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Charles University in Prague Faculty of Pharmacy in HradecKrlov Department of Biological and Medical Sciences Evaluation of endoglin and P-selectin expression and co-expression in aortas of apoE-deficient mice Diploma thesis MonikaBrlicov Supervisor: Mgr.JanaRathousk Background: We observed the expression and the reciprocal co-expression of endoglin (receptor III for TGF- cytokine) and P-selectin (adhesion molecule and marker of endothelial dysfunction) in ascending aortas of apoE-deficient mice which were fed by standard diet for rodents and Western type diet (high-cholesterol diet) for achieving of different phases of the atherosclerotic process. The changes of total cholesterol levels in mice after administration of both types of diets were also evaluated. Methods: The modified strain C57BL/6J of mice with a deficiency of apolipoprotein E, which is prone to aterogenesis was used for this diploma thesis. Mice were divided into three groups. The first group was fed by standard diet (so-called "chow" diet) for a period of two months and the second two groups were fed by Western type diet for a period of two and four months. The levels of total cholesterol in the blood were biochemically determinated and then we statistically evaluated this levels in all groups. Immunohistochemical...

Disruption of the integrity of vascular endothelium plays an essential role in the development and the progression of numerous human diseases, including sepsis, atherosclerosis and others. A complex array of transmembrane adhesive proteins located in junctional structures, support endothelial integrity and control vascular permeability. Furthermore, they are able to transmit intracellular signals to coordinate various endothelial biological responses to insure normal vascular function. Immunoglobulin-containing and proline rich receptor-1 (IGPR-1) is a novel cell adhesion molecule that is involved in angiogenesis and in the regulation of endothelial permeability. IGPR-1 is phosphorylated at Ser220, which is required for its ability to mediate actin fibril reorganization. In this study, we demonstrate that the phosphorylation of IGPR-1 at Ser220 is stimulated by cell spreading and cell adhesion in porcine aortic endothelial (PAE) cells. Blocking homophilic trans-dimerization of IGPR-1 by a blocking antibody inhibited cell-density phosphorylation of IGPR-1. More importantly, phosphorylation of IGPR-1 at Ser220 is increased in PAE cells under shear stress, which was essential for IGPR-1-mediated endothelial cell alignment in response to shear stress. Taken together, this study demonstrate that IGPR-1 activity is regulated be endothelial cell spreading and density. And its activity plays an important role in endothelial cell alignment in response to shear stress. / 2020-07-03T00:00:00Z

In der regenerativen Medizin gewinnt die Herstellung eines funktionsfähigen und biokompatiblen Gewebeersatzes durch Techniken des Tissue Engineerings zunehmende Bedeutung. Eine Grundlage dieser Technologie bilden körpereigene Zellen, die sich in vitro kultivieren und in verschiedene Gewebetypen differenzieren lassen, sogenannte adulte mesenchymale Stammzellen. Diese können u.a. aus Fettgewebe leicht und in größerer Anzahl isoliert und kultiviert werden (adipose-derived stem cells, ASC). In Anwesenheit Zelllinien-spezifischer Induktoren lassen sich diese Zellen zu Adipozyten, Osteoblasten und Chondrozyten differenzieren und für die Herstellung entsprechender Gewebekonstrukte nutzen. Eine erfolgreiche Differenzierung dieser Stammzellen zu Endothelzellen könnte in den durch Tissue Engineering generierten Gewebekonstrukten die Ausbildung eines funktionsfähigen Blutgefäßsystems in vivo beschleunigen. Ziel der vorliegenden Arbeit war es, die endotheliale Differenzierung von ASC unter Zusatz angiogener Wachstumsfaktoren sowie hypoxischer Behandlung der Zellen zu untersuchen und im Hinblick auf eine Anwendung im Tissue Engineering zu optimieren. Dabei sollte gleichzeitig untersucht werden, ob unter diesen Bedingungen die Differenzierung der ASC in eine andere Zelllinie (Adipozyten) möglich ist. Die Untersuchungen wurden mit Stammzellen durchgeführt, welche mittels Liposuktion aus subkutanem Fettgewebe gewonnen wurden. Diese Zellen wurden zunächst vergleichend in endothelzellspezifischem Medium mit angiogenen Faktoren (VEGF, bFGF) bzw. unter hypoxischen Bedingungen (3% Sauerstoff) kultiviert und die Differenzierung zu Endothelzellen anhand verschiedener endothelzellspezifischer Marker nachgewiesen. Zunächst wurde mittels Immunfluoreszenzfärbung die Expression des endothelialen Oberflächenantigens CD31 untersucht. Eine Quantifizierung der CD31-positiven Zellpopulation erfolgte im Anschluss durch Auszählung mit Hilfe des Fluoreszenzmikroskops. Die endotheliale Differenzierung der ASC konnte bereits nach Zugabe der einzelnen Wachstumsfaktoren nachgewiesen werden. Der