elastin and Neointima

Balloon angioplasty, stent implantation, and application of an arterial clamp during surgery can induce artery injury such as elastin breaks and endothelium injury, but there is little research focused on the injury induced by these therapeutic manipulations. We established a simple and reproducible small animal aortic injury model and examined intramural injection as a potential therapeutic method to alleviate injury.. The abdominal aorta of male Sprague Dawley (SD) rats or C57BL/6 J mice was clamped sequentially throughout its length. Transforming growth factor β1 (TGFβ1), SB431542, lipopolysaccharide (LPS), Necrostatin-1 (Nec-1), rapamycin, or MHY1485 contained in Pluronic gel was injected intramurally at day 0 or day 7. Animals were fed with chow containing 0.25% beta-aminopropionitrile (BAPN) to evaluate the influence of BAPN. All samples were harvested and examined by immunohistochemistry and immunofluorescence.. The clamped rat aorta showed luminal dilation, elastin fiber breaks, neointimal hyperplasia, and dissection (days 0-90). Intramural injection of TGFβ1, rapamycin and Nec-1 showed a protective effect on the injured aorta, whereas SB431542, MHY1485 and LPS showed more severe wall damage. The aortic lumen in rats fed with BAPN was significantly larger than in control rats (day 7). Mouse aorta showed similar injury with neointimal hyperplasia and elastin fiber breaks.. The rodent arterial injury model is reproducible and may mimic early changes of arterial injury. The model accommodates intramural injection of different drugs that may show mechanisms of arterial injury. Although this is a preliminary animal model, the intramural injection method may have potential clinical application in the future.

Topics: Aminopropionitrile; Animals; Aorta, Abdominal; Disease Models, Animal; Elastin; Hyperplasia; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Neointima; Poloxamer; Rats; Rats, Sprague-Dawley; Sirolimus

Using a mouse model of Eln (elastin) insufficiency that spontaneously develops neointima in the ascending aorta, we sought to understand the origin and phenotypic heterogeneity of smooth muscle cells (SMCs) contributing to intimal hyperplasia. We were also interested in exploring how vascular cells adapt to the absence of Eln. Approach and Results: We used single-cell sequencing together with lineage-specific cell labeling to identify neointimal cell populations in a noninjury, genetic model of neointimal formation. Inactivating Eln production in vascular SMCs results in rapid intimal hyperplasia around breaks in the ascending aorta's internal elastic lamina. Using lineage-specific. These results highlight the unique developmental origin and transcriptional signature of cells contributing to neointima in the ascending aorta. Our findings also show that the absence of Eln, or changes in elastic fiber integrity, influences the SMC biological niche in ways that lead to altered cell phenotypes.

Topics: Animals; Aorta; Cell Differentiation; Elastin; Extracellular Matrix; Female; Male; Mice, Inbred Strains; Models, Animal; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima

Topics: Aorta; Elastin; Humans; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima

Elastin is an important ECM (extracellular matrix) protein in large and small arteries. Vascular smooth muscle cells (SMCs) produce the layered elastic laminae found in elastic arteries but synthesize little elastin in muscular arteries. However, muscular arteries have a well-defined internal elastic lamina (IEL) that separates endothelial cells (ECs) from SMCs. The extent to which ECs contribute elastin to the IEL is unknown.. To use targeted elastin (Eln) deletion in mice to explore the relative contributions of SMCs and ECs to elastic laminae formation in different arteries.. We used SMC- and EC-specific. Combined with lineage-specific fate mapping systems, our knockout results document an unexpected heterogeneity in vascular cells that produce the elastic laminae. SMCs and ECs can independently form an IEL in most elastic arteries, whereas ECs are the major source of elastin for the IEL in muscular and resistance arteries. Neointimal formation at IEL disruptions in the ascending aorta confirms that the IEL is a critical physical barrier between SMCs and ECs in the large elastic arteries. Our studies provide new information about how SMCs and ECs contribute elastin to the arterial wall and how local elastic laminae defects may contribute to cardiovascular disease.

