Normal Vascular Endothelial Cells Research Articles

Short-chain fatty acids and trichostatin A alter tight junction permeability in human umbilical vein endothelial cells

Objective The short-chain fatty acids (SCFAs), butyrate, propionate, and acetate, produced by bacterial fermentation of dietary fiber, can modulate the transcription of certain genes by inhibiting histone deacetylase in colonocytes and several other cell types in vitro. We previously reported that butyrate decreases tight junction permeability by activating lipoxygenase (LOX) in intestinal monolayer cells. In the present study, we evaluated the effects of SCFAs on tight junction permeability in an endothelial cell culture and their possible mechanisms of action via histone deacetylase inhibitor activity. We also investigated the factors modulating tight junction permeability. Methods The effects of butyrate, propionate, and acetate on tight junction permeability in human umbilical vein endothelial cells were examined using Transwell chamber cultures. The contributions of inducible nitric oxide synthase (NOS), endothelial NOS, estrogen receptor, cyclo-oxygenase, and LOX to SCFAs' effects were also evaluated. The effects of SCFAs were compared with those of trichostatin A, a typical histone deacetylase inhibitor. Results Low concentrations of butyrate and propionate decreased paracellular permeability without inducing cell damage. However, acetate decreased paracellular permeability in a concentration-dependent manner. An estrogen receptor antagonist attenuated the effects of SCFAs on tight junction permeability. The influences of inducible NOS, cyclo-oxygenase, and LOX inhibitors and the expressions of cyclo-oxygenase and LOX mRNAs were different for each SCFA. Trichostatin A slightly decreased paracellular permeability when used at lower concentrations, but higher concentrations of trichostatin A increased permeability. Conclusion The SCFAs play an important role in the assembly of tight junctions in normal vascular endothelial cells.

Adrenomedullin stimulates angiogenic response in cultured human vascular endothelial cells: Involvement of the vascular endothelial growth factor receptor 2

In recent years, evidence has accumulated that many endogenous peptides play an important regulatory role in angiogenesis by modulating endothelial cell behavior. Adrenomedullin (AM), one such factor, was previously shown to exert a clearcut proangiogenic effect in vitro when tested on specialized human endothelial cells, such as HUVECs and immortalized endothelial cell lines. In the present study we used normal adult vascular endothelial cells isolated from human saphenous vein to analyze in vitro the role of AM, related to both early (increased cell proliferation) and late (differentiation and self-organization into capillary-like structures) angiogenic events and their relationship with the vascular endothelial growth factor (VEGF) signaling cascade. The results indicated that also in this endothelial cell phenotype AM promoted cell proliferation and differentiation into cord-like structures. These actions resulted specific and were mediated by the binding of AM to its AM1 (CRLR/RAMP2) receptor. Neither the administration of a VEGF receptor 2 (VEGFR-2) antagonist nor the downregulation of VEGF production by gene silencing were able to suppress the proangiogenic effect of AM. However, when the experiments were performed in the presence of SU5416 (a selective inhibitor of the VEGFR-2 receptor at the level of the intra-cellular tyrosine kinase domain) the proangiogenic effect of AM was abolished. This result suggests that in vascular endothelial cells the binding of AM to its AM1 receptor could trigger a transactivation of the VEGFR-2 receptor, leading to a signaling cascade inducing proangiogenic events in the cells.

Chemokine SR-PSOX/CXCL16 expression in peripheral blood of patients with acute coronary syndrome

