[Effect of bone marrow cells transplantation on the decidua formation in pseudopregnant rats].

One of the most common causes of the current pregnancy loss is the failure of the decidual reaction of endometrial cells. It is assumed that a partial source of decidual cells in endometrial tissue is bone marrow cells (BMCs). In the present work, we have studied possible effect of BMCs transplantation on the process of decidualization using the model of pseudopregnancy in rats. BMCs were flushed from the rat femurs and tibias. The obtained suspension of single BMCs was injected into one of rat uterine horns on the 5th day of pseudopregnancy. PBS without cells was injected into the contralateral horn served as the control. Rats were sacrificed on the 11th day of pseudopregnancy. Decidua formed in the experimental uterine horn showed an increase in the meso-antimezometral direction of their diameter of about 1.5-2 times as compared with a control horn. The weight of decidual tissue in the experimental horn exceeded 3 times the weight of the control one. The presence of transplanted BMCs in decidual tissue was documented by preliminary double staining of BMCs with membrane dye PKH 26 Red and nuclear dye Hoechst 33342. Histological analysis of decidua sections after transplantation revealed any alterations neither in cell differentiation nor in tissue structure. We conclude that BMCs transplantation stimulates decidualization in animals.

[BDNF secretion in human mesenchymal stem cells isolated from bone marrow, endometrium and adipose tissue].

The ability of mesenchymal stem cells (MSCs) to differentiate into neuronal lineage determines the potential of these cells as a substrate for a cell replacement therapy. In this paper we compare the neurogenic potential of MSCs isolated from bone marrow (BMSC), subcutaneous adipose tissue (AD MSC) and menstrual blood (eMSC). It was found that the native eMCSs, BMSCs and AD MSCs express neuronal marker ß-III-tubulin with a frequency of 90, 50 and 14%, respectively. We also showned that eMSCs have a high endogenous level of brain-derived neurotrophic factor (BDNF), whereas the BMSCs and the AD MSCs are characterized by low basal BDNF levels. As induction of neuronal differentiation in the studied MSCs using differentiation medium containing B27 and N2 supplements, 5-azacytidine, retinoic acid, IBMX and dbcAMF caused changes in the cells morphology, the increased expression of ß-III-tubulin, and the appearance of neuronal markers GFAP, NF-H, NeuN and MAP2. BDNF secretion during differentiation was significantly enhanced in the BMSCs and decreased in the eMSCs cultures. However, no correlation between the basal and induced levels of the neuronal markers expression and BDNF secretion in the studied MSCs has been established.

[Menstrual blood stem cells as a potential substrate of cell therapy].

Cell replacement and restorative therapies have great perspectives in the treatment of various diseases and traumas. Various types of stem cells, most different in the biological properties, are evaluated as the potential substrates of cell therapy for such diseases. Mesenchymal stem cells (MSC) posses relatively high proliferative activity and high level of plasticity, and can be differentiated not only to the cells of the mesenchymal lineage, but also to the neurons. Among the MSC populations, a population of endometrial stem cells, including that present in the menstrual blood, is available most readily. In the current study, we analyze biological properties of the menstrual blood stem cells and evaluate those cells as a potential substrate of cell therapy.

[Mesenchymal stem cells of human endometrium do not undergo spontaneous transformation during long-term cultivation].

Mesenchymal stem cells isolated from human endometrium (eMSC) are perspective source of stem cells for regenerative medicine. Large amount of these cells accumulated by in vitro cultivation is usually required for transplantation into patients. We established several cell eMSC lines and cultivated them during long period of time to examine the possibility of their spontaneous transformation. All cell lines demonstrate limited lifespan, undergo replicative senescence and die. Karyotypic analysis on different passages reveals that most cells display karyotypic stability. Thus, extended in vitro cultivation of eMSCs does not lead to spontaneous transformation that makes therapeutic application of these cells safety for patients. During long-term cultivation eMSCs sustain the expression of surface markers.

