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1.
Life Sci ; 254: 117787, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32417372

RESUMO

AIMS: To evaluate the effects of esculin treatment on P2X7 receptor and mitochondrial dysfunction in the renal cortex of diabetic rats. MAIN METHODS: Male Wistar rats, 7 weeks old, were unilaterally nephrectomized. Part of these animals were induced to diabetes using streptozotocin (60 mg/kg). Diabetes was confirmed 48 h after induction, with blood glucose levels ≥200 mg/dL. Part of control and diabetic animals were selected to receive daily doses of esculin (50 mg/kg), during 8 weeks. The animals were placed in metabolic cages at the eighth week of protocol for 24 h urine collection and a small aliquot of blood was collected for biochemical analysis. After this procedure, the animals were euthanized and the remaining kidney was stored for histopathological analysis, Western blotting and mitochondrial high-resolution respirometry. KEY FINDINGS: Although esculin did not change metabolic parameters, renal biochemical function, neither TBARS in DM rats, esculin reduced P2X7 levels in these animals and restored mitochondrial function via glycolysis substrates and ß-oxidation. Besides, at the histological analysis, we observed that esculin reduced inflammatory infiltrates and collagen IV deposits as compared to diabetic group. SIGNIFICANCE: Esculin attenuated the development of renal injuries caused by hyperglycemia, proinflammatory and oxidative mechanisms mediated by P2X7 receptor, as seen by histological findings and improved mitochondrial function in diabetic animals. This suggests that esculin could be used as an adjuvant therapy to prevent the diabetic nephropathy.


Assuntos
Diabetes Mellitus Experimental/metabolismo , Esculina/farmacologia , Córtex Renal/metabolismo , Mitocôndrias/metabolismo , Receptores Purinérgicos P2X7/metabolismo , Animais , Glicemia/metabolismo , Diabetes Mellitus Experimental/patologia , Colágenos Fibrilares/metabolismo , Glicólise/efeitos dos fármacos , Inflamação/prevenção & controle , Córtex Renal/patologia , Masculino , Oxirredução/efeitos dos fármacos , Ratos , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
2.
PLoS One ; 15(2): e0227856, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084141

RESUMO

Despite the significant progress in characterizing mechanical functions of individual scleral extracellular matrix (ECM) components, the biomechanical contribution of sulfated glycosaminoglycans (sGAGs) is still poorly understood. The primary purpose of this study was to determine the possible function of sGAGs in scleral mechanical response by characterizing the tensile behavior of normal and sGAG-depleted samples. We used chondroitinase ABC solution to remove sGAGs from scleral samples that were dissected from posterior porcine eyes. We performed biochemical analyses for assessing the efficacy of sGAG removal protocol. Furthermore, we conducted stress-controlled uniaxial tensile tests to characterize the influence of sGAG removal on mechanical properties of sclera. The tensile behavior of scleral strips right after dissection and after being soaked in buffer was also determined. Biochemical analyses confirmed that 18 hour incubation in 0.125 U/ml Chondroitinase ABC solution removed over 90% of chondroitin and dermatan sGAGs. No significant difference was observed in the thickness/hydration of samples because of enzyme- and buffer-treated samples. Furthermore, it was found that sGAG depletion did not significantly alter the tangent modulus, energy dissipation, and peak strain of posterior scleral strips. It was concluded that sGAGs did not influence the stress-controlled viscoelastic tensile response of sclera.


Assuntos
Glicosaminoglicanos/metabolismo , Esclera/fisiopatologia , Estresse Mecânico , Sulfatos/metabolismo , Resistência à Tração , Animais , Elasticidade , Colágenos Fibrilares/metabolismo , Tamanho do Órgão , Suínos , Viscosidade
3.
J Vet Med Sci ; 81(11): 1649-1654, 2019 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-31582603

