scholarly journals Progressive Microstructural Deterioration Dictates Evolving Biomechanical Dysfunction in the Marfan Aorta

2021 ◽  
Vol 8 ◽  
Author(s):  
Cristina Cavinato ◽  
Minghao Chen ◽  
Dar Weiss ◽  
Maria Jesús Ruiz-Rodríguez ◽  
Martin A. Schwartz ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Ex Vivo ◽  
Elastic Fiber ◽  
Three Dimensional ◽  
Microstructural Characterization ◽  
Aortic Aneurysms ◽  
Elastic Fibers ◽  
Cell Phenotype ◽  
Medial Degeneration ◽  
Fibrillin 1

Medial deterioration leading to thoracic aortic aneurysms arises from multiple causes, chief among them mutations to the gene that encodes fibrillin-1 and leads to Marfan syndrome. Fibrillin-1 microfibrils associate with elastin to form elastic fibers, which are essential structural, functional, and instructional components of the normal aortic wall. Compromised elastic fibers adversely impact overall structural integrity and alter smooth muscle cell phenotype. Despite significant progress in characterizing clinical, histopathological, and mechanical aspects of fibrillin-1 related aortopathies, a direct correlation between the progression of microstructural defects and the associated mechanical properties that dictate aortic functionality remains wanting. In this paper, age-matched wild-type, Fbn1C1041G/+, and Fbn1mgR/mgR mouse models were selected to represent three stages of increasing severity of the Marfan aortic phenotype. Ex vivo multiphoton imaging and biaxial mechanical testing of the ascending and descending thoracic aorta under physiological loading conditions demonstrated that elastic fiber defects, collagen fiber remodeling, and cell reorganization increase with increasing dilatation. Three-dimensional microstructural characterization further revealed radial patterns of medial degeneration that become more uniform with increasing dilatation while correlating strongly with increased circumferential material stiffness and decreased elastic energy storage, both of which comprise aortic functionality.

scholarly journals Clinical Relevance of Elastin in the Structure and Function of Skin

2021 ◽  
Author(s):  
Leslie Baumann ◽  
Eric F Bernstein ◽  
Anthony S Weiss ◽  
Damien Bates ◽  
Shannon Humphrey ◽  
...  
Keyword(s):  
Wound Healing ◽  
Clinical Relevance ◽  
Structural Integrity ◽  
Elastic Fiber ◽  
Subcutaneous Fat ◽  
Structure And Function ◽  
Fiber Formation ◽  
Elastic Fibers ◽  
Superficial Dermis ◽  
And Function

Abstract Elastin is the main component of elastic fibers, which provide stretch, recoil, and elasticity to the skin. Normal levels of elastic fiber production, organization, and integration with other cutaneous extracellular matrix proteins, proteoglycans, and glycosaminoglycans are integral to maintaining healthy skin structure, function, and youthful appearance. Although elastin has very low turnover, its production decreases after individuals reach maturity and it is susceptible to damage from many factors. With advancing age and exposure to environmental insults, elastic fibers degrade. This degradation contributes to the loss of the skin’s structural integrity; combined with subcutaneous fat loss, this results in looser, sagging skin, causing undesirable changes in appearance. The most dramatic changes occur in chronically sun-exposed skin, which displays sharply altered amounts and arrangements of cutaneous elastic fibers, decreased fine elastic fibers in the superficial dermis connecting to the epidermis, and replacement of the normal collagen-rich superficial dermis with abnormal clumps of solar elastosis material. Disruption of elastic fiber networks also leads to undesirable characteristics in wound healing, and the worsening structure and appearance of scars and stretch marks. Identifying ways to replenish elastin and elastic fibers should improve the skin’s appearance, texture, resiliency, and wound-healing capabilities. However, few therapies are capable of repairing elastic fibers or substantially reorganizing the elastin/microfibril network. This review describes the clinical relevance of elastin in the context of the structure and function of healthy and aging skin, wound healing, and scars and introduces new approaches being developed to target elastin production and elastic fiber formation.

