Effect of Intranasal Administration of Multipotent Mesenchymal Stromal Cell Exosomes on Memory of Mice in Alzheimer's Disease Model.

We studied the effect of intranasal administration of exosomes obtained by culturing of multipotent mesenchymal stromal cells (MMSC) isolated from the Wharton's jelly of the human umbilical cord on spatial memory of olfactory bulbectomized mice demonstrating the basic signs of a sporadic form of Alzheimer's disease. Intranasal administration of isolated exosomes expressing typical markers CD9, CD63 and CD81 improved spatial memory in bulbectomized animals, which manifested in a significant increase in the number of visits to the target sector and the time spent there in comparison with indifferent sectors. After administration, labeled exosomes were found in the hippocampus and neocortex, the structures playing an important role in learning and memory processes and affected by Alzheimer's disease. The advantages of exosomes in comparison with MMSC are their small size, low immunogenicity, and inability to cause cell transformation together with high therapeutic efficacy.

Effect of Transplantation of Neural Stem and Progenitor Cells on Memory in Animals with Alzheimer's Type Neurodegeneration.

The effects of systemic and intracerebral transplantation of human fetal neural stem and progenitor cells were studied on the model of olfactory bulbectomy in mice with developing signs of sporadic Alzheimer's disease. It was found that transplantation of these cells at certain stages of disease development contributed to improvement of spatial memory and preservation of hippocampal neurons in these animals.

Neuroregeneration: Regulation in Neurodegenerative Diseases and Aging.

It had been commonly believed for a long time, that once established, degeneration of the central nervous system (CNS) is irreparable, and that adult person merely cannot restore dead or injured neurons. The existence of stem cells (SCs) in the mature brain, an organ with minimal regenerative ability, had been ignored for many years. Currently accepted that specific structures of the adult brain contain neural SCs (NSCs) that can self-renew and generate terminally differentiated brain cells, including neurons and glia. However, their contribution to the regulation of brain activity and brain regeneration in natural aging and pathology is still a subject of ongoing studies. Since the 1970s, when Fuad Lechin suggested the existence of repair mechanisms in the brain, new exhilarating data from scientists around the world have expanded our knowledge on the mechanisms implicated in the generation of various cell phenotypes supporting the brain, regulation of brain activity by these newly generated cells, and participation of SCs in brain homeostasis and regeneration. The prospects of the SC research are truthfully infinite and hitherto challenging to forecast. Once researchers resolve the issues regarding SC expansion and maintenance, the implementation of the SC-based platform could help to treat tissues and organs impaired or damaged in many devastating human diseases. Over the past 10 years, the number of studies on SCs has increased exponentially, and we have already become witnesses of crucial discoveries in SC biology. Comprehension of the mechanisms of neurogenesis regulation is essential for the development of new therapeutic approaches for currently incurable neurodegenerative diseases and neuroblastomas. In this review, we present the latest achievements in this fast-moving field and discuss essential aspects of NSC biology, including SC regulation by hormones, neurotransmitters, and transcription factors, along with the achievements of genetic and chemical reprogramming for the safe use of SCs in vitro and in vivo.

Myths, reality and future of mesenchymal stem cell therapy.

Mesenchymal stem cell (MSC) therapy represents an alternative approach for tissue regeneration and inflammation control. In spite of a huge amount of preclinical data that has been accumulated on the therapeutic properties of MSCs, there are many conflicting results, possibly due to differences in the properties of MSCs obtained from different sources or underestimated mechanisms of MSC in vivo behavior. This review consolidates the in vivo effects of MSC therapy, discusses the fate of MSCs after intravascular and local delivery and proposes possible trends in MSC therapy.

Activation of NK Cells in Mixed Cultures of Wharton's Jelly Mesenchymal Stromal Cells and Peripheral Blood Lymphocytes.

Mesenchymal stromal cells possess immunosuppressive properties that might be used for the therapy of inflammatory diseases of various geneses. The effects of mesenchymal stromal cells depend on their lifetime in the recipient tissues. During heterologous transplantation, mesenchymal stromal cells are eliminated by NK cells. We studied NK cell formation in mixed cultures of Wharton's jelly mesenchymal stromal cells and peripheral blood lymphocytes from an autologous donor. Lymphocytes were activated by a mitogen or IL-2. The lifetime of mesenchymal stromal cells was estimated by MTT test. Cytotoxic activity and phenotype of NK cells were evaluated by flow cytometry. It was found that activation of NK cells depended on IL-2 and was registered on day 2 of incubation with IL-2. In cultures with mitogen-activated lymphocytes, cytotoxicity was observed after 5-6 days. Cytotoxicity of NK correlated with significant decrease in CD16+ and increase in CD56+ NK and with reduction of mesenchymal stromal cell viability. Thus, the main mechanism of elimination of mesenchymal stromal cells is cytotoxicity of NK cells that depended on IL-2 production.

Characteristics of Trophoblasts in Long-Term Culture.

