The galactose-specific receptor system in rat liver during development

Development ◽  
1987 ◽  
Vol 100 (1) ◽  
pp. 13-22
Author(s):  
L. Dini ◽  
L. Conti-Devirgiliis ◽  
S. Russo-Caia
Keyword(s):  
Endothelial Cells ◽  
Ligand Binding ◽  
Rat Liver ◽  
Binding Capacity ◽  
Specific Binding ◽  
Cell Types ◽  
Receptor System ◽  
In Situ Experiments

The number and distribution of galactose-specific binding sites were investigated in rat liver cells during perinatal development. Ligand binding to hepatocytes, macrophages and endothelial cells was followed with in vitro and in situ experiments by electron microscopy, using lactosylated bovine serum albumin adsorbed onto 5 nm colloidal gold particles as ligand. Binding capacity, starting at a late stage of fetal development, is very low both on the hepatocyte and on the macrophage surface, which show single particles statistically distributed. By contrast, bound particles are absent from fetal endothelial cells, which also lack the typical coated regions. In vivo, experiments at 37 degrees C show that endocytosis occurs to some extent in prenatal life. These results indicate that the expression of galactose-specific receptors' activity on the different liver cell types follows different developmental patterns, which are independently modulated.

scholarly journals Studies in vitro on the uptake and degradation of sodium hyaluronate in rat liver endothelial cells

1984 ◽  
Vol 223 (3) ◽  
pp. 617-626 ◽  
Author(s):  
B Smedsrød ◽  
H Pertoft ◽  
S Eriksson ◽  
J R E Fraser ◽  
T C Laurent
Keyword(s):  
Endothelial Cells ◽  
Rat Liver ◽  
Degradation Products ◽  
Binding Capacity ◽  
Primary Cultures ◽  
Sodium Hyaluronate ◽  
Physiological Concentration ◽  
Liver Endothelial Cells

Rat liver endothelial cells in primary cultures at 7 degrees C bind radioactively labelled sodium hyaluronate (HA; Mr 400 000) specifically and with high affinity (Kd = 6 × 10(-11) M). Maximal binding capacity is approx. 10(4) molecules per cell. Inhibition experiments with unlabelled HA and oligosaccharides from HA indicate that each molecule is bound by several receptors acting co-operatively and that the single receptor recognizes a tetra- or hexa-saccharide sequence of the polysaccharide. At 37 degrees C the liver endothelial cells endocytose the HA. The process combines the features of a receptor-mediated and a fluid-phase endocytosis. The rate of internalization does not show any saturation with increasing HA concentration, but is approximately proportional to the polysaccharide concentration at and above the physiological concentration. At 50 micrograms of free HA/l each liver endothelial cell accumulates 0.1 fg of the polysaccharide/min. Fluorescent HA accumulates in perinuclear granules, presumably lysosomes. Degradation products from HA appear in the medium about 30 min after addition of the polysaccharide to the cultures. The radioactivity from HA containing N-[3H]acetyl groups or 14C in the sugar rings is recovered mainly as [3H]acetate and [14C]acetate respectively. Estimations of the capacity of liver endothelial cells to internalize and degrade HA in vitro indicate that these cells may be primarily responsible for the clearance of HA from human blood in vivo.

The mechanism of low molecular weight heparin (LMWH) inhibition of tumor growth

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 13093-13093 ◽  
Author(s):  
S. L. Smiley ◽  
D. O. Henry ◽  
M. K. Wong
Keyword(s):  
Endothelial Cells ◽  
Tumor Growth ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Receptor System ◽  
Fgf Receptor ◽  
Tumor Inhibition ◽  
Inhibition Of Tumor Growth

13093 Background: Clinical studies show that LMWHs improve survival in cancer patients. There is compelling and mounting evidence that non-anticoagulation factors are at play, and that these may be contributing in a major way to improved patient outcome. Methods and Results: Dalteparin, enoxaparin, and tinzaparin were tested for their in vivo ability to inhibit tumor lines engineered for aggressive angiogenesis-driven growth. Therapeutic daily doses of drug administered the day following tumor inoculation resulted in significant angiogenesis and tumor inhibition. We previously showed that LMWHs inhibit fibroblast growth factor (FGF) -induced mitogenesis of Tumor Derived Endothelial Cells (TDECs) in a time and concentration dependent manner in vitro. We now show that this endothelial inhibition occurs through LMWHs-mediated reduction of phosphorylation and down stream signaling through ERK. The potency of LMWH was significantly reduced when TDECs were pretreated with heparinase- suggesting that the molecular target for LMWH may be the cell surface, low affinity FGF receptor system. Both our in vivo and in vitro studies demonstrate that angiogenesis and tumor inhibition are greatest for dalteparin > tinzaparin > enoxaparin. Clues to the heparin-TDECs interaction comes from tracking the real-time movement of FGF using a highly fluorescent nanocrystal bead decorated on its surface with FGF. High resolution video-microscopy shows FGF binding onto TDEC surfaces, but once heparin enters the environment, FGF detaches from the TDECs and migrates to the heparin. This ultimately results in significant TDEC growth inhibition as compared to controls. Conclusion: LMWH treatment at pharmacologic doses significantly blunts tumor growth and angiogenesis. This inhibition resides in part via heparin’s ability to sequester FGF from the low affinity receptor system on tumor endothelial cells. No significant financial relationships to disclose.

