Rumen Dimitrov

Adipose tissue-derived mesenchymal stem cells are more potent suppressors of dendritic cells differentiation compared to bone marrow-derived mesenchymal stem cells

Both mesenchymal stem cells (MSCs) and dendritic cells (DCs) are engaged in the regulation of the immune response parallel to their numerous functions. The main objective of this study was to compare the effects of mesenchymal stem cells isolated from human adipose tissue or human bone marrow on the expression of specific cell surface markers as well as the secretion of some cytokines by monocyte-derived dendritic cells. The set of methods used includes cell cultures, magnetic beads isolation of cells, flow cytometry, ELISA and proteome profiler kit assays. The results obtained show that MSCs isolated from human adipose tissue are more potent immunomodulators of differentiation of human DCs in comparison to the bone marrow-derived MSCs. In both cases the percentages of CD14+ cells were increased in co-cultures of MSCs and DCs and at the same time down-regulated the expression of CD80, CD86 and CD83 as in all experiments the effect of adipose tissue MSCs was stronger. Similarly, the secretion of IL-10 by dendritic cells was up-regulated in co-cultures of MSCs and dendritic cells and the effect was stronger when adipose tissue-derived MSCs were used. Taken together all results presented reveal the higher potential of the adipose tissue-derived MSCs to inhibit the differentiation and expression of functionally important co-stimulatory molecules on the surface of monocyte-derived dendritic cells than the bone marrow-derived MSCs.

Characterization of clonogenic stromal cells isolated from human endometrium

Human endometrium is an object of extensive restructuring and remodeling during the female reproductive life and it is quite tempting to assume that these periodic changes happen with the participation of cells that should have the basic characteristics of multipotent cells. The aim of this study was to search for the presence of cells with plastic adherence, clonogenicity, and differentiation in human endometrium. To this end, human endometrial stromal cells were cultured in vitro for more than 15 passages. Flow cytometry analysis of the cultured cells showed that they were positive for CD29, CD73 and CD90, which are considered to be the markers of cells with mesenchymal origin. The cells were negative for the hematopoietic cell markers (CD45, CD34, CD14, CD3, CD19, CD16/56, and HLA-DR). Further, it was shown that the cultured cells had 15% clonogenic efficiency and could be induced to differentiate into adipogenic cells containing typical lipid-rich vacuoles. These results demonstrate that the human endometrium contains a low number of cells with the characteristics of endometrial stromal stem/progenitor cells, which seem to belong to the family of the mesenchymal stem cells. It can be speculated that these cells are engaged into the monthly restructuring and remodeling of human endometrium.

Conditioned Medium from Adipose Tissue-Derived Mesenchymal Stem Cells Induces CD4+FOXP3+ Cells and Increases IL-10 Secretion

Mesenchymal stem cells (MSCs) are a new and promising tool for therapy of autoimmune disorders. In recent years their possibility to take part in the modulation of the immune response is discussed. The exact mechanisms for immunoregulation realized by MSCs are not clear yet, but interactions with other immunoregulatory cells may be involved in this process. The investigation of the influence of MSCs on the expression of FoxP3 and cytokine secretion by T helper cells was the aim of this study. T helper cells were isolated from PBMCs by magnetic separation and MSCs were isolated from human adipose tissue, and CD4+ T cells were cultured with conditional medium of MSCs. The methods which were used include flow cytometry, ELISA, and Human Proteome profiler kits. The results demonstrated that secretory factors in MSCs conditional medium lead to increased expression of FoxP3 and increased secretion of IL-10 by T helpers. The obtained results give us opportunity to discuss the interaction between two kinds of immunoregulatory cells: MSCs and FoxP3+ T helpers. We suppose that this interaction leads to increased number of immunosuppressive helpers which secrete IL-10. MSCs provide some of their immunosuppressive functions acting on T regulatory cells, and we believe that IL-6 secreted by MSCs is involved in this process.