RESUMO

We have previously shown that secreted protein acidic and rich in cysteine (SPARC) promotes myogenic differentiation of rat skeletal muscle progenitor cells in vitro, and in vivo small interfering RNA (siRNA)-mediated transient suppression of SPARC expression in skeletal muscle of mice causes atrophic changes of myofibers, suggesting that SPARC plays a role in the maintenance of skeletal muscle function. In order to know the effect of long-term deficiency of SPARC on skeletal muscle, we performed phenotypic analyses of skeletal muscle of SPARC-null mice. Age-associated changes of myofiber diameters were comparable between wild type (WT) and SPARC-null mice at all ages examined, indicating that the growth of myofibers is unaffected by the absence of SPARC. On the other hand, accumulation of fibrillar collagen was significantly reduced in SPARC-null mice compared to WT mice after 5 months of age without significant changes of collagen I gene expression. The results obtained in the present study suggest that SPARC plays a role to maintain the stiffness of skeletal muscle by regulating collagen accumulation.


Assuntos
Colágenos Fibrilares/metabolismo , Músculo Esquelético/metabolismo , Osteonectina/metabolismo , Envelhecimento/metabolismo , Animais , Expressão Gênica , Masculino , Camundongos , Camundongos Knockout , Miofibrilas , Osteonectina/genética
4.
Mol Vis ; 25: 415-426, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31523119

RESUMO

Purpose: Maintenance of a transparent corneal stroma is imperative for proper vision. The corneal stroma is composed of primarily collagen fibrils, small leucine-rich proteoglycans (SLRPs), as well as sparsely distributed cells called keratocytes. The lattice arrangement and spacing of the collagen fibrils that allows for transparency may be disrupted due to genetic mutations and injuries. The purpose of this study is to examine the therapeutic efficacy of human umbilical cord mesenchymal stem/stromal cells (UMSCs) in treating congenital and acquired corneal opacity associated with the loss of collagen V. Methods: Experimental mice, i.e., wild-type, Col5a1f/f and Kera-Cre/Col5a1f/f (Col5a1∆st/∆st , collagen V null in the corneal stroma) mice in a C57BL/6J genetic background, were subjected to a lamellar keratectomy, and treated with or without UMSC (104 cells/cornea) transplantation via an intrastromal injection or a fibrin plug. In vivo Heidelberg retinal tomograph (HRT II) confocal microscopy, second harmonic generated (SHG) confocal microscopy, histology, and immunofluorescence microscopy were used to assess the corneal transparency of the regenerated corneas. Results: Col5a1∆st/∆st mice display a cloudy cornea phenotype that is ameliorated following intrastromal transplantation of UMSCs. Loss of collagen V in Col5a1∆st/∆st corneas augments the formation of cornea scarring following the keratectomy. UMSC transplantation with a fibrin plug improves the healing of injured corneas and regeneration of transparent corneas, as determined with in vivo HRT II confocal microscopy. Second harmonic confocal microscopy revealed the improved collagen fibril lamellar architecture in the UMSC-transplanted cornea in comparison to the control keratectomized corneas. Conclusions: UMSC transplantation was successful in recovering some corneal transparency in injured corneas of wild-type, Col5a1f/f and Col5a1∆st/∆st mice. The production of collagen V by transplanted UMSCs may account for the regeneration of corneal transparency, as exemplified by better collagen fiber organization, as revealed with SHG signals.


Assuntos
Opacidade da Córnea/congênito , Opacidade da Córnea/terapia , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Animais , Colágeno Tipo V/metabolismo , Opacidade da Córnea/patologia , Substância Própria/patologia , Colágenos Fibrilares/metabolismo , Humanos , Camundongos Endogâmicos C57BL , Resultado do Tratamento , Cordão Umbilical/citologia
5.
Int J Med Sci ; 16(8): 1072-1077, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31523168

RESUMO

Corneal endothelial tissue engineering aims to find solutions for blindness due to endothelial dysfunction. A suitable combination of endothelial cells, substrates and environmental cues should be deployed for engineering functional endothelial tissues. This manuscript reviews up-to-date topics of corneal endothelial tissue engineering with special emphasis on biomaterial substrates and their properties, efficacy, and mechanisms of supporting functional endothelial cells in vitro.