kombinierte Einsatz der beiden Faktoren führte zu einem Anstieg CD31-positiver Zellen. Des Weiteren ließ sich eine stärkere induktive Wirkung für bFGF im Vergleich zu VEGF demonstrieren. Durch Kultivierung der Zellen unter hyoxischen Bedingungen konnte ebenfalls eine endotheliale Differenzierung erzielt werden. Diese entsprach im Umfang etwa dem Ausmaß an differenzierten Zellen unter Wachstumsfaktoreneinfluss in Normoxie. Als aussichtsreichste Kultivierungsstrategie für die endotheliale Differenzierung der ASC stellte sich jedoch die Kultivierung der Zellen unter Einsatz der Wachstumsfaktorenkombination (bFGF und VEGF) in Hypoxie dar. Hier konnte zum einen eine Abhängigkeit von der Konzentration der eingesetzten Faktoren demonstriert werden und zum andern ein Synergismus zwischen Hypoxie und kombiniertem Wachstumsfaktoreneinsatz festgestellt werden. Denn die Anzahl an CD31-positiven Zellen in der Gruppe mit den hochkonzentriert zugesetzten Wachstumsfaktoren entsprach nicht einfach der Addition der Zellzahl unter Einzelbedingungen, sondern lag deutlich höher. Insgesamt ist das Ausmaß der endothelial differenzierten ASC im Vergleich zur Ausgangspopulation allerdings als gering zu beurteilen, denn nur 0,5 - 1,1% der eingesetzten ASC zeigten endotheliale Marker. Zur weiteren Charakterisierung der endothelial differenzierten ASC wurden die endothelzellspezifische Aufnahme von DilacLDL, ein mit dem Farbstoff Dil markiertes Lipoprotein, und die tube formation auf Matrigel untersucht. Hier konnte bei einigen Zellen die Inkorporation von DilacLDL nachgewiesen werden. Beim Matrigel-Assay zeigten sich allerdings deutliche morphologische Unterschiede im Vergleich zu naiven Endothelzellen. Eine Immunfluoreszenzfärbung gegen den von Willebrand Faktor fiel negativ aus. Um den positiven Einfluss der hypoxischen Kulturbedingungen weiter zu ermitteln, wurde der Effekt der Hypoxie auf die Sekretion angiogener Wachstumsfaktoren am Beispiel von VEGF mittels enzyme linked immunosorbent assay (ELISA) untersucht. Es zeigte sich ein deutlicher Anstieg der endogenen VEGF-Sekretion unter hypoxischen Bedingungen im Vergleich zur Normoxie. Die Steigerung der endogenen Wachstumsfaktorsekretion hat möglicherweise einen Anteil am Mechanismus des Hypoxieeffektes. Hier sollten weitere Untersuchungen, allen voran zur bFGF-Sekretion angeschlossen werden. Neben der endothelialen Differenzierung der ASC wurde überprüft, ob unter den oben genannten Bedingungen eine adäquate Adipogenese stattfindet. Das wurde durch quantitative Messung des Triglyceridgehalts sowie Untersuchung der Expression adipogener Marker wie CEBPα, PPARγ, FABP und GLUT 4 erfasst. Hier konnte gezeigt werden, dass die Adipogenese der Stammzellen unter den beschriebenen Bedingungen unbeeinträchtigt bleibt und somit eine Anwendung im TE von Fettgewebe möglich macht. Mit der endothelialen Differenzierung unter unterschiedlichen Bedingungen zeigen die Ergebnisse der Arbeit eine Facette des Potentials der ASC. Ob die endothelial differenzierten ASC tatsächlich zu einer Verbesserung der Vaskularisierung von TE-Konstrukten führen, sollte in einer weiterführenden In-vivo-Studie evaluiert werden. / In regenerative medicine the production of a functional and biocompatible tissue replacement by means of tissue engineering is gaining in importance. A basis of this technology is formed by endogenic cells, so-called adult mesenchymal stem cells, which can be cultivated in vitro and can be diversified into different types of tissues. These cells can easily and in great numbers be isolated and cultivated from adipose tissue (adipose-derived stem cells). In the presence of inducing factors, these cells can be differentiated into adipocytes, osteoblasts or chondrocytes and can be used for the production of appropriate tissue constructs. A successful differentiation of these stem cells into endothelial cells could potentially accelerate the formation of a functioning vasculature in vivo in tissue-engineered constructs. It was the aim of this doctoral thesis to examine the endothelial differentiation of ASC under both the supplementation of angiogenic growth factors and hypoxic treatment of cells, and to optimize this strategy for application in tissue engineering. Further, it was examined whether the differentiation of ASC into different cellular lineage is possible under these conditions. The analyses were carried out with ASC extracted from subcutaneous fat tissue by liposuction. These cells were initially cultivated with angiogenic factors in an endothelial-specific medium as well as under hypoxic conditions (3% oxygen), and the differentiation into endothelial cells was verified on the basis of various markers specific to endothelial cells. First, the expression of the endothelial surface marker CD31 was examined by immune florescence staining and endothelial differentiation could already be verified upon addition of the individual growth factors. The combined