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Investigating mechanisms of angiogenesis in health and disease using zebrafish models
Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Angiogenesis, the growth of blood vessels from an existing vasculature, can occur by sprouting from preexisting vessels or by vessel splitting (intussusception). Pathological angiogenesis drives choroidal neovascularization (CNV) in age related macular degeneration (AMD) which is commonly restricted under the retinal pigment epithelium (RPE), called occult CNV, but may also involve vessels penetrating through the RPE into the sub-retinal space. Pathological vessels are poorly developed, insufficiently perfused and highly leaky, phenotypes that are considered to drive disease progression and lead to poor prognosis. Currently, a number of anti-angiogenic drugs exists, the majority of which target vascular endothelial factor (VEGF), but although they often are highly beneficial for treating eye diseases in the short-term, they are generally of limited efficacy in other diseases such as cancer, and also have poorer efficacy when used for treatment of eye diseases in the long-term. A better understanding of the mechanisms underlying pathological angiogenesis can generate new targets for treatment leading to development of better drugs for cancer and retinopathies, but perhaps also other angiogenesis-dependent diseases, in the future. In this thesis mechanisms involved in developmental angiogenesis or pathological angiogenesis in the choroid, cornea or melanoma was identified. These findings highlight the need to further elaborate our knowledge related to angiogenesis in different tissues/conditions for a more targeted, and potentially effective treatment of diseases in the future.

In paper I, we for the first time identified the choriocapillaries (CCs) in adult zebrafish and found that occult CNV could be induced by exposing the fish to severe hypoxia. Interestingly, we found that occult CNV relied on intussusception, involving not only de novo generation of intussusceptive pillars but also a previously poorly understood mechanism called pillar splitting. This involved HIF-VEGF-VEGFR2 signaling and evidence that this also occurred in both rats and humans suffering from AMD suggested that the mechanism was conserved and clinically relevant.

In contrast, we found in paper II that the development of CCs in the zebrafish relies on sprouting angiogenesis, involve continuous remodeling, and delayed maturation of the vasculature in 2D. The initial development was found to occur by a unique process of tissuewide synchronized vasculogenesis. As expected, VEGFA via VEGFR2 was also critical for the development of these vessels in the zebrafish embryo, but surprisingly this was independent on hypoxia-inducible factor (HIF)-1.

Inflammatory nuclear factor-kB (NF-kB) signaling is involved in the progression of angiogenesis, but this signaling pathway has mainly been studied in the inflammatory cells and the role of NF-kB in the endothelial cells during angiogenesis is poorly understood. In paper III, we found that blocking NF-kB signaling using a specific IKK2 blocker IMD0354, specifically blocks pathological as well as developmental angiogenesis by targeting endothelial cell NF-kB signaling in the endothelial cells. Using a rat model for suture-induced corneal neovascularization, IMD0354 treatment lead to reduced production of inflammatory C-C motif chemokine ligand 2 (CCL2), C-X-C motif chemokine ligand 5 (CXCL5) and VEGF, and thereby reduced pathological corneal angiogenesis in this model.

Using the zebrafish tumor xenograft model in paper IV, we found an association between Microphthalmia associated transcription factor (MITF) and pigment epithelium derived factor (PEDF), which was involved in pathological tumor angiogenesis and metastasis. Similarly, in paper V we used zebrafish transplantation models to study and investigate the use of biocompatible polymers for the delivery of pro-angiogenic FGF-2 as a potential treatment strategy for ischemic diseases such as myocardial infarction (MI). Conclusively, this thesis provides new insights into diverse fields of angiogenic assays using zebrafish, and reveals new mechanisms of angiogenesis in health and disease. This work will hopefully provide a foundation for further studies into occult CNV related to AMD, a process that has not been possible to study previously in pre-clinical models. In addition, zebrafish xenograft or other transplantation models used in this work will likely be important to study cancer biology and to develop more attractive pharmaceutical preparations based on biocompatible hydrogels formulated as microspheres in the future.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. , p. 49
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1646
National Category
Pharmacology and Toxicology
Identifiers
URN: urn:nbn:se:liu:diva-153266DOI: 10.3384/diss.diva-153266ISBN: 9789176851999 (print)OAI: oai:DiVA.org:liu-153266DiVA, id: diva2:1268873
Public defence
2018-12-14, Belladonna, Campus US, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2018-12-07 Created: 2018-12-07 Last updated: 2018-12-07Bibliographically approved
List of papers
1. Selective IKK2 inhibitor IMD0354 disrupts NF-kappa B signaling to suppress corneal inflammation and angiogenesis
Open this publication in new window or tab >>Selective IKK2 inhibitor IMD0354 disrupts NF-kappa B signaling to suppress corneal inflammation and angiogenesis
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2018 (English)In: Angiogenesis, ISSN 0969-6970, E-ISSN 1573-7209, Vol. 21, no 2, p. 267-285Article in journal (Refereed) Published
Abstract [en]