[Neurogenic potential of human mesenchymal stem cells isolated from bone marrow, adipose tissue and endometrium: a comparative study].

Mesenchymal stem cells (MSCs) can be isolated from many adult tissue sources. These cells are a valuable substrate in cell therapy for many diseases and injuries. Different types of MSCs vary in plasticity. We performed a comparative study of the neurogenic potential of three types of human MSCs derived from bone marrow (BMSCs), subcutaneous adipose tissue (ADSCs) and endometrium (isolated from the menstrual blood) (eMSCs). It was shown that all three types of MSC cultures demonstrate multipotent plasticity and predisposition to neurogenesis, based on the expression of pluripotency markers SSEA-4 and neuronal precursors' markers nestin and beta-III-tubulin. Further analysis revealed the transcription of the neuronal marker MAP2 and neurotrophin-3 in undifferentiated BMSCs and ADSCs. Additionally, a significant basal level of synthesis of brain-derived neurotrophic factor (BDNF) in eMSC culture was also observed. Stimulation of neural induction with such agents as 5-azacytidine, recombinant human basic fibroblast growth factor (bFGF), recombinant human epidermal growth factor (EGF), a recombinant human fibroblast growth factor 8 (FGF8), morphogen SHH (sonic hedgehog), retinoic acid (RA) and isobutyl-methyl-xanthine (IBMX), showed further differences in the neurogenic potential of the MSCs. The components of the extracellular matrix, such as Matrigel and laminin, were also the important inducers of differentiation. The most effective neural induction in BMSCs proceeded without the RA participation while the cells pretreated with 5-azacytidine. In contrary, in the case of eMSCs RA was a necessary agent of neural differentiation as it stimulated the transcription of neurotrophin-4 and the elevation of secretion level of BDNF. The use of laminin as the substrate in eMSCs appeared to be critical, though an incubation of the cells with 5-azacytidine was optional. As far as ADSCs, RA in combination with 5-azacytidine caused the elevation of expression of MAP2, but reduced the secretion of BDNF. Thus, the effect of RA on neural differentiation of ADSCs in ambiguous and, together with the study of its signaling pathways in the MSCs, requires further research. The therapeutic effect of transplanted MSCs is commonly explained by their paracrine activity. The high basal level of BDNF synthesis in the eMSCs, along with their high proliferative rate, non-invasive extraction and neural predisposition, is a powerful argument for the use of the intact eMSCs as a substrate in cell therapy to repair nerve tissue.

[ATM/ATR signaling pathway activation in human embryonic stem cells after DNA damage].

Embryonic stem cells (ESCs) are the progenitors of all adult cells so any disruption in their genome can have disastrous consequences for the developing organism. ESCs are characterized by a high proliferation activity and do not undergo checkpoints upon DNA-damage executing only G2/M delay after DNA damage. ATM and ATR kinase are key sensors of DNA double strands breaks and activate downstream signaling pathways involving checkpoints, DNA repair and apoptosis. We estimated ATM/ATR signaling pathway activation in human ESCs and have revealed that irradiation induced ATM, ATR Chk2 phosphorylation, γH2AX foci formation and their co-localization with 53BP1 and Rad51 proteins. Interestingly, human ESCs display non-induced yH2AX foci co-localized with Rad51 and marking DNA single-strand breaks. Next we have revealed the substantial contribution of ATM, Chk1 and Chk2 kinases to G2/M block after irradiation of human ESCs and ATM-dependent activation (phosphorylation) of p53. However p53 activation and subsequent induction of p21 gene expression after DNA damage do not result in p21 protein accumulation due to proteasomal degradation.

[Differences in defense mechanisms against oxidative stress in both human embryonic and endometrium-derived mesenchymal stem cells].