Controlled Adipose-derived Stromal Cells Differentiation into Adipose and Endothelial Cells in a 3D Structure Established by Cell-assembly Technique

2009 ◽  
Vol 24 (1_suppl) ◽  
pp. 31-47 ◽  
Author(s):  
Mingen Xu ◽  
Yongnian Van ◽  
Haixia Liu ◽  
Rui Yag ◽  
Xiaohong Wang
Keyword(s):  
Endothelial Cells ◽  
3D Structure ◽  
Spherical Shape ◽  
Cell Types ◽  
Tissue Growth ◽  
Cell Assembly ◽  
Adipose Tissue Engineering ◽  
Assembly Technique

One of the major obstacles in engineering thick and complex tissues while vascularizing tissues in vitro is to maintain cell viability during tissue growth and structural organization. Adipose-derived stromal (ADS) cells were used to establish a multicellular system through a cell-assembly technique. Attempts were made to control ADS cells differentiation into different targeted cell types according to their positions within an orderly 3D structure. Oil red 0 staining confirmed that the ADS cells in the structure differentiated into adipocytes with a spherical shape while immunostaining tests confirmed that the endothelial growth factor induced ADS cells on the walls of channels differentiated into mature endothelial cells and then organized into tubular structures throughout the engineered 3D structure. The endothelin-1 and nitric oxide release rules of the endothelial cells were coincidental with those in vivo. This study provides a new approach to engineer orderly endothelial vessel networks in vitro and has potential applications in adipose-tissue engineering.

Receptor-mediated clearance of G-CSF derivative nartograstim in bone marrow of rats

1995 ◽  
Vol 269 (1) ◽  
pp. E1-E9 ◽  
Author(s):  
T. Kuwabara ◽  
T. Uchimura ◽  
H. Kobayashi ◽  
S. Kobayashi ◽  
Y. Sugiyama
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Binding Capacity ◽  
Specific Binding ◽  
Maximal Velocity ◽  
Rate Dependent ◽  
Elimination Mechanism ◽  
Total Body

To clarify the role of the granulocyte colony-stimulating factor (G-CSF) receptor in the nonlinear elimination of a recombinant human G-CSF derivative, nartograstim (NTG), the accompanying changes in the in vivo NTG total body clearance at steady state (CLss) or the early-phase tissue uptake clearance (CLuptake) in rats were compared with the change in the number of G-CSF receptors in bone marrow. The infusion rate-dependent decrease in CLss in control rats confirmed the existence of a saturable elimination mechanism for NTG. The Michaelis-Menten constant (Km) and maximal velocity for this saturable process were estimated to be 107 pM and 15.5 pmol.h-1.kg-1, respectively. The Km for this saturable process was comparable with the dissociation constant (Kd) for the specific binding of NTG to bone marrow cells. After administration of excess NTG, the CLuptake of tracer amounts of 1251-NTG by bone marrow and spleen, which corresponds to the receptor density in the tissues, was reduced at 2 h but gradually recovered. This change in CLuptake corresponds well to the change in the in vitro NTG-binding capacity in each isolated cell. This reduction in CLuptake might be due to the downregulation of G-CSF receptors on the cell surface. On the other hand, the saturable CLss in cyclophosphamide-treated rats was 17% of that in control rats, whereas the saturable CLss in rats given NTG repeatedly was twofold greater than in controls, which is associated with the upregulation of G-CSF receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of inducible nitric oxide synthase in the regulation of leucocyte recruitment

2000 ◽  
Vol 100 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Michael J. HICKEY
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Nitric Oxide Synthase ◽  
Cell Types ◽  
Adhesive Interactions ◽  
Oxide Synthase ◽  
Leucocyte Recruitment

