| 1. |
- Barkefors, Irmeli, 1981-
(författare)
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Directing Angiogenesis : Cellular Responses to Gradients in vitro
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Blood vessels are essential for the delivery of nutrients and oxygen to tissues, as well as for the removal of waste products. Patients with tumors, wounds or diabetes all have active angiogenesis, formation and remodeling of blood vessels, a process that is initiated and manipulated by gradients of secreted signaling proteins. This thesis describes the development of new microfluidic in vitro assays where directed migration of single endothelial cells and three dimensional vascular structures can be monitored in real time. Combining these assays with live imaging microscopy we have studied the behavior of endothelial cells in gradients of proangiogenic factors as well as directed sprouting in embryonic kidneys and stem cell cultures. With the 2D assay we have quantified endothelial cell chemotaxis towards FGF2, VEGFA165 and VEGFA121 and we also demonstrate that constant levels of VEGFA165, but not of FGF2, are able to reduce chemokinesis of endothelial cells. In the 3D migration chamber we have studied directed endothelial cell sprouting in mouse embryonic kidneys and embryoid bodies in response to VEGFA gradients. In both models directed angiogenesis is detected towards increasing levels of growth factor. Using the microarray technique on differentiating embryonic stem cells we have been able to identify the gene exoc3l2 as potentially involved in angiogenesis and endothelial cell migration and we present evidence that ExoC3l2 is associated with the exocyst complex; an important regulator of cell polarity. We have also shown that siRNA mediated gene silencing of exoc3l2 results in impaired VEGFR2 phosphorylation as well as loss of directionality in response to a VEGFA gradient.
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| 2. |
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| 3. |
- Fredlund Fuchs, Peder, 1984-
(författare)
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Myofibroblasts and the Vascular Endothelium : Impact of Fibrin Degradation Products and miRNA on Vascular Motility and Function
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Angiogenesis is the formation of new blood vessels from pre-existing vasculature and is important during development as well as wound healing and tissue remodeling. Angiogenesis also occurs during pathological conditions such as diabetic retinopathy and cancer. This thesis is centered on the biology of endothelial cells, lining the blood vessels, and myofibroblasts, important for wound healing.We investigated an endothelial cell specific gene, ExoC3l2, and its role in VEGFR2 signaling and migration. EXOC3L2 co-localize with members of the exocyst complex, involved in vesicular transport, as well as VEGFR2. Reducing the level of EXOC3L2 in microvascular endothelial cells results in reduced VEGFR2 signaling and subsequently reduced chemotactic response to VEGF-A.MicroRNA (miRNA) have been shown to be regulators of gene transcription and cell type specific miRNAs have been identified. We investigated two miRNAs, miR-145 and miR-24. miR-145 is expressed in pericytes and fibroblasts but was shown to regulate fli1, an endothelial transcription factor. miR-145 overexpression reduced chemotaxis in both fibroblasts and endothelial cells, as did suppression of the endogenous miR-145 level in fibroblasts.miR-24 in contrast is expressed by endothelial cells and are able to target Ndst1, important for heparan sulfate (HS) sulfation. Sulfation of HS is important for many processes, amongst them growth factor signaling. Overexpression of miR-24 resulted in lower sulfation of HS chains, decreasing the ability of HS to interact with VEGF-A. Overexpressing miR-24 resulted in disturbed chemotaxis, similar to suppressing Ndst1 using siRNA.Myofibroblast recruitment is an important step in wound healing. The myofibroblasts contract the wound, synthesize new extracellular matrix and contribute to revascularization by looping angiogenesis. Maturation from resting fibroblast to myofibroblast is dependent on TGF-β. We found that fibrin fragment E (FnE), a degradation product of fibrin, potentiated the response of fibroblasts to TGF-β thus enhancing TGF-β-induced myofibroblast differentiation. FnE was also found to influence the migration of fibroblasts. These responses are dependent on integrins and toll-like receptors.These findings may serve to further increase the understanding of angiogenesis and wound healing to develop new therapies against pathological conditions.
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| 4. |
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| 5. |
- Gerwins, Pär, et al.
(författare)
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Function of fibroblast growth factors and vascular endothelial growth factors and their receptors in angiogenesis
- 2000
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Ingår i: Critical reviews in oncology/hematology. - 1040-8428 .- 1879-0461. ; 34:3, s. 185-194
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Tidskriftsartikel (refereegranskat)abstract
- Angiogenesis, formation of new vessels from pre-existing ones, results from stimulation of endothelial cells, which line the vessel wall. These cells will leave their resting state and start to digest the basement membrane, proliferate, migrate and eventually differentiate to form a hollow tube. All these steps can be induced by growth factors and this review will focus on two important types of angiogenic growth factors, vascular endothelial growth factor (VEGF; also denoted vascular permeability factor, VPF) and fibroblast growth factor (FGF). Both types of factors bind to cell surface expressed receptors, which are ligand-stimulatable tyrosine kinases. Binding of the growth factors to their receptors leads to activation of the intrinsic tyrosine kinase and signal transduction to downstream signalling cascades. This results in transcriptional changes and biological responses. The molecular aspects of signalling cascades critical for endothelial cell proliferation and migration are beginning to be delineated. In contrast, signalling cascades leading to endothelial cell differentiation remain to be determined. Angiogenesis is essential for a number of physiological events such as embryonic development, ovulation, and wound healing. It has become increasingly clear that a number of diseases depend on angiogenesis. For future development of therapeutic tools, it is important to understand the molecular mechanisms that regulate angiogenesis.
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| 6. |
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| 7. |
- Heindryckx, Femke, et al.
(författare)
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Endoplasmic reticulum stress enhances fibrosis through IRE1α-mediated degradation of miR-150 and XBP-1 splicing
- 2016
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Ingår i: EMBO Molecular Medicine. - : Wiley-Blackwell. - 1757-4676 .- 1757-4684. ; 8:7, s. 729-744
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Tidskriftsartikel (refereegranskat)abstract
- ER stress results in activation of the unfolded protein response and has been implicated in the development of fibrotic diseases. In this study, we show that inhibition of the ER stress-induced IRE1α signaling pathway, using the inhibitor 4μ8C, blocks TGFβ-induced activation of myofibroblasts in vitro, reduces liver and skin fibrosis in vivo, and reverts the fibrotic phenotype of activated myofibroblasts isolated from patients with systemic sclerosis. By using IRE1α(-/-) fibroblasts and expression of IRE1α-mutant proteins lacking endoribonuclease activity, we confirmed that IRE1α plays an important role during myofibroblast activation. IRE1α was shown to cleave miR-150 and thereby to release the suppressive effect that miR-150 exerted on αSMA expression through c-Myb. Inhibition of IRE1α was also demonstrated to block ER expansion through an XBP-1-dependent pathway. Taken together, our results suggest that ER stress could be an important and conserved mechanism in the pathogenesis of fibrosis and that components of the ER stress pathway may be therapeutically relevant for treating patients with fibrotic diseases.
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| 8. |
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| 9. |
- Heindryckx, Femke, et al.