Scavenger receptor that binds phosphatidylserine and oxidized lipoprotein/CXC chemokine ligand 16 (SR-PSOX/CXCL16) promotes foam cell formation through the tumor necrosis factor (TNF)-alpha mediated mechanism. Because chemokine CXCL16 could be expressed in atherosclerotic lesions and induce smooth muscle cell (SMC) proliferation, we presume that the monocyte SR-PSOX/CXCL16 detection in the patients' peripheral blood will be important for early diagnosis and prognosis of atherosclerosis (AS). Enrolled in this study were 40 patients with acute coronary syndrome (ACS), including 20 patients with acute myocardial infarction (AMI) and 20 patients with unstable angina pectoris (UAP), and 20 normal controls. Monocytes in the peripheral blood were isolated, and the changes of expression of CXCL16/SR-PSOX mRNA were compared using reverse transcription-polymerase chain reaction (RT-PCR), with beta-actin as internal control. We compared the expression of CXCL16/SR-PSOX in the ACS subgroups, using Western-blot to analyze protein expression levels. Tissue sections were made from biopsy specimens taken from patients with infective endocarditis, liver cirrhosis, and lung cancer as well as normal controls. And the expression of CXCL16/SR-PSOX was analyzed with a confocal microscope. The expression of CXCL16/SR-PSOX mRNA and protein in the monocytes of peripheral blood was significantly higher in ACS patients than in normal controls (P < 0.05); however, there was no significant difference in CXCL16/SR-PSOX expression between UAP group and AMI group (P > 0.05). Immunofluorescence showed that there were low expression of SR-PSOX in normal vascular endothelial cells and enhanced expression in every layer of the infected vessels, while spreading from endothelial cells to surrounding tissues as infection worsens. Confocal microscopy showed that the expression of SR-PSOX was enhanced in the infiltrated lymphocytes in liver cirrhosis, and that the expression level was proportionate to the degree of inflammation in the portal hepatis and folia. The expression of CXCL16/SR-PSOX in the monocytes of peripheral blood was significantly higher in ACS patients than in the controls. CXCL16/SR-PSOX-mediated inflammation may contribute to the pathogenesis of ACS, and CXCL16 may play an important role in the pathogenesis and development of AS in humans.

Targeting tissue factor-expressing tumor angiogenesis and tumors with EF24 conjugated to factor VIIa

Tissue factor (TF) is aberrantly expressed on tumor vascular endothelial cells (VECs) and on cancer cells in many malignant tumors, but not on normal VECs, making it a promising target for cancer therapy. As a transmembrane receptor for coagulation factor VIIa (fVIIa), TF forms a high-affinity complex with its cognate ligand, which is subsequently internalized through receptor-mediated endocytosis. Accordingly, we developed a method for selectively delivering EF24, a potent synthetic curcumin analog, to TF-expressing tumor vasculature and tumors using fVIIa as a drug carrier. EF24 was chemically conjugated to fVIIa through a tripeptide-chloromethyl ketone. After binding to TF-expressing targets by fVIIa, EF24 will be endocytosed along with the drug carrier and will exert its cytotoxicity. Our results showed that the conjugate inhibits vascular endothelial growth factor-induced angiogenesis in a rabbit cornea model and in a Matrigel model in athymic nude mice. The conjugate-induced apoptosis in tumor cells and significantly reduced tumor size in human breast cancer xenografts in athymic nude mice as compared with the unconjugated EF24. By conjugating potent drugs to fVIIa, this targeted drug delivery system has the potential to enhance therapeutic efficacy, while reducing toxic side effects. It may also prove to be useful for treating drug-resistant tumors and micro-metastases in addition to primary tumors.

Immunohistochemical Analysis of Cellular Prion Protein Expression on Vascular Endothelial Cells.

The majority of the cellular prion protein (PrPc), the normal counterpart of the putative infectious agent of variant Creutzfeldt-Jakob (vCJD) disease, present in human blood is associated with the plasma compartment. But the source of this ‘soluble' prion protein is unclear. Based on the results of in-vitro experiments using cultured umbilical cord or adult vascular endothelial cells, some investigators have suggested that vascular endothelial cells may be an important source of plasma PrPc. Our previous immunohistochemical studies using tissue specimens obtained from healthy individuals and a monoclonal antibody to PrP (3F4 recognising an epitope between aminoacids 109–111 of the protein), however, have shown that normal vascular endothelial cells exhibit minimal or no expression of this protein. Our finding has raised an important question whether the lack of expression seen with the above antibody may be a result of truncation of PrPc in tissues resulting in removal of 3F4-binding site. In order to establish the true nature of prion protein expression on normal, unstimulated, unmanipulated endothelial cells, we have extended the study using seven antibodies that recognise different domains, spanning the whole human PrP protein molecule. Antibodies against epitopes 23–85 (FH11 & BG4), 63–99 (BE12), 79–97 (AHP498T, CD230), 109–112 (3F4), 140–180 (KG9 & DF7) were chosen for the study. Institutional and Local Research Ethics Committee approvals were obtained for this study. Formalin fixed, paraffin- embedded tissue blocks from normal human umbilical cord (12), aorta (4), saphenous vein (4), kidney (1) and cerebrum (1) were selected from the tissue bank at Peterborough District Hospital, United Kingdom. Cerebral tissue and a platelet ‘clot' prepared from pooled normal platelet concentrates were used as positive controls for PrPc expression. Sections of normal kidney were included as positive control for antibody QBEND10 which was used to demonstrate endothelial cells. Tissue sections from all cases were studied with haematoxylin and eosin (H&E) and immunohistochemistry (avidin-biotin horseradish peroxidase technique) using above antibodies. All the sections were examined by light microscopy to assess qualitatively the presence or absence of immunostaining. The intensity of labeling was evaluated by a scoring system: W - weak immunostaining, S- strong immunostaining, and N- negative immunostaining. The results show that the monoclonal antibody QBEND10 clearly identifies and delineates vascular endothelial cells in umbilical cord and adult blood vessels. All anti-PrPc antibodies show positive reaction, albeit to varying intensities, with cerebrum and platelets. None of the seven anti-PrP antibodies used in this study show positive reactivity with endothelial cells of umbilical cord, aorta or saphenous vein. Based on these results we conclude that normal, uncultured, unstimulated vascular endothelial cells do not express cellular prion protein in detectable quantities and, therefore, it is unlikely that vascular endothelial cell is a major source of PrPc in plasma in healthy individuals.