Constitutively produced nitric oxide released by endothelial cells has been shown to act as an endogenous agent which inhibits the rolling and adhesion of leucocytes in the microcirculation. However, during various types of inflammation, expression of the inducible form of nitric oxide synthase (iNOS) can dramatically increase the amount of nitric oxide present in tissues. Furthermore, as iNOS can be expressed by a wide variety of cell types, the distribution of nitric oxide is likely to be altered relative to that in unstimulated tissue. Under these conditions, it is less well understood whether iNOS-derived nitric oxide retains the anti-adhesive capabilities of constitutively produced nitric oxide. This review summarizes work done to examine this issue. Three main approaches have been used. In vitro studies have examined the role of iNOS in adhesive interactions between stimulated endothelial cells and leucocytes, providing evidence of an anti-adhesive effect of iNOS. In addition, the role of iNOS has been examined in vivo in animal models of inflammation using pharmacological iNOS inhibitors. These experiments were extended by the advent of the iNOS-deficient (iNOS-/-) mouse. Intravital microscopy studies of these mice have indicated that, under conditions of low-dose endotoxaemia, iNOS-derived nitric oxide can inhibit leucocyte rolling and adhesion. The potential mechanisms for these effects are discussed. In contrast, several other studies have observed either no effect or an enhancing effect of iNOS on inflammatory leucocyte recruitment. Taken together, these studies suggest that the importance of iNOS in modulating leucocyte recruitment can vary according to the type of inflammatory response.

Origin and diversity of embryonic endothelium/endocardium

2018 ◽  
Author(s):  
LeShana SaintJean ◽  
H.S. Baldwin
Keyword(s):  
Endothelial Cells ◽  
Heart Development ◽  
Vascular Endothelial Cells ◽  
Coronary Vessels ◽  
Cell Types ◽  
Genetic Profile ◽  
Vascular Endothelial ◽  
Tremendous Progress

The endocardium represents a distinct population of endothelial cells that arises during the initiation of heart development. Endocardial cells can easily be distinguished from most of the other cardiac cell types. However, endocardial and vascular endothelial cells contain a similar genetic profile that limits the ability to study each group independently. Despite these limitations, tremendous progress has been made in identifying the different roles of endocardial cells throughout heart development. Initial studies focused on the origin of endocardial cells and their role in valvulogenesis, trabeculation, and formation of the ventricular and atrial septum. With the advancement of microscopy and the availability of endocardial specific reporter models (in vitro and in vivo) we have obtained more insight into the molecular, structural, and functional complexity of the endocardium. Additional studies have demonstrated how the endocardium is also involved in the development of coronary vessels within the compact myocardium and in heart regeneration.

scholarly journals Utilizing a Kidney-Targeting Peptide to Improve Renal Deposition of a Pro-Angiogenic Protein Biopolymer

Pharmaceutics ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 542 ◽  
Author(s):  
Fakhri Mahdi ◽  
Alejandro R. Chade ◽  
Gene L. Bidwell
Keyword(s):  
Endothelial Cells ◽  
Cell Types ◽  
Endothelial Cell Proliferation ◽  
Microvascular Endothelial Cell ◽  
Similar Distribution ◽  
Target Tissue ◽  
Cell Binding ◽  
Targeting Peptide

Elastin-like polypeptides (ELP) are versatile protein biopolymers used in drug delivery due to their modular nature, allowing fusion of therapeutics and targeting agents. We previously developed an ELP fusion with vascular endothelial growth factor (VEGF) and demonstrated its therapeutic efficacy in translational swine models of renovascular disease and chronic kidney disease. The goal of the current work was to refine renal targeting and reduce off-target tissue deposition of ELP–VEGF. The ELP–VEGF fusion protein was modified by adding a kidney-targeting peptide (KTP) to the N-terminus. All control proteins (ELP, KTP–ELP, ELP–VEGF, and KTP–ELP–VEGF) were also produced to thoroughly assess the effects of each domain on in vitro cell binding and activity and in vivo pharmacokinetics and biodistribution. KTP–ELP–VEGF was equipotent to ELP–VEGF and free VEGF in vitro in the stimulation of primary glomerular microvascular endothelial cell proliferation, tube formation, and extracellular matrix invasion. The contribution of each region of the KTP–ELP–VEGF protein to the cell binding specificity was assayed in primary human renal endothelial cells, tubular epithelial cells, and podocytes, demonstrating that the VEGF domain induced binding to endothelial cells and the KTP domain increased binding to all renal cell types. The pharmacokinetics and biodistribution of KTP–ELP–VEGF and all control proteins were determined in SKH-1 Elite hairless mice. The addition of KTP to ELP slowed its in vivo clearance and increased its renal deposition. Furthermore, addition of KTP redirected ELP–VEGF, which was found at high levels in the liver, to the kidney. Intrarenal histology showed similar distribution of all proteins, with high levels in blood vessels and tubules. The VEGF-containing proteins also accumulated in punctate foci in the glomeruli. These studies provide a thorough characterization of the effects of a kidney-targeting peptide and an active cytokine on the biodistribution of these novel biologics. Furthermore, they demonstrate that renal specificity of a proven therapeutic can be improved using a targeting peptide.