(författare)
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Targeting the tumor stroma in hepatocellular carcinoma
- 2015
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Ingår i: World Journal of Hepatology. - : Baishideng Publishing Group Inc.. - 1948-5182. ; 7:2, s. 165-176
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Tidskriftsartikel (refereegranskat)abstract
- Hepatocellular carcinoma (HCC) is one of the most common and deadly cancers worldwide. In ninety percent of the cases it develops as a result of chronic liver damage and it is thus a typical inflammation-related cancer characterized by the close relation between the tumor microenvironment and tumor cells. The stromal environment consists out of several cell types, including hepatic stellate cells, macrophages and endothelial cells. They are not just active bystanders in the pathogenesis of HCC, but play an important and active role in tumor initiation, progression and metastasis. Furthermore, the tumor itself influences these cells to create a background that is beneficial for sustaining tumor growth. One of the key players is the hepatic stellate cell, which is activated during liver damage and differentiates towards a myofibroblast-like cell. Activated stellate cells are responsible for the deposition of extracellular matrix, increase the production of angiogenic factors and stimulate the recruitment of macrophages. The increase of angiogenic factors (which are secreted by macrophages, tumor cells and activated stellate cells) will induce the formation of new blood vessels, thereby supplying the tumor with more oxygen and nutrients, thus supporting tumor growth and offering a passageway in the circulatory system. In addition, the secretion of chemokines by the tumor cells leads to the recruitment of tumor associated macrophages. These tumor associated macrophages are key actors of cancer-related inflammation, being the main type of inflammatory cells infiltrating the tumor environment and exerting a tumor promoting effect by secreting growth factors, stimulating angiogenesis and influencing the activation of stellate cells. This complex interplay between the several cell types involved in liver cancer emphasizes the need for targeting the tumor stroma in HCC patients.
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| 10. |
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| 11. |
- Heldin, Johan, et al.
(författare)
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FGD5 sustains vascular endothelial growth factor A (VEGFA) signaling through inhibition of proteasome-mediated VEGF receptor 2 degradation
- 2017
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 40, s. 125-132
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Tidskriftsartikel (refereegranskat)abstract
- The complete repertoire of endothelial functions elicited by FGD5, a guanine nucleotide exchange factor activating the Rho GTPase Cdc42, has yet to be elucidated. Here we explore FGD5's importance during vascular endothelial growth factor A (VEGFA) signaling via VEGF receptor 2 (VEGFR2) in human endothelial cells. In microvascular endothelial cells, FGD5 is located at the inner surface of the cell membrane as well as at the outer surface of EEAl-positive endosomes carrying VEGFR2. The latter finding prompted us to explore if FGD5 regulates VEGFR2 dynamics. We found that depletion of FGD5 in microvascular cells inhibited their migration towards a stable VEGFA gradient. Furthermore, depletion of FGD5 resulted in accelerated VEGFR2 degradation, which was reverted by lactacystin-mediated proteasomal inhibition. Our results thus suggest a mechanism whereby FGD5 sustains VEGFA signaling and endothelial cell chemotaxis via inhibition of proteasome-dependent VEGFR2 degradation.
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| 12. |
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| 13. |
- Kasza, Z., et al.
(författare)
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MicroRNA-24 Suppression of N-Deacetylase/N-Sulfotransferase-1 (NDST1) Reduces Endothelial Cell Responsiveness to Vascular Endothelial Growth Factor A (VEGFA)
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:36, s. 25956-25963
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Tidskriftsartikel (refereegranskat)abstract
- Heparan sulfate (HS) proteoglycans, present at the plasma membrane of vascular endothelial cells, bind to the angiogenic growth factor VEGFA to modulate its signaling through VEGFR2. The interactions between VEGFA and proteoglycan co-receptors require sulfated domains in the HS chains. To date, it is essentially unknown how the formation of sulfated protein-binding domains in HS can be regulated by microRNAs. In the present study, we show that microRNA-24 (miR-24) targets NDST1 to reduce HS sulfation and thereby the binding affinity of HS for VEGFA. Elevated levels of miR-24 also resulted in reduced levels of VEGFR2 and blunted VEGFA signaling. Similarly, suppression of NDST1 using siRNA led to a reduction in VEGFR2 expression. Consequently, not only VEGFA binding, but also VEGFR2 protein expression is dependent on NDST1 function. Furthermore, overexpression of miR-24, or siRNA-mediated reduction of NDST1, reduced endothelial cell chemotaxis in response to VEGFA. These findings establish NDST1 as a target of miR-24 and demonstrate how such NDST1 suppression in endothelial cells results in reduced responsiveness to VEGFA.
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| 14. |
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| 15. |
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| 16. |
- Kilarski, Witold, et al.
(författare)
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A quantitative neovascularization assay for screening pro- and anti-angiogenic factors
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Therapeutic regulation of tissue vascularization has appeared as an attractive approach to treat a number of human diseases. However, promising results obtained in animal models have largely failed when translated into clinical trials. This suggests that current experimental models do not properly reflect the physiological situation and that there is a need for new in vivo assay that allows quantitative and qualitative analysis of non-developmental neovascularization. In this report we present a new assay where the effects of activators and inhibitors of neovascularization can be quantitatively measured. A provisional matrix composed of collagen and fibrin was formed in a plastic cylinder and implanted onto the chick chorioallantoic membrane. A nylon mesh separated the implanted matrix from the underlying tissue to distinguish new from pre-existing vessels. Vascularization of the matrix in response to FGF-2 and PDGF-BB was scored in a double-blinded manner, or vessel density measured using a semi-automated image analysis procedure. Evaluation of thalidomide, fumagillin, wortmannin, cortisol and U0126, which are compounds that has been reported to inhibit angiogenesis, revealed that while some only inhibited ingrowth of neo-vessels into the matrix, others also caused pre-existing vessels to regress. This quantitative, inexpensive and rapid in vivo angiogenesis assay might be a valuable tool in screening and characterizing factors that influence tissue vascularization.
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| 17. |
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| 18. |
- Kilarski, Witold, 1975-
(författare)
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Mechanisms of Tissue Vascularization
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tissue neovascularization in postnatal life occurs during post-traumatic tissue healing, neoplastic growth and in the endometrium during the reproductive cycle of females. Although embryonic angiogenesis has been intensively studied, far less is known about tissue revascularization and vessel remodeling in adults due to methodological difficulties. In the current studies, we developed a novel in vivo model of neovascularization that is performed on the chicken chorioallantoic membrane (CAM). A provisional matrix placed on the CAM was vascularized in response to FGF-2. In order to distinguish new from pre-existing vessels, the matrix was separated from the CAM by a nylon grid. Techniques to visualize the three dimensional structure of vascular networks and a method for rapid and semi-automated quantification were developed. This novel model allowed us to study the effects of potential inhibitors of tissue vascularization and their effects on the pre-existing vasculature. We found that while fumagillin or inhibition of MEK and Src inhibited only neovascularization, addition of cortisol or wortmannin was toxic to pre-existing vessels. The CAM model allowed intravital observations during extended periods of time, which together with immunohistochemical analysis revealed a novel mechanism of tissue vascularization. Tensional forces generated by myofibroblast-mediated contraction of the provisional matrix, induced and directed ingrowth of vascular tissue. During the initial stages of vascularization, the vascular network was recruited from the surrounding tissue through a non-angiogenic mechanism by elongation and enlargement of pre-existing vessels, which were moved as vascular loops with constant functional circulation. Ingrown vessels were remodeled, presumably through intussusception, fusion and pruning. The CAM model was validated by observations of neovascularization associated with healing of the injured mouse cornea.
