Daniel Pedziwiatr

Hematopoietic Stem/Progenitor Cells Express Several Functional Sex Hormone Receptors—Novel Evidence for a Potential Developmental Link Between Hematopoiesis and Primordial Germ Cells

Evidence has accumulated that hematopoietic stem progenitor cells (HSPCs) share several markers with the germline, a connection supported by reports that prolactin, androgens, and estrogens stimulate hematopoiesis. To address this issue more directly, we tested the expression of receptors for pituitary-derived hormones, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), on purified murine bone marrow (BM) cells enriched for HSPCs and tested the functionality of these receptors in ex vivo signal transduction studies and in vitro clonogenic assays. We also tested whether administration of pituitary- and gonad-derived sex hormones (SexHs) increases incorporation of bromodeoxyuridine (BrdU) into HSPCs and expansion of hematopoietic clonogenic progenitors in mice and promotes recovery of blood counts in sublethally irradiated animals. We report for the first time that HSPCs express functional FSH and LH receptors and that both proliferate in vivo and in vitro in response to stimulation by pituitary SexHs. Furthermore, based on our observations that at least some of CD45(-) very small embryonic-like stem cells (VSELs) may become specified into CD45(+) HSPCs, we also evaluated the expression of pituitary and gonadal SexHs receptors on these cells and tested whether these quiescent cells may expand in vivo in response to SexHs administration. We found that VSELs express SexHs receptors and respond in vivo to SexHs stimulation, as evidenced by BrdU accumulation. Since at least some VSELs share several markers characteristic of migrating primordial germ cells and can be specified into HSPCs, this observation sheds new light on the BM stem cell hierarchy.

Identification of Heme Oxygenase 1 (HO-1) as a Novel Negative Regulator of Mobilization of Hematopoietic Stem/Progenitor Cells

Activation of complement cascade (ComC) play and important role in mobilization of hematopoietic stem/progenitor cells (HSPCs) from bone marrow (BM) into peripheral blood (PB). While there are vast experimental data on the mechanisms and factors that induce or promote mobilization of HSPCs, there is relatively less data on negative regulators of this process. We demonstrate for the first time that heme oxygenase-1 (HO-1) that has a well-documented anti-inflammatory potential plays an important and heretofore unrecognized role in retention of HSPCs in BM niches by i) modulating negatively activation of mobilization promoting ComC, ii) maintaining stromal derived factor-1 (SDF-1) level in the BM microenvironment and iii) attenuating chemotactic responsiveness of HSPCs to SDF-1 and sphingosine-1 phosphate (S1P) gradients in PB. Furthermore, our data showing a positive mobilizing effect by a non-toxic small-molecule inhibitor of HO-1 (SnPP) suggest that blockade of HO-1 would be a promising strategy to facilitate mobilization of HSPCs. Further studies are also needed to evaluate better the molecular mechanisms responsible for the potential effect of HO-1 in homing of HSPCs after transplantation.

Vitamin D3 stimulates embryonic stem cells but inhibits migration and growth of ovarian cancer and teratocarcinoma cell lines

BackgroundDeficiency in Vitamin D3 (cholecalciferol) may predispose to some malignancies, including gonadal tumors and in experimental models vitamin D3 has been proven to inhibit the growth of cancer cells. To learn more about the potential role of vitamin D3 in cancerogenesis, we evaluated the expression and functionality of the vitamin D receptor (VDR) and its role in metastasis of ovarian cancer cells and of murine and human teratocarcinoma cell lines.MethodsIn our studies we employed murine embrynic stem cells (ESD3), murine (P19) and human (NTERA-2) teratocarcimona cells lines, human ovarian cancer cells (A2780) as well as purified murine and human purified very small embryonic like stem cells (VSELs). We evaluated expression of Vitamin D3 receptor (VDR) in these cells as well as effect of vitamin D3 exposure on cell proliferation and migration.ResultsWe here provide also more evidence for the role of vitamin D3 in germline-derived malignancies, and this evidence supports the proposal that vitamin D3 treatment inhibits growth and metastatic potential of several germline-derived malignancies. We also found that the ESD3 murine immortalized embryonic stem cell line and normal, pluripotent, germline-marker-positive very small embryonic-like stem cells (VSELs) isolated from adult tissues are stimulated by vitamin D3, which suggests that vitamin D3 affects the earliest stages of embryogenesis.ConclusionsWe found that however all normal and malignant germ-line derived cells express functional VDR, Vitamin D3 differently affects their proliferation and migration. We postulate that while Vitamin D3 as anticancer drug inhibits proliferation of malignant cells, it may protect normal stem cells that play an important role in development and tissue/organ regeneration.

