| 1. |
- Cao, Renhai, et al.
(författare)
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Mouse corneal lymphangiogenesis model.
- 2011
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Ingår i: Nature protocols. - : Springer Science and Business Media LLC. - 1750-2799 .- 1754-2189. ; 6:6, s. 817-26
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Tidskriftsartikel (refereegranskat)abstract
- This protocol describes a powerful in vivo method to quantitatively study the formation of new lymphatic vessels in the avascular cornea without interference of pre-existing lymphatics. Implantation of 100 ng of lymphangiogenic factors such as vascular endothelial growth factor (VEGF)-A, VEGF-C or fibroblast growth factor-2, together with slow-release polymers, into a surgically created micropocket in the mouse cornea elicits a robust lymphangiogenic response. Newly formed lymphatic vessels are detected by immunohistochemical staining of the flattened corneal tissue with lymphatic endothelial-specific markers such as lymphatic vessel endothelial hyaluronan receptor-1; less-specific markers such as vascular endothelial growth factor receptor 3 may also be used. Lymphatic vessel growth in relation to hemangiogenesis can be readily detected starting at day 5 or 6 after pellet implantation and persists for ∼14 d. This protocol offers a unique opportunity to study the mechanisms underlying lymphatic vessel formation, remodeling and function.
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| 2. |
- Dong, Mei, et al.
(författare)
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Cold Exposure Promotes Atherosclerotic Plaque Growth and Instability via UCP1-Dependent Lipolysis
- 2013
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Ingår i: Cell Metabolism. - : Elsevier (Cell Press). - 1550-4131 .- 1932-7420. ; 18:1, s. 118-129
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Tidskriftsartikel (refereegranskat)abstract
- Molecular mechanisms underlying the cold-associated high cardiovascular risk remain unknown. Here, we show that the cold-triggered food-intake-independent lipolysis significantly increased plasma levels of small low-density lipoprotein (LDL) remnants, leading to accelerated development of atherosclerotic lesions in mice. In two genetic mouse knockout models (apolipoprotein E-/- [ApoE(-/-)] and LDL receptor(-/-) [Ldlr(-/-)] mice), persistent cold exposure stimulated atherosclerotic plaque growth by increasing lipid deposition. Furthermore, marked increase of inflammatory cells and plaque-associated microvessels were detected in the cold-acclimated ApoE(-/-) and Ldlr(-/-) mice, leading to plaque instability. Deletion of uncoupling protein 1 (UCP1), a key mitochondrial protein involved in thermogenesis in brown adipose tissue (BAT), in the ApoE(-/-) strain completely protected mice from the cold-induced atherosclerotic lesions. Cold acclimation markedly reduced plasma levels of adiponectin, and systemic delivery of adiponectin protected ApoE(-/-) mice from plaque development. These findings provide mechanistic insights on low-temperature-associated cardiovascular risks.
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| 3. |
- Honek, Jennifer
(författare)
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Angiogenesis modulates obesity and insulin sensitivity
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Both white and brown fat are highly vascularized tissues and vascular functions in adipose tissues remain largely unknown. In this thesis work, we aimed to study blood vessels in modulation of adipose tissue functions under physiological conditions. To achieve these goals, we have used genetic mouse models in combination with pharmacological approaches as powerful tools to investigate adipose vascularization in modulation of adipose tissue functions and metabolism. We have developed unique in vitro and in vivo methods and techniques to functionally and mechanistically address the interactions between endothelial cells (ECs) and adipocytes (ACs). These novel methods and findings may potentially pave new avenues for development of therapeutics for treatment of obesity and metabolic diseases by targeting the adipose vasculature. In paper I, we describe novel methods to induce browning and angiogenic phenotypes in white adipose tissues (WAT) by exposing mice to cold ambient temperature (4°C). We have also defined methodologies to measure basal and non-shivering thermogenesis-related metabolism in mice. Several immunohistological methods that are coupled to confocal microscopy analysis were established to accurately quantify expression of gene products that are associated with thermogenesis and angiogenesis. These model systems and methodologies have provided a fundamental basis for subsequent projects within and outside our laboratory to study adipogenesis and metabolism. With the available methods developed in paper I, in paper II we have studied the age-related vascular effects in modulation of fat mass, AC functions, blood lipid profiles and insulin sensitivity. Notably, Vegf expression levels in various WATs underwent continuous changes in different age