scholarly journals Isochoric supercooled preservation and revival of human cardiac microtissues

2021 ◽  
Author(s):  
Matthew J. Powell-Palm ◽  
Verena Charwat ◽  
Berenice Charrez ◽  
Brian A Siemons ◽  
Kevin E. Healy ◽  
...  
Keyword(s):  
Pluripotent Stem Cells ◽  
Organ Preservation ◽  
Drug Exposure ◽  
Structural Integrity ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Robust Method ◽  
On Demand ◽  
Engineered Tissues ◽  
Induced Pluripotent

Low-temperature ex vivo preservation and tissue engineering based on human induced pluripotent stem cells (hiPSC) represent two of the most promising routes towards on-demand access to organs for transplantation. While these fields are often considered divergent from one another, advances in both fields present critical new opportunities for crossover. Herein we demonstrate the first-ever sub-zero centigrade preservation and revival of autonomously beating three-dimensional hiPSC-derived cardiac microtissues via isochoric supercooling, without the use of chemical cryoprotectants. We show that these tissues can cease autonomous beating during preservation and resume it after warming, that the supercooling process does not affect sarcomere structural integrity, and that the tissues maintain responsiveness to drug exposure following revival. Our work suggests both that functional three dimensional (3D) engineered tissues may provide an excellent high-content, low-risk testbed to study organ preservation in a genetically human context, and that isochoric supercooling may provide a robust method for preserving and reviving engineered tissues themselves.

scholarly journals Developmental expression of fibrillin genes suggests heterogeneity of extracellular microfibrils.

1995 ◽  
Vol 129 (4) ◽  
pp. 1165-1176 ◽  
Author(s):  
H Zhang ◽  
W Hu ◽  
F Ramirez
Keyword(s):  
Spatial Organization ◽  
Developmental Stages ◽  
Elastic Fiber ◽  
Biomechanical Properties ◽  
Developmental Expression ◽  
Elastic Fibers ◽  
Fiber Assembly ◽  
Structural Support ◽  
Functional Relationships ◽  
Fibrillin 1

Extracellular microfibrils, alone or in association with elastin, confer critical biomechanical properties on a variety of connective tissues. Little is known about the composition of the microfibrils or the factors responsible for their spatial organization into tissue-specific macroaggregates. Recent work has revealed the existence of two structurally related microfibrillar components, termed fibrillin-1 and fibrillin-2. The functional relationships between these glycoproteins and between them and other components of the microfibrils and elastic fibers are obscure. As a first step toward elucidating these important points, we compared the expression pattern of the fibrillin genes during mammalian embryogenesis. The results revealed that the two genes are differentially expressed, in terms of both developmental stages and tissue distribution. In the majority of cases, fibrillin-2 transcripts appear earlier and accumulate for a shorter period of time than fibrillin-1 transcripts. Synthesis of fibrillin-1 correlates with late morphogenesis and the appearance of well-defined organ structures; fibrillin-2 synthesis, on the other hand, coincides with early morphogenesis and, in particular, with the beginning of elastogenesis. The findings lend indirect support to our original hypothesis stating that fibrillins contribute to the compositional and functional heterogeneity of the microfibrils. The available evidence is also consistent with the notion that the fibrillins might have distinct, but related roles in microfibril physiology. Accordingly, we propose that fibrillin-1 provides mostly force-bearing structural support, whereas fibrillin-2 predominantly regulates the early process of elastic fiber assembly.