Corneal neovascularization is a sight-threatening condition caused by angiogenesis in the normally avascular cornea. Neovascularization of the cornea is often associated with an inflammatory response, thus targeting VEGF-A alone yields only a limited efficacy. The NF-kappa B signaling pathway plays important roles in inflammation and angiogenesis. Here, we study consequences of the inhibition of NF-kappa B activation through selective blockade of the IKK complex I kappa B kinase beta (IKK2) using the compound IMD0354, focusing on the effects of inflammation and pathological angiogenesis in the cornea. In vitro, IMD0354 treatment diminished HUVEC migration and tube formation without an increase in cell death and arrested rat aortic ring sprouting. In HUVEC, the IMD0354 treatment caused a dose-dependent reduction in VEGF-A expression, suppressed TNF alpha-stimulated expression of chemokines CCL2 and CXCL5, and diminished actin filament fibers and cell filopodia formation. In developing zebrafish embryos, IMD0354 treatment reduced expression of Vegf-a and disrupted retinal angiogenesis. In inflammation-induced angiogenesis in the rat cornea, systemic selective IKK2 inhibition decreased inflammatory cell invasion, suppressed CCL2, CXCL5, Cxcr2, and TNF-alpha expression and exhibited anti-angiogenic effects such as reduced limbal vessel dilation, reduced VEGF-A expression and reduced angiogenic sprouting, without noticeable toxic effect. In summary, targeting NF-kappa B by selective IKK2 inhibition dampened the inflammatory and angiogenic responses in vivo by modulating the endothelial cell expression profile and motility, thus indicating an important role of NF-kappa B signaling in the development of pathologic corneal neovascularization.

Place, publisher, year, edition, pages
Springer Netherlands, 2018
Keywords
Cornea; Neovascularization; NF-kappa B; IMD0354; IKK2; VEGF
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-147373 (URN)10.1007/s10456-018-9594-9 (DOI)000428924500007 ()29332242 (PubMedID)2-s2.0-85041334437 (Scopus ID)
Note

Funding Agencies|Swedish Research Council [2012-2472]; Swedish Foundation Stiftelsen Synframjandets Forskningsfond/Ogonfonden; Svenska Sallskapet for Medicinsk Forskning; Linkoping Universitet; Jeanssons Stiftelser

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2019-05-01Bibliographically approved
2. Regulatory and Functional Connection of Microphthalmia-Associated Transcription Factor and Anti-Metastatic Pigment Epithelium Derived Factor in Melanoma
Open this publication in new window or tab >>Regulatory and Functional Connection of Microphthalmia-Associated Transcription Factor and Anti-Metastatic Pigment Epithelium Derived Factor in Melanoma
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2014 (English)In: Neoplasia, ISSN 1522-8002, E-ISSN 1476-5586, Vol. 16, no 6, p. 529-542Article in journal (Refereed) Published
Abstract [en]

