Fetal and neonatal immune thrombocytopenia (FNIT) is a severe bleeding disorder which results from fetal platelet destruction by maternal antibodies against platelet antigens, including GPIIbIIIa (αIIbβ3 integrin) and GPIbα. β3 integrin is also expressed by angiogenic endothelial cells (ECs) and is required for angiogenesis. Therefore, we investigated whether anti-β3 antibodies in FNIT cross-react with blood vessels of the fetus/neonate and contribute to pathogenesis. Antibodies to GPIbα were used as controls. To mimic human FNIT, β3 integrin- or GPIbα-deficient female mice were immunized with wild-type platelets and bred with wild-type male mice. Pups in both groups had thrombocytopenia but intracranial hemorrhage was only observed in anti-β3-mediated FNIT. Anti-β3-mediated FNIT pups had increased apoptosis in the brain and impaired vascularization of the brain and retina. In addition, anti-β3 sera inhibited proliferation and vascular-like tube formation by ECs in vitro. Therefore, anti-β3 antibodies in FNIT likely impair angiogenesis in the developing fetus/neonate.

Fetal and neonatal immune thrombocytopenia (FNIT) is a severe bleeding disorder which results from fetal platelet destruction by maternal antibodies against platelet antigens, including GPIIbIIIa (αIIbβ3 integrin) and GPIbα. β3 integrin is also expressed by angiogenic endothelial cells (ECs) and is required for angiogenesis. Therefore, we investigated whether anti-β3 antibodies in FNIT cross-react with blood vessels of the fetus/neonate and contribute to pathogenesis. Antibodies to GPIbα were used as controls. To mimic human FNIT, β3 integrin- or GPIbα-deficient female mice were immunized with wild-type platelets and bred with wild-type male mice. Pups in both groups had thrombocytopenia but intracranial hemorrhage was only observed in anti-β3-mediated FNIT. Anti-β3-mediated FNIT pups had increased apoptosis in the brain and impaired vascularization of the brain and retina. In addition, anti-β3 sera inhibited proliferation and vascular-like tube formation by ECs in vitro. Therefore, anti-β3 antibodies in FNIT likely impair angiogenesis in the developing fetus/neonate.

Recently a whole cell based biosensor has been developed in our laboratory that consists of a monolayer of human umbilical vein endothelial cells (HUVECs) on the asymmetric cellulose triacetate (CTA) membrane of an ion selective electrode (ISE). When a confluent cell monolayer is formed across the membrane, response from the sensor is inhibited due to inhibited ion transport across the membrane. When the cell based biosensor is exposed to permeability modifying agents, the permeability across the cell monolayer is altered facilitating more ion transport and as a result the response from the sensor increases. This sensor response can be related to the concentration of these agents. One objective of this research was to investigate the ability of the sensor to detect a physiological toxin, alpha toxin from Staphylococcus aureus. Studies demonstrated that the biosensor can detect 0.1ng/ml alpha toxin. Considering the fact that the concentration of this toxin is 100-250 ng/ml in whole blood in humans, this biosensor has the ability to act as the diagnostic tool for staphylococcal diseases. Another part of this research was to investigate the ability of the biosensor to measure angiogenesis by measuring the changes in permeability induced by cytokines such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF) and tumor necrosis factor andamp;aacute; (TNF- andamp;aacute;) individually and in combination. The sensor response was then compared with the common in vitro assays for angiogenesis. The study demonstrated that at the concentrations studied the sensor response in the presence of cytokines was much higher than that observed for other angiogenesis assays, thereby bolstering the potential of the biosensor to act as a quick screening tool for angiogenesis. Furthermore, epithelial cell based sensor responses to the same cytokines were compared with the responses from endothelial cell based sensor and the mechanisms behind the increased sensor response were elucidated. Finally, to investigate the ability of the sensor to screen cancer, the biosensor was exposed to the serum from healthy individuals and cancer patients. The results showed that the sensor can distinguish between healthy individuals and cancer patients and the results correlate with the stages of cancer.