Assuntos
Epitélio Posterior , Engenharia Tecidual/métodos , Técnicas de Cultura de Células , Células Cultivadas , Colágeno/fisiologia , Células Endoteliais , Epitélio Posterior/citologia , Colágenos Fibrilares/metabolismo , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Humanos , Integrinas/fisiologia , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais
6.
Commun Biol ; 2: 321, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31482140

RESUMO

Knee pain is one of the most common musculoskeletal complaints that brings people to medical attention. Approximately 50% of individuals over the age of 50 report an experience of knee pain within the past 12 months. We sought to identify the genetic variants associated with knee pain in 171,516 subjects from the UK Biobank cohort and seek supporting evidence in cohorts from 23andMe, the Osteoarthritis Initiative, and the Johnston County Osteoarthritis Project. We identified two loci that reached genome-wide significance in the UK Biobank: rs143384, located in GDF5 (P = 1.32 × 10-12), a gene previously implicated in osteoarthritis; and rs2808772, located near COL27A1 (P = 1.49 × 10-8). These findings were supported in cohorts with self-reported osteoarthritis/radiographic knee osteoarthritis without pain information. In this report on genome-wide association of knee pain, we identified two loci in or near GDF5 and COL27A1 that are associated with knee pain.


Assuntos
Bancos de Espécimes Biológicos , Colágenos Fibrilares/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Fator 5 de Diferenciação de Crescimento/genética , Articulação do Joelho/patologia , Dor/genética , Estudos de Casos e Controles , Estudos de Coortes , Feminino , Regulação da Expressão Gênica , Humanos , Desequilíbrio de Ligação/genética , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Reino Unido
7.
Avian Dis ; 63(1): 48-60, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31251519

RESUMO

The wooden breast myopathy is identified by the palpation of a rigid pectoralis major muscle and results in myofiber necrosis and fibrosis in fast-growing, meat-type broilers. The fibrosis in wooden breast-affected muscle is characterized by the replacement of myofibers with extracellular matrix proteins, especially fibril-forming collagens. Studies have shown differences in collagen organization in fast-growing broiler lines, with tightly packed and highly aligned collagen organizations having a higher phenotypic incidence of wooden breast. The objective of the current study was to analyze collagen fibril organization further in two fast-growing broiler lines (Lines A and B) with incidence of wooden breast compared with a slower growing broiler Line C with no phenotypically detectable wooden breast. The small leucine-rich proteoglycan decorin was also studied for its interaction with collagen by immunogold detection. Decorin binds to fibrillar collagens and organizes their alignment and crosslinking, both of which will affect collagen functional properties. Key findings from the study showed that collagen shifts to larger diameter collagen fibril bundles with the wooden breast myopathy. Specifically, broilers affected with wooden breast from Line A had a more dramatic shift toward larger collagen fibril bundles compared with those affected from Line B. Wooden breast-affected Line A had collagen fibril bundles up to 8.4 µm, whereas Line B maximum size was 5.1 µm. Although decorin-collagen binding was not different overall in the wooden breast myopathy or broiler line, for small-diameter collagen fibril bundles, wooden breast-affected Line A had more decorin-collagen binding than wooden breast-affected Line B. Taken together, these data provide further evidence that multiple fibrotic myopathies are likely in fast-growing meat-type broilers.


Assuntos
Galinhas , Colágeno/metabolismo , Decorina/metabolismo , Colágenos Fibrilares/ultraestrutura , Doenças Musculares/veterinária , Músculos Peitorais/fisiopatologia , Doenças das Aves Domésticas/fisiopatologia , Animais , Carne , Microscopia Eletrônica de Transmissão/veterinária , Doenças Musculares/fisiopatologia , Ligação Proteica
8.
Biomech Model Mechanobiol ; 18(6): 1809-1819, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31161353