We analyzed more than 40 cytotrophoblast cultures derived from cell islets that grew from trypsinized tissue fragments of placental microvilli. Phenotypic variability of trophoblasts was demonstrated. Changes in trophoblast morphology from epithelium-like or oval cells to bipolar and spindle-shaped or twisted and then to mesenchymal-like cells as well as intensive expression of cytokeratin-7 and vimentin attested to epithelial-mesenchymal transition of trophoblasts during in vitro culturing. Analysis of the expression of specific markers in long-term trophoblast culture (≥7 passages) revealed the possibility of culture contamination with other non-trophoblast cells including fibroblasts. High risk of trophoblast culture contamination with rapidly growing cells necessitates regular control of the cultures used in fundamental studies. Our experiments confirmed the possibility of long-term culturing of cells maintaining trophoblast properties. The identity and purity of 4 trophoblast cultures free from contamination and retaining the properties of pure culture during long-term (>10 passages) culturing in vitro were confirmed.

Proliferation of Peripheral Blood Lymphocytes and Mesenchymal Stromal Cells Derived from Wharton's Jelly in Mixed and Membrane-Separated Cultures.

We studied the effect of mesenchymal stromal cells on proliferation of CFSE-stained T cells in mixed and membrane-separated (Transwell) cultures and in 3D culture of mesenchymal stromal cells from Wharton's jelly. The interaction of mesenchymal stromal cells with mitogen-activated peripheral blood lymphocytes from an allogeneic donor was followed by suppression of T-cell proliferation in a wide range of cell proportions. Culturing in the Transwell system showed the absence of suppression assessed by the fraction of proliferating cells and by the cell cycle analysis. In 3D cultures, contact interaction of mesenchymal stromal cells and lymphocytes was demonstrated that led to accumulation of G2/M phase lymphocytes and G0/G1 phase mesenchymal stromal cells. The suppressive effect of mesenchymal stromal cells from Wharton's jelly is mediated by two mechanisms. The effects are realized within 6 days, which suggests that the therapeutic effects of mesenchymal stromal cells persist until their complete elimination from the body.

Cytokine Production in Mixed Cultures of Mesenchymal Stromal Cells from Wharton's Jelly and Peripheral Blood Lymphocytes.

We compared the production of 19 humoral factors in mixed cultures of mesenchymal stromal cells from Wharton's jelly and allogenic peripheral blood lymphocytes. For evaluation of the specificity of immunosuppressive activity of mesenchymal stromal cells, comparative analysis of the production of these humoral factors in mixed cultures of lymphocytes and epithelial BxPC-3 cells was conducted. The production of soluble factors in both mono- and mixed cultures significantly correlated (p<0.05). The maximum production was found for proinflammatory chemokine IP-10 and IFN-γ and anti-inflammatory cytokine IL-10. The major difference of mesenchymal stromal cells from epithelial BxPC-3 cells was 7-fold higher production of IL-10, which can explain the immunosuppressive effect of mesenchymal stromal cells.

Albumin in the Vitreous Body, Retina and Lens of Human Fetal Eye.

The content of serum albumin was evaluated in the vitreous body, retina, and lens of human fetuses of 14, 16, 17, 18 and 24 weeks of gestation. Albumin was detected in these tissues. PCR analysis revealed no albumin mRNA in the retina or in the lens, while in fetal liver (control) mRNA for this protein was expressed. These findings suggest that serum albumin is not synthesized by cells of retina and lens, but is captured by them. The presence of serum albumin in human eye tissues suggests its involvement in the metabolism, maintenance of tissue volume, and antioxidant reactions.

Ultrastructural Characteristics of Placental Telocytes.

Telocytes of placental villi were studied by electronic microscopy during physiological pregnancy. Ultrastructural features of telocytes indicating their heterogeneity and presence of at least three types of villi depending on their localization and kind were observed. All placental telocytes were characterized by small amount of organelles including mitochondria. Presence of long thin processes, which generated a branching network by contacting with each other, served as a typical feature of telocytes including telocytes of the stroma and intermediate villi. Telocytes were absent in the terminal villi.

Conditions for Collection of Placental Tissue Samples for Culturing of Multipotent Mesenchymal Stromal Cells.

Placentas from women aged 25-32 years with normal course of gestation were studied. It is essential to stick to certain methodological approaches for preparing viable multipotent mesenchymal stromal cell culture and to carry out morphological (macro and micro) evaluation of the chorionic villi, umbilical cords, and placentas. At stage I of the study, patients' histories, labor course, and examinations of the newborns should be analyzed to exclude women with genital and extragenital diseases. At stage II, it is essential to stick to special regulations and methods for collection of specimens of the cord, amnion, and placental tissue proper. Histological control of the placental structures collected for multipotent mesenchymal stromal cell culturing is obligatory.

[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.

Antiproliferative Effects of Mesenchymal Stem Cells and Epithelial Cells on Lymphocytes.