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| 19. |
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| 20. |
- Kilarski, Witold W., et al.
(författare)
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A new mechanism of blood vessel growth - hope for new treatment strategies
- 2009
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Ingår i: Discovery medicine. - 1539-6509. ; 8:40, s. 23-27
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Tidskriftsartikel (refereegranskat)abstract
- Growth of new blood vessels (angiogenesis) is essential for embryo development as well as for wound healing and progression of a number of diseases such as cancer, inflammatory conditions, eye diseases, psoriasis, and rheumatoid arthritis in the adult. Current paradigms explain blood vessel growth entirely by sprouting angiogenesis or by vessel splitting through so called intussusceptive angiogenesis. However, these mechanisms are mainly derived from experiments on the developing embryo while less is known about angiogenesis in the adult during, e.g., wound healing, tumor growth, and inflammation. Recently we showed that blood vessel growth in the adult can be induced and directed by mechanical forces that naturally develop during healing or remodeling of tissues. In contrast to sprouting and intussusception, the new biomechanical hypothesis assumes that functional blood vessels are passively translocated which, if found generic, may drastically change the approach for developing anti- and pro-angiogenic therapies in the treatment of a variety of diseases.
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| 21. |
- Kilarski, Witold W., et al.
(författare)
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An ex vivo model for functional studies of myofibroblasts
- 2005
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Ingår i: Laboratory Investigation. - : Elsevier BV. - 0023-6837 .- 1530-0307. ; 85:5, s. 643-54
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Tidskriftsartikel (refereegranskat)abstract
- Migration, proliferation and invasive growth of myofibroblasts are key cellular events during formation of granulation tissue in situations of wound healing, arteriosclerosis and tumor growth. To study the invasive phenotype of myofibroblasts, we established an assay where arterial tissue from chicken embryos was embedded in fibrin gels and stimulated with growth factors. Addition of serum, PDGF-BB and FGF-2, but not VEGF-A, resulted in an outgrowth of cellular sprouts with a pattern that was similar to the organization of cells invading a provisional matrix in an in vivo model of wound healing using the chicken chorioallantoic membrane. Sprouting cells were defined as myofibroblasts based on being alpha-smooth muscle actin-positive but desmin-negative. There was no contribution of endothelial cells in outgrowing sprouts. The acquired myofibroblastic phenotype was stable since sprout-derived cells resumed sprouting in a growth factor-independent manner when re-embedded as spheroids in a fibrin matrix. Invasive growth and sprouting of vascular smooth muscle cells was not limited to chicken cells since a similar response was seen when spheroids composed of purified primary human aortic smooth muscle cells were embedded in fibrin. Finally, a technique for flat visualization of the three-dimensional sprouting and a quantification method is described. This ex vivo model allows quantitative analysis of invasive growth and differentiation of vascular smooth muscle cells and fibroblasts into myofibroblasts.
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| 22. |
- Kilarski, Witold W, et al.
(författare)
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An in vivo neovascularization assay for screening regulators of angiogenesis and assessing their effects on pre-existing vessels
- 2012
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Ingår i: Angiogenesis. - : Springer Science and Business Media LLC. - 0969-6970 .- 1573-7209. ; 15:4, s. 643-655
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Tidskriftsartikel (refereegranskat)abstract
- Therapeutic regulation of tissue vascularization has appeared as an attractive approach to treat a number of human diseases. In vivo neovascularization assays that reflect physiological and pathological formation of neovessels are important in this effort. In this report we present an assay where the effects of activators and inhibitors of angiogenesis can be quantitatively and qualitatively measured. A provisional matrix composed of collagen I and fibrin was formed in a plastic cylinder and implanted onto the chick chorioallantoic membrane. A nylon mesh separated the implanted matrix from the underlying tissue to distinguish new from pre-existing vessels. Vascularization of the matrix in response to fibroblast growth factor-2 or platelet-derived growth factor-BB was scored in a double-blinded manner, or vessel density was measured using a semi-automated image analysis procedure. Thalidomide, fumagillin, U0126 and TGFβ inhibited neovessel growth while hydrocortisone exerted a negative and wortmannin a toxic effect on the pre-existing vasculature. This quantitative, inexpensive and rapid in vivo angiogenesis assay might be a valuable tool in screening and characterizing factors that influence wound or tumor induced vascularization and in assessing their effects on the normal vasculature.
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| 23. |
- Kilarski, Witold W., et al.
(författare)
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Biomechanical regulation of blood vessel growth during tissue vascularization
- 2009
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 15:6, s. 657-664
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Tidskriftsartikel (refereegranskat)abstract
- Formation of new vessels in granulation tissue during wound healing has been assumed to occur solely through sprouting angiogenesis. In contrast, we show here that neovascularization can be accomplished by nonangiogenic expansion of preexisting vessels. Using neovascularization models based on the chick chorioallantoic membrane and the healing mouse cornea, we found that tissue tension generated by activated fibroblasts or myofibroblasts during wound contraction mediated and directed translocation of the vasculature. These mechanical forces pulled vessels from the preexisting vascular bed as vascular loops with functional circulation that expanded as an integral part of the growing granulation tissue through vessel enlargement and elongation. Blockade of vascular endothelial growth factor receptor-2 confirmed that biomechanical forces were sufficient to mediate the initial vascular growth independently of endothelial sprouting or proliferation. The neovascular network was further remodeled by splitting, sprouting and regression of individual vessels. This model explains the rapid appearance of large functional vessels in granulation tissue during wound healing.
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| 24. |
- Larsson, Annika, et al.
(författare)
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Lactadherin binds to elastin -a starting point for medin amyloid formation?
- 2006
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Ingår i: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 13:2, s. 78-85
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Tidskriftsartikel (refereegranskat)abstract
- Medin amyloid is found in the medial layer of the aorta in almost 100% of the Caucasian population over 50 years of age. The medin fragment is 5.5 kDa and derives from the C2-like domain of the precursor protein lactadherin. We have previously reported immunohistochemical findings showing that medin amyloid co-localizes with elastic fibers of arteries and herein we show that lactadherin also is associated with elastic structures of human aortic material. In addition, results from in vitro binding assays demonstrate that both medin and lactadherin bind to tropoelastin in a concentration-dependent fashion, suggesting that the lactadherin-tropoelastin interaction is mediated via the medin domain. It is possible that lactadherin, which is a cell adhesion protein, in this way connects smooth muscle cells to the elastic fibers of arteries. Given that both medin and lactadherin interact with elastic fibers, elastin is probably an important component in the formation of medin amyloid.
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| 25. |
- Larsson, Erik, 1975, et al.
