Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS). Neuropathological studies in both human MS and the experimental autoimmune encephalomyelitis (EAE) animal model have shown that endothelial cell (EC) inflammation, associated with focal breakdown of the blood-brain barrier (BBB) and neo-angiogenesis, is prevalent in demyelinating plaques. Neo-angiogenesis and BBB damage contribute to leakage of serum components, infiltration of immune cells into the CNS, neuroinflammation, axonal demyelination, neuronal dysfunction, and disease progression. In Chapter 1, I introduce MS and its pathological hallmarks related to immune and vascular dysfunctions, the clinical course of MS progression, genetic and environmental influences, current treatments, and animal models. Next, I elaborate upon the pathways and processes involved in the development of a functioning CNS vascular system and the BBB. Finally, I discuss what is currently known about the contribution and the underlying mechanisms of neo-angiogenesis in MS and other diseases. While an increase in vessel density has been documented for both MS and EAE lesions, the origin and pathways that drive formation of new, but leaky, blood vessels in EAE are poorly understood. In Chapter 3, I address these questions by performing single-cell RNA-sequencing (scRNA-seq) of 45309 ECs isolated from the spinal cord of control, acute and chronic MOG35-55 EAE mice. Based on expression patterns of blood vessel subtype-specific markers, I identified 23 distinct EC clusters with arterial, capillary, venule, and vein identities in either control or disease states. I performed differential gene expression and gene set enrichment analyses comparing control and disease EC clusters for each vascular subtype to identify which vessels exhibited gene expression profiles indicative of neo-angiogenesis in EAE. I found that molecular signatures of neo-angiogenesis are upregulated specifically in venous ECs during acute and, to a lesser extent, chronic EAE. Consistent with these data, EC proliferation is upregulated in veins in the EAE spinal cord. RNA fluorescent in situ hybridization and immunofluorescence staining confirmed increased expression of key angiogenic markers Egfl7, Ecm1, Serpine1 and Emcn, and the tip cell marker Mcam, with a corresponding increase in vein density, in demyelinating white matter lesions of EAE spinal cords relative to controls. I also assessed changes in expression of some of these markers in human MS tissue and discovered upregulated expression of EGFL7 in cortical white matter lesions of MS patients, concomitant with increased vascular density. In Chapter 4, I examine the signaling pathways that may trigger pathogenic angiogenesis in EAE. I discovered that, in contrast to developmental angiogenesis, VEGF-A and TGF-β signaling may act as the driver of neo-angiogenesis in EAE. To test this hypothesis, I used a humanized VEGF-A blocking antibody, bevacizumab, to block VEGF signaling and found that this treatment ameliorated the MOG35-55 EAE neurological score by reducing expression of several angiogenic markers Egfl7, Ecm1, Serpine1, and Emcn, as confirmed by both in situ hybridization and computational analysis of scRNA-seq data. Immune profiling of spleens and spinal cords by flow cytometry did not show changes in immune cell activation in bevacizumab-treated mice relative to IgG controls, indicating that the protective effects of VEGF blockade are not due to defects in the initiation of the immune response. Finally, in Chapter 5, I summarize the major findings of my dissertation and propose a model for the mechanisms by which neo-angiogenesis contributes to pathology in MS/EAE. I also present several future avenues of research that can be pursued to further our understanding of the molecular and cellular changes underlying pathogenic angiogenesis and its role in MS/EAE. While most current disease-modifying MS therapies aim to reduce inflammation and infiltration of immune cells into the CNS, these findings may lead to development of additional potential therapeutics that may reduce pathogenic neo-angiogenesis in order to alleviate long-term neurological deficits in MS. Additionally, since postcapillary venules and veins are the major sites of immune cell infiltration, BBB damage and neo-angiogenesis in EAE, the findings of this study suggest that development of treatment modalities that target venous ECs with anti-angiogenic compounds may be more effective in inhibiting the growth of pathogenic neovessels than therapies directed against the entire endothelium.