populations. Anti-VEGF and anti-VEGFR2 treatment showed marked variations of vascular regression, with middle-aged mice exhibiting modest sensitivity. Interestingly, anti-VEGF treatment produced opposing effects on WAT AC sizes in different age populations and affected vascular density and AC sizes in brown adipose tissue (BAT). Consistent with changes of vasculatures and AC sizes, anti-VEGF treatment significantly increased insulin sensitivity in all groups, except for a rather modest improvement of insulin sensitivity in the middle-aged group. Similar to healthy mice, anti-VEGF treatment substantially improved insulin sensitivity in obese mice on a high fat diet. Our findings demonstrate that adipose vasculatures show differential responses to anti-VEGF treatment in various age populations and have therapeutic implications for treatment of obesity and diabetes with anti-VEGF-based drugs. In paper III, we studied the paracrine regulation of AC functions by angiogenic ECs following cold- or pharmacologically induced adrenergic activation. We have found that ECs play an essential role in modulating AC functions during WAT browning. This paracrine effect is mediated by EC-derived PDGF-CC, which acts on progenitor cells to induce differentiation into ACs. Deletion of the Pdgfc gene in mice or blocking of PDGFRα largely impairs the paracrine regulation of AC functions during WAT browning. In paper IV, we have developed an effective and reliable lymphangiogenesis assay that allows us to study the lymphangiogenic capacity of various factors in the absence of pre-existing lymphatics and other angiogenic stimuli. We took advantage of the avascular nature of the cornea to study the lymphangiogenic effect of any given factor or combination of factors. To this end, we have tested several angiogenic factors that are commonly present in adipose tissues and quantitatively studied corneal lymphangiogenesis.
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| 4. |
- Honek, Jennifer, et al.
(författare)
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Modulation of age-related insulin sensitivity by VEGF-dependent vascular plasticity in adipose tissues
- 2014
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 111:41, s. 14906-14911
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Tidskriftsartikel (refereegranskat)abstract
- Mechanisms underlying age-related obesity and insulin resistance are generally unknown. Here, we report age-related adipose vascular changes markedly modulated fat mass, adipocyte functions, blood lipid composition, and insulin sensitivity. Notably, VEGF expression levels in various white adipose tissues (WATs) underwent changes uninterruptedly in different age populations. Anti-VEGF and anti-VEGF receptor 2 treatment in different age populations showed marked variations of vascular regression, with midaged mice exhibiting modest sensitivity. Interestingly, anti-VEGF treatment produced opposing effects on WAT adipocyte sizes in different age populations and affected vascular density and adipocyte sizes in brown adipose tissue. Consistent with changes of vasculatures and adipocyte sizes, anti-VEGF treatment increased insulin sensitivity in young and old mice but had no effects in the midaged group. Surprisingly, anti-VEGF treatment significantly improved insulin sensitivity in midaged obese mice fed a high-fat diet. Our findings demonstrate that adipose vasculatures show differential responses to anti-VEGF treatment in various age populations and have therapeutic implications for treatment of obesity and diabetes with anti-VEGF-based antiangiogenic drugs.
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| 5. |
- Lim, Sharon, et al.
(författare)
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Cold-induced activation of brown adipose tissue and adipose angiogenesis in mice
- 2012
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Ingår i: Nature Protocols. - : Nature Publishing Group. - 1754-2189 .- 1750-2799. ; 7:3, s. 606-615
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Tidskriftsartikel (refereegranskat)abstract
- Exposure of humans and rodents to cold activates thermogenic activity in brown adipose tissue (BAT). This protocol describes a mouse model to study the activation of BAT and angiogenesis in adipose tissues by cold acclimation. After a 1-week exposure to 4 degrees C, adult C57BL/6 mice show an obvious transition from subcutaneous white adipose tissue (WAT) into brown-like adipose tissue (BRITE). The BRITE phenotype persists after continuous cold exposure, and by the end of week 5 BRITE contains a high number of uncoupling protein-1-positive mitochondria, a characteristic feature of BAT. During the transition from WAT into BRITE, the vascular density is markedly increased owing to the activation of angiogenesis. In BAT, cold exposure stimulates thermogenesis by increasing the mitochondrial content and metabolic rate. BAT and the increased metabolic rate result in a lean phenotype. This protocol provides an outstanding opportunity to study the molecular mechanisms that control adipose mass.
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