Extracellular Microvesicles (ExMVs) in Cell to Cell Communication: A Role of Telocytes.

There are several mechanisms by which cells communicate with each other. Evidence accumulates that the evolutionary oldest mechanisms of cell-cell communication involves extracellular microvesicles (ExMVs). Generally, these circular membrane fragments enriched for mRNA, miRNA, proteins, and bioactive lipids are released by exocytosis from endosomal compartment or are directly formed by budding from cell surface membranes. ExMVs from endosomal compartment called exosomes are smaller in size ~100 nM as compared to larger ones released from cell membranes that are in size up to 1 μM. In this chapter we will present an emerging link between ExMVs and recently identified novel cell-cell communication network involving a new type of cell known as telocyte. Mounting evidence accumulates that telocytes mediate several of their biological effects in several organs by releasing ExMVs enriched in mRNA, miRNA, proteins, and several biological mediators to the target cells.

Mobilization of Peripheral Blood Stem Cells and Changes in the Concentration of Plasma Factors Influencing their Movement in Patients with Panic Disorder

In this paper we examined whether stem cells and factors responsible for their movement may serve as new biological markers of anxiety disorders. The study was carried out on a group of 30 patients diagnosed with panic disorder (examined before and after treatment), compared to 30 healthy individuals forming the control group. We examined the number of circulating HSCs (hematopoetic stem cells) (Lin−/CD45 +/CD34 +) and HSCs (Lin−/CD45 +/AC133 +), the number of circulating VSELs (very small embryonic-like stem cells) (Lin−/CD45−/CD34 +) and VSELs (Lin−/CD45−/AC133 +), as well as the concentration of complement components: C3a, C5a and C5b-9, SDF-1 (stromal derived factor) and S1P (sphingosine-1-phosphate). Significantly lower levels of HSCs (Lin−/CD45 +/AC133 +) have been demonstrated in the patient group compared to the control group both before and after treatment. The level of VSELs (Lin−/CD45−/CD133 +) was significantly lower in the patient group before treatment as compared to the patient group after treatment.The levels of factors responsible for stem cell movement were significantly lower in the patient group compared to the control group before and after treatment. It was concluded that the study of stem cells and factors associated with their movement can be useful in the diagnostics of panic disorder, as well as differentiating between psychotic and anxiety disorders.

A lack of positive effect of enhanced vegetative nervous system tonus on mobilization of hematopoietic stem and progenitor cells in patients suffering from acute psychotic syndromes.

A lack of positive effect of enhanced vegetative nervous system tonus on mobilization of hematopoietic stem and progenitor cells in patients suffering from acute psychotic syndromes

Pituitary sex hormones enhance the pro‑metastatic potential of human lung cancer cells by downregulating the intracellular expression of heme oxygenase‑1