Nitric oxide–releasing biopolymers inhibit thrombus formation in a sheep model of arteriovenous bridge grafts

Nitric oxide (NO), produced by normal vascular endothelial cells, reduces platelet aggregation and thrombus formation. NO-releasing biopolymers have the potential to prolong vascular graft and stent patency without adverse systemic vasodilation. 5-mm polyurethane vascular grafts coated with a polymer containing the NO-donor dialkylhexanediamine diazeniumdiolate were implanted for 21 days in a sheep arteriovenous bridge-graft model. Eighty percent (4/5) of grafts coated with the NO-releasing polymer remained patent through the 21 day implantation period, compared to fifty percent (2/4) of sham-coated grafts and no (0/3) uncoated grafts. Thrombus-free surface area (+/-SEM) of explanted grafts was significantly increased in NO-donor coated grafts (98.2% +/- 0.9%) compared with sham-coated (79.2% +/- 8.6%) and uncoated (47.2% +/- 5.4%) grafts ( P = .00046). Examination of the graft surface showed no adherent thrombus or platelets and no inflammatory cell infiltration in NO-donor coated grafts, while control grafts showed adherent complex surface thrombus consisting of red blood cells in an amorphous fibrin matrix, as well as significant red blood cell and inflammatory cell infiltration into the graft wall. In this study we determined that local NO release from the luminal surface of prosthetic vascular grafts can reduce thrombus formation and prolong patency in a model of prosthetic arteriovenous bridge grafts in adult sheep. These findings may translate into improved function and improved primary patency rates in small-diameter prosthetic vascular grafts.

Synthesis of the Novel Liqustrazine Derivatives and Their Protective Effect on Injured Vascular Endothelial Cell Damaged by Hydrogen Peroxide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of the novel liqustrazine derivatives and Their protective effect on injured vascular endothelial cell damaged by hydrogen peroxide.

A series of novel 2-acyloxymethyl-3,5,6-trimethylpyrazine derivatives was designed and synthesized. Most compounds were found to be 1.5-4.5-fold higher potency than tetramethylpyrazine (TMP) in stimulating the proliferation of normal vascular endothelial cells and in protecting against hyperoxic acute injury. The most active one is the 2-nicotinoyl ester 5a exhibiting the maximum proliferation rate (P(max)) of 88.57% at the concentration of 0.1 mmol L(-1). Structure-activity relationships of these compounds were discussed.