A biological assay is designed to set up a rapid and robust drug-screening system on a small scale. An assay is considered as a single unit of a platform to screen various compounds for aiding in drug discovery. Each assay is carried out in a 96-well plate, each of whose wells consists of the biological component called the Spheroids. The value of each assay lies in it facilitating for versatile screening applications. The spheroid is considered as a micro-structural product. And the addition of various compounds for testing is performed in each well (consisting of the spheroids). The focus has been to put forth the production principles and validation strategies to run the biological assay and test its efficacy to be used for screening in high volumes. The assay development illustrates processing and validation techniques. The goal is to develop optimized standards to process the assay, addressing various quality control issues, from the raw material to the end-product stage. Such an approach also brings interesting analogies of biological process in a manufacturing scenario. The developed system incorporates a value stream approach, by pulling the product from the customer end. The process involves simply encapsulating HUVECs (Human Umbelical Vein Endothelial cells) from the raw material stage, culturing to form the spheroid and transferring the component to assemblage in a 96-well format undergoing stages of heat treatments. The small scale screening system allows the use of small amounts of drug, which is especially essential for new drug synthesis or in rapid decision making to find out any unknown potent compounds. The design of optimal processes in product development of the spheroid assay is illustrated. Thus in light of the value of this assay, developing the production system has been pivotal so as to produce quality spheroids in the 96-well plate formats. The quantification of the stimulatory and inhibitory effects of the different agents is required to help understand the complex biological behavior involved. The goal is to validate the data using image analysis software. The image analysis helps determine the quantification to be accurate, objective, and consistent. The quality of the product is tested by the reproducibility and robustness of the assay.

Tumors are composed not only of malignant cells, but also of various types of normal cells, including vascular cells and infiltrating immune cells, which drive tumor development and progression. The tumor vasculature is abnormal and dysfunctional due to sustained tumor angiogenesis driven by high levels of pro-angiogenic factors. Proteins differentially expressed in tumor vessels affect vascular function and the tumor microenvironment and may serve as targets for therapy. The tumor is also a site of sustained chronic inflammation. The recruitment and activation of inflammatory cells significantly influence tumor progression and regression. Targeting molecules regulating tumor angiogenesis and inflammation in the tumor microenvironment is therefore a promising strategy for the treatment of cancer. This thesis is aiming to understand and investigate the molecular regulation of these two processes in tumors. αB-crystallin is a heat shock protein previously proposed as a target for cancer therapy due to its role in increasing survival of tumor cells and enhancing tumor angiogenesis. In this thesis, we demonstrate a novel role of αB-crystallin in limiting expansion of CD11b+Gr1+ immature myeloid cells in pathological conditions, including tumor development. In addition, we show that αB-crystallin regulates leukocyte recruitment by promoting expression of adhesion molecules ICAM-1, VCAM-1 and E-selectin during TNF-α-induced endothelial activation. Therefore, targeting of αB-crystallin may influence tumor inflammation by regulating immature myeloid cell expansion and leukocyte recruitment. Abnormal, dysfunctional vessels are characteristic of glioblastomas, which are aggressive malignant brain tumors. We have identified the orphan G-protein coupled receptor ELTD1 as highly expressed in glioblastoma vessel and investigated its role in tumor angiogenesis. Interestingly, deficiency of ELTD1 was associated with increased growth of orthotopic GL261 glioma and T241 fibrosarcoma, but did not affect vessel density in any model. Further investigation is warranted to evaluate whether ELTD1 serves a suitable vascular target for glioblastoma treatment. Anti-angiogenic drugs targeting VEGF signaling is widely used in the clinic for various types of cancer. However, the influences of anti-angiogenic treatment on tumor inflammation have not been thoroughly investigated. We demonstrate that VEGF inhibits TNF-α-induced endothelial activation by repressing NF-κB activation and expression of chemokines involved in T-cell recruitment. Sunitinib, a small molecule kinase inhibitor targeting VEGF/VEGFR2 signaling increased expression of chemokines CXCL10, CXCL11, and enhanced T-lymphocyte infiltration into tumors. Our study suggests that anti-angiogenic therapy may improve immunotherapy by enhancing endothelial activation and facilitating immune cell infiltration into tumors.