HLA-G expression is up-regulated by progesterone in mesenchymal stem cells.

Problem  Maternal immune response to fetal tissues is modified in such way that it favors the development of pregnancy. Human leukocyte antigen (HLA)‐G, progesterone and mesenchymal stem cells (MSCs) have been identified as potent immunomodulatory agents in different experimental systems and the interactions between these three factors are studies in this paper.

FIRST-TRIMESTER HUMAN DECIDUA CONTAINS A POPULATION OF MESENCHYMAL STEM CELLS

OBJECTIVE To determine whether first-trimester human decidua contains multipotent stromal cells capable of differentiating into other cell lines. DESIGN In vitro-cultured decidual stromal cells were analyzed by flow cytometry and induced to differentiate into osteogenic and adipogenic lineages, endothelial cells, and PRL-secreting mature decidual cells. SETTING Research laboratory. PATIENT(S) Eight decidua samples were collected from healthy women aged 26-32 years undergoing elective vaginal surgical terminations of early pregnancy (8-10 gestational weeks). INTERVENTION(S) Cell suspensions from human decidual stromal cells were cultured at clonogenic concentrations and in bulk under differentiation conditions and analyzed for specific markers. MAIN OUTCOME MEASURE(S) Multipotent differentiation potential of decidual stromal cells. RESULT(S) Decidual stromal cells express the surface markers specific to cells of mesenchymal origin as analyzed by flow cytometry. A pool of the decidual stromal cells can be induced to differentiate into mature PRL-secreting decidual cells and into osteogenic, adipogenic, and endothelial cells expressing the corresponding specific markers. CONCLUSION(S) It is demonstrated for the first time that first-trimester human decidua contains multipotent mesenchymal stem cells that can be grown in vitro for prolonged periods, have clonogenic properties, can differentiate into different cell lineages, and express surface markers specific to mesenchymal stem cells.

ORIGINAL ARTICLE: HLA-G Expression Is Up-Regulated by Progesterone in Mesenchymal Stem Cells

Problem  Maternal immune response to fetal tissues is modified in such way that it favors the development of pregnancy. Human leukocyte antigen (HLA)‐G, progesterone and mesenchymal stem cells (MSCs) have been identified as potent immunomodulatory agents in different experimental systems and the interactions between these three factors are studies in this paper.

Assessment of presence and characteristics of multipotent stromal cells in human endometrium and decidua

This review discusses the presence and characteristics of multipotent stromal cells in human endometrium and decidua. A number of research groups have reported the isolation and characterization of multipotent stromal cells from the basal layer of the endometrium, and in a single case just from the menstrual blood, i.e. the superficial functional layer. Similarly, multipotent pre-decidual stromal cells are isolated from early decidua and characterized accordingly. Multipotent endometrial stromal cells and multipotent decidual stromal cells are shown to express the basic features of adult stem cells, which are clonogenicity, self-renewal, a potential to differentiate into adipogenic, osteogenic, chrondrogenic, endothelial-like cells and a specific set of surface molecules (CD73, CD90 and CD105). So far, it is not clear whether the same population of multipotent stromal cells is isolated from the basal endometrium or early decidua because it has been shown that in some cases the differentiation potential of endometrial stromal cells is more restricted in comparison to the decidual stromal cells. It is reasonable to assume that it is one cell population under different control by hormonal, paracrine and autocrine factors. Thus far, the functions of these cells have not been convincingly revealed.

ORIGINAL ARTICLE: HLA-G Expression Is Up-Regulated by Progesterone in Mesenchymal Stem Cells: HLA-G IN MSCS IS UP-REGULATED BY PROGESTERONE

Problem  Maternal immune response to fetal tissues is modified in such way that it favors the development of pregnancy. Human leukocyte antigen (HLA)‐G, progesterone and mesenchymal stem cells (MSCs) have been identified as potent immunomodulatory agents in different experimental systems and the interactions between these three factors are studies in this paper.