Human Vascular Endothelial Cells Express Pattern Recognition Receptors for Fungal Glucans Which Stimulates Nuclear Factor κB Activation and Interleukin 8 Production

Fungal cell wall glucans nonspecifically stimulate various aspects of innate immunity via interaction with membrane receptors on macrophages, neutrophils, and natural killer cells. We investigated the binding of water-soluble glucans in primary cultures of normal human coronary or dermal vascular endothelial cells (VECs). Membranes from VECs exhibited saturable binding. Competition studies demonstrated the presence of at least two glucan binding sites on VECs. Glucan phosphate competed for all binding sites with a KDof 3.7 μm for coronary VECs and 11 μm for dermal VECs, respectively. Laminarin, a low molecular weight glucan, competed for 47 to 51 per cent of binding ( KD= 2.8–2.9 μm), indicating the presence of at least two binding sites. Glucan (1 μg/mL) stimulated VEC nuclear factor κB nuclear binding activity and Interleukin 8 expression—but not that of vascular endothelial growth factor—in a time-dependent manner. This is the first report of pattern recognition receptors for glucan on human VECs. It also provides the first evidence that glucans can directly modulate the functional activity of VECs by stimulating cytokine gene. These results provide new insights into the mechanisms by which the host recognizes and responds to fungal cell wall products and suggests that the response to glucans may not be confined to leukocytes.

Endothelial cells at inflammatory sites as target for therapeutic intervention.

In the course of an inflammation, vascular endothelial cells (VECs) are strongly involved in processes like leukocyte recruitment, cytokine production, and angiogenesis. Specific interference in these processes may yield great therapeutic benefit in the treatment of (chronic) inflammatory disorders. Drug targeting to VECs at inflamed sites may allow such intervention. VECs at inflamed sites represent a very well-accessible target cell population for circulating drug-targeting systems, which may also be selectively distinguished from normal VECs by the expression of several cell surface receptors involved in the inflammation. One group of specifically expressed molecules are the adhesion molecules (AMs), which have a major function in adhesion of cells to each other, to the extracellular matrix, or in the adhesion and subsequent recruitment of circulating immune cells. This review describes AMs with regard to their function in the inflammatory disease and their usefulness in functioning as a specific target receptor for drug-targeting approaches in general and with an emphasis on liposome-based drug delivery.

Expression of Vascular Endothelial Growth Factor (VEGF) and Specific Receptors (Flt-1 and Flk-1) in Rat Tongue Carcinogenesis Induced by 4-Nitroquinoline 1-Oxide.

Tongue carcinoma is one of the most common malignant neoplasms in the oral cavity. To assess the role for angiogenesis in carcinogenesis of tongue carcinoma, we performed qualitative and quantitative analyses of vascular endothelial growth factor (VEGF) and two forms of the specific receptors (VEGFRs), Flt-1 and Flk-1, in rat tongue squamous cell carcinoma induced by 4-nitroquinoline 1-oxide. In situ hybridization and immunohistochemistry revealed the colocalization of VEGF and VEGFRs mRNA signals and protein immunoreactivities, respectively in the cytoplasm of the normal epithelial cells, dysplastic cells, cancer cells, and vascular endothelial cells. Both the labeling indices of VEGF and VEGFRs in immunostained sections and the immunoreactive intensities on immunoblots for VEGF and VEGFRs disclosed a duration-dependent increase along with disease progression. An increase in the VEGF labeling index positively correlated with increases in the Ki-67 labeling index and blood vessel density. The present results suggest that angiogenesis is necessary for carcinogenesis, and that VEGF has relevance to the pathomechanism of tongue carcinoma via paracrine and autocrine mechanisms.

Keratin 1 expression in endothelia and mesenchymal tumors: An immunohistochemical analysis of normal and neoplastic tissues

Keratin polypeptides of the nonhair type, numbered 1 through 20 in the Moll catalog, are selectively expressed in normal and neoplastic tissues. Keratin 1 (K1), the highest-molecular-weight keratin (67 kd), was generally considered specific for keratinizing squamous epithelia. However, recent studies have shown that it is an integral component of the multiprotein kininogen receptor of endothelial cells. A library of formalin-fixed, paraffin-embedded tissue samples was evaluated immunohistochemically (avidin-biotin peroxidase complex method) for K1 expression using a specific monoclonal antibody (Novocastra clone 34βB4). The study group included a wide variety of normal tissues and 541 tumors of epithelial or mesenchymal derivation. The specificity of the antibody to K1 was verified in normal epithelial tissues, where the staining was essentially limited to the epidermis and Hassal corpuscles of the thymus and focally to other squamous epithelia. Among carcinomas, it was essentially limited to keratinizing squamous carcinomas. It was also regularly found in endothelial cells of normal capillaries, veins, and arteries. Capillary, cavernous, and venous hemangiomas often had endothelia with K1 positivity. Among the malignant vascular tumors, epithelioid hemangioendotheliomas were consistently positive (8 of 8). However, angiosarcomas had more variable expression (59 of 81 were positive), with well-differentiated tumors generally having greater reactivity than poorly differentiated examples. Mesenchymal tumors with K1 expression included schwannomas (10 of 16), epithelioid sarcomas (26 of 37), and synovial sarcomas (19 of 68). In the last 2 tumor types, K1 reactivity was detected in both epithelioid and spindled neoplastic populations. In addition to its specificity for keratinizing squamous epithelia, K1 can be immunohistochemically detected in normal vascular endothelial cells and a spectrum of vascular tumors. However, its expression in poorly differentiated vascular tumors is variable, suggesting that this marker is poorly conserved in highly transformed endothelia. The unexpected K1 immunoreactivity in nonvascular soft tissue tumors, such as synovial sarcoma, epithelioid sarcoma, and schwannomas, requires further study. HUM PATHOL 32:873-879. This is a US government work. There are no restrictions on its use.