Glioblastoma, grade IV glioma, is the one of the deadliest cancers, with a median survival of only 12-15 months despite aggressive treatment including surgery, chemotherapy and radiation. One hallmark of glioblastoma is the morphological and functional abnormalization of tumor blood vessels. The molecular mechanisms involved in this process and their functional and pathological implications are not yet fully understood. Indentification of molecular mechanisms that underlie vascular abnormalization in GBM is necessary to develop efficient treatment regimens for normalizing vascular function. By analyzing the RNA-content of laser microdissected vessels from human biobank specimens using affymetrix microarray analysis, we found that the abnormal glioblastoma vessels have a distinct gene expression signature. We found 95 genes which were differentially expressed in grade IV glioma vessels as compared to vessels in low grade tumors and control brain. 78 of which were up-regulated while 17 were down-regulated. Many of these genes are regulated by VEGFA or TGFβ signaling. In addition, we show a significant increase in Smad signaling complexes in the vasculature of human glioblastoma in situ, suggesting that TGFβ signaling may play important role in vessel abnormalization. CD93 is a single-pass transmembrane glycoprotein, which we found to be up-regulated in high grade glioma. Vascular expression of CD93 correlates to tumor grade in human glioma. Moreover, high grade glioma patients with high CD93 expression in the vasculature are associate with poor prognosis. We found that knocking down CD93 in endothelial cells with siRNA clearly impaired endothelial cell adhesion, migration and tube formation due to defects in cytoskeletal rearrangement. In addition, tumor growth was severely delayed in the CD93-/- mice. Pleiotrophin, a multi-functional heparin-binding growth factor, promotes glioma growth in several ways. Here, we identify pleiotrophin as a driver of vascular abnormalization in glioma. We found that high pleiotrophin expression correlates with poor survival of patients with astrocytomas. Pleiotrophin overexpression in orthotopic GL261 gliomas increases microvessel density, enhances tumour growth and decreases survival. Vessels in pleiotrophin-expressing gliomas are poorly perfused and display a high degree of abnormality, coinciding with elevated levels of vascular endothelial growth factor (VEGF) deposited in direct proximity to the vasculature. In addition to its role in vessel abnormalization, pleiotrophin enhanced PDGF-B-induced gliomagenesis. Taken together, our results indicate that PTN has an important role in glioma initiation and establishment of the characteristic abnormal tumor vasculature in glioblastoma, identifying PTN as a potential target for therapy.

Induction of an endogenous antibody response by therapeutic vaccination could provide an alternative to cost-intensive monoclonal antibody-based treatments for cancer. Since the target of a cancer vaccine will most likely be a self-antigen, self-tolerance of the immune system must be circumvented. Using fusion proteins consisting of the self-antigen to be targeted and a part derived from a foreign antigen, it is possible to break tolerance against the self-antigen. Furthermore, a potent adjuvant is required to support an immune response against a self-molecule. Currently no adjuvant suitable for this purpose is approved for use in humans. This thesis describes the development of a therapeutic vaccine targeting the vasculature of tumors. As tumor cells have developed strategies to escape immune surveillance, targeting of molecules associated with the tumor stroma is an interesting alternative. The alternatively spliced extra domain-A and B (ED-A and ED-B) of fibronectin and the glycan-binding protein galectin-1 are selectively expressed during events of tumor angiogenesis. We have designed recombinant proteins to target ED-B, ED-A and galectin-1, containing bacterial thioredoxin (TRX) as a non-self part, resulting in TRX-EDB, TRX-EDA and TRX-Gal-1. Vaccination against ED-B induced anti-ED-B antibodies and inhibited growth of subcutaneous fibrosarcoma. Immunization against ED-A decreased tumor burden and reduced the number of lung metastases in the MMTV-PyMT model for metastatic mammary carcinoma in a therapeutic setting. Analysis of the tumor tissue from ED-B and ED-A-immunized mice indicated an attack of the tumor vasculature by the immune system. Finally, we show that galectin-1 immunization reduced tumor burden and increased leukocyte numbers in the tumor tissue. Galectin-1 is pro-angiogenic and immunosuppressive, and therefore allows simultaneous targeting of fundamental characteristics of tumorigenesis. We furthermore show that the biodegradable squalene-based Montanide ISA 720 combined with CpG oligo 1826 (M720/CpG) is at least as potent as Freund’s adjuvant with respect to breaking self-tolerance, when comparing several immunological parameters. Freund’s is a potent but toxic adjuvant used in the majority of preclinical studies. The work presented in this thesis shows that therapeutic cancer vaccines targeting the tumor vasculature are a feasible and promising approach for cancer therapy.

