Mild anemia during pregnancy upregulates placental vascularity development

The connection between maternal hematological status and pregnancy outcome has been shown by many independent researchers. Attention was initially focused on the adverse effects of moderate and severe anemia. Interestingly, some studies revealed that mild anemia was associated with optimal fetal development and was not affecting pregnancy outcome. The explanation for this phenomenon became a target for scientists. Hemodilution, physiologic anemia and relative decrease in hemoglobin concentration are the changes observed during pregnancy but they do not explain the reasons for the positive influence of mild anemia on a fetomaternal unit. It is hypothesized that hemodilution facilitates placental perfusion because blood viscosity is reduced. Subsequently, it may lead to a decline in hemoglobin concentration. Anemia from its definition implies decreased oxygen carrying capacity of the blood and can result in hypoxemia and even hypoxia, which is a common factor inducing new blood vessels formation. Therefore, we raised the hypothesis that the lowered hemoglobin concentration during pregnancy may upregulate vascular growth factor receptors expression such as VEGFR-1 (Flt-1) and VEGFR-2 (FLK-1/KDR). Consecutively, increased fetoplacental vasculogenesis and angiogenesis provide further expansion of vascular network development, better placental perfusion and hence neither fetus nor the mother are affected.

Decreased effectiveness of ischemic heart preconditioning in the state of chronic inflammation

There is growing evidence, that beneficial effects of ischemic heart preconditioning (IPC) may be lost or limited due to diabetes, hyperlipidemia, hypertension, atherosclerosis, heart failure and senility. It is plausible, that these conditions interfere with the biochemical pathways underlying the IPC response, but the detailed explanation is not clear. Pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), monocyte chemotactic protein-1 (MCP-1), histamine and many other agents used in a single dose before prolonged ischemia mimic IPC. However prolonged exposure to preconditioning mimetics leads to tolerance (tachyphylaxis). In the state of such tolerance ischemic preconditioning is no longer protective. Studies suggest that diabetes, hyperlipidemia, hypertension, atherosclerosis, heart failure and older age are accompanied by increased plasma levels of pro-inflammatory cytokines, MCP-1 and other inflammatory mediators. Therefore, we raised the hypothesis, that the reported lack of benefits of IPC in the listed states may be due to tolerance to IPC developed during prolonged exposure of the myocardium to preconditioning mimetics.

Involvement of histamine and histamine H2 receptors in nicotinamide-induced differentiation of human amniotic epithelial cells into insulin-producing cells

OBJECTIVE AND DESIGN

Human amniotic epithelial cells (HAEC) resemble stem cells in their ability to differentiate into all three germ layers: endoderm, mesoderm, and ectoderm. Histamine receptors are expressed on HAEC. We examined the influence of histamine, and H(1) and H(2) antagonists on the generation of pancreatic islet beta-like cells from HAEC.

MATERIALS AND METHODS

HAEC were isolated after term pregnancies (N = 12) and cultured for 14 days with nicotinamide (10 mM) in normoxia. Altogether, 72 cultures were established. Histamine (100 microM) effects were investigated with mepyramine (10 microM) or cimetidine (10 microM). After 7 and 14 days, the mean concentration of C-peptide (MCCP) in the culture medium was measured immunoenzymatically as a marker of pancreatic differentiation.

RESULTS

MCCP was approximately threefold higher on day 14, compared to day 7. Histamine significantly increased MCCP, and more evident differences were observed after 7 days of culture than after 14 days. The mean percent increase +/-SEM in MCCP amounted to 142.19 +/- 21.7 and 79.03 +/- 12.35 compared to the controls on day 7 and 14, respectively. H(2) blockade significantly reduced histamine-related increase in MCCP, both on day 7 and 14 by 88.7 +/- 14.3 and 39.2 +/- 12.4%, respectively. H(1) receptor antagonist did not affect MCPP.

CONCLUSION

Nicotinamide-induced pancreatic differentiation of HAEC into beta-like cells may be augmented, probably at its earlier stage, by histamine acting via H(2) receptors.