Endothelial Cell Apoptosis Induced by Oxidized LDL Is Associated with the Down-regulation of the Cellular Caspase Inhibitor FLIP

Fas (CD-95/APO-1) is a death receptor that initiates an apoptotic signal when activated by its ligand, FasL. Normal vascular endothelial cells are resistant to Fas-mediated apoptosis though they express both Fas and FasL. Oxidized low density lipoprotein (OxLDL) or lysophosphatidylcholine (LPC), a major component of OxLDL, induces endothelial cell suicide by sensitizing endothelial cells to Fas-mediated apoptosis. Here, we show that endothelial cell apoptosis by OxLDL and LPC-C16:0 was dose-dependent and correlated with down-regulation of FLICE-inhibitory protein (FLIP), an intracellular caspase inhibitor. FLIP down-regulation also occurred when endothelial cells were treated with toxic doses of LPC-C18:0 or minimally modified low density lipoprotein (LDL). In contrast, FLIP was not down-regulated by native LDL, acetylated LDL, LPC-C12:0, cholesterol, or 7-ketocholesterol, which are not toxic to endothelial cells. The cytotoxicity of oxidized lipids was reversed by transfecting endothelial cells with a FLIP expression plasmid. The results demonstrate, for the first time, FLIP regulation under conditions that lead to pathological tissue destruction.

Macrophages induce apoptosis in normal cells in vivo.

It is well established that macrophages have a function in scavenging apoptotic bodies from cells undergoing programmed cell death. Here we show that macrophages can also induce apoptosis of normal cells. Using injected toxic liposomes to eliminate macrophages in the anterior chamber of the rat eye, we provide direct evidence that, in vivo, macrophages induce apoptosis in normal vascular endothelial cells during programmed capillary regression. Macrophage elimination resulted in the survival of endothelial cells that normally would die and the persistence of functional capillaries. Furthermore, replacement of eliminated macrophages with bone-marrow-derived macrophages 'rescued' lack of capillary regression. Viability of the persistent target cells was demonstrated through their lack of apoptotic morphology, expression of intracellular esterases and synthesis of DNA. These results uncover a new function for macrophages in the remodeling of tissues through the induction of programmed cell death and provide direct evidence of a key role for macrophages in capillary regression.

Effect of dibutyryl cyclic adenosine monophosphate on skeletal muscle reperfusion injury in the rat.

To clarify the action of dibutyryl cyclic adenosine monophosphate (DBcAMP) on reperfused ischemic muscle, experiments were conducted using the hindlimbs of 18 male Lewis rats. At the midportion of the thigh all tissues except for the femoral artery and vein were transected, and a route for continuous intravenous infusion was secured in a contralateral limb vein. After inducing total ischemia by clamping the femoral artery and vein with a vascular clamp for 4 h, the limb was reperfused for 1 h. Blood flow was then compared using the hydrogen gas clearance method in a group in which DBcAMP 10 mg was continuously infused from a vein in the contralateral hindlimb from 1 h prior to the induction of ischemia to 1 h after the completion of ischemia (DBcAMP group), a group in which saline was infused in the same manner (control group), and a group which was subjected to biopsy alone (biopsy group). The percent change in blood flow was significantly higher in the DBcAMP group than in the control group at 15 and 30 min after the release of the clamp. Adenosine triphosphate (ATP), phosphocreatine (PCr), and lipid peroxide (LPO) were measured in tissue samples obtained 1 h after reperfusion. Serum LPO was measured in blood samples collected at the same time. ATP values were higher in the DBcAMP group than in the control group. PCr was significantly higher in the DBcAMP group than in the control group. LPO levels in skeletal muscle tissue did not differ significantly between the DBcAMP and control groups. In contrast, serum LPO levels were significantly lower in the DBcAMP group than the control group. On morphologic analysis the control and DBcAMP groups showed normal vascular endothelial cells and absence of the 'no-reflow' phenomenon. These data confirm that in this reperfusion model the administration of DBcAMP enhances the viability of skeletal muscle cells. Moreover, mediated by an effect on vascular endothelial cells this agent is thought to be of help in mitigating the vascular endothelial cell injury occurring in acute ischemic injury. DBcAMP may be a useful agent in mitigating skeletal muscle ischemia-reperfusion injury.

