechanism as well as the nature of iPSCs. The iPSCs technique makes it possi ble to produce patient-specific pluripotent stem ce lls for transplantation therapy without immune rejectio n. However, some restriction still remain, includin g viral vector integration into the genome, the existence o f exogenous oncogenic factors and low induction efficiency. In this review we discuss recent advanc es in methods of generating safer iPSCs lines and t heir possible use for biomedical applications.

Skeletal muscle contains at least two distinct populations of adult stem cells — satellite cells and multipotent muscle-derived stem cells. Monopotential satellite cells are located under the basal lamina of muscle fibers. They are capable of giving rise only to cells of myogenic lineage, which play an important role in the processes of muscle regeneration. Multipotent muscle-derived stem cells are considered to be predecessors of the satellite cells. Under proper conditions, both in vitro and in vivo, they undergo myogenic, cardiogenic, chondrogenic, osteogenic and adipogenic differentiation. The main purpose of the present article is to summarize current information about adult stem cells derived from skeletal muscle, and to discuss their isolation and in vitro expansion techniques, biological properties, as well as their potential for regenerative medicine.

Malignant cancers of urinary bladder are the second most common malignancy of the urinary tract and the fourth most common malignancy in general, especially in men. The aim of this study was a retrospective analysis of selected markers (p53, Ki -67 and E-cadherin) of urinary bladder cancers from the Department of Urology in Bratislava, Slovak Rep ublic between years 2007 and 2009. We analysed 244 patients (202 males, 42 females) with diagnosed bladder cancer via cystoscopy and subsequent transurethral resection. Patients’ age varied from 36 to 98 years. Obtained samples were fixed by 10% buffered formalin for 24 to 48 h. Subsequently, the y were dehydrated in ascending ethanol series and embedded in paraffin. The parafin sections of 5 µ m were prepared by microtome and they were stained by haematoxylin and eosin. The antibodies against t o p53, Ki-67 and E-cadherin were used in immunohistochemical analysis. Statistical evaluatio n was performed via SPSS using non-parametric Kruskal-Wallis test and p values