Oxidative stress has been shown to induce either apoptosis or stress-induced premature senescence (SIPS) in different cell types. At present, it is generally accepted that stem cells have high resistance to oxidative stress; however data reported by various authors are controversial. In this study, we investigated stress responses of human embryonic stem cells (hESC) and human mesenchymal stem cells (hMESC) derived from desquamated endometrium to hydrogen peroxide (H2O2). Cell viability was evaluated by MTT assay. LD50 were determined as 300-350, 350-400 and 600-700 µM for hESC, human embryonic fibroblasts and hMESC, respectively. Thus, among the cell lines studied, hMESC demonstrated the most resistance to increased H2O2 concentration. We have found for the first time that sub-lethal doses of H2O2 induce premature senescence phenotype in hMESC, like in HEF, which is characterized by increased expression of cyclin-dependent kinase inhibitor p21(Waf1/Cip1), an irreversible cell cycle arrest, the permanent loss of proliferative potential, cell hypertrophy and SA-ß-Gal staining. While a sub-lethal H2O2 dose (200 µM) promoted in hMESC only SIPS, the higher H2O2 doses induced also apoptosis in the part of the cell population. On the contrary, in hESC, H2O2 regardless of the doses tested (from 50 to 500 µM) triggered apoptosis, that was the only pronounced response of these cells to oxidative damage. The data obtained demonstrate that stem cells of various origins under oxidative stress utilize the different defense mechanisms: hESC rapidly eliminate damaged cells through apoptosis, whereas hMESC may enter SIPS.

[Comparison of human endometrial stem cells and fibroblasts resistance to oxidative stress].

The response of human endometrial stem cells (hESCs) to oxidative stress has been investigated by flow cytometry. Two terminally differentiated cell lines were used for the comparison: human embryonic lung fibroblasts and human dermal fibroblasts. The oxidative stress was designed by hydrogen peroxide (H2O2) action in the wide range of concentrations (50-1500 microM) during 24 h. It has been shown that the H2O2 amount per one cell (pM/cell), but not H2O2 concentration in the growth medium, should be taken into account for the accurate evaluation of H2O2 effect on different cell lines. Therefore, in our experiments LD50 reflects the amount of H2O2 per cell, at which 50% cells survived after 24 h. We have demonstrated that hESCs are more resistant to H2O2 than embryonic lung fibroblasts, but less resistant than dermal fibroblasts.

[Examination of cytotoxic effect of anti-cancer drug doxorubicin on human embryonic stem cells].

Cytotoxic effect of anti-cancer drug, doxorubicin (DR), has been examined on human embryonic stem cells (ESC) C910 and fibroblasts spontaneously differentiated from these cells. The fibroblasts retained diploid karyotype. It was found that ESC are more sensitive to DR than fibroblasts: DR dose killing 20% cells was 0.01 and 0.1 microg/ml, respectively. DR induced ESC apoptotic death and reduced both ESC and fibroblast proliferation. Unlike fibroblasts DR reversibly inhibited ESC proliferation. Thus, we have demonstrated that ESC and their differentiated derivates differ their sensitivity and response to the genotoxic agent.

[Multipotent mesenchymal stem cells of desquamated endometrium: isolation, characterization and use as feeder layer for maintenance of human embryonic stem cell lines].