INCREASED EXPRESSION OF bFGF IN CHILDREN WITH HIV ASSOCIATED HEMOLYTIC UREMIC SYNDROME (HIV-HUS). † 2193

The Hemolytic Uremic Syndrome (HUS) is characterized by hemolytic anemia, thrombocytopenia and acute renal failure. The ability of an infectious agent to injury microvascular endothelial cells is a primary requisite for the development of HUS. To investigate potential growth factors released during endothelial injury that could be implicated in the pathogenesis of HIV-HUS, we tested the ability of urine samples obtained from two patients with HIV-HUS to stimulate the growth of renal mesangial, epithelial and endothelial cells. Control samples were obtained from five HIV infected children without renal disease. Concentrated (5X) urine samples derived from children with HIV-HUS, induced normal vascular endothelial cells to acquire “spindle cell morphology ”, to proliferate, and to form tube-like structures when these cells were grown on a reconstituted basement membrane. Since bFGF has been implicated in the pathogenesis of HIV associated Kaposi's sarcoma (KS), and is known to induce these endothelial cell behaviors, we performed heparin Shepharose column chromatography. Western blot analysis performed in HIV-HUS urinary fractions eluted with 1.5 M NaCl, revealed a 18 kDA band, consistent with the presence of bFGF in the urine of both patients. By radioimmunoassay, we found increased bFGF in the plasma and urine of children with HIV-HUS. Immunohistochemistry studies using specific bFGF antibodies revealed increased expression of bFGF in renal cortex, medulla and extracellular matrix surrounding renal tubules. Renal tubular epithelial cells (RPTEc) isolated from HIV-HUS patients released bFGF into the conditioned media, and proliferate in response to bFGF. Thus, the accumulation of bFGF in the kidney of children with HIV associated HUS may be one of the mechanisms for the induction and progression of this syndrome. The ability of HIV-1 to induce endothelial cell injury and bFGF release may play a relevant role in the pathogenesis of HIV associated HUS.

Plasma membrane-dependent activation of gelatinase A in human vascular endothelial cells.

The initiation of the angiogenic process requires a locally confined and time-limited proteolysis of the basement membrane (BM) components at the site of new vessel sprout. Gelatinase A, a member of the matrix metalloproteinase family, degrades BM type IV collagen and is involved in the BM breakdown by migrating tumor cells and endothelial cells (EC). Gelatinase A is synthesized as latent proenzyme and must be activated in order to express its proteolytic activity. A plasma membrane-dependent mechanism of activation has been described for several tumor and transformed cells lines. In the present study, we show that latent (72 kD) and mature (62-59 kD) forms of gelatinase A are present in EC membrane fraction from Triton X-114 extract while only latent form is found in the cytosolic fraction. The incubation of EC membrane fraction with exogenous latent gelatinase A resulted in a significant activation giving rise to 62-59 kD mature forms. 12-O-tetradecanoylphorbol-13-acetate (TPA), a strong potentiator of angiogenesis in vitro and in vivo, increases the amount of both latent and activated forms of gelatinase A in EC membrane fraction as well as the ability of this latter fraction to activate exogenous latent gelatinase A. We show that the mRNA transcript coding for the membrane-integrated MMP, the MT-MMP, previously described as a potential gelatinase A activator in invasive tumor cells is also expressed in vascular EC and is regulated through a TPA sensitive process. This enzyme may be responsible for membrane-dependent gelatinase A activation in normal vascular EC and may therefore be a determinant in the control of BM proteolysis during angiogenesis.

