IFATS collection: Identification of hemangioblasts in the adult human adipose tissue.

The stromal-vascular fraction (SVF) of human adipose tissue contains, among other cell types, mesenchymal stem cells and precursors of adipocyte and endothelial cells. Here we show that, in addition, the nonhematopoietic fraction of the SVF has hematopoietic activity, since all types of hematopoietic colony-forming units (CFUs) developed when cultured in methylcellulose-based medium. This hematopoietic activity was restricted to the CD45(-)CD105(+) cell subset, well correlated with KDR(+) cell content, and increased after culture with a combination of early-acting hematopoietic cytokines.

Human platelet lysate enhances the proliferative activity of cultured human fibroblast-like cells from different tissues.

Several studies have shown the presence of fibroblast-like cells in the stromal fraction of different tissues with a high proliferative and differentiation potential. Platelet alpha granules contain growth factors released into the environment during activation. The effects of different supplements for culture medium (human serum, bovine serum and platelet lysate) on cultured human fibroblast-like cells from bone marrow, adipose tissue, trabecular bone and dental pulp have been compared.

The functional immaturity of dendritic cells can be relevant to increased tolerance associated with cord blood transplantation.

Background: Cord blood (CB) transplants have a significantly lower incidence of graft-versus-host disease (GVHD) compared to marrow or peripheral blood transplants. Because antigen-presenting cells and regulatory T cells (Treg) are involved in transplant tolerance, this study was aimed at analyzing the distribution of dendritic cells (DCs) and CD14+ monocyte-specific subsets in CB and adult peripheral blood (APB) and comparing the ability of DCs from these two blood sources to induce CD4+ Treg.

Study Design And Methods: Myeloid DCs (mDCs), plasmacytoid DCs, the CD14+ cell subsets CD14+CD16+ and CD14+CD209+, and CD4+ T cells were analyzed by fluorescence-activated cell sorting (FACS) in whole blood.

Selective generation of different dendritic cell precursors from CD34+ cells by interleukin-6 and interleukin-3.

There is a growing interest in generating dendritic cells (DCs) for using as vaccines. Several cytokines, especially stem cell factor (SCF) and FLT3-ligand (FL), have been identified as essential to produce large numbers of myeloid precursors and even to increase DC yield obtained by the action of granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor alpha (TNF-alpha). However, there are few studies on the effect of the early-acting cytokines, commonly used to expand CD34+ progenitor cells, on DC generation.

IL-6 precludes the differentiation induced by IL-3 on expansion of CD34+ cells from cord blood.

Background And Objectives: Ex vivo expansion of hematopoietic progenitor cells (HPC) from umbilical cord blood (UCB) is an interesting strategy to obtain a sufficient number of transplantable cells for adults. To define the optimal culture conditions allowing the generation of HPC that retain their proliferative capacity without loss of long-term culture-initiating cells (LTC-IC), the effect of different cytokine combinations on the expansion of CD34+ cells from UCB was assessed.

Design And Methods: CD34+ cells were cultured in serum-free culture medium with four cytokine combinations: stem cell factor plus thrombopoietin plus flk2/flt3 ligand (STF), STF plus interleukin-3 (IL-3), STF plus interleukin-6 (IL-6) and STF plus IL-6 plus IL-3.

CD34+CD38- is a good predictive marker of cloning ability and expansion potential of CD34+ cord blood cells.

Background: Ex vivo expansion of HPCs is an attractive approach to overcoming the current limitations of human cord blood transplantation. It is important not only to define the optimal culture conditions but also to know the number of progenitor cells that can be obtained. CD34+ cells have a great variability in their cloning capacity and in their ability to expand HPCs.

Different sensitivity of isoprenaline-induced responses in ventricular muscle to sodium nitroprusside in normotensive and spontaneously hypertensive rats.

1. The aim of the present work was to study the possible modulatory role of nitric oxide (NO) on the positive inotropic effect induced by the beta-adrenoceptor agonist isoprenaline in myocardial contractility, and whether this modulation is altered by hypertension. 2.