Histamine influence on apoptosis in trophoblast cell cultures

INTRODUCTION

It has been demonstrated that histamine plays an important role in the pathogenesis of preeclampsia. Histamine regulates the process of differentiation of trophoblast cells; it also acts as a growth factor in malignant melanoma cells, and prevents monocytic apoptosis. Trophoblast research has shown that in preeclampsia placentas, trophoblast apoptosis is significantly increased.

AIM OF THE STUDY

The aim of our study was to demonstrate the influence of histamine on the process of apoptosis in human trophoblast cell cultures.

MATERIALS AND METHODS

Placentas were obtained after vaginal delivery. Tissue samples were excised from placentas and, with the use of modified Kliman's method, trophoblast cell cultures were established. The cultures were incubated with dexamethasone as an apoptosis inducer 48 hours prior to apoptosis detection assays. Along with dexamethasone, selected cell cultures were incubated with histamine (1 micromol/l) or histamine (1 micromol/l) and terfenadine (from 1 to 5 micromol/l), a H(1) receptor antagonist. For apoptotic activity detection, and quantitative analysis, we used an ELISA assay. M30-Apoptosense ELISA Kit is based on the M30 monoclonal antibody that binds only the caspase-cleaved cytokeratin 18 formed during apoptosis in trophoblast cells.

RESULTS

Our investigation showed significantly (p < 0.05) increased apoptotic activity in cultures incubated with dexamethasone, histamine and terfenadine (% of reference value, +/-SEM): up to 113.1 +/- 4.33%. Cell cultures incubated with dexamethasone and histamine only showed significantly lower apoptotic activity 90.2 +/- 5.17%. We suggest that histamine may inhibit apoptotic activity in trophoblast cell cultures via H(1) receptor. Thus histamine may regulate the process of trophoblast differentiation (via integrin aV-b3 expression, as we previously suggested), and influence cell turnover in the placenta.

[Culture of human trophoblast cells in vitro as a research method--review of techniques (Part II)]

In part II, management of the human trophoblast cell-cultures and methods of quality control are presented. The examples of application of this in vitro model for scientific research are also given.

[Culture of human trophoblast cells in vitro as a research method--review of techniques (Part I)]

In part I, several histological techniques applied for establishing the human trophoblast cell cultures are characterized. The methods of isolation and purification of trophoblast cells, as well as the management of selective culture are discussed.

Generating autogenous cartilage on the basis of subperichondrial grafts of demineralized bone matrix with local stimulation by growth factors

Cartilage tissue acquired de novo is a very attractive material for the surgical reconstruction of joint surfaces, trachea, and maxillofacial elements. One of the primary challenges for tissue engineering is to determine the procedures that lead to the creation of material meeting the established qualitative and quantitative criteria. The goal of this work was to determine whether and how growth factors (IGF-1 and FGF) and ethyl alcohol administered locally affect the course and final outcome of the chondrogenetic process under in vitro conditions in New Zealand rabbits. In order to generate cartilage, a collagen scaffold (demineralized ZMK bone matrix) was used, wrapped in a pedunculated flap of perichondrium (from the rabbit's ear), which, beginning on the 3rd day after the operation, was injected with growth factors every 3 days. Grafts were collected in the 3rd and 6th week after the ZMK implantation, and the silvers made from them were stained for the presence of collagen II, collagen I, and macrophages, and analyzed morphometrically. It was found that the application of growth factors only slighty, intensified the synthesis of collagen II, and had no effect on the degree of macrophage infiltration or collagen I contents, while the numerous injections exerted a negative impact on the architecture of the newly-formed tissue and contributed to an increased number of complications (hematomas, infections).

Mast cells in the mouse mammary gland--correlation with the development of lactiferous structures

Specimens of mouse mammary glands obtained from animals being in different phases of reproductive cycle were collected. After staining MCN, the total mast cell area (TMC), mean mast cell area (MMC), and lactiferous structure density index (LDI) were examined in sections, using a computer image analysis system. Statistically significant (P < 0.05) results were: 1. An increase in MCN observed in Group I (4-5 and 9-10 days of pregnancy), a decrease in MCN observed in Group II (2nd and 10th day of lactation); 2. Changes of TMC fully corresponding to changes of MCN; 3. Increase in MMC observed in Group I at mid (days 9-10) and at the end (days 18-19) of pregnancy, decrease in MMC observed in Group IIB (10th day of lactation); 4. LDI (%) higher at the end of pregnancy (Group IC) and during lactation (groups IIA, IIB), compared with control (23.5 +/- 4.12, 37.6 +/- 3.24, 71.0 +/- 4.33 vs. 3.8 +/- 0.39). The observed changes in the number and size of MC strictly correspond to physiological phenomena leading to alternation of the mouse mammary gland functional status by development/involution of the lactiferous structures.