(författare)
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Discovery of microvascular miRNAs using public gene expression data : miR-145 is expressed in pericytes and is a regulator of Fli1
- 2009
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Ingår i: Genome Medicine. - : Springer Science and Business Media LLC. - 1756-994X. ; 1:11, s. 108-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUNDA function for the microRNA (miRNA) pathway in vascular development and angiogenesis has been firmly established. miRNAs with selective expression in the vasculature are attractive as possible targets in miRNA-based therapies. However, little is known about the expression of miRNAs in microvessels in vivo. Here, we identified candidate microvascular-selective miRNAs by screening public miRNA expression datasets.METHODSBioinformatics predictions of microvascular-selective expression were validated with real-time quantitative reverse transcription PCR on purified microvascular fragments from mouse. Pericyte expression was shown with in situ hybridization on tissue sections. Target sites were identified with 3' UTR luciferase assays, and migration was tested in a microfluid chemotaxis chamber.RESULTSmiR-145, miR-126, miR-24, and miR-23a were selectively expressed in microvascular fragments isolated from a range of tissues. In situ hybridization and analysis of Pdgfb retention motif mutant mice demonstrated predominant expression of miR-145 in pericytes. We identified the Ets transcription factor Friend leukemia virus integration 1 (Fli1) as a miR-145 target, and showed that elevated levels of miR-145 reduced migration of microvascular cells in response to growth factor gradients in vitro.CONCLUSIONSmiR-126, miR-24 and miR-23a are selectively expressed in microvascular endothelial cells in vivo, whereas miR-145 is expressed in pericytes. miR-145 targets the hematopoietic transcription factor Fli1 and blocks migration in response to growth factor gradients. Our findings have implications for vascular disease and provide necessary information for future drug design against miRNAs with selective expression in the microvasculature.
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| 26. |
- Lennmyr, Fredrik, et al.
(författare)
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Activation of mitogen-activated protein kinases in experimental cerebral ischemia
- 2002
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 106:6, s. 333-40
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Mitogen-activated protein kinases (MAPK) regulate cell survival and differentiation. The aim of the present study is to investigate the activation pattern of different MAPKs [extracellular signal-regulated kinase (ERK), c-jun-N-terminal kinase (JNK) and p38] after cerebral ischemia. MATERIAL AND METHODS: Rats were subjected to cerebral ischemia using a model for transient (2 h) and permanent middle cerebral artery occlusion (MCAO). The rats were allowed 6 h to 1 week of survival before immunohistochemical evaluation with phospho-specific antibodies, recognizing activated MAPKs. RESULTS: ERK was activated in ipsilateral blood vessels, neurons and glia, but also in contralateral vessels. JNK activation was absent in neurons but appeared in arterial blood vessels and glia at the lesion side. Active p38 was observed in macrophages in maturing infarcts. CONCLUSIONS: ERK and JNK may participate in the angiogenic response to cerebral ischemia. ERK, but not JNK, was activated in neurons, possibly indicating a pathophysiologic role. Active p38 might be involved in the inflammatory reaction.
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| 27. |
- Lennmyr, Fredrik, et al.
(författare)
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Increased brain injury and vascular leakage after pretreatment with p38-inhibitor SB203580 in transient ischemia
- 2003
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 108:5, s. 339-45
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Focal cerebral ischemia activates intracellular signaling pathways including the mitogen-activated protein kinase p38, which may be involved in the process of ischemic brain injury. In this study, the effect of pretreatment with the p38-inhibitor SB203580 on infarct size and blood-brain barrier (BBB) breakdown was investigated with magnetic resonance imaging (MRI). MATERIALS AND METHODS: Rats were given SB203580 (n = 6) or vehicle (n = 6) in the right lateral ventricle prior to transient (90 min) middle cerebral artery occlusion (MCAO) on the left side. The rats were examined with serial MRI during MCAO, at reperfusion and after 1 and 4 days. RESULTS: The mean infarct size on T2-weighted images after 1 day was significantly higher in the SB203580-treated group than in controls (300 +/- 95 mm3 vs 126 +/- 75 mm3; P < 0.01). Vascular gadolinium leakage, indicating BBB breakdown, was significantly larger in the SB203580-treated group than in controls after 1 day (median leakage score 18.5; range 15-21 vs 6.5; 4-17; P < 0.05) and 4 days (11; 6-15 vs 3.5; 1-9; P < 0.05), although no significant difference was seen initially. CONCLUSION: Pretreatment with SB203580 may aggravate ischemic brain injury and cerebral vascular leakage in the present model of transient ischemia.
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| 28. |
- Lennmyr, Fredrik, et al.
(författare)
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Src family kinase-inhibitor PP2 reduces focal ischemic brain injury
- 2004
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 110:3, s. 175-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the neuroprotective potential of the Src family kinase (SFK) inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo(3,4-d)pyrimidine (PP2) in transient focal cerebral ischemia in the rat. MATERIAL AND METHODS: Sprague-Dawley rats were exposed to transient (90 min) middle cerebral artery occlusion (MCAO) and evaluated after 1 day of survival. PP2 (1.5 mg/kg i.p.) or vehicle was given 30 min after MCAO. The lesions were examined with magnetic resonance imaging (MRI), tri-phenyl tetrazolium chloride (TTC) staining and the functional outcome was determined using neurological scoring according to Bederson et al. RESULTS: PP2-treated rats showed approximately 50% reduction of infarct size on T2-weighted MRI and in TTC staining compared with controls (P < 0.05). Moreover, the neurological score was better in the PP2 group than controls (P < 0.05). CONCLUSION: PP2 is a potential neuroprotective agent in cerebral ischemia-reperfusion. The interference of PP2 with SFKs and/or other pathways remains to be elucidated.
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| 29. |
- Liu, Minghui, et al.
(författare)
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Efficient human interferon-alpha gene transfer to neuroendocrine tumor cells with long-term and stable expression
- 2005
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Ingår i: Neuroendocrinology. - : S. Karger AG. - 0028-3835 .- 1423-0194. ; 82:5-6, s. 264-73
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Tidskriftsartikel (refereegranskat)abstract
- Interferon (IFN)-alpha has been used in the treatment of neuroendocrine (NE) tumors; however, the feasibility of IFN-alpha gene therapy has not been evaluated in NE tumor cells. In this study, human IFN-alpha2 (hIFN-alpha2) gene has been transferred into a NE tumor cell line BON. hIFN-alpha2-expressing BON cells were subcutaneously inoculated in nude mice. The results demonstrated that hIFN-alpha2 exerted significant antiproliferative effects on NE tumor cell lines (BON and LCC18) and other tumor cell lines (CA46 and SW480) as well as porcine aorta cell line. Furthermore, hIFN-alpha2 demonstrated its antineovascular activity in mice tumor and a direct antiangiogenic effect in chicken chorioallantoic membrane assay. hIFN-alpha2-expressing BON cells had a stable and long-term expression. Mice implanted with hIFN-alpha2-expressing BON cells showed a lower incidence, a delayed development and a significantly longer doubling time of the tumor compared to both wild-type (WT) and vector group. In addition, IFN-alpha significantly inhibited cell adhesion of WT BON cells. hIFN-alpha2-expressing BON tumors had a high level of hIFN-alpha2 protein. Finally, mice implanted with a mixture of WT and hIFN-alpha2-expressing BON cells (1:1) presented a delayed tumor development and had an even lower incidence of tumors than those implanted with hIFN-alpha2-expressing BON cells only. The doubling time of tumor was also longest in the mixture group. Our data suggest that hIFN-alpha2 gene therapy might be possible to be used as a new treatment for NE tumor patients. Further studies on the regulation of hIFN-alpha expression are needed, especially in combination with other cytokines, which could lead to a better understanding and improvements of hIFN-alpha gene therapy.