In dieser Studie wurde der Einfluss von anabol-androgenen Steroiden (AAS) wie Testosteron auf die Angiogenese im peripubertären Hengsthoden untersucht. Sieben von 14 Junghengsten erhielten Durateston® und wurden vier [n=3; Versuchsgruppe 1 (VG1)] bzw. zwölf [n=4; Versuchsgruppe 2 (VG2)] Wochen nach der letzten Applikation kastriert, während die übrigen sieben Tiere ohne eine Behandlung in dem gleichen Zeitraum kastriert wurden. Im Rahmen der morphometrischen Untersuchung konnte ein Anstieg der Volumendichte und der Numerischen Dichte bezüglich der Blutgefäße in der Versuchsgruppe festgestellt werden, während die Fläche der Blutgefäßanschnitte in den Kapillaren der Versuchsgruppe kleiner ist als bei den Tieren in der Kontrollgruppe. Die erhöhte Angiopietin2- und transforming growth factor alpha-Expression in der VG1 könnte möglicherweise für diese morphometrischen Be-funde verantwortlich sein. Die Blutgefäße der Versuchsgruppen zeigen, möglicherweise stimuliert durch Testoste-ron, eine höhere vascular endothelial growth factor-receptor2-Expression als die der Kontrollgruppe. Aufgrund der signifikanten Abnahme der morphometrischen Parameter von der VG1 zu der VG2 handelt es sich vermutlich um einen temporären Effekt.

Biomarkers measured in the blood can provide information about disease pathophysiology, diagnosis and prognosis. Pronounced proinflammatory responses are characteristic of severe malaria, and excessive activation of the immune system is central to the pathophysiology of both cerebral malaria and placental malaria. Severe malaria is characterized by cytoadherence of parasitized erythrocytes to the microvasculature; impaired tissue perfusion; dysregulated inflammatory responses; and activation of the complement system, mononuclear cells, and endothelium. Despite the availability of effective antimalarial drugs, the mortality rate in severe malaria remains unacceptably high. To glean further insight into malaria pathophysiology, we investigated host biomarkers of immune activation in the blood of subjects with different manifestations of severe disease. C5 has been identified as being necessary and sufficient for the development of experimental cerebral malaria. We hypothesized that C5a (a terminal component of the complement cascade with potent inflammatory properties) may mediate its action by inducing and exacerbating inflammatory processes in severe malaria, leading to endothelial activation and dysregulated angiogenesis. I tested this hypothesis in vitro, and found that C5a interacted with malaria toxin PfGPI to drive deleterious inflammatory and anti-angiogenic responses. As C5a and anti-angiogenic factor sFlt-1 have been implicated in models of pathologic pregnancies, we asked whether increased levels of C5a in subjects with placental malaria were associated with altered angiogenesis and poor birth outcomes. Our results suggest that C5a impairs angiogenic remodelling in placental malaria leading to vascular insufficiency and fetal growth restriction. Further, altered profiles of inflammatory and angiogenic biomarkers in the periphery may identify occult placental malaria infections. We extended these observations to cerebral malaria where similar pathogenic pathways contribute to disease pathophysiology. In adults and children with cerebral malaria, altered profiles of angiogenic proteins were associated with disease severity and mortality and represent putative diagnostic and prognostic biomarkers in severe malaria.

Discovering novel compounds that stimulate or abrogate angiogenesis can lead to development of new therapeutic agents that may effectively treat diseases with pathological angiogenesis. The zebrafish model allows for a whole-organism approach to drug discovery. Advantages over other animal models include small embryo size, fecundity, rapid embryonic development, optical clarity and easy accessibility of the embryos. My goal is to validate the therapeutic efficacy and identify the molecular mechanisms of action of three compounds identified from our previous chemical genetic screens. Fenretinide promoted angiogenesis in zebrafish embryos but inhibited the angiogenesis-dependent process of fin regeneration. The pro-angiogenic effects of fenretinide appear secondary to the stimulation of somitogenesis. I3M potently inhibited angiogenesis and fin regeneration, and may act partially through the notch pathway. Lastly, I validated the anti-angiogenic effect of a novel compound DHM. Comprehensively, my studies support the utility of zebrafish as a versatile tool for anti-angiogenic drug discovery.