No / Background: In previous experiments, we showed that heparin oligosaccharides inhibit the angiogenic cytokine fibroblast growth factor-2. Here, we present the first in vivo study of size-fractionated heparin oligosaccharides in four models of angiogenesis that are progressively less dependent on fibroblast growth factor-2. Experimental Design: Heparin oligosaccharides were prepared using size-exclusion gel filtration chromatography and characterized through depolymerization and strong anion exchange high-performance liquid chromatography. Size-defined oligosaccharides (20 mg/kg/d) were given to mice bearing s.c. sponges that were injected with fibroblast growth factor-2 (100 ng/d). After 14 days, octasaccharides and decasaccharides reduced the microvessel density to levels below control. In a second experiment, HEC-FGF2 human endometrial cancer cells that overexpress fibroblast growth factor-2 were implanted in a hollow fiber placed s.c. in vivo. Oligosaccharides were given at 20 mg/kg/d for 2 weeks and the data again showed that octasaccharides significantly reduced microvessel density around the fiber (P = 0.03). In a more complex model, where angiogenesis was induced by a broad spectrum of growth factors, including vascular endothelial growth factor, we implanted H460 lung carcinoma cells in hollow fibers and treated the animals with oligosaccharides at 20 mg/kg/d over 3 weeks. Octasaccharides reduced the microvessel density to that of control. Preliminary investigation of 6-O-desulfated heparins showed that these also had antiangiogenic activity. Results: Finally, we examined the inhibitory potential of hexasaccharides and octasaccharides given at 20 mg/kg/d and these inhibited the growth of H460 lung carcinoma in vivo. At clinically attainable concentrations, significant anticoagulation (activated partial thromboplastin time, anti-factor Xa, and anti-factor IIa) was not observed in vitro unless species containing 16 saccharide residues were investigated. Conclusions: Thus, our preclinical data show that heparin octasaccharides represent novel antiangiogenic compounds that can be given without the anticoagulant effects of low molecular weight heparin.

Nasopharyngeal cancer (NPC) is endemic in Southern China and Hong Kong. It has traditionally been treated by local radiotherapy with great success especially for early stage disease. However the treatment outcome in advanced stage disease is unsatisfactory. / Results from this series of combined clinical, translational and laboratory studies have redefined the role of hypoxia, angiogenesis and metastasis as new therapeutic targets in NPC. Novel biomarkers and new therapeutic approaches were developed based on these targets. / To develop new therapies in NPC, we demonstrated in a randomized controlled phase 2 clinical trial that sequential therapy of neoadjuvant chemotherapy followed by chemoradiotherapy was well tolerated with a manageable toxicity profile that allowed subsequent delivery of full dose chemoradiotherapy. This strategy reduced distant metastasis which translated into improved patient survival. In preclinical studies, the antiangiogenesis agent sunitinib demonstrated potent in vitro and in vivo growth inhibition in NPC. In a phase 2 clinical trial, sunitinib demonstrated modest clinical activity in heavily pretreated NPC patients. However, the unexpected high incidence of severe hemorrhage from upper aero-digestive tract in NPC patients who received prior high dose RT to the region is of concern. We propose to exclude NPC patients with disease recurrence within previous radiation field and/or with vascular invasion from future antiangiogenesis therapy. / To investigate potential new therapeutic targets and biomarkers in NPC, we first confirmed from the Hong Kong NPC study group of 2915 patients' database that distant metastasis was the leading cause of NPC failure after primary radiotherapy. We further showed that hypoxia induced broad changes of both up- and down-regulated gene expressions involved in diverse biological processes in NPC cells. Over-expression of biomarkers of hypoxia and angiogenesis (including HIF-1alpha, CA IX and VEGF) is common in NPC and is associated with poor prognosis. Elevated plasma osteopontin is a biomarker of distant metastasis, and pre-treatment plasma osteopontin level may be a useful biomarker of response to radiotherapy in NPC. / Hui, Pun. / "September 2010." / Adviser: Anthony Chan. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 269-293). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