Recent updates on the molecular network of elastic fiber formation

2019 ◽  
Vol 63 (3) ◽  
pp. 365-376 ◽  
Author(s):  
Seung Jae Shin ◽  
Hiromi Yanagisawa
Keyword(s):  
Elastic Fiber ◽  
Building Blocks ◽  
Fiber Formation ◽  
Elastic Fibers ◽  
Fiber Network ◽  
Associated Proteins ◽  
Fibrillin 1 ◽  
A Cell ◽  
Self Aggregation

Abstract Elastic fibers confer elasticity and recoiling to tissues and organs and play an essential role in induction of biochemical responses in a cell against mechanical forces derived from the microenvironment. The core component of elastic fibers is elastin (ELN), which is secreted as the monomer tropoelastin from elastogenic cells, and undergoes self-aggregation, cross-linking and deposition on to microfibrils, and assemble into insoluble ELN polymers. For elastic fibers to form, a microfibril scaffold (primarily formed by fibrillin-1 (FBN1)) is required. Numerous elastic fiber-associated proteins are involved in each step of elastogenesis and they instruct and/or facilitate the elastogenesis processes. In this review, we designated five proteins as key molecules in elastic fiber formation, including ELN, FBN1, fibulin-4 (FBLN4), fibulin-5 (FBLN5), and latent TGFβ-binding protein-4 (LTBP4). ELN and FBN1 serve as building blocks for elastic fibers. FBLN5, FBLN4 and LTBP4 have been demonstrated to play crucial roles in elastogenesis through knockout studies in mice. Using these molecules as a platform and expanding the elastic fiber network through the generation of an interactome map, we provide a concise review of elastogenesis with a recent update as well as discuss various biological functions of elastic fiber-associated proteins beyond elastogenesis in vivo.

Microfibrils and fibrillin-1 induce integrin-mediated signaling, proliferation and migration in human endothelial cells

2010 ◽  
Vol 299 (5) ◽  
pp. C977-C987 ◽  
Author(s):  
Boubacar Mariko ◽  
Zeinab Ghandour ◽  
Stéphanie Raveaud ◽  
Mickaël Quentin ◽  
Yves Usson ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Marfan Syndrome ◽  
Intracellular Signaling ◽  
Aortic Aneurysms ◽  
Endothelial Cell Proliferation ◽  
Elastic Fibers ◽  
Calcium Stores ◽  
Fibrillin 1 ◽  
And Migration ◽  
Proliferation And Migration

Microfibrils are macromolecular complexes associated with elastin to form elastic fibers that endow extensible tissues, such as arteries, lungs, and skin, with elasticity property. Fibrillin-1, the main component of microfibrils, is a 350-kDa glycoprotein for which genetic haploinsufficiency in humans can lead to Marfan syndrome, a severe polyfeatured pathology including aortic aneurysms and dissections. Microfibrils and fibrillin-1 fragments mediate adhesion of several cell types, including endothelial cells, while fibrillin-1 additionally triggers lung and mesangial cell migration. However, fibrillin-1-induced intracellular signaling is unknown. We have studied the signaling events induced in human umbilical venous endothelial cells (HUVECs) by aortic microfibrils as well as recombinant fibrillin-1 Arg-Gly-Asp (RGD)-containing fragments PF9 and PF14. Aortic microfibrils and PF14, not PF9, substantially and dose dependently increased HUVEC cytoplasmic and nuclear calcium levels measured using the fluorescent dye Fluo-3. This effect of PF14 was confirmed in bovine aortic endothelial cells. PF14 action in HUVECs was mediated by αvβ3 and α5β1 integrins, phospholipase-C, inosital 1,4,5-trisphosphate, and mobilization of intracellular calcium stores, whereas membrane calcium channels were not or only slightly implicated, as shown in patch-clamp experiments. Finally, PF14 enhanced endothelial cell proliferation and migration. Hence, fibrillin-1 sequences may physiologically activate endothelial cells. Genetic fibrillin-1 deficiency could alter normal endothelial signaling and, since endothelium dysfunction is an important contributor to Marfan syndrome, participate in the arterial anomalies associated with this developmental disease.

scholarly journals Inducible Prmt1 ablation in adult vascular smooth muscle leads to contractile dysfunction and aortic dissection