In this study, we characterize new multipotent human mesenchymal stem cell (MSC) lines derived from desquamated (shedding) endometrium in menstrual blood. The isolated endometrial MSC (eMSC) is an adhesive to plastic heterogeneous population composed mainly of endometrial glandular and stromal cells. The established cell lines meet the criteria of the International Society for Cellular Therapy for defining multipotent human MSC of any origin. The eMSCs have positive expression of CD73, CD90, CD105, CD13, CD29, CD44 markers and the absence of expression of the hematopoietic cell surface antigens CD19, CD34, CD45, CD117, CD130 and HLA-DR (class II). Multipotency of the established eMSC is confirmed by their ability to differentiate into other mesodermal cell types such as osteocytes and adipocytes. Besides, the isolated eMSC lines partially (over 50%) express the pluripotency marker SSEA-4, but do not express Oct-4. Immunofluorescent analysis of the derived cells revealed the expression of the neural precursor markers nestin and beta-III-tubulin. This suggests a neural predisposition of the established eMSC. These cells are characterized by high rate of cell proliferation (doubling time 22-23 h) and high cloning efficiency (about 60%). In vitro the eMSCs undergo more than 45 population doublings revealing normal karyotype without karyotipic abnormalilies. We demonstrate, that the mititotically inactivated eMSCs are perfect feeder cells for human embryonic stem cell lines (hESC) C612 and C910. The eMSC being a feeder culture maintain the pluripotent status of the hESC, which is revealed by the expression of Oct-4, alkaline phosphatase and SSEA-4. When co-culturing, hESC retain their morphology, proliferative rate for more than 40 passages and capability for spontaneous differentiation into embryoid bodies comprising the three embryonic germ layers. Thus, an easy and non-invasive extraction of the eMSC in menstrual blood, their multipotency and high proliferative activity in vitro without karyotypic abnormalities demonstrate the potential of use of these stem cells in regenerative medicine. Using the derived eMSCs as the feeder culture eliminates the risks associated with animal cells while transferring hESC to clinical setting.

[Metalloprotease-mediated HB-EGF release regulates EGF receptor transactivation in A431 cells under oxidative stress].

We have shown earlier that H2O2 induces EGF receptor transactivation in different cells overexpressing EGF receptor. Mechanism of H2O2-induced EGF receptor transactivation in A431 human epidermoid carcinoma cells was examined in this work. We have demonstrated autophosphorylation of Tyr1045, 1068, 1148, 1173 as well as phosphorylation of Tyr845 of EGF receptor in response to H2O2, as assessed by autophosphorylation specific antibody. Tyrosine phosphorylation of EGF receptor by H2O2 did not involve receptor autophosphorylation at Tyr992. Blocking functions of metalloproteases by broad-spectrum inhibitor GM6001 suppressed H2O2-induced phosphorylation of EGF receptor, suggesting dependence of the transactivation on metalloproteases activity. To elucidate the possible role of EGF receptor agonists in its activation we used HB-EGF and TGF-alpha neutralizing antibody. H2O2-induced EGF receptor phosphorylation was inhibited by HB-EGF, but not TGF-alpha, neutralizing antibody. Taken together, our data suggest that, in human epidermoid carcinoma A431 cells, H2O2 stimulates EGF receptor transactivation via metalloprotease-dependent HB-EGF release and autophosphorylation.

[Characteristic of tumors developed after transplantation of transgenic GFP-positive C57BL/6 mice bone-marrow mesenchymal stem cells to mdx mice muscle].

The purpose of the study was the morphological and histochemical characteristics of differentiation of tumors developed after transplantation of GFP-positive mesenchymal bone-marrow stem cells (MSC) of transgenic mice C57BL/6 into M. quadriceps femoris of mdx mice. The tumors occurred only after transplantation of MSCs of 43-45th passages and did not arise after transplantation of MSCs of the 15th passage. No tumors developed also after transplantation of MSCs of 43-45th passages into muscle of C57BL/6 mice. The average weight of tumors appeared in 4 mdx mice studied was 1.3 +/- 0.5 g. All four tumors were classified as mesenchymomas because they originated from mesenchymal stem cells. Most of the periphery of the tumors was classified as fibrosarcomas with mitotic index 0.9 +/- 0.1%. The central parts of tumors had areas with epithelial like morphology of cells. Such cells showed positive reactivity for alcyan blue staining at pH 2.5, which indicated chondrocyte nature of the cells. No mitosis was observed in epithelial like cells. In the tumors, there were also areas with bone trabeculae containing megacaryocytes and foci of myeloid and erythrocyte hematopoiesis. There were also areas with neuronal and glial cells, and accumulations of adipocytes. One of the tumors was classified as a round cells sarcoma. The observed types of tumor cell differentiation in vivo were in accordance with described in literature types of MSCs differentiation after induction in vitro with special inductors. The spectrum of in vivo differentiation of transgenic GFP-positive MSCs after transplantation to mdx mice was broader than the spectrum of in vivo differentiation of transfected or transformed in vitro adult MSCs after transplantation to immunodeficient mice and mdx mice.