RESUMO

Loading in cartilage is supported primarily by fibrillar collagen, and damage will impair the function of the tissue, leading to pathologies such as osteoarthritis. Damage is initiated by two types of matrix metalloproteinases, collagenase and gelatinase, that cleave and denature the collagen fibrils in the tissue. Experimental and modeling studies have revealed insights into the individual contributions of these two types of MMPs, as well as the mechanical response of intact fibrils and fibrils that have experienced random surface degradation. However, no research has comprehensively examined the combined influences of collagenases and gelatinases on collagen degradation nor studied the mechanical consequences of biological degradation of collagen fibrils. Such preclinical examinations are required to gain insights into understanding, treating, and preventing degradation-related cartilage pathology. To develop these insights, we use sequential Monte Carlo and molecular dynamics simulations to probe the effect of enzymatic degradation on the structure and mechanics of a single collagen fibril. We find that the mechanical response depends on the ratio of collagenase to gelatinase-not just the amount of lost fibril mass-and we provide a possible mechanism underlying this phenomenon. Overall, by characterizing the combined influences of collagenases and gelatinases on fibril degradation and mechanics at the preclinical research stage, we gain insights that may facilitate the development of targeted interventions to prevent the damage and loss of mechanical integrity that can lead to cartilage pathology.


Assuntos
Colagenases/metabolismo , Colágenos Fibrilares/metabolismo , Gelatinases/metabolismo , Simulação de Dinâmica Molecular , Método de Monte Carlo , Fenômenos Biomecânicos , Estresse Mecânico , Tropocolágeno/metabolismo
9.
Invest Ophthalmol Vis Sci ; 60(7): 2406-2422, 2019 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-31157833

RESUMO

Purpose: The purpose of this study was to measure the 2D collagen network structure of the human lamina cribrosa (LC), analyze for the correlations with age, region, and LC size, as well as the correlations with pressure-induced strains. Methods: The posterior scleral cups of 10 enucleated human eyes with no known ocular disease were subjected to ex vivo inflation testing from 5 to 45 mm Hg. The optic nerve head was imaged by using second harmonic generation imaging (SHG) to identify the LC collagen structure at both pressures. Displacements and strains were calculated by using digital volume correlation of the SHG volumes. Nine structural features were measured by using a custom Matlab image analysis program, including the pore area fraction, node density, and beam connectivity, tortuosity, and anisotropy. Results: All strain measures increased significantly with higher pore area fraction, and all but the radial-circumferential shear strain (Erθ) decreased with higher node density. The maximum principal strain (Emax) and maximum shear strain (Γmax) also increased with larger beam aspect ratio and tortuosity, respectively, and decreased with higher connectivity. The peripheral regions had lower node density and connectivity, and higher pore area fraction, tortuosity, and strains (except for Erθ) than the central regions. The peripheral nasal region had the lowest Emax, Γmax, radial strain, and pore area fraction. Conclusions: Features of LC beam network microstructure that are indicative of greater collagen density and connectivity are associated with lower pressure-induced LC strain, potentially contributing to resistance to glaucomatous damage.


Assuntos
Módulo de Elasticidade/fisiologia , Colágenos Fibrilares/metabolismo , Pressão Intraocular/fisiologia , Disco Óptico/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Anisotropia , Fenômenos Biomecânicos , Enucleação Ocular , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Disco Óptico/diagnóstico por imagem , Estresse Mecânico , Doadores de Tecidos
10.
Biochim Biophys Acta Mol Cell Res ; 1866(11): 118496, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31229648

RESUMO

Assembly of cell-surface receptors into specific oligomeric states and/or clusters before and after ligand binding is an important feature governing their biological function. Receptor oligomerization can be mediated by specific domains of the receptor, ligand binding, configurational changes or other interacting molecules. In this review we summarize our understanding of the oligomeric state of discoidin domain receptors (DDR1 and DDR2), which belong to the receptor tyrosine kinase family (RTK). DDRs form an interesting system from an oligomerization perspective as their ligand collagen(s) can also undergo supramolecular assembly to form fibrils. Even though DDR1 and DDR2 differ in the domains responsible to form ligand-free dimers they share similarities in binding to soluble, monomeric collagen. However, only DDR1b forms globular clusters in response to monomeric collagen and not DDR2. Interestingly, both DDR1 and DDR2 are assembled into linear clusters by the collagen fibril. Formation of these clusters is important for receptor phosphorylation and is mediated in part by other membrane components. We summarize how the oligomeric status of DDRs shares similarities with other members of the RTK family and with collagen receptors. Unraveling the multiple macro-molecular configurations adopted by this receptor-ligand pair can provide novel insights into the intricacies of cell-matrix interactions.