Changes of cardiac calcium homeostasis in spontaneously hypertensive rats.

The aim of the present study was to assess the alterations in cardiac Ca2+ homeostasis induced by hypertension using electrically paced right ventricular strips from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). 2 Basal contractile force was higher in SHR than in WKY. Similarly, the beta-adrenoceptor agonist isoprenaline (10 nM-10 microM) induced a concentration-dependent positive inotropic effect that was higher in SHR than in WKY, which was in turn inhibited by the beta-adrenoceptor antagonist propranolol (1 microM) in both strains.

Role of K+ channels and sodium pump in the vasodilation induced by acetylcholine, nitric oxide, and cyclic GMP in the rabbit aorta.

The endothelium-dependent relaxation caused by acetylcholine (ACh) in rabbit aorta segments was reduced by the nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine methyl ester and by blockade of: Na+ pump with ouabain, large-conductance Ca2+-activated K+ (BK(Ca)) channels with charybdotoxin (ChTx), or voltage-dependent K+ (Kv) channels with 4-aminopyridine (4-AP). ACh relaxation was unaltered by glibenclamide, apamin, and Ba2+, blockers of ATP-sensitive K+ channels, small-conductance Ca2+-activated K+ channels, and inward rectifier K+ channels, respectively. The relaxation induced by exogenous NO and 8-bromocyclic GMP (8-BrcGMP) was similar in intact and endothelium-denuded segments, and it was reduced or unaltered by the same drugs used in the case of ACh.

Mechanisms involved in the cellular calcium homeostasis in vascular smooth muscle: calcium pumps.

The regulation of cytosolic Ca2+ homeostasis is essential for cells, and particularly for vascular smooth muscle cells. In this regulation, there is a participation of different factors and mechanisms situated at different levels in the cell, among them Ca2+ pumps play an important role. Thus, Ca2+ pump, to extrude Ca2+; Na+/Ca2+ exchanger; and different Ca2+ channels for Ca2+ entry are placed in the plasma membrane.

The cardiac acetylcholine-activated, inwardly rectifying K+-channel subunit GIRK1 gives rise to an inward current induced by free oxygen radicals.

Reactive oxygen species (ROS) play a crucial role in pathophysiology of the cardiovascular system. The present study was designed to analyze the redox sensitivity of G-protein-activated inward rectifier K+ (GIRK) channels, which control cardiac contractility and excitability. GIRK1 subunits were heterologously expressed in Xenopus laevis oocytes and the resulting K+ currents were measured with the two-electrode voltage clamp technique.

Involvement of protein kinase C in the supersensitivity to 5-HT caused by oxidized low-density lipoproteins.

The effect of native (n-LDL) and oxidized (ox-LDL) low-density lipoproteins and lysophosphatidylcholines (LPCs) on: (1) vasodilator responses induced by acetylcholine (ACh) in intact rabbit aorta segments, and (2) vasoconstrictor responses to serotonin (5-HT), and potassium (K+) in endothelium denuded segments was investigated. In intact vessels, 100 microg/ml ox-LDL did not modify ACh-induced relaxation, while it was diminished by 300 microg/ml ox-LDL and abolished by 50 microM LPCs. In contrast, this relaxation was unaltered by n-LDL (100 or 300 microg/ml).

Effect of clenbuterol on the modulation of noradrenaline release in the rat tail artery.

1. Exposure of rat tail arteries to clenbuterol, a beta 2-adrenoceptor agonist, for 20 or 90 min, did not change or increase, respectively, tritium overflow induced by electrical field stimulation in arteries preincubated with [3H]-noradrenaline (NA). This facilitatory effect was antagonized by propranolol.

Inhibition of a store-operated Ca2+ entry pathway in human endothelial cells by the isoquinoline derivative LOE 908.

1. The novel cation channel blocker, LOE 908, was tested for its effects on Ca2+ entry and membrane currents activated by depletion of intracellular Ca2+ stores in human endothelial cells. 2.