2021 ◽  
Author(s):  
Jung-Hoon Pyun ◽  
Byeong-Yun Ahn ◽  
Tuan Anh Vuong ◽  
Su Woo Kim ◽  
Yunju Jo ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Aortic Dissection ◽  
Vascular Smooth Muscle ◽  
Vascular Function ◽  
Ex Vivo ◽  
Elastic Fiber ◽  
Aortic Aneurysms ◽  
Aortic Dilation ◽  
Smooth Muscle Contractility

AbstractVascular smooth muscle cells (VSMCs) have remarkable plasticity in response to diverse environmental cues. Although these cells are versatile, chronic stress can trigger VSMC dysfunction, which ultimately leads to vascular diseases such as aortic aneurysm and atherosclerosis. Protein arginine methyltransferase 1 (Prmt1) is a major enzyme catalyzing asymmetric arginine dimethylation of proteins that are sources of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase. Although a potential role of Prmt1 in vascular pathogenesis has been proposed, its role in vascular function has yet to be clarified. Here, we investigated the role and underlying mechanism of Prmt1 in vascular smooth muscle contractility and function. The expression of PRMT1 and contractile-related genes was significantly decreased in the aortas of elderly humans and patients with aortic aneurysms. Mice with VSMC-specific Prmt1 ablation (smKO) exhibited partial lethality, low blood pressure and aortic dilation. The Prmt1-ablated aortas showed aortic dissection with elastic fiber degeneration and cell death. Ex vivo and in vitro analyses indicated that Prmt1 ablation significantly decreased the contractility of the aorta and traction forces of VSMCs. Prmt1 ablation downregulated the expression of contractile genes such as myocardin while upregulating the expression of synthetic genes, thus causing the contractile to synthetic phenotypic switch of VSMCs. In addition, mechanistic studies demonstrated that Prmt1 directly regulates myocardin gene activation by modulating epigenetic histone modifications in the myocardin promoter region. Thus, our study demonstrates that VSMC Prmt1 is essential for vascular homeostasis and that its ablation causes aortic dilation/dissection through impaired myocardin expression.

The development of a method for the preparation of rat intestinal epithelial cell primary cultures

1992 ◽  
Vol 101 (1) ◽  
pp. 219-231 ◽  
Author(s):  
G.S. Evans ◽  
N. Flint ◽  
A.S. Somers ◽  
B. Eyden ◽  
C.S. Potten
Keyword(s):  
Structural Integrity ◽  
Ex Vivo ◽  
Primary Cultures ◽  
Three Dimensional ◽  
Culture Conditions ◽  
Intestinal Epithelial ◽  
Digestion Technique ◽  
Reproducible Method ◽  
Differential Sedimentation

We describe a reproducible method for growing small intestinal epithelium (derived from the suckling rat intestine) in short-term (primary) cultures. Optimal culture conditions were determined by quantitative assays of proliferation (i.e. changes in cellularity and DNA synthesis). Isolation of the epithelia and, significantly, preservation of its three-dimensional integrity was achieved using a collagenase/dispase digestion technique. Purification of the epithelium was also facilitated by the use of a simple differential sedimentation method. The results presented below support the idea that proliferation of normal gut epithelium ex vivo is initially dependent upon the maintenance of the structural integrity of this tissue and upon factors produced by heterologous mesenchymal cells. Proliferation in vitro was also critically dependent upon the quality of the medium and constituents used. Cultures reached confluence within 10–14 days and consisted of epithelial colonies together with varying amounts of smooth-muscle-like cells. Cultures have been maintained for periods up to one month, but the longer-term potential for growth by sub-culturing has not been examined. Strategies for reducing the proliferation of these non-epithelial cells are also described.

scholarly journals Effects of Elastase Digestion on the Murine Vaginal Wall Biaxial Mechanical Response