We analyzed the interactions between peripheral blood lymphocytes from heterologous donors with mesenchymal stem cells obtained from the tooth pulp and trophoblast. In mixed cultures, proliferation of both lymphocytes and mesenchymal stem cells was suppressed. Similar suppressive effects were observed in lymphocyte cultures mixed with epithelial cells (hepatocytes HeG2 and renal epithelial cells HEK293). This suppression can be determined by impairment of normal adhesion contacts between cells of different origin.

Interaction of Lymphocytes with Mesenchymal Stem Cells.

We studied the interaction of neural stem cells and dental pulp-derived mesenchymal stem cells with lymphocytes from autologous and heterologous donors. Flow cytometry analysis with the use of CFSE-labeled lymphocytes demonstrated an increase in the content of proliferating CD8, CD16 and CD56 cells, but not CD4 cells in cultures of HLA-DR-negative mesenchymal stromal cells from the dental pulp co-cultured with lymphocytes. In neural cultures expressing HLA-DR, all subpopulations of T cells and NK cells were activated. No differences between the autologous and heterologous cultures were revealed.

Analysis of Neural Stem Cells from Human Cortical Brain Structures In Vitro.

Comparative immunohistochemical analysis of the neocortex from human fetuses showed that neural stem and progenitor cells are present in the brain throughout the gestation period, at least from week 8 through 26. At the same time, neural stem cells from the first and second trimester fetuses differed by the distribution, morphology, growth, and quantity. Immunocytochemical analysis of neural stem cells derived from fetuses at different gestation terms and cultured under different conditions showed their differentiation capacity. Detailed analysis of neural stem cell populations derived from fetuses on gestation weeks 8-9, 18-20, and 26 expressing Lex/SSEA1 was performed.

Comparative analysis of the expression of surface markers on fibroblasts and fibroblast-like cells isolated from different human tissues.

Expression of 20 surface markers was analyzed in cultures of mesenchymal stromal cells of the umbilical cord, fibroblasts from adult and fetal human skin, and fibroblast-like cells of fetal liver was analyzed by fl ow cytometry. The studied cultures did not express hemopoietic cells markers, but were positive for CD73, CD90, and CD105 markers recommended by the International Society of Cell Therapy for the identification of the multipotent mesenchymal stromal cells. Fetal liver fibroblast-like cells were positive for CD54; this marker was absent in skin fibroblast cultures, but was expressed by umbilical cord mesenchymal stromal cells. Further study of these cells revealed a minor subpopulation of cells co-expressing CD24 and CD90 or CD24 and CD54. We hypothesized that these cells probably participate in epithelial mesenchymal transition.

Mesenchymal stem cells from human dental pulp: isolation, characteristics, and potencies of targeted differentiation.

We studied cell cultures isolated from the pulp of third molar germ of an adult human and from the skin of a human fetus on gestation day 10. Both cultures expressed similar repertoire of surface markers typical of multipotent mesenchymal cells (CD44, CD90, and CD105). Under in vitro conditions, dental pulp cells were more susceptible to factors inducing their differentiation into adipogenic, chondrogenic, and osteogenic lineage cells.

Localization and differentiation pattern of transplanted human multipotent mesenchymal stromal cells in the brain of bulbectomized mice.

Replacement cell therapy with transplantation of stem cells is a promising approach for the therapy of various neurodegenerative diseases, e.g. Alzheimer's disease. However, the behavior of transplanted cells in the damaged tissue should be thoroughly studied before introduction of this method into clinical practice. We studied the pathways of migration of human multipotent mesenchymal stromal cells after their systemic transplantation into the brain of bulbectomized mice characterized by the development of Alzheimer-type neurodegenerative process. Immunohistochemical analysis with antibodies to human nuclear antigen (HNA) and immunofluorescent analysis of the results of transplantation of multipotent mesenchymal stromal cells carrying green fluorescent protein (GFP) gene showed that these cells can cross the blood-brain barrier and penetrate into some structures of recipient brain. Analysis of differentiation of transplanted human cells using antibodies to neurospecific enolase (NSE) or astroglial marker (GFAP) with parallel staining for human nuclear antigen revealed no neural differentiation of transplanted cells in the brains of bulbectomized animals. However, some of these cells differentiated into astrocytes, which brought us to an assumption on important role of astroglial abnormalities in the pathogenesis of Alzheimer's disease.

Therapeutic effect of mesenchymal multipotent stromal cells on memory in animals with Alzheimer-type neurodegeneration.

Transplantation of human mesenchymal multipotent stromal cells improved spatial memory in bulbectomized mice with Alzheimer-type neurodegeneration. The positive effect was observed in 1 month after intracerebral transplantation and in 3 months after systemic injection of mesenchymal multipotent stromal cells. No cases of malignant transformation were noted. These findings indicate prospects of using mesenchymal multipotent stromal cells for the therapy of Alzheimer disease and the possibility of their systemic administration for attaining the therapeutic effect.