Identification and Culture of Kaposi's Sarcoma-Like Spindle Cells From the Peripheral Blood of Human Immunodeficiency Virus-1–Infected Individuals and Normal Controls

We examined 26 patients with human immunodeficiency virus-1 (HIV-1)-associated Kaposi's sarcoma (KS), and 76 HIV-1-infected (HIV-1+) people without KS or uninfected (HIV-1-) controls for the presence of circulating KS-like spindle cells. Adherent cells that had spindle morphology and several characteristics of spindle cells of KS lesions (KS cells) were identified in the peripheral blood mononuclear cell fraction only after culture in the presence of conditioned medium (CM) from activated lymphocytes. The peripheral blood-derived spindle cells (PBsc) expressed a variety of endothelial cell markers, such as Ulex europaeus I lectin, EN4, EN2/3, EN7/44, CD13, CD34, CD36, CD54, ELAM-1, and HLA-DR. However, they were negative for CD2, CD19, PaIE, and factor VIII-related antigen. The PBsc produced angiogenic factors as evidenced by the ability of CM from these cells to promote growth of normal vascular endothelial cells. In addition, subcutaneously injected PBsc stimulated angiogenesis in vivo in athymic nude mice. We determined that the number of PBsc grown from the peripheral blood of HIV-1+ patients with KS or at high risk to develop KS were increased by 78-fold (P = .0001) and 18-fold (P = .005), respectively, when compared with HIV-1- controls. The number of spindle cells cultured from the HIV-1+ patients at low risk for developing KS, eg, HIV-1+ injection drug users, showed no statistical increase when compared with HIV-1- controls. The presence of increased PBsc with characteristics of KS cells in HIV-1+ KS patients or patients at high risk for developing KS gives insights into the origin of KS cells and may explain the multifocal nature of the disease. In addition, this may be useful in predicting the risk of KS development.

Identification and culture of Kaposi's sarcoma-like spindle cells from the peripheral blood of human immunodeficiency virus-1-infected individuals and normal controls [see comments

We examined 26 patients with human immunodeficiency virus-1 (HIV-1)- associated Kaposi′s sarcoma (KS), and 76 HIV-1-infected (HIV-1+) people without KS or uninfected (HIV-1-) controls for the presence of circulating KS-like spindle cells. Adherent cells that had spindle morphology and several characteristics of spindle cells of KS lesions (KS cells) were identified in the peripheral blood mononuclear cell fraction only after culture in the presence of conditioned medium (CM) from activated lymphocytes. The peripheral blood-derived spindle cells (PBsc) expressed a variety of endothelial cell markers, such as Ulex europaeus I lectin, EN4, EN2/3, EN7/44, CD13, CD34, CD36, CD54, ELAM-1, and HLA-DR. However, they were negative for CD2, CD19, PaIE, and factor VIII-related antigen. The PBsc produced angiogenic factors as evidenced by the ability of CM from these cells to promote growth of normal vascular endothelial cells. In addition, subcutaneously injected PBsc stimulated angiogenesis in vivo in athymic nude mice. We determined that the number of PBsc grown from the peripheral blood of HIV-1+ patients with KS or at high risk to develop KS were increased by 78- fold (P = .0001) and 18-fold (P = .005), respectively, when compared with HIV-1- controls. The number of spindle cells cultured from the HIV- 1+ patients at low risk for developing KS, eg, HIV-1+ injection drug users, showed no statistical increase when compared with HIV-1- controls. The presence of increased PBsc with characteristics of KS cells in HIV-1+ KS patients or patients at high risk for developing KS gives insights into the origin of KS cells and may explain the multifocal nature of the disease. In addition, this may be useful in predicting the risk of KS development.

Immunohistochemical localization of p53 protein in malignant hemangioendothelioma.

The immunohistochemical localization of p53 protein was examined in skin tissue sections, including normal vascular endothelial cells and the skin tissue sections from lesions of granuloma telangiectaticum with proliferation of vascular endothelial cells and malignant hemangioendothelioma, a malignant tumor originated from vascular endothelial cells. It was found that p53 protein was positive in 2 out of 4 cases of malignant hemangioendothelioma. Thus, immunohistochemical detection of p53 protein proved useful in the diagnosis of malignant hemangioendothelioma.