Acute myocardial infarction (AMI) rat model was adopted to test the effect of AngioT in vivo. AngioT was directly injected into the ischaemic region of the left ventricle immediately after the ligation of left anterior descending artery. The densities of vessels in AngioT treated hearts were on average 3-4 folds higher compared with non-treated hearts after two and seven days post infarction. Using TUNEL method, approximately 3-fold lower numbers of apoptotic cardiomyocytes were detected in AngioT treated AMI hearts compared with controls. The infarcted volume estimated by Masson's Trichrome staining was significantly decreased in AngioT treated hearts (27.44%+/-7.34% vs. 39.53%+/-5.97%, p<0.05) compared with control hearts 14 days post infarction. Echocardiography demonstrated that left ventricular ejection fraction and fraction shortening in AngioT treated hearts were significantly improved by 10.4% and 22.3% compared to those in the control hearts 2-day post infarction (p<0.05). These improvements were maintained for 2-week post infarction. / Based on the analysis of rat angiogenesis specific superarray, VEGFb, VEGFc and FGF7, were found to be highly expressed in AngioT treated AMI hearts compared to the controls. The expression levels of survival related genes Bcl2 and Akt1 were increased to 3.3 and 2.8 folds respectively in AngioT treated AMI hearts compared with the controls (both p<0.05). Based on the signal transduction pathway finder superarray, Jak-Stat pathway activators, Interleukin 4 receptor and Interferon regulatory factor 1 (IL4R and IRF1), were found to be highly expressed in the AngioT treated AMI heart. / In conclusion, bioactive angiogenic factors (AngioT) were isolated from Geum. japonicum Thunb. Var. Chinense F. Bolle (GJ). Intra-cardiomuscular injection of AngioT had beneficial effects on the acute myocardial infarction. The underlying mechanisms might be related to the activation of Jak-Stat Pathway and over expressions of angiogenic factors and survival associated genes. The therapeutic properties of AngioT appear entirely novel and may provide a new dimension for therapeutic angiogenesis for the treatment of acute ischaemic heart disease. / In the present study, an angiogenic tannins fraction (AngioT) was isolated from Geum. japonicum Thunb. Var. Chinense F. Bolle using bio-assay guided strategy. AngioT increased the proliferation of human umbilical vein endothelial cell (HUVEC) in culture within 24-hour, 48-hour and 72-hour treatment in a dose-dependent pattern. The EC50 of AngioT on HUVEC was less than 25mug/ml. Conditional media from AngioT treated HUVEC stimulated the proliferation of HUVEC significantly greater than conditional media from non-treated HUVEC. Using 2-dimensional electrophoresis and MALDI-TOF, VEGFa was identified in the AngioT treated conditional medium. / Ischaemic heart disease remains the leading cause of morbidity and mortality in most countries. Severe ischaemia of myocardium induces myocardial infarction and results in an irreversible loss of myocardium. Restoration of coronary blood flow by rapid angiogenesis may offer a direct and effective therapeutic way to intractable ischaemic heart diseases. / Key words. ischaemic heart disease; myocardial infarction; therapeutic angiogenesis; Geum japonicum; apoptosis; tannins; VEGF; Jak-Stat pathway / Gu, Xuemei. / "Sep 2007." / Adviser: Peter Tong Chun Yip. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4615. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 159-177). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Age-related macular degeneration (AMD) is the leading cause for visual impairment and blindness in the elder population of developed countries. The primary underlying cause for significant visual loss is the choroidal neovascularization (CNV). Current treatment strategies for AMD include laser photocoagulation, photodynamic therapy (PDT) and excision of neovascular membranes, but have met with limited success. In our previous studies, we demonstrated that gene delivery of angiogenesis inhibitor vasostatin (VS) attenuated the corneal neovascularization in animals. The primary objective of this study was to investigate gene delivery of vasostatin (VS) attenuated the choroidal neovascularization in animals. Retinal and visual function will be evaluated. However, systematic expression of angiogenesis inhibitor may bring adverse effects to physiological processes. The feasibility, efficiency and safety of gene delivery with systemic and local routes were evaluated. Intramuscular polymer-based gene delivery had no side effect such as virus vector and revealed the safety. Recombinant adenovirus (Ad) was used gene delivery system because of its high titer, wide host range, and transduction efficiency. Adeno-associated virus (AAV) represents highly efficient that can facilirate long-term transduction. We propose to improve the efficacy and safety of VS gene delivery, and to search for the effective delivery route and other adjuvant therapy in conjunction with VS for treatment of CNV. Recently, PDT with veteporfin is an established treatment for subfoveal CNV secondary to AMD. We tried to compare the effect and safety of standard and reduced-dose light application PDT in an animal mocel of CNV. The 180-residue VS and its 48-residue (VS48) inhibited the migration and tube formation in cultured endothelial cells. Topical VS application suppresses the progression of laser-induced CNV via angiogenesis ihhibition, as well as in VS48. VS-48 inhibited the growthof vessels in arota rings. Electroretinograms (ERG) analysis revealed that topical VS-48 application for 21 days had no effect on rat retinal functions. Topical VS-48 treatment significantly reversed the CNV-induced alterations in ERG. Transfection of pCMV3-VS into muscle cells resulted in increased production and release of exogenous VS, which specifically inhibited the proliferation of endothelial cells. Rats treated with intrmuscular injection with PVP-VS also showed a significant reduction in the CNV lesions for at least 42 days. Subconjunctival injection with Ad vector revealed no retinal toxicity in ERG. Ad-luciferase via subconjunctival injections showed ocular expression for as long as 112 days by using bioluminescence image analysis in rodent. AAV-luciferase via subconjunctival injections showed ocular expression for as long as 365 days by using bioluminescence image analysis in mice, and AAV serotype 5-luciferase even showed expression lasting for 2 years. Suppression of laser photocoagulation¡Vinduced CNV by Ad-VS was documented in rat model. Combination therapies are important as treatment options. We demonstrated that PDT could effectively attenuate CNV in a rat model, and reduced doses, worked just as well as the standard dose. In the preliminary study of PDT combined topical VS application, treatment led to CNV attenuation more than alone with PDT. The above experiments would enable us to demonstrate that the vasostatin delivery might be a promising strategy for the treatment of AMD and other retinal or ocular disorders. Furthermore, the results from animal studies might be extrapolated for future clinical application.