Topics: Animals; Arteries; Blood Pressure; Cell Lineage; Cell Proliferation; Elastic Tissue; Elastin; Endothelial Cells; Female; Male; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima; Signal Transduction

Current synthetic vascular grafts are not suitable for use in low-diameter applications. Silk fibroin is a promising natural graft material which may be an effective alternative. In this study, we compared two electrospun silk grafts with different manufacturing processes, using either water or hexafluoroisopropanol (HFIP) as solvent. This resulted in markedly different Young's modulus, ultimate tensile strength and burst pressure, with HFIP spun grafts observed to have thicker fibres, and greater stiffness and strength relative to water spun. Assessment in a rat abdominal aorta grafting model showed significantly faster endothelialisation of the HFIP spun graft relative to water spun. Neointimal hyperplasia in the HFIP graft also stabilised significantly earlier, correlated with an earlier SMC phenotype switch from synthetic to contractile, increasing extracellular matrix protein density. An initial examination of the macrophage response showed that HFIP spun conduits promoted an anti-inflammatory M2 phenotype at early timepoints while reducing the pro-inflammatory M1 phenotype relative to water spun grafts. These observations demonstrate the important role of the manufacturing process and physical graft properties in determining the physiological response. Our study is the first to comprehensively study these differences for silk in a long-term rodent model.

Topics: Animals; Aorta, Abdominal; Blood Vessel Prosthesis; Bombyx; Elastic Modulus; Elastin; Fibroins; Hyperplasia; Male; Materials Testing; Microscopy, Electron, Scanning; Neointima; Porosity; Propanols; Prosthesis Design; Rats; Rats, Sprague-Dawley; Solvents; Tensile Strength; Vascular Grafting; Water

Topics: Animals; Carotid Arteries; Carotid Artery Injuries; Cathepsins; Cell Movement; Cell Proliferation; Elastin; Hyperplasia; Ligation; Macrophages; Matrix Metalloproteinases; Mice; Mice, Knockout; Myocytes, Smooth Muscle; Neointima; Plaque, Atherosclerotic; Restraint, Physical; RNA, Messenger; Stress, Psychological

Marfan syndrome is an autosomal dominant inherited disorder of connective tissue. The vascular complications of Marfan syndrome have the biggest impact on life expectancy. The aorta of Marfan patients reveals degradation of elastin layers caused by increased proteolytic activity of matrix metalloproteinases (MMPs). In this study we performed adenoviral gene transfer of human tissue inhibitor of matrix metalloproteinases-1 (hTIMP-1) in aortic grafts of fibrillin-1 deficient Marfan mice (mgR/mgR) in order to reduce elastolysis.. We performed heterotopic infrarenal transplantation of the thoracic aorta in female mice (n = 7 per group). Before implantation, mgR/mgR and wild-type aortas (WT, C57BL/6) were transduced ex vivo with an adenoviral vector coding for human TIMP-1 (Ad.hTIMP-1) or β-galactosidase (Ad.β-Gal). As control mgR/mgR and wild-type aortas received no gene therapy. Thirty days after surgery, overexpression of the transgene was assessed by immunohistochemistry (IHC) and collagen in situ zymography. Histologic staining was performed to investigate inflammation, the neointimal index (NI), and elastin breaks. Endothelial barrier function of native not virus-exposed aortas was evaluated by perfusion of fluorescent albumin and examinations of virus-exposed tissue were performed by transmission electron microscopy (TEM).. IHC and ISZ revealed sufficient expression of the transgene. Severe cellular inflammation and intima hyperplasia were seen only in adenovirus treated mgR/mgR aortas (Ad.β-Gal, Ad.hTIMP-1 NI: 0.23; 0.43), but not in native and Ad.hTIMP-1 treated WT (NI: 0.01; 0.00). Compared to native mgR/mgR and Ad.hTIMP-1 treated WT aorta, the NI is highly significant greater in Ad.hTIMP-1 transduced mgR/mgR aorta (p = 0.001; p = 0.001). As expected, untreated Marfan grafts showed significant more elastolysis compared to WT (p = 0.001). However, elastolysis in Marfan aortas was not reduced by adenoviral overexpression of hTIMP-1 (compared to untreated Marfan aorta: Ad.hTIMP-1 p = 0.902; control Ad.β-Gal. p = 0.165). The virus-untreated and not transplanted mgR/mgR aorta revealed a significant increase of albumin diffusion through the endothelial barrier (p = 0.037). TEM analysis of adenovirus-exposed mgR/mgR aortas displayed disruption of the basement membrane and basolateral space.. Murine Marfan aortic grafts developed severe inflammation after adenoviral contact. We demonstrated that fibrillin-1 deficiency is associated with relevant dysfunction of the endothelial barrier that enables adenovirus to induce vessel-harming inflammation. Endothelial dysfunction may play a pivotal role in the development of the vascular phenotype of Marfan syndrome.

