Morphological Features of the Ascending Aorta Remodeling and Activation of Regeneratory Potential in Intima when Forming Aneurysm.

In patients with an ascending aorta aneurysm, restructuring of all its layers and, first of all, the intima and media was revealed. The thickness of the intima was 79.3±63.1 µm in patients with aortic diameter <55 mm (group Ao<55) and 162.7±177.4 µm (p<0.05) in patients with aortic diameter ⩾55 mm (Ao⩾55 group), the thickness of the aortic media was 1184.0±198.2 and 1144.3±288.4 µm, respectively. In patients of the Ao<55 group, aortic dilatation was accompanied by compensatory thickening of the inner and middle layers of the aorta. In the Ao⩾55 group, thinning of the aortic media, fragmentation of elastic fibers, and its cystic degeneration were revealed. c-kit+ Stem cells were detected in the subendothelium of the thickened intima of the dilated ascending aorta. The appearance of c-kit+ cells correlated with intimal remodeling and its colonization with CD34+ and CD44+ myofibroblast-like cells.

Telocytes in the Myocardium of Children with Congenital Heart Disease Tetralogy of Fallot.

Telocytes, a new type of interstitial stem cells with long thin processes that form a three-dimensional network around cardiomyocytes, vessels, and nerve fibers were described in the myocardium of children with tetralogy of Fallot. Two types of morphologically different telocytes, spindle-shaped and rounded, were identified. Contacts of telocytes with stem cells and interstitial macrophages were found. Telocytes were more common in the immature myocardium, where the assembly of myofibrils in cardiomyocytes was not completed and small Ki-67+ cardiomyocyte progenitor cells were present. Telocytes expressed immunohistochemical markers CD117, vimentin, CD34, and CD44. Localization and ultrastructural characteristics of telocytes suggested their participation in stem cell differentiation, coordination of neoangiogenesis, and paracrine regulation of all components of the interstitium.

[Ultrastructural features of cardiomyocytes in infants with tetralogy of Fallot in the first year of life]. / Osobennosti ul'trastruktury kardiomiotsitov u detei pervykh let zhizni s tetradoi Fallo.

OBJECTIVE: To analyze cardiomyocyte (CMC) ultrastructural changes in the right ventricle outflow tract (RVOT) of infants with tetralogy of Fallot (TF) in the first years of life and to compare the findings with clinical parameters in these patients. MATERIAL AND METHODS: Intraoperative RVOT myocardial biopsy specimens obtained from 51 patients aged 3-33 months with TF during radical correction of defect were investigated. CMC diameter and length were measured using the semithin myocardial sections stained with periodic acid-Schiff. The ultrathin sections were examined in the electron microscope. RESULTS: The diameter of CMCs in the RVOT of infants with TF varied significantly (7.3-17.0 µm) and averaged 10.8±2.2 µm; a large number of multinucleated CMCs were observed. There were ultrastructural signs of incomplete differentiation of CMCs: active myofibril assembly in the free sarcoplasmic region; gap junctions on the lateral surfaces of CMCs; and centrioli in their sarcoplasm. Myofibrillogenesis in babies under 6 months increased in response to hemodynamic overload and hypoxemia. In addition, organelles suggestive of the synthetic activity of CMCs, such as cisterns and vesicles of the Golgi complex and granular endoplasmic reticulum, were detected in the sarcoplasm of a number of CMCs. TF infants' myocardium also displayed focal disorders of CMC interposition; the change in the shape of myocytes was accompanied by the appearance of additional lateral insert discs. Some CMCs showed the abnormal localization of the nucleus beneath the sarcolemma, sarcoplasmic bulging areas, and dystrophic changes. CONCLUSION: There were ultrastructural features characteristic for the myocardium that was at the state of active growth and differentiation (increases in the diameter and length of CMCs and in the number of nuclei; myofibrillogenesis; signs of synthetic and proliferative activity along with insignificant dystrophic changes) in the CMCs of myocardial RVOT in infants with TF in the first years of life.

[Morphological features of the myocardium of the atrial appendages in patients with different forms of atrial fibrillation]. / Morfologicheskie osobennosti miokarda ushek predserdii u patsientov s raznymi formami fibrilliatsii predserdii.