Abstract 376: Downregulation of Endogenous Apelinergic Axis Mediates Endothelial and Organismal Senescence

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Rahul Rai ◽  
Asish K Ghosh ◽  
Layton H Smith ◽  
Douglas E Vaughan
Keyword(s):  
Endothelial Cells ◽  
Replicative Senescence ◽  
Cell Types ◽  
Ang Ii ◽  
Systematic Assessment ◽  
Multiple Cell ◽  
Deficient Mice

Background: Apelinergic signaling is a recently discovered GPCR mediated pathway. Endothelial cells are the main source of endogenous apelin (apln) while apelin receptor (aplnr) is present on multiple cell types. Since the role of endogenous apelinergic pathway within the context of senescence is largely unknown, we ask if levels of apln- aplnr vary with aging. We also investigate the effects of downregulated apln- aplnr on cellular and organismal aging. Approach and Results: To assess variations in endogenous apln- aplnr with aging, we compared their levels in 1 month (young) and 1 year old (old) WT mice. We noticed significant downregulation of apln- aplnr with chronological senescence in multiple tissues. Expression of apelin was also reduced with replicative senescence of endothelial cells. L-NAME administration, a model of stress induced senescence, also repressed aortic and cardiac apln. To address the mechanism involved in downregulation of apln- aplnr, we administered young wild type mice with Ang II. After a week of Ang II, there was significant downregulation of aortic apln and aplnr. Ang II and TGF-β also repressed apln and aplnr in vitro . Next we investigated the effects of downregulated apln on endothelial cells. In response to shRNA mediated apelin knockdown, cells exhibited slower proliferation and upregulated senescence associated markers. We observed similar results when endothelial aplnr was blocked with an antagonist, ML221. In addition, apln and aplnr deficient mice also exhibited features of cardiovascular aging, including ventricular hypertrophy and lower EF. Importantly, aplnr deficient mice at eight months of age were also hypertensive. Conclusion: We provide a systematic assessment of senescence associated variation in levels of apln- aplnr. We demonstrate the role of Ang II- TGF-β axis in downregulating apln- aplnr during chronological and stress induced senescence in vivo and in vitro . We propose a novel model of Ang II- TGF-β induced senescence. Where in, with aging Ang II and TGF-β repress endogenous apln- aplnr. Downregulation of endogenous apln- aplnr axis decreases beneficial “youthful” effects of apelin, resulting in endothelial dysfunction and accelerated organismal aging.

scholarly journals Endocytosis of ricin by rat liver cells in vivo and in vitro is mainly mediated by mannose receptors on sinusoidal endothelial cells

1993 ◽  
Vol 291 (3) ◽  
pp. 749-755 ◽  
Author(s):  
S Magnússon ◽  
T Berg
Keyword(s):  
Endothelial Cells ◽  
Mannose Receptor ◽  
Cell Types ◽  
Plant Toxin ◽  
Sinusoidal Endothelial Cells ◽  
Liver Uptake ◽  
Parenchymal Cells ◽  
Mannose Receptors

Upon intravenous injection into rats, the plant toxin ricin was rapidly cleared from the circulation by the liver. Among the different liver cell populations, most of the injected ricin associated with the sinusoidal endothelial cells (EC), whereas the liver parenchymal cells (PC) and Kupffer cells (KC) yielded minor contributions to the total liver uptake in vivo. Co-injection of mannan strongly inhibited ricin uptake by the EC, showing that it was mediated by mannose receptors. On the other hand, co-injection of lactose, which inhibits the galactose-specific association of ricin with cells, enhanced ricin uptake by the EC. The carbohydrate-dependency of the EC contribution to the uptake of ricin in vivo was reflected in the carbohydrate-dependency of the uptake in vivo by whole liver. In vitro, the EC also endocytosed ricin more efficiently than did the PC or KC. Whereas uptake in vitro in the EC was mainly mannose-specific, uptake in the two other cell types was mainly galactose-specific. Western blotting showed that the mannose receptors of liver non-parenchymal cells are identical with the mannose receptor previously isolated from alveolar macrophages. The mannose receptors are expressed at a higher level in EC than in KC. Ligand blotting showed that, in the presence of lactose, the mannose receptor is the only protein in the EC that binds ricin, and the binding is mannose-specific and Ca(2+)-dependent.

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