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| 30. |
- Massena, Sara, et al.
(författare)
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Identification and characterization of VEGF-A-responsive neutrophils expressing CD49d, VEGFR1, and CXCR4 in mice and humans
- 2015
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 126:17, s. 2016-2026
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor A (VEGF-A) is upregulated during hypoxia and is the major regulator of angiogenesis. VEGF-A expression has also been found to recruit myeloid cells to ischemic tissues where they contribute to angiogenesis. This study investigates the mechanisms underlying neutrophil recruitment to VEGF-A as well as the characteristics of these neutrophils. A previously undefined circulating subset of neutrophils shown to be CD49d(+)VEGFR1(high)CXCR4(high) was identified in mice and humans. By using chimeric mice with impaired VEGF receptor 1 (VEGFR1) or VEGFR2 signaling (Flt-1tk(-/-), tsad(-/-)), we found that parallel activation of VEGFR1 on neutrophils and VEGFR2 on endothelial cells was required for VEGF-A-induced recruitment of circulating neutrophils to tissue. Intravital microscopy of mouse microcirculation revealed that neutrophil recruitment by VEGF-A versus by the chemokine macrophage inflammatory protein 2 (MIP-2 [CXCL2]) involved the same steps of the recruitment cascade but that an additional neutrophil integrin (eg, VLA-4 [CD49d/CD29]) played a crucial role in neutrophil crawling and emigration to VEGF-A. Isolated CD49d(+) neutrophils featured increased chemokinesis but not chemotaxis compared with CD49d(-) neutrophils in the presence of VEGF-A. Finally, by targeting the integrin α4 subunit (CD49d) in a transplantation-based angiogenesis model that used avascular pancreatic islets transplanted to striated muscle, we demonstrated that inhibiting the recruitment of circulating proangiogenic neutrophils to hypoxic tissue impairs vessel neoformation. Thus, angiogenesis can be modulated by targeting cell-surface receptors specifically involved in VEGF-A-dependent recruitment of proangiogenic neutrophils without compromising recruitment of the neutrophil population involved in the immune response to pathogens.
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| 31. |
- Matsumoto, Taro, et al.
(författare)
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p38 MAP kinase negatively regulates endothelial cell survival,proliferation, and differentiation in FGF-2-stimulated angiogenesis
- 2002
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Ingår i: Journal of Cell Biology. - 0021-9525 .- 1540-8140. ; 156:1, s. 149-160
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Tidskriftsartikel (refereegranskat)abstract
- The p38 mitogen-activated protein kinase (p38) is activated in response to environmental stress and inflammatory cytokines. Although several growth factors, including fibroblast growth factor (FGF)-2, mediate activation of p38, the consequences for growth factor-dependent cellular functions have not been well defined. We investigated the role of p38 activation in FGF-2-induced angiogenesis. In collagen gel cultures, bovine capillary endothelial cells formed tubular growth-arrested structures in response to FGF-2. In these collagen gel cultures, p38 activation was induced more potently by FGF-2 treatment compared with that in proliferating cultures. Treatment with the p38 inhibitor SB202190 enhanced FGF-2-induced tubular morphogenesis by decreasing apoptosis, increasing DNA synthesis and cell proliferation, and enhancing the kinetics of cell differentiation including increased expression of the Notch ligand Jagged1. Overexpression of dominant negative mutants of the p38-activating kinases MKK3 and MKK6 also supported FGF-2-induced tubular morphogenesis. Sustained activation of p38 by FGF-2 was identified in vascular endothelial cells in vivo in the chick chorioallantoic membrane (CAM). SB202190 treatment enhanced FGF-2-induced neovascularization in the CAM, but the vessels displayed abnormal features indicative of hyperplasia of endothelial cells. These results implicate p38 in organization of new vessels and suggest that p38 is an essential regulator of FGF-2-driven angiogenesis.
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| 32. |
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| 33. |
- Pavlovic, Natasa, et al.
(författare)
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Activated platelets contribute to the progression of hepatocellular carcinoma by altering the tumor environment
- 2021
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Ingår i: Life Sciences. - : Elsevier. - 0024-3205 .- 1879-0631. ; 277
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Tidskriftsartikel (refereegranskat)abstract
- AimHepatocellular carcinoma (HCC) is a primary liver cancer that usually develops in a background of chronic liver disease and prolonged inflammation. A major contributor in the complex molecular pathogenesis of HCC is the highly intertwined cross-talk between the tumor and the surrounding stromal cells, such as hepatic stellate cells, endothelial cells, macrophages and other immune cells. These tumor-stroma interactions actively fuel tumor growth and modulate the hepatic microenvironment to benefit tumor invasion and disease progression. Platelets have been reported to interact with different cell types in the tumor microenvironment, including tumor cells, stellate cells and macrophages.Materials and methodsMice were treated with hepatocarcinogenic compound diethylnitrosamine for 25 weeks to induce HCC in the background of fibrosis and inflammation. From week 10, anti-platelet drug Clopidogrel was added to the drinking water and mice were given ad libitum access.Key findingsIn this study, we show that activated platelets promote tumor cell proliferation and contribute to the adverse tumor-stroma cross-talk that fuels tumor progression. We also show that inhibiting platelet activation with the P2Y12-inhibitor Clopidogrel decreases the number of tumors in a chemically induced mouse model for HCC.SignificanceThese results suggest an important role for platelets in the pathogenesis of HCC and that the use of anti-platelet drugs may be therapeutically relevant for patients with liver cancer.
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| 34. |
- Pavlovic, Natasa, et al.
(författare)
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Inhibiting IRE1α-endonuclease activity decreases tumor burden in a mouse model for hepatocellular carcinoma
- 2020
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Ingår i: eLIFE. - 2050-084X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Hepatocellular carcinoma (HCC) is a liver tumor that usually arises in patients with cirrhosis. Hepatic stellate cells are key players in the progression of HCC, as they create a fibrotic micro-environment and produce growth factors and cytokines that enhance tumor cell proliferation and migration. We assessed the role of endoplasmic reticulum (ER) stress in the cross-talk between stellate cells and HCC cells. Mice with a fibrotic HCC were treated with the IRE1α-inhibitor 4μ8C, which reduced tumor burden and collagen deposition. By co-culturing HCC-cells with stellate cells, we found that HCC-cells activate IREα in stellate cells, thereby contributing to their activation. Inhibiting IRE1α blocked stellate cell activation, which then decreased proliferation and migration of tumor cells in different in vitro 2D and 3D co-cultures. In addition, we also observed cell-line-specific direct effects of inhibiting IRE1α in tumor cells.
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| 35. |
- Pavlović, Natasa, et al.