application of both factors, bFGF and VEGF, led to an increase of CD31-positive cells. Additionally, a stronger inductive effect for bFGF compared to VEGF could be demonstrated. Similarly, upon cultivation of cells under hypoxic conditions endothelial differentiation could be achieved. This corresponded in its extent approximately to the yield of differentiated cells under the influence of growth factors under normal oxygen supply. The cultivation of cells with the combination of growth factors (bFGF and VEGF) in hypoxia turned out to be the most promising strategy of cultivation for the endothelial differentiation of ASC. Here, on the one hand, a dependency on the concentration of the applied factors could be shown and on the other hand a synergism between hypoxia and the combined application of growth factors was observed. In the group treated with highly concentrated growth factors the number of CD31-positive cells did not only correspond to the addition of the number of cells under particular conditions but was distinctly higher. Altogether, the amount of endothelial differentiated ASC compared to the original population has to be judged as low, as only 0.5 – 1.1 % of the applied ASC showed endothelial markers. For further characterization of the endothelial specific absorption of DilacLDL, a lipoprotein marked with the colorant Dil, as well as tube formation were assessed in Matrigel. Here the incorporation of DilacLDL could be verified in several cells. For the Matrigel assay, distinct morphological differences in comparison to naïve endothelial cells became apparent. An immune fluorescence staining towards the Willebrand Factor turned out to be negative. In order to further elucidate the effect of hypoxia on the secretion of angiogenic growth factors, VEGF was analyzed by means of an enzyme linked immunosorbent assay (ELISA). A distinct increase in endogenic VEGF secretion under hypoxic conditions in contrast to normoxic conditions was observed. This increase of endogenic growth factors possibly has a share of the mechanism of the hypoxia effect. Further research, above all on the bFGF secretion, ought to follow. Together with the endothelial differentiation of ASC, it was examined whether under conditions mentioned above adequate adipogenesis takes place. This data was gathered both by quantitative measurement of the content of triglycerides and the examination of the expression of adipogenic markers like CEBP α, PPARγ, FABP and GLUT-4. Here it could be proven that adipogenesis of stem cells remains unaffected under the conditions mentioned above and therefore enables their application in the tissue engineering of adipose tissue. Whether this endothelial differentiated ASC really lead to an improvement of the vascularization of tissue-engineered constructs should be evaluated in further in vivo studies.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This study examined the differential gene expression patterns between endothelial cells (EC) from 2D monolayer and EC from angiogenic capillary-like network in 3D matrices. Our microarray analysis comparing 3D to 2D EC cultures detected upregulation of 854 protein-coding genes and downregulation of 863 genes. We show that Notch signaling pathway is highly regulated in angiogenesis, induced by change in ECM dimension. Notch target genes Hey1, HeyL, Hes1 and Hes4 transcription factors were upregulated in 3D angiogenic EC, which were confirmed with qRT-PCR. Moreover, we are the first to report enrichment of FoxS1 transcription factor mRNA during angiogenesis in 3D ECM. Next, we asked whether epigenetic mechanisms partly mediate cis-trans response in angiogenesis. Our sodium bisulfite sequencing analyses did not indicate a role for DNA methylation in the expression of key Notch signaling components. However, our pilot studies indicate a potential role for lncRNAs in controlling EC phenotype in angiogenic response.

This study examined the differential gene expression patterns between endothelial cells (EC) from 2D monolayer and EC from angiogenic capillary-like network in 3D matrices. Our microarray analysis comparing 3D to 2D EC cultures detected upregulation of 854 protein-coding genes and downregulation of 863 genes. We show that Notch signaling pathway is highly regulated in angiogenesis, induced by change in ECM dimension. Notch target genes Hey1, HeyL, Hes1 and Hes4 transcription factors were upregulated in 3D angiogenic EC, which were confirmed with qRT-PCR. Moreover, we are the first to report enrichment of FoxS1 transcription factor mRNA during angiogenesis in 3D ECM. Next, we asked whether epigenetic mechanisms partly mediate cis-trans response in angiogenesis. Our sodium bisulfite sequencing analyses did not indicate a role for DNA methylation in the expression of key Notch signaling components. However, our pilot studies indicate a potential role for lncRNAs in controlling EC phenotype in angiogenic response.