[Generation of dopamine neurons from human embryonic stem cells in vitro].

The aim of the study was to generate dopaminergic (DA) neurons from human embryonic stem cells (ESC) in vitro. It was shown that human ESCs are able to differentiated into DA neurons without co-culture with stromal cells. Terminal differentiation into DA neurons was reached by successive application of noggin and bFGF growth factors on collagen and matrigel substrates during 3-4 weeks. Differentiation efficiency was evaluated by the number of colonies with cells expressing tyrosine hydroxylase (TH), a DA neuron marker, and by the number of TH-positive cells in cell suspension using flow cytometry. No cells with pluripotent markers were detected in DA-differentiated cultures. It makes possible to propose that the protocol of human ESC differentiation might be applied to generate DA neurons for their transplantation into the animals modeling neurodegenerative (Parkinson) disease without the risk of tumor growth.

[Interferon gamma-mediated growth regulation of epithelial cells].

Interferon gamma (IFNgamma) is known to inhibit proliferation of certain transformed cell lines. Recently, we have demonstrated the transactivation of the epidermal growth factor receptor (EGFR) in response to IFNgamma (Burova et al., 2007) and provided direct evidence for the dependence of IFNgamma-induced EGFR transactivation upon EGFR expression level in epithelial cells (Gonchar et al., 2008). This study examines an antiproliferative effect of IFNgamma on human epithelial cells lines A431 and HeLa which express high levels of EGFR, as well as HEK293, which expresses low levels of EGFR. We characterized the IFNgamma-induced changes in these cells by studying cell growth, the cell cycle and induction of apoptosis. The response to IFNgamma differed in the tested cell lines: cell growth was inhibited in both A431 and HeLa cells, but not in HEK293 cells, as shown by cell counts and MTT. The cell cycle phases analyzed by flow cytometry were disturbed in A431 and HeLa cells in response to IFNgamma. In contrast, IFNgamma treatment did not alter distribution by cell cycle phases in HEK293. Our results indicate that IFNgamma exhibit an antiproliferative effect depending on the increased expression of EGFR in A431 and HeLa cells. Further, it was demonstrated that IFNgamma induced the caspase 3 activation in A431 cells, suggesting an involvement of active caspase 3 in IFNgamma-induced apoptosis.

[Novel human embryonic stem cell lines C612 and C910].

Novel human embryonal stem cell lines C612 and C910 have been established from hatching blastocytes. Cells were cultivated in mTeST medium on mouse fibroblast feeder-layers. They express common pluripotent markers such as alkaline phosphatase, Oct 3/4, SEEA-4, Nanog, Rex1. Immunophenotyping of these cells by flow cytometry revealed expression of CD90 (Thy-1) and CD117 (c-kit) antigens and weak or no expression of CD13, CD34, CD45, CD130, HLA class I and HLA class II antigens. This pattern of surface antigen expression is common for human embryonic stem cells. G-banding assay of C612 and C910 metaphase plates showed that karyotypic structure of these cells was normal both in chromosome number and structure. The cells are pluripotent because of their capability to generate embryoid bodies, undergo spontaneous differentiation and express markers of all germ layers: nestin, keratin, vimentin (ectoderm), alpha-fetoprotein (entoderm), and muscle alpha-actinin (mesoderm). Thus, C612 and C910 cells have all attributes of typical human embryonic stem cells (diploid, capable of self-renewal, express pluripotent markers and differentiate into three germ layers) and may be of potential use for fundamental and regenerative medicine researches.

[The level of EGF receptor expression effects its transactivation by IFN gamma in epithelial cells].