(författare)
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Inhibiting P2Y12 in Macrophages Induces Endoplasmic Reticulum Stress and Promotes an Anti-Tumoral Phenotype
- 2020
-
Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:21
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Tidskriftsartikel (refereegranskat)abstract
- The P2Y12 receptor is an adenosine diphosphate responsive G protein-coupled receptor expressed on the surface of platelets and is the pharmacologic target of several anti-thrombotic agents. In this study, we use liver samples from mice with cirrhosis and hepatocellular carcinoma to show that P2Y12 is expressed by macrophages in the liver. Using in vitro methods, we show that inhibition of P2Y12 with ticagrelor enhances tumor cell phagocytosis by macrophages and induces an anti-tumoral phenotype. Treatment with ticagrelor also increases the expression of several actors of the endoplasmic reticulum (ER) stress pathways, suggesting activation of the unfolded protein response (UPR). Inhibiting the UPR with tauroursodeoxycholic acid (Tudca) diminishes the pro-phagocytotic effect of ticagrelor, thereby indicating that P2Y12 mediates macrophage function through activation of ER stress pathways. This could be relevant in the pathogenesis of chronic liver disease and cancer, as macrophages are considered key players in these inflammation-driven pathologies.
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| 36. |
- Pavlovic, Natasa, et al.
(författare)
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Platelets as Key Factors in Hepatocellular Carcinoma
- 2019
-
Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 11:7
-
Forskningsöversikt (refereegranskat)abstract
- Hepatocellular carcinoma (HCC) is a primary liver cancer that usually develops in the setting of chronic inflammation and liver damage. The hepatic microenvironment plays a crucial role in the disease development, as players such as hepatic stellate cells, resident liver macrophages (Kupffer cells), endothelial cells, extracellular matrix, and a variety of immune cells interact in highly complex and intertwined signaling pathways. A key factor in these cross-talks are platelets, whose role in cancer has gained growing evidence in recent years. Platelets have been reported to promote HCC cell proliferation and invasion, but their involvement goes beyond the direct effect on tumor cells, as they are known to play a role in pro-fibrinogenic signaling and the hepatic immune response, as well as in mediating interactions between these factors in the stroma. Anti-platelet therapy has been shown to ameliorate liver injury and improve the disease outcome. However, platelets have also been shown to play a crucial role in liver regeneration after organ damage. Therefore, the timing and microenvironmental setting need to be kept in mind when assessing the potential effect and therapeutic value of platelets in the disease progression, while further studies are needed for understanding the role of platelets in patients with HCC.
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| 37. |
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| 38. |
- Peng, Siwei, et al.
(författare)
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Role of aggregated medin in the pathogenesis of thoracic aortic aneurysm and dissection
- 2007
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Ingår i: Laboratory Investigation. - : Elsevier BV. - 0023-6837 .- 1530-0307. ; 87:12, s. 1195-1205
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenesis of sporadic thoracic aortic aneurysm and dissection, which may lead to rupture of the aorta, remains largely unknown. Amyloid deposits, formed from the medin peptide, are very prevalent in the media of the thoracic aorta. We have studied the occurrence of medin-derived amyloid in specimens from patients with thoracic aortic aneurysm, aortic dissection type A and normal dimensioned aorta. Surprisingly, the amount of amyloid was significantly lower in the aneurysm and dissection groups (0.63+/-0.13 and 0.36+/-0.24 amyloid particles per mm2, respectively) compared to the control material (2.37+/-0.58). However, focal medin immunoreactivity not associated with amyloid was found more conspicuously in the media of the two diseased groups. Recent amyloid research indicates that prefibrillar oligomeric aggregates, rather than mature amyloid fibrils, are toxic to the surrounding cells. The non-amyloid medin immunoreactivity observed may represent such toxic oligomers. This is supported by the fact that aggregated medin induced death of aortic smooth muscle cells in vitro. In addition, cells incubated together with medin increased the production of matrix metalloproteinase-2, a protease that degrades elastin and collagen and subsequently weakens the vessel wall. We therefore propose that medin oligomers are involved in the degeneration process of sporadic thoracic aortic aneurysm and dissection.
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| 39. |
- Petersson, Ludvig, et al.
(författare)
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The role of growth factor receptor signaling for angiogenesis and vessel stability in an experimental wound healing model
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Tissue vascularization during wound healing is regulated by a variety of growth factors. Although addition of a single growth factor is sufficient to induce vascularization, at least in experimental models, the question remains on how important other endogenously produced growth factors are. We have used receptor kinase inhibitors to investigate the role of FGF-, VEGF-, PDGF- and TGFb-receptor signaling for FGF-2 and PDGF-BB induced vascularization in a wound healing model based on neovascularization of a provisional matrix implanted on the chick chorioallantoic membrane. Inhibition of the PDGF pathway with Imatinib reduced FGF-2 induced angiogenesis while FGF-receptor inhibition with PD173074 did not. FGF-2 induced angiogenesis was markedly reduced when VEGF receptors were inhibited with PTK787 as was the PDGF-BB response albeit at higher inhibitor concentrations. In agreement, sequestration of VEGF with the VEGF Trap blocked both FGF-2 and PDGF-BB induced vascularization. Inactivation of TGFbR1 with SB431542 did not influence FGF-2 or PDGF-BB induced vascularization. Higher concentrations of inhibitors did not only inhibit angiogenesis but also caused established vessels to regress. While VEGF inhibition with PTK787 mainly caused micro-vessels to regress the response to PDGF receptor inhibition with Imatinib was more profound with detachment of mural cells and regression of both micro- and macro-vessels. In summary, we found an absolute requirement of PDGF- and VEGF-receptor signaling for wound vascularization while FGF- and TGFb-receptor signalling was dispensable. Higher concentrations of growth factor inhibitors caused vessel regression which suggests a mechanism for adverse effects such as bleedings following VEGF or PDGF inhibition in clinical settings.
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| 40. |
- Petersson, Ludvig, 1978-
(författare)
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The Roles of Growth Factor Interactions and Mechanical Tension in Angiogenesis
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Angiogenesis, the formation of new blood vessels from preexisting ones through creation of new vessel branch points by sprouting or vessel splitting, is an important part of tissue growth in both physiological processes like wound healing and pathological conditions such as cancer. Growth factors like VEGF-A, FGF-2 and PDGF-BB are involved in both types of angiogenesis. Screening for genes regulated by VEGF-A stimulation in endothelial cells revealed up regulation of the endothelial cell specific glycoprotein endocan. Endocan itself did not stimulate angiogenesis. VEGF was a specific inducer since FGF-2, PDGF-BB, HGF and EGF did not alter expression. The signaling molecule PI3K was a negative regulator of endocan expression. Endocan was expressed in tumor cells and vessels, suggesting that although endocan did not directly regulate angiogenesis it can serve as a marker for angiogenic tumors. In two models of wound healing angiogenesis, the chick extra-embryonal CAM assay and the mouse cornea assay, we observed that blood vessels grew into avascular areas as functional mural cell covered loops by elongation of preexisting vessels. Loop formation was simultaneous with contraction of the avascular matrix mediated by proto/myofibroblasts. Reducing the contractibility of the stroma reduced vessel ingrowth, showing that contraction was necessary for mediating and directing growth of the vascular loops. These findings suggest a model for biomechanical regulation of vascularization that is complementary to sprouting angiogenesis which is guided by gradients of growth factors. In defining the role of growth factors, in the CAM assay, we found that FGF-2 and PDGF-BB induced vessel ingrowth, while VEGF-A, EGF and HGF did not. TGF-beta reduced the effect of FGF-2. By use of specific receptor kinase inhibitors we found an absolute requirement VEGF- and PDGF-receptor activity for vascularization while FGF- and TGF-beta-receptor function was dispensable. This suggests that functional VEGF- and PDGF-receptors are needed for vessel elongation.