AIM: to analyze the morphological features of the myocardium of the atrial appendages in patients with different forms of atrial fibrillation (AF) and to compare the findings with the clinical parameters of patients. MATERIAL AND METHODS: Light and electron microscopies were used to examine the myocardium of the atrial appendages in adult patients with paroxysmal (PAF), persistent (PrAF), or long-standing persistent atrial fibrillation (LPAF) and in comparison group patients with sinus rhythm without history of AF. A morphometric method was employed to evaluate myocardial fibrosis and to measure the diameter of cardiomyocytes (CMCs); the degree of lipomatosis and amyloidosis was semiquantitatively determined; and the content of CMC myofibrils was estimated. Atrial natriuretic peptide content in the myocytes was measured by immunoconfocal microscopy. RESULTS: In all groups, the patients with AF were found to have signs of atrial structural remodeling: fibrosis, lipomatosis, isolated atrial amyloidosis, CMC hypertrophy with the phenomena of a partial loss of myofibrils without significant differences between these parameters in different groups. In PAF patients, atrial remodeling was accompanied by hypertrophy of a number of CMCs with their higher myofibrilar mass; the increased CMC size in the left atrial appendage prevented left atrial enlargement; the degree of amyloidosis negatively correlated with the CMC myofibrillar loss that was recorded in the minor CMCs; the degree of CMC myolysis positively correlated with mitral valve insufficiency and left atrial enlargement. In contrast to the clinical and morphological changes that are typical of PAF, in LPAF the increase in CMC sizes was positively correlated with left atrial enlargement and mitral annular dilatation; while the myofibrillar loss phenomenon was noted in the most hypertrophied CMCs; the degree of amyloidosis was positively correlated with CMC myofibrillar loss. In the patients with PrAF, the size of CMCs did not correlate with their myofibril content. CONCLUSION: The patients with PAF were ascertained to have opposite changes in the ratio of CMC hypertrophy to left atrial enlargement, amyloidosis, and CMC myofibrillar loss, hypertrophy of CMCs and their myofibril content in comparison with these indicators in LPAF.

[Morphological Features of Mesenhymal Stroma Cells of Chorionic Villi].

Background: Nowadays autologous mesenchymal placental stromal cells (MSCs) may use to treat for various diseases both of the mother and the child. Stroma of the placenta villi is appropriated origin for cell culture isolation. Aim: of the study was to evaluate the possibility for selection and use of placental tissue for mesenchymal stromal cells. Materials and methods: The present study was based on 45 placental samples of women aged 27−38 yy. who underwent surgical delivery at 36−40 weeks of gestation. 30 of these women have been enrolled in the basic group including children with congenital abnormalities (CA). The comparison group consisted of 15 patients with physiological pregnancy. We performed histological examination (with hematoxylin and eosin staining), immunohistochemical examination (with use monoclonal antibodies CD90 (1:25; Abcam, UK), СD105 (1:500; Abcam, UK), CD44 (1:25; Dako), СD73 (1:200, Abcam, UK), and electron microscopy (by microscope Philips/FEI Corporation, Eindhoven, Holland). Eclipse 80i microscope (Nikon Corporation, Japan) was used to examine the immunohistochemical reactions as a brown staining. The evaluation of the intensity of reaction was conducted by NIS-Elements Advanced Research 3.2 program (Czech Republic). Student's t-test and analysis of variance were used to compare the mean values. Differences were considered statistically significant at p<0.05. Results: Interstitial cells of the stroma of the villi with CA had fibroblastic differentiation as revealed degenerative changes of the cells. The histologic examination with hematoxylin and eosin staining revealed significant fibrosis of the stroma of the placenta villi in CA group (p<0,01). Immunohistochemical study of stem and intermediate chorionic villi revealed no significant differences in staining of CD44+, СD90+, СD73+, and CD105+ cells if compared to the control group (p>0.05). Although CD105 expression was significantly lower in the CA group (0.058±0.0049) than in the control group (0.088±0.0039) (p<0.05). However, electron microscopy detected the villi interstitial stromal cells with fibroblastic differentiation in CA group. Conclusions: Thus, it is necessary to exclude placenta with obstetrical history, somatic, and congenital pathology of the mother and the child when selecting the placental cell culture. Moreover, choosing a sample the morphological structure of the placenta should be taken into consideration. However, congenital malformations of the fetus, pathology of the mother cultivate mesenchymal stromal cells of placentas is inappropriate and should be taken advantage of the donor cells.

Isolated Atrial Amyloidosis in Patients with Various Types of Atrial Fibrillation.

The myocardium of the right and left atrial appendages (auricles) in patients with paroxysmal, persistent, and permanent forms of atrial fibrillation was examined by histological methods and electron microscopy. Isolated atrial amyloidosis was detected in the left (50.0-56.3% patients) and in the right (45.0-55.6% patients) atrial appendages. In all cases, immunohistochemistry revealed atrial natriuretic peptide in fibrillary amyloid deposits. Ultrastructurally, amyloid masses formed clusters of myofibrils 8-10 nm in diameter. They were chaotically located in the extracellular space along the sarcolemma as well as in membrane invaginations, dilated tubules of cardiomyocyte T-tubular system, and vascular walls. Amyloidosis was predominantly observed in women; its degree positively correlated with age of patients and duration of atrial fibrillation but negatively correlated with atrial fibrosis. The study revealed positive (in permanent atrial fibrillation) and negative (in paroxysmal atrial fibrillation) correlation of amyloidosis with myofibril content in atrial cardiomyocytes.