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Akinjide R. Akintunde ◽  
Kathryn M. Robison ◽  
Daniel J. Capone ◽  
Laurephile Desrosiers ◽  
Leise R. Knoepp ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Response ◽  
Elastic Fiber ◽  
Pelvic Organ ◽  
Vaginal Wall ◽  
Elastic Fibers ◽  
Vaginal Tissue ◽  
Fiber Damage ◽  
Increased Risk ◽  
Before And After

Although the underlying mechanisms of pelvic organ prolapse (POP) remain unknown, disruption of elastic fiber metabolism within the vaginal wall extracellular matrix (ECM) has been highly implicated. It has been hypothesized that elastic fiber fragmentation correlates to decreased structural integrity and increased risk of prolapse; however, the mechanisms by which elastic fiber damage may contribute to prolapse are poorly understood. Furthermore, the role of elastic fibers in normal vaginal wall mechanics has not been fully ascertained. Therefore, the objective of this study is to investigate the contribution of elastic fibers to murine vaginal wall mechanics. Vaginal tissue from C57BL/6 female mice was mechanically tested using biaxial extension–inflation protocols before and after intraluminal exposure to elastase. Elastase digestion induced marked changes in the vaginal geometry, and biaxial mechanical properties, suggesting that elastic fibers may play an important role in vaginal wall mechanical function. Additionally, a constitutive model that considered two diagonal families of collagen fibers with a slight preference toward the circumferential direction described the data reasonably well before and after digestion. The present findings may be important to determine the underlying structural and mechanical mechanisms of POP, and aid in the development of growth and remodeling models for improved assessment and prediction of changes in structure–function relationships with prolapse development.

scholarly journals Bcl11b is a Newly Identified Regulator of Vascular Smooth Muscle Phenotype and Arterial Stiffness

2017 ◽  
Author(s):  
Jeff Arni C. Valisno ◽  
Pavania Elavalakanar ◽  
Christopher Nicholson ◽  
Kuldeep Singh ◽  
Dorina Avram ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Arterial Stiffness ◽  
Vascular Smooth Muscle ◽  
Actin Polymerization ◽  
Genome Wide Association Study ◽  
Ex Vivo ◽  
Aortic Aneurysms ◽  
Cell Phenotype ◽  
Gene Desert ◽  
A Genome

ABSTRACTB-cell leukemia 11b (Bcl11b) is a zinc-finger transcription factor known as master regulator of T lymphocytes and neuronal development during embryogenesis. Bcl11b-interacting protein COUP-TFII is required for atrial development and vasculogenesis, however a role of Bcl11b in the adult cardiovascular system is unknown. A genome-wide association study (GWAS) recently showed that a gene desert region downstream ofBCL11Band known to function asBCL11Benhancer harbors single nucleotide polymorphisms (SNPs) associated with increased arterial stiffness. Based on these human findings, we sought to examine relations between Bcl11b and arterial function using mice with Bcl11b deletion. We report for the first time that Bcl11b is expressed in vascular smooth muscle (VSM) and transcriptionally regulates the expression of VSM contractile proteins smooth muscle myosin and smooth muscle α-actin. Lack of Bcl11b in VSM-specific Bcl11b null mice (BSMKO) resulted in increased expression of Ca++-calmodulin-dependent serine/threonine phosphatase calcineurin in BSMKO VSM cells, cultured in serum-free condition, and in BSMKO aortas, which showed an inverse correlation with levels of phosphorylated VASPS239, a regulator of cytoskeletal actin rearrangements. Moreover, decreased pVASPS239in BSMKO aortas was associated with increased actin polymerization (F/G actin ratio). Functionally, aortic force, stress and wall tension, measured ex vivo in organ baths, were increased in BSMKO aortas and BSMKO mice had increased pulse wave velocity, thein vivoindex of arterial stiffness, compared to WT littermates. Despite having no effect on baseline blood pressure or angiotensin II-induced hypertension, Bcl11b deletion in VSM increased the incidence of aortic aneurysms in BSMKO mice. Aneurysmal aortas from angII-treated BSMKO mice had increased number of apoptotic VSM cells. In conclusion, we identified VSM Bcl11b as a novel and crucial regulator of VSM cell phenotype and vascular structural and functional integrity.