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| 41. |
- Rennel, Emma, et al.
(författare)
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Endocan is a VEGF-A and PI3K regulated gene with increased expression in human renal cancer
- 2007
-
Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 313:7, s. 1285-1294
-
Tidskriftsartikel (refereegranskat)abstract
- An in vitro model of VEGF-A-induced angiogenesis was used to generate transcription profiles of human microvascular endothelial cells. Microarray analysis showed increased transcription of genes known to regulate angiogenesis, but also genes that previously have not been firmly associated with angiogenesis such as endocan, pinin, plakophilin, phosphodiesterase 4B and gelsolin. Increased endocan mRNA levels in response to VEGF-A in endothelial cells and in human renal cancer have previously been reported. We now show increased endocan protein levels in VEGF-A treated endothelial cells and in human renal clear cell carcinoma. Increased protein expression was observed both in tumor cells and in a subset of tumor vessels, while expression in normal kidney tissue was low. VEGF-A seemed to be a specific inducer of endocan transcription since FGF-2, PDGF-BB, HGF/SF and EGF did not alter expression levels. Inhibition of PI3K with LY294002 caused a 12-fold increase in endocan transcription suggesting a repressive function of PI3K. In contrast inhibition of Src or MEK, which are signaling pathways activated by VEGF-A, did not influence basal or VEGF-A-induced endocan levels. In conclusion our study shows that, among angiogenic growth factors, VEGF-A is a specific inducer of endocan transcription which is translated into increased protein levels in VEGF-A treated endothelial cells. Increased endocan protein expression in human renal cancer suggests a role in tumor growth.
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| 42. |
- Rennel, Emma, et al.
(författare)
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How to make tetracycline-regulated transgene expression go on and off
- 2002
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Ingår i: Analytical Biochemistry. - 0003-2697 .- 1096-0309. ; 309:1, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- Tetracycline-regulated gene expression systems are widely used to allow temporal and quantitative control of transgene expression in cultured cells and transgenic animals. While working with the Tet-Off system, where tetracycline or the analogue doxycycline suppresses expression, we noted a considerable variability in induced transgene expression after removal of doxycycline. Variable expression of the transgene could not be explained by clonal variation since it was noted when working with clonal cell lines. Instead we found that doxycycline bound nonspecifically to cells and extracellular matrix and was slowly released after it had been removed from tissue culture media. The released doxycycline reached sufficiently high levels to completely suppress transgene expression. The effect was not dependent on cell type or the nature of the transgene. However, robust and rapid transgene expression could be induced if released doxycycline were removed by washing cells 3h after the initial removal of doxycycline. The use of different vector systems, harboring the tetracycline-regulatable components, yielded similar results. These results not only help explain why tetracycline-regulatable transgene expression systems sometimes are variable but also provide simple ways to substantially improve the efficiency, utility, and reliability of these widely used expression systems.
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| 43. |
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| 44. |
- Rennel, Emma, 1974-
(författare)
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Molecular Mechanisms in Endothelial Cell Differentiation
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Angiogenesis is the formation of new blood vessels from the pre-existing blood vessels. Blood vessels are composed of endothelial cells and supporting musculature. Angiogenesis is regulated by numerous soluble ligands and by cell-matrix interactions. We have studied the molecular mechanisms in fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor-A (VEGF-A)-induced angiogenesis using immortalized endothelial cell lines in different angiogenesis assays.The role of the signaling protein H-Ras in FGF-2-induced in vitro angiogenesis was studied by expressing mutated versions of H-Ras in immortalized mouse brain endothelial cells using a tetracycline-regulated expression system. In vitro angiogenesis was analyzed as the ability of cells to invade a fibrin matrix and form branching structures in response to a combination of FGF-2 and tumor necrosis factor-α (TNF-α). Inhibition of H-Ras through the expression of dominant negative (S17N) H-Ras or pharmacological inactivation of H-Ras with a farnesyl transferase inhibitor, did not inhibit growth factor-induced invasion. In contrast, expression of constitutively active (G12V) H-Ras caused cells to adopt a transformed phenotype which inhibited invasive growth and cells formed solid tumors when injected in nude mice. These studies suggest that H-Ras activity is not required for differentiation but its activity must be tightly regulated as aberrant activity impairs endothelial cell differentiation.In order to screen for both known and novel genes that regulate angiogenesis we used large scale microarray analysis. In VEGF-A-stimulated telomerase immortalized human microvascular endothelial cells undergoing invasive growth in fibrin gels, or forming cord-like structures on collagen, we identified several genes that were differentially expressed. Some of these are known to be important for endothelial cell functions and angiogenesis while others have no previous connection with endothelial cell function or were transcripts with no assigned function. Further analysis of these proteins will aid in elucidating the molecular mechanisms underlying endothelial cell differentiation.
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| 45. |
- Rennel, Emma, et al.
(författare)
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Regulation of endothelial cell differentiation and transformation by H-Ras
- 2003
-
Ingår i: Experimental Cell Research. - 0014-4827 .- 1090-2422. ; 291:1, s. 189-200
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Tidskriftsartikel (refereegranskat)abstract
- Angiogenesis is regulated by growth factors which activate tyrosine kinase receptors leading to the activation of a number of intracellular signaling pathways. The specific function of H-Ras during FGF-2 stimulated endothelial cell differentiation, defined as invasive growth and formation of branching networks in fibrin gels, was investigated by using conditionally immortalized endothelial cell lines induced to express H-Ras mutants. Expression of inhibitory N17Ras did not impair differentiation in response to FGF-2 and TNF-alpha. The farnesyltransferase inhibitor FTI-277 inhibited farnesylation of Ras but did not inhibit differentiation of human microvascular endothelial cells or mouse brain endothelial cells. In contrast, activated V12Ras inhibited endothelial cell differentiation and cells displayed a transformed phenotype with an increased rate of proliferation and loss of contact inhibited growth. Furthermore, V12Ras expressing endothelial cells grew as solid tumors when injected subcutaneously into mice. Our data suggest that, in endothelial cells, H-Ras activity is not required for differentiation. However, this activity must be tightly regulated as aberrant activity can disturb the ability of endothelial cells to undergo differentiation.
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| 46. |
- Sakata, Naoki, et al.