Age-Related Features of Cardiomyocyte Ploidy in Patients with Hypertrophic Obstructive Cardiomyopathy.

Endomyocardial biopsy samples of the interventricular septum from patients with hypertrophic cardiomyopathy isolated during myectomy were examined. We revealed significant variability of cardiomyocyte ploidy (from 2.9c to 13.5c) that directly correlated with myocyte size; the maximum ploidy was found in young patients. Ultrastructural signs of increased contractile and synthetic activity of cells were observed in patients with high DNA content in cardiomyocytes.

Resident stem cells in the myocardium of patients with obstructive hypertrophic cardiomyopathy.

Interventricular septum myocardium was studied in 40 patients with obstructive hypertrophic cardiomyopathy. Immunohistochemical assay revealed c-kit-positive resident cardiac stem cells in 82.5% patients. The content of the connective tissue and myofibrillar disarray zones and the degree of cardiomyocyte hypertrophy and myolysis were determined. In 30% cases, cardiomyocytes containing atrial natriuretic peptide were detected in the interventricular septum myocardium. The data were compared with clinical and functional parameters of patients. It was found that cardiac stem cells are present in patients, whose myocardium was characterized by increased density of the connective tissue, hypertrophy of mature cardiomyocytes, medium degree of myolysis in them, and accumulation of natriuretic peptide, a cardiac failure marker, in cardiomyocytes.

Resident cardiomyocyte precursor stem cells in the myocardium of infants of the first two years of life with tetralogy of Fallot.

We studied the content of resident myocardial stem cells, cardiomyocyte precursors, in myocardial biopsy specimens from the right ventricular outflow tract of patients of the first two years of life with tetralogy of Fallot. Myocardial resident stem cells were detected by the method of confocal immunohistochemistry using antibodies to c-kit and sarcomeric α-actin. The diameter of right ventricular cardiomyocytes was measured; the presence of myolysis zones was semiquantitatively evaluated. Electron microscopic analysis of right ventricular cardiomyocytes was performed. The data on the content of resident myocardial stem cells were compared with clinical and functional parameters of the patients and morphological peculiarities of the myocardium. C-kit-positive resident myocardial stem cells were detected in the right ventricle of 17.4% patients with tetralogy of Fallot. The content of resident myocardial stem cells in these patients varied from 4 to 45 (median 11) per 1 mln cardiomyocytes; this parameter was higher in patients with high content of small cardiomyocytes (diameter <10 µ) and cardiomyocytes with incomplete myofibril assembly in the right ventricular myocardium.

Destructive effect of DNA topoisomerase II inhibitor vepesid on mouse spermatogenesis.

Inhibition of DNA topoisomerase II with vepesid induced structural and functional reorganization of chromatin in meiotically dividing spermatocytes I, which later led to the block of their differentiation and long-lasting disorders in spermatogenesis. Vepesid induced decondensation of spermatocyte I chromatin, block of desynapsis, and elongation of lateral elements of spermatocyte autosome synaptonemal complexes during late pachytene and diplotene of meiosis. This confirms the involvement of type II DNA topoisomerase in chromatin condensation and homologous chromosome desynapsis at the stage of diplotene and the role of this enzyme in structural organization of the synaptonemal complex. Vepesid induced the formation of dichotomy and breaks of the pericentromer regions of subelements of lateral elements of the autosomal synaptonemal complexes; the number of cells with associations of axial elements of sex chromosomes with autosomal synaptonemal complexes increased, univalents of autosomes and sex chromosomes appeared. Mesna, a modifier of toxic effects of antitumor drugs, had no toxic effect on spermatogenic cells. Mesna reduced the lethal effect of vepesid during combined treatment, but did not ensure long-term protection of spermatogenesis.

Damaging effect of taxol on mouse spermatogenesis.

Taxol produced a specific effect on mouse spermatocytes I and on stem spermatogonia, which leads to overall degeneration of spermatocytes I and long lasting disorders of spermatogenesis. Breaks of the axial and lateral elements of the synaptonemal complex, aneuploidies in spermatocytes in early, middle, and late pachytene, and accumulation of cells with associations of sex chromosomes and autosomes were observed, which attested to blockade of spermatogenesis in late pachytene and diplotene of meiosis prophase I. Mesna, a chemoprotective agent, reduced total toxicity and lethal effects of taxol, but did not prevent destruction of the testes.