We report that human lung cancer cell lines express functional receptors for pituitary sex hormones (SexHs) and respond to stimulation by follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL). Expression of these receptors has also been confirmed in patient lung cancer samples at the mRNA level. Stimulation of human lung cancer cell lines with FSH, LH, or PRL stimulated migration and chemotaxis, and some cell lines responded by enhanced proliferation. Moreover, priming of human lung cancer cells by exposing them to pituitary SexHs resulted in enhanced seeding efficiency of injected human lung cancer cells into bone marrow, liver, and lungs in an immunodeficient mouse model. The chemotaxis of lung cancer cell lines corresponded with the activity of heme oxygenase-1 (HO-1), as stimulation of these cells by FSH, LH, and PRL downregulated its expression in a p38 MAPK-dependent manner. Moreover, while downregulation of HO-1 by the small-molecule inhibitor tin protoporphyrin (SnPP) promoted migration, upregulation of HO-1 by the small-molecule activator cobalt protoporphyrin (CoPP) showed the opposite effect. Based on this finding, we propose that pituitary SexHs play a significant role in the pathogenesis of lung cancer, particularly when the blood level of FSH increases due to gonadal dysfunction with advanced age. Finally, we propose that upregulation of HO-1 expression by a small-molecule activator may be effective in controlling SexH-induced cell migration in lung cancer.

Do Cancer Cell Lines Have Fixed or Fluctuating Stem Cell Phenotypes? – Studies with the NTera2 Cell Line

One of the important questions when studying established cancer cell lines is whether such cells contain a subpopulation of primitive cancer stem cells that maintains the expansion of the cell line. To address this issue, we performed studies on the established human embryonal carcinoma cell line NTera2 by evaluating the potential stemness of cells sorted according to their expression of the cell surface stem cell markers CD133 and SSEA4. By performing in vitro and in vivo assays, we observed different properties of cells expressing both, one, or neither of these antigens. While sorted SSEA4+ subpopulations exhibited the greatest propensity for migration toward normal serum and the highest seeding efficiency in the lungs of immunodeficient mice, CD133−SSEA4− cells displayed high seeding efficiency to the bone marrow after injection in vivo. It is worth noting that these properties did not depend on the size of the evaluated cells. To address the question of whether cancer stem cell phenotypes in cell lines are fixed or fluctuating, we sorted single cells according to their expression of CD133 and SSEA4 antigens and observed that cells which did not express these cancer stem cell markers gave rise to cells that express these markers after expansion in vitro. Therefore, our results support the idea that within established cancer cell lines, the phenotype of the cell subpopulation expressing cancer stem cell markers is not fixed but fluctuates during cell line expansion, and cells negative for these markers may acquire their expression.

Sterile Inflammation of Brain, due to Activation of Innate Immunity, as a Culprit in Psychiatric Disorders

Evidence has accumulated that the occurrence of psychiatric disorders is related to chronic inflammation. In support of this linkage, changes in the levels of circulating pro-inflammatory cytokines and chemokines in the peripheral blood (PB) of psychiatric patients as well as correlations between chronic inflammatory processes and psychiatric disorders have been described. Furthermore, an inflammatory process known as “sterile inflammation” when initiated directly in brain tissue may trigger the onset of psychoses. In this review, we will present the hypothesis that prolonged or chronic activation of the complement cascade (ComC) directly triggers inflammation in the brain and affects the proper function of this organ. Based on the current literature and our own work on mechanisms activating the ComC we hypothesize that inflammation in the brain is initiated by the mannan-binding lectin pathway of ComC activation. This activation is triggered by an increase in brain tissue of danger-associated molecular pattern (DAMP) mediators, including extracellular ATP and high-mobility group box 1 (HMGB1) protein, which are recognized by circulating pattern-recognition receptors, including mannan-binding lectin (MBL), that activate the ComC. On the other hand, this process is controlled by the anti-inflammatory action of heme oxygenase 1 (HO-1). In this review, we will try to connect changes in the release of DAMPs in the brain with inflammatory processes triggered by the innate immunity involving activation of the ComC as well as the inflammation-limiting effects of the anti-inflammatory HO-1 pathway. We will also discuss parallel observations that during ComC activation subsets of stem cells are mobilized into PB from bone marrow that are potentially involved in repair mechanisms.