Pigment epithelium-derived factor (PEDF), a member of the serine protease inhibitor superfamily, has potent anti-metastatic effects in cutaneous melanoma through its direct actions on endothelial and melanoma cells. Here we show that PEDF expression positively correlates with microphthalmia-associated transcription factor ( MITF) in melanoma cell lines and human samples. High PEDF and MITF expression is characteristic of low aggressive melanomas classified according to molecular and pathological criteria, whereas both factors are decreased in senescent melanocytes and naevi. Importantly, MITF silencing down-regulates PEDF expression in melanoma cell lines and primary melanocytes, suggesting that the correlation in the expression reflects a causal relationship. In agreement, analysis of Chromatin immunoprecipitation coupled to high throughput sequencing (ChIP-seq) data sets revealed three MITF binding regions within the first intron of SERPINF1, and reporter assays demonstrated that the binding of MITF to these regions is sufficient to drive transcription. Finally, we demonstrate that exogenous PEDF expression efficiently halts in vitro migration and invasion, as well as in vivo dissemination of melanoma cells induced by MITF silencing. In summary, these results identify PEDF as a novel transcriptional target of MITF and support a relevant functional role for the MITF-PEDF axis in the biology of melanoma.

Place, publisher, year, edition, pages
Neoplasia, 2014
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-110497 (URN)10.1016/j.neo.2014.06.001 (DOI)000340553600007 ()25030625 (PubMedID)
Note

Funding Agencies|Ministerio de Ciencia y Competitividad of Spain [SAF-2010-19256, SAF-2011-24225, SAF-2012-32117, FIS 11/02568, RD09/0076/0101, PT13/0010/0012, PI12/01552]; LiU-Cancer; Svenska Sallskapet for Medicinsk Forskning; Ake Wibergs Stiftelse; Goesta Fraenkels Stifelse; Fundacion Cientifica de la Asociacion Espanola Contra el Cancer

Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2018-12-07
3. Adjustable delivery of pro-angiogenic FGF-2 by alginate: collagen microspheres
Open this publication in new window or tab >>Adjustable delivery of pro-angiogenic FGF-2 by alginate: collagen microspheres
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2018 (English)In: BIOLOGY OPEN, ISSN 2046-6390, Vol. 7, no 3, article id UNSP bio027060Article in journal (Refereed) Published
Abstract [en]

Therapeutic induction of blood vessel growth (angiogenesis) in ischemic tissues holds great potential for treatment of myocardial infarction and stroke. Achieving sustained angiogenesis and vascular maturation has, however, been highly challenging. Here, we demonstrate that alginate: collagen hydrogels containing therapeutic, pro-angiogenic FGF-2, and formulated as microspheres, is a promising and clinically relevant vehicle for therapeutic angiogenesis. By titrating the amount of readily dissolvable and degradable collagen with more slowly degradable alginate in the hydrogel mixture, the degradation rates of the biomaterial controlling the release kinetics of embedded proangiogenic FGF-2 can be adjusted. Furthermore, we elaborate a microsphere synthesis protocol allowing accurate control over sphere size, also a critical determinant of degradation/release rate. As expected, alginate: collagen microspheres were completely biocompatible and did not cause any adverse reactions when injected in mice. Importantly, the amount of pro-angiogenic FGF-2 released from such microspheres led to robust induction of angiogenesis in zebrafish embryos similar to that achieved by injecting FGF-2-releasing cells. These findings highlight the use of microspheres constructed from alginate: collagen hydrogels as a promising and clinically relevant delivery system for pro-angiogenic therapy.

Place, publisher, year, edition, pages
COMPANY OF BIOLOGISTS LTD, 2018
Keywords
Hydrogels; Microspheres; Angiogenesis; Vasculature; Zebrafish
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-147419 (URN)10.1242/bio.027060 (DOI)000429100500002 ()29449216 (PubMedID)
Note

Funding Agencies|Svenska Sallskapet for Medicinsk Forskning; Ake-Wiberg Foundation; Goesta Fraenkel Foundation; Ahrens Stiftelse; Ollie och Elof Ericssons Stiftelse; Carmen och Bertil Ragners Stiftelse; KI Stiftelser och fonder; Loo och Hans Ostermans Stiftelse for Medicinsk Forskning; Vetenskapsradet; Linkoping University

Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2018-12-07

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