Heterogeneity of endothelium-dependent mechanisms in different rabbit arteries.

The possible endothelial factors involved in endothelium-dependent relaxations induced by acetylcholine (ACh) in aorta, mesenteric and femoral arteries of rabbit were analyzed. In thoracic aorta precontracted with noradrenaline, NG-nitro-L-arginine methyl ester (L-NAME) and methylene blue (MB), inhibitors of nitric oxide (NO) synthase and guanylate cyclase, practically abolished ACh relaxation. This relaxation was reduced by the Na+ pump inhibition with ouabain and K(+)-free solution, and by the blockade of Ca(2+)-dependent K+ channels with tetraethylammonium (TEA).

Angiotensin modulation of vascular tone and adrenergic neurotransmission in cat femoral arteries.

1. AI and AII induced contractions in cat femoral arteries, which were inhibited by saralasin. 2.

Treatment with the anabolic steroid, nandrolone, reduces vasoconstrictor responses in rabbit arteries.

The objective of this study was to analyze the effect of chronic treatment of rabbits for 4, 8 and 12 weeks with the anabolic steroid, nandrolone, on the contractile responses induced by different agents in segments of thoracic aorta and mesenteric and femoral arteries. In the three types of arteries, the contractions elicited by noradrenaline, 5-hydroxytryptamine and angiotensin II were increased by endothelium removal. The treatment reduced the contractions elicited by the three agents (mainly those caused by 5-hydroxytryptamine) in aorta, and only those caused by 5-hydroxytryptamine in mesenteric arteries.

Chronic treatment with the anabolic steroid, nandrolone, inhibits vasodilator responses in rabbit aorta.

The effect of chronic treatment of rabbits for 4, 8 and 12 weeks with the anabolic steroid, nandrolone, on vasodilator responses was studied in segments of different arteries. The treatment abolished endothelium-dependent relaxation caused by acetylcholine and the Ca(2+)-ionophore, A23187, in thoracic aorta, and reduced endothelium-independent relaxations induced by exogenous nitric oxide (NO) or sodium nitroprusside. The inhibitor of NO synthesis, NG-monomethyl-L-arginine, abolished vasodilator responses to acetylcholine and A23187.

Phorbol dibutyrate induces contractions in bovine cerebral arteries by an extracellular calcium-independent mechanism.

The aim of the present study was to analyse the ability of phorbol 12,13-dibutyrate (PDB) to activate protein kinase C (PKC), measured by its capacity to translocate the enzyme from the cytosol to the membrane fraction, as well as to induce vasconstrictive responses in segments from branches of bovine cerebral arteries. PDB (0.1 microM) produced a marked translocation of PKC activity from the cytosolic to the membranous fraction.

Comparison of the vasoconstrictor responses induced by endothelin and phorbol 12,13-dibutyrate in bovine cerebral arteries.

The vascular effects of endothelin-1 (ET-1) were compared with those elicited by phorbol 12,13-dibutyrate (PDB), an activator of the protein kinase C (PKC), to analyze the involvement of this enzyme on ET-1 responses. PDB and ET-1 caused slow-developing contractions (sustained and transient, respectively), which were reduced by the PKC inhibitor, staurosporine (1 and 10 nM). Only the contractile effects evoked by ET-1 were reduced in Ca-free medium and by the Ca channel antagonist, nifedipine (1 microM), and increased by the Ca channel agonist, BAY K 8644 (10 nM).

Vasoconstrictive effects of angiotensin I and II in cat femoral arteries. Role of endothelium.

1. AI and AII induced concentration-dependent contractions in cat femoral artery segments, the potency of AII being greater than that of AI. 2.

Vasoconstrictive responses elicited by endothelin in bovine cerebral arteries.

1. Endothelin (ET-1) induced concentration-dependent contractions, which were slowly developed in segments of bovine cerebral arteries. Furthermore, this agent produced tachyphylaxis.