P1937Deficiency of PI 3-kinase isoform p110alpha in smooth muscle cells impairs vascular integrity and promotes aortic aneurysm formation

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
M Vantler ◽  
E M Berghausen ◽  
M Zierden ◽  
M Mollenhauer ◽  
D Mehrkens ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Inflammation ◽  
Elastic Fiber ◽  
Muscle Cells ◽  
Aortic Aneurysms ◽  
Elastic Fibers ◽  
Infrarenal Aorta ◽  
Vascular Integrity ◽  
Anti Inflammatory

Abstract Background The pathobiology of aortic aneurysms is characterized by vascular inflammation, extracellular matrix degeneration, and particularly by loss and dedifferentiation of vascular smooth muscle cells (SMCs). In SMCs, the PI 3-kinase isoform p110α mediates receptor tyrosine kinase dependent proliferation, chemotaxis, and survival. Smooth muscle specific p110α deficient mice (SM-p110α−/− mice) display reduced medial wall thickness, substantially reduced neointima formation and media hypertrophy after balloon injury of the carotid artery. Objective We hypothesized that loss of p110α signaling impairs vascular integrity and promotes development and progression of abdominal aortic aneurysms (AAA). We aimed to elucidate the impact of p110α deficiency on vascular integrity, SMC phenotypic modulation, vascular inflammation, and AAA formation. Methods and results Ultra-structural characterization of aortic wall morphology in abdominal aortas from SM-p110α−/− mice by transmission electron microscopy (TEM) revealed disarranged structure of tunica media as indicated by disorganized elastic fibers, detached SMCs, and elastic fiber breaks. Western blots showed reduced elastin and fibrillin expression in SMCs from p110α−/− mice. Media thickness was significantly reduced in abdominal aortas from SM-p110α−/− mice compared to wild type (WT) controls (29.0±3.1 vs. 42.5±4.1 μm). Lack of p110α decreased expression of differentiation markers SM-α-actin and SM-MHC. p110α deficiency significantly diminished responsiveness of aortic rings to vasodilator acetylcholine. These data indicate loss of differentiation and impaired contractility of p110α−/− SMCs. We subjected SM-p110α−/− mice and WT littermate controls to the porcine pancreatic elastase (PPE) model of AAA. PPE was infused into the infrarenal aorta, respectively, to induce AAA formation. Ultrasonic examination of abdominal aortas demonstrated an enlarged aortic diameter in PPE challenged mice. AAA formation was significantly (p<0.01) enhanced in SM-p110α−/− (0.46±0.12 mm, n=8) compared to SM-p110α+/+ mice (0.18±0.03 mm, n=4). These data indicate a protective function of p110α in AAA formation. Immunocytochemistry of the aortic medial compartment from PPE-perfused SM-p110α−/− mice revealed significantly increased MOMA-2+ monocyte/macrophage content indicating augmented aortic inflammation during AAA formation compared to WT controls. Furthermore, SMCs from SM-p110α−/− mice expressed reduced amounts of anti-inflammatory angiopoietin1 compared to p110α+/+ SMCs. Moreover, frequent apoptotic/necrotic SMCs were found in the aortic media of SM-p110α−/− mice by TEM, potentially contributing to vascular inflammation in a critical fashion. Conclusion These data indicate that p110α signaling critically contributes to vascular integrity via maintaining SMC plasticity, elastic fiber homeostasis, and anti-inflammatory processes. Consequently, lack of proper p110α signaling promotes progression of AAA formation.

Sign in / Sign up

Export Citation Format

Share Document