Topics: Adenoviridae; Animals; Aorta; beta-Galactosidase; Cells, Cultured; Elastin; Endothelium, Vascular; Female; Fibrillin-1; Fibrillins; Genetic Therapy; Inflammation; Marfan Syndrome; Mice; Mice, Inbred C57BL; Microfilament Proteins; Neointima; Tight Junctions; Tissue Inhibitor of Metalloproteinase-1

This study investigated the role and mechanism of Hyperhomocysteinemia (HHcy) on vascular remodeling in mice. We assessed the effect of HHcy on vascular remodeling using a carotid arterial vein patch model in mice with the gene deletion of cystathionine-beta-synthase (Cbs). Vein grafts were harvested 4 weeks after surgery. Cross sections were analyzed using Verhoeff-van Gieson staining, Masson`s Trichrome staining, and immunostaining for morphological analysis and protein level assessment. The effect of Hcy on collagen secretion was examined in cultured rat aortic smooth muscle cells (RASMC). We found that Cbs-/- mice with severe HHcy exhibited thicker neointima and a higher percentage of luminal narrowing in vein grafts. In addition, severe HHcy increased elastin and collagen deposition in the neointima. Further, severe HHcy increases CD45 positive cells and proliferative cells in vein grafts. Finally, Hcy increases collagen secretion in RASMC. These results demonstrate that HHcy increases neointima formation, elastin and collagen deposition following a carotid arterial vein patch. The capacity of Hcy to promote vascular fibrosis and inflammation may contribute to the development of vascular remodeling.

Topics: Animals; Blotting, Western; Carotid Arteries; Cell Proliferation; Cells, Cultured; Collagen; Cystathionine beta-Synthase; Elastin; Homocysteine; Hyperhomocysteinemia; Jugular Veins; Leukocyte Common Antigens; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima; Rats; Vascular Remodeling

Tissue engineering techniques have emerged that allow bioresorbable grafts to be implanted that restore function and transform into biologically active arteries. However, these implants are susceptible to calcification during the remodeling process. The objective of this study was to evaluate the role of pore size of bioabsorbable grafts in the development of calcification.. Two types of grafts were prepared: a large-pore graft constructed of poly(L-lactic acid) (PLA) fibers coated with poly(L-lactide-co-ε-caprolactone) (PLCL) (PLA-PLCL), and a small-pore graft made of electrospun PLA nanofibers (PLA-nano). Twenty-eight PLA-PLCL grafts and twenty-five PLA-nano grafts were implanted as infra-renal aortic interposition conduits in 8-week-old female SCID/Bg mice, and followed for 12 months after implantation.. Large-pore PLA-PLCL grafts induced a well-organized neointima after 12 months, and Alizarin Red S staining showed neointimal calcification only in the thin neointima of small-pore PLA-nano grafts. At 12 months, macrophage infiltration, evaluated by F4/80 staining, was observed in the thin neointima of the PLA-nano graft, and there were few vascular smooth muscle cells (VSMCs) in this layer. On the other hand, the neointima of the PLA-PLCL graft was composed of abundant VSMCs, and a lower density of macrophages (F4/80 positive cells, PLA-PLCL; 68.1 ± 41.4/mm(2) vs PLA-nano; 188.3 ± 41.9/mm(2), p = 0.007). The VSMCs of PLA-PLCL graft expressed transcription factors of both osteoblasts and osteoclasts.. These findings demonstrate that in mouse arterial circulation, large-pore PLA-PLCL grafts created a well-organized neointima and prevented calcific deposition compared to small-pore, electrospun PLA-nano grafts.

Topics: Animals; Arteries; Calcinosis; Collagen; Elastin; Female; Inflammation; Lactic Acid; Macrophages; Mice; Mice, SCID; Microscopy, Electron, Scanning; Models, Animal; Neointima; Osteoblasts; Osteoclasts; Osteogenesis; Polyesters; Polymers; Porosity; Tissue Engineering; Transcription Factors; Vascular Grafting