(författare)
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Differential activation and regulation of mitogen activated protein kinases through the antigen receptor and CD40 in human B cells
- 1999
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Ingår i: European Journal of Immunology. - 0014-2980 .- 1521-4141. ; 29:9, s. 2999-3008
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Tidskriftsartikel (refereegranskat)abstract
- In human B cells, antigen receptor ligation and CD40 ligation are known to activate the extracellular-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) pathways, which in turn regulate many important B cell functions. We previously reported that antigen receptor ligation activated the ERK pathway whereas CD40 ligation activated the JNK/stress-activated protein kinase (SAPK) pathway. Here, we demonstrate that another SAPK, p38/Hog1, is activated by both antigen receptor ligation or CD40 ligation in a human B-lymphoblastoid cell line and tonsillar B cells. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, partially inhibited ERK2 and p38 activation triggered through the B cell receptor whereas activation of JNK1 and p38 through CD40 was not affected. PD98059, a specific inhibitor of mitogen-activated extracellular response kinase kinase (MEK), significantly inhibited ERK2 activation and partially inhibited p38 activation triggered by anti-IgM antibody treatment, but did not affect CD40-dependent signaling events. In addition, anti-IgM antibody-induced signaling pathways were shown to be PKC-dependent in contrast to the CD40-induced signaling pathways. Thus, the B cell receptor and CD40 recruit the ERK, JNK and p38 pathways by using different upstream effectors.
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| 47. |
- Sakata, Naoki, et al.
(författare)
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Differential regulation of CD40-mediated human B cell responses by antibodies directed against different CD40 epitopes
- 2000
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749 .- 1090-2163. ; 201:2, s. 109-123
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Tidskriftsartikel (refereegranskat)abstract
- Ligation of CD40 using anti-CD40 or soluble CD40-ligand activates numerous intracellular kinases which transduce signals to the nucleus. The nature whereby these signaling events are coupled to distal functional events in B cells is poorly understood. In this study, using anti-CD40 monoclonal antibodies which recognize different epitopes on CD40, we compare the ability to activate the stress-activated protein kinases (SAPK) such as c-Jun NH(2) terminal kinase and p38 in human B cells with CD40 function. Activation of the SAPK pathway correlated with levels of activation of Rel/NF-kappaB transcription factors, but did not appear to be associated with rescue from anti-IgM induced apoptosis by suppressing caspase (CPP32) activity. Somewhat surprisingly, in the presence of IL-4, those antibodies to CD40 which failed to activate SAPK were most active in IgE production. IgE production was augmented in the presence of wortmannin. These studies suggest that rescue from apoptosis and IgE production mediated via CD40 may be independent of SAPK activation, induction of Rel/NF-kappaB, or suppression of CPP32 and that IgE production is, at least in part, regulated by signaling pathways that are dependent on phosphatidylinositol 3-kinase.
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| 48. |
- Strese, Sara, et al.
(författare)
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The novel alkylating prodrug melflufen (J1) inhibits angiogenesis in vitro and in vivo
- 2013
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Ingår i: Biochemical Pharmacology. - : Elsevier BV. - 0006-2952 .- 1356-1839 .- 1873-2968. ; 86:7, s. 888-895
-
Tidskriftsartikel (refereegranskat)abstract
- Aminopeptidase N (APN) has been reported to have a functional role in tumor angiogenesis and repeatedly reported to be over-expressed in human tumors. The melphalan-derived prodrug melphalan-flufenamide (melflufen, previously designated J1) can be activated by APN. This suggests that this alkylating prodrug may exert anti-angiogenic properties, which will possibly contribute to the anti-tumoral activity in vivo. This work presents a series of experiments designed to investigate this effect of melflufen. In a cytotoxicity assay we show that bovine endothelial cells were more than 200 times more sensitive to melflufen than to melphalan, in HUVEC cells the difference was more than 30-fold and accompanied by aminopetidase-mediated accumulation of intracellular melphalan. In the chicken embryo chorioallantoic membrane (CAM) assay it is indicated that both melflufen and melphalan inhibit vessel ingrowth. Two commercially available assays with human endothelial cells co-cultured with fibroblasts (TCS Cellworks AngioKit, and Essen GFP-AngioKit) also illustrate the superior anti-angiogenic effect of melflufen compared to melphalan. Finally, in a commercially available in vivo assay in mice (Cultrex DIVAA angio-reactor assay) melflufen displayed an anti-angiogenic effect, comparable to bevacizumab. In conclusion, this study demonstrates through all methods used, that melphalan-flufenamide besides being an alkylating agent also reveals anti-angiogenic effects in different preclinical models in vitro and in vivo.
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| 49. |
- Winberg, Hans, et al.
(författare)
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Massive Chylous Ascites in a 9-Year-Old Girl with Malrotation-A Case Report
- 2024
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Ingår i: EUROPEAN JOURNAL OF PEDIATRIC SURGERY REPORTS. - : Georg Thieme Verlag KG. - 2194-7619 .- 2194-7627. ; 12:01, s. e1-e3
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Tidskriftsartikel (refereegranskat)abstract
- Malrotation leading to massive chylous ascites is rare. A 9-year-old girl was investigated for slowly increasing abdominal distension under a year. She had no vomiting, weight loss, or pain, but was bothered in social situations. Medical investigations, including ultrasound and computed tomography scans, revealed massive ascites. Laparocentesis yielded milk-colored fluid, confirmed as lymph through laboratory analysis. A complete blood count, liver function and hematologic parameters, chyle cytology, bacterial cultures, and polymerase chain reaction for tuberculosis were all within normal limits.She was referred to a tertiary center for vascular anomalies. A dynamic contrast-enhanced magnetic resonance lymphangiography showed normal lymphatic anatomy without leakage or flow obstruction. A whole-body magnetic resonance imaging revealed a central mesenteric rotation.She was referred to a tertiary center for pediatric surgery, where a laparoscopic Ladd's procedure was performed using a new 5 mm pediatric sealing device, along with an appendectomy using a 5 mm stapler. To derotate the bowel, fenestrations were created in compartments containing a substantial amount of chyle and ascites, resulting in the drainage of 2.4 L of fluid. She was discharged the day after surgery and has been in good health for 1 year. We present a video illustrating the Ladd's procedure steps in this patient.
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| 50. |
- Öhman Fuchs, Peder, 1984-, et al.
(författare)
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Fibrin fragment E potentiates TGF-beta-induced myofibroblast activation and recruitment
- 2020
-
Ingår i: Cellular Signalling. - : Elsevier. - 0898-6568 .- 1873-3913. ; 72
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Tidskriftsartikel (refereegranskat)abstract
- Fibrin is an essential constituent of the coagulation cascade, and the formation of hemostatic fibrin clots is central to wound healing. Fibrin clots are over time degraded into fibrin degradation products as the injured tissue is replaced by granulation tissue. Our goal was to study the role of the fibrin degradation product fragment E (FnE) in fibroblast activation and migration. We present evidence that FnE is a chemoattractant for fibroblasts and that FnE can potentiate TGF-beta-induced myofibroblast formation. FnE forms a stable complex with alpha(v)beta(3) integrin, and the integrin beta(3) subunit is required both for FnE-induced fibroblast migration and for potentiation of TGF-beta-induced myofibroblast formation. Finally, subcutaneous infusion of FnE in mice results in a fibrotic response in the hypodermis. These results support a model where FnE released from clots in wounded tissue promote wound healing and fibrosis by both recruitment and activation of fibroblasts. Fibrin fragment E could thus represent a therapeutic target for treatment of pathological fibrosis.
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