Earlier, we demonstrated transactivation of the epidermal growth factor receptor (EGFR) in response to interferon gamma (IFNgamma) in epidermal carcinoma A431 cells. It was shown that IFNgamma-induced EGFR transactivation is impossible in some cancer epithelial cells. Here, we hypothesize that IFNgamma-dependent EGFR transactivation in these cells correlates with EGFR quantity on the cell surface. To test this suggestion, a line of stably transfected HEK293 cells (HEK293delta99 cells) expressing high level of mutant EGFR lacking 99 C-terminal residues has been established. HEK293delta99 cells demonstrated EGFR transactivation in response to IFNgamma unlike the parent HEK293 cells, in which transactivation lacked. In HEK293delta99 and A431 cells, the time courses of EGFR activation induced by IFNgamma have the same pattern. In HEK293delta99 cells like A431, IFNgamma-induced EGFR transactivation requires EGFR kinase activity and occurs via autophosphorylation mechanism. Taken together, these data provide direct evidence of the dependence of IFNgamma-induced EGFR transactivation upon EGFR expression level in epithelial cells.

[Human embryonic stem cells. Problems and perspectives].

Establishment of human embryonic stem cell lines is one the major achievements in the biological science in the XX century and has excited a wide scientific and social response as embryonic stem cells can be regarded in future as unlimited source of transplantation materials for the replacement cell therapy. To date human embryonic cell lines are obtained in more than 20 countries. In our country the embryonic stem cell researches are carried out in the Institute of Cytology RAS and the Institute of Gene Biology RAS. ESC lines are derived from placed in culture inner cell mass of human preimplantation blastocysts used in the in vitro fertilization procedure. Studies with human ESC go in several directions. Much attention is paid to the elaboration of the optimal conditions for ESC cultivation, mainly to the development of cultivation methods excluding animal feeder cells and other components of animal origin. Another direction is a scale analysis of gene expression specific for the embryonic state of the cells and corresponding signaling pathways. Many efforts are concentrated to find conditions for the directed differentiation of ESC into different tissue-specific cells. It has been shown that ESC are able to differentiate in vitro practically into any somatic cells. Some works are initiated to develop methods for the "therapeutic cloning", that is transfer and reactivation of somatic nuclei into enucleated oocytes or embryonic stem cell cytoblasts. Of great importance is human ESC line standardization. However, the standard requirements for the cells projected for research or therapeutic purposes may be different. It has been found that many permanent human ESC lines undergo genetic and epigenetic changes and, therefore, the cell line genetic stability should be periodically verified. The main aim of the review presented is a detailed consideration of the works analyzing the genetic stability of human and mouse ESC lines. Human ESC lines established in our and as well as in other countries couldn't be used so far in clinical practice. It is highly probable that undifferentiated ESC cannot be applied for therapeutic purposes because of the risk of their malignant transformation. Therefore, main efforts should be focused on the production of progenitor and highly differentiated cells suitable for transplantation derived from ESC.

[Assembly of correct kinetochore architecture in Xenopus laevis egg extract requires transition of sperm DNA through interphase].

Xenopus egg extracts provide a powerful tool for studying formation and function of chromosomes. Two alternative protocols are generally used to obtain mitotic chromosomes. The first one employs direct assembly of chromatin from sperm nuclei in CSF-arrested meiotic extracts, while the second is based on transition of sperm DNA through a replication step, followed by re-establishing of CSF arrest. In this study we show that general kinetochore structure is disrupted in chromosomes assembled directly in CSF egg extracts: the amounts of outer kinetochore proteins such as Bub1, BubR1 and Dynactin subunit p150glued are reduced and the components of the inner centromeric region (Aurora B kinase and Survivin) show compromised recruitment to centromeres. In contrast, kinetochores on chromosomes assembled according to the second protocol closely resemble those in somatic cells. Our results argue that transition of sperm nuclei through interphase is an essential step for proper kinetochore assembly.