[Truncated abstract] One of the barriers to understanding and preventing proliferative diabetic retinopathy in humans has been the lack of an appropriate animal model. Historically dog, rat and mouse models of diabetic retinopathy have been studied but none of these exhibit the later changes of proliferative diabetic retinopathy. Animals can be rendered diabetic by surgical pancreatectomy or the use of chemicals such as allozan or streptozotocin or by feeding of a high galactose diet. Alternatively, spontaneous rodent models of diabetes have been examined such as the BB rat, KK mouse or NOD mouse. However, in each case the retinal vascular changes observed are those of early nonproliferative diabetic retinopathy comprising at most saccular microaneurysms, increased thickness of the capillary basement membrane, acellular capillaries and pericyte ghosts. … Fluorecein angiography of this transgenic line clearly demonstrates the presence of leaky new vessels, by the appearance of leakage spots scattered throughout the retina from 1 month of age. These mice constitute a valuable model of diabetic retinopathy. Neovascularization in this animal model is induced by VEGF as in human diabetic retinopathy. The source of VEGF in human diabetic retinopathy is the ischemic inner retina. In this transgenic model the source of VEGF are the photoreceptor cells, which are situated just underneath the inner retina. The neovascularization is not dependent on a particular developmental stage and there is no spontaneous regression of new vessels. Thus any results generated in this model are highly relevant to human diabetic retinopathy.

Diss. (sammanfattning) Stockholm : Karol inst., 2004. / Härtill 4 uppsatser.

Thesis (M.S.)--University of Michigan, 1994. / Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains ix, 224 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

published_or_final_version / abstract / Surgery / Doctoral / Doctor of Philosophy