Constitutive expression of cyclooxygenase-2 (COX-2) in developing brain. A. Choroid plexus in human fetuses

It is believed that prostanoids produced by COX-1 activity are essential for the physiological functions of tissues while those produced by COX-2 lead to various pathological changes in these tissues. Brain is an exceptional organ where in some neurons COX-2 mRNA and its protein are constitutively expressed. Since some prostaglandins may play an important role in the control of blood-brain barrier and cerebral blood flow the purpose of the present study was to examine the COX-2 expression in choroid plexus, which participate in the nutrition of brain parenchyma of human fetuses. Study was performed on 25 brains of human fetuses from 12 to 38 weeks of gestation. In light and electron microscopy characteristic developmental transformation of choroid morphology was observed. In young fetuses from 12 to 20 week of gestation epithelial cells of choroid plexus are cuboidal, contain large amount of glycogen storage and their nuclei are COX-2 immunopositive. From 25 week of gestation until term the amount of glycogen in the choroid plexus diminishes, some apical nuclei are shifted toward central parts of the cells and number of cytoplasm organelles increases. In these cells expression of COX-2 protein is located in cytoplasm but epithelial nuclei are immunonegative. Our results provided evidence that COX-2 is constitutively expressed in the developing human choroid plexus. Different localization of COX-2 in choroid epithelial cells suggests that this enzyme may play a different role in various periods of the choroid plexus development.

In vitro effect of bioactive natriuretic peptides on perfusion pressure in placentas from normal and pre-eclamptic pregnancies

The number of placental vascular guanylate-coupled receptors. corresponding to bioactive natriuretic peptide receptors is greater in preeclampsia. but there are no clear data about atrial natriuretic peptide (ANP) concentration in preeclampsia. The influence of various doses of ANP and urodilatin (URO) on placental perfusion pressure in preeclampsia was investigated by perfusing 16 human placentas in vitro. The placental vessels were submaximally preconstricted by continuous infusion of N-omega-nitro-L-arginine (NOLA). Perfusion pressure was measured continuously. Over 180 min various doses of alphaANP or URO were administrated (25, 50, 100, 200 nmol/l, 2 min increments). The effects of pretreatment with the guanylate cyclase inhibitor, LY 83583 was also examined. We found that ANP and URO attenuated NOLA-induced vasoconstriction, that URO given in higher doses produced stronger vasocilation than ANP, and that the mean decrease of perfusion pressure was higher in preeclampsia. The possibility of a non cGMP-mediated pathway of ANP and URO action should be considered.

Polycystic ovary syndrome--searching for an animal model

At present, the understanding of the pathogenesis of polycystic ovary syndrome (PCOS) has advanced significantly, and improvements have been made in the treatment of PCOS symptoms. These achievements are to some extent the result of studies on experimental animals. However, a fully convincing animal model for study of polycystic ovaries, or of PCOS as whole, has not been established. This review article discusses several rat models for PCOS. Characteristics with respect to ovarian morphology, serum levels of LH, FSH, estradiol and androgens have been described and similarities to PCOS in women are discussed. The large number of the animal models for PCOS is a result of difficulties in induction of all pathological conditions similar to those seen in human PCOs. Two important considerations should be made that concern the development of an animal model for PCOs. Firstly, what is the main purpose of the model: study of ovarian morphology in PCOs or study of human disorders? Secondly, there is no reason (and probably even a possibility) for creation of an "universal" PCOS animal model. The multifactorial etiology of the syndrome justifies such a point. Depending on what PCOS-related disorder is investigated, the most suitable animal model should be used.