Assuntos
Receptores com Domínio Discoidina/química , Receptores com Domínio Discoidina/metabolismo , Ligação Proteica , Sítios de Ligação , Colágeno/química , Domínio Discoidina , Receptor com Domínio Discoidina 1/química , Receptor com Domínio Discoidina 1/metabolismo , Receptor com Domínio Discoidina 2/química , Receptor com Domínio Discoidina 2/metabolismo , Colágenos Fibrilares , Humanos , Ligantes , Fosforilação , Receptores Proteína Tirosina Quinases , Receptores de Colágeno/química , Receptores de Colágeno/metabolismo
11.
Cardiovasc J Afr ; 30(4): 208-215, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31140539

RESUMO

Atherosclerosis begins during foetal development and is enhanced by maternal hypercholesterolaemia during pregnancy. This study assessed the effect of natural cocoa on atherosclerosis in offspring conceived in maternal hypercholesterolaemia. Female rabbits were fed a cholesterol-enriched diet for two weeks and hypercholesterolaemia was confirmed, after which they were crossed with normocholesterolaemic males. One group of hypercholesterolaemic mothers (HCC) received natural cocoa powder (NCP) in their drinking water, whereas the other group (HC) received only water. Histological analysis of three segments of the aorta (arch, thoracic and abdominal) from offspring of both groups was compared with a control group (NC). Intima-media thickness of the aortic arch in offspring born to hypercholesterolaemic rabbits (HC: 146 µm) was higher compared to HCC (99 µm) and control rabbits (58.5 µm). All the sections from the aortic arch of the HC group had atherosclerotic lesions while none of the sections of the aortic arch from the NC and HCC groups had lesions present. Inferentially, regular and voluntary consumption of NCP during pregnancy may inhibit aortic atherogenesis in offspring of hypercholesterolaemic mothers.


Assuntos
Aorta Torácica/patologia , Doenças da Aorta/prevenção & controle , Aterosclerose/prevenção & controle , Chocolate , Hipercolesterolemia/dietoterapia , Placa Aterosclerótica , Efeitos Tardios da Exposição Pré-Natal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Animais Recém-Nascidos , Doenças da Aorta/etiologia , Doenças da Aorta/patologia , Aterosclerose/etiologia , Aterosclerose/patologia , Dieta Hiperlipídica , Modelos Animais de Doenças , Tecido Elástico/patologia , Feminino , Colágenos Fibrilares , Hipercolesterolemia/sangue , Hipercolesterolemia/complicações , Fenômenos Fisiológicos da Nutrição Materna , Gravidez , Coelhos
12.
Biomech Model Mechanobiol ; 18(5): 1507-1528, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31065952

RESUMO

Abdominal aortic aneurysm is a prevalent cardiovascular disease with high mortality rates. The mechanical response of the arterial wall relies on the organizational and structural behavior of its microstructural components, and thus, a detailed understanding of the microscopic mechanical response of the arterial wall layers at loads ranging up to rupture is necessary to improve diagnostic techniques and possibly treatments. Following the common notion that adventitia is the ultimate barrier at loads close to rupture, in the present study, a finite element model of adventitial collagen network was developed to study the mechanical state at the fiber level under uniaxial loading. Image stacks of the rabbit carotid adventitial tissue at rest and under uniaxial tension obtained using multi-photon microscopy were used in this study, as well as the force-displacement curves obtained from previously published experiments. Morphological parameters like fiber orientation distribution, waviness, and volume fraction were extracted for one sample from the confocal image stacks. An inverse random sampling approach combined with a random walk algorithm was employed to reconstruct the collagen network for numerical simulation. The model was then verified using experimental stress-stretch curves. The model shows the remarkable capacity of collagen fibers to uncrimp and reorient in the loading direction. These results further show that at high stretches, collagen network behaves in a highly non-affine manner, which was quantified for each sample. A comprehensive parameter study to understand the relationship between structural parameters and their influence on mechanical behavior is presented. Through this study, the model was used to conclude important structure-function relationships that control the mechanical response. Our results also show that at loads close to rupture, the probability of failure occurring at the fiber level is up to 2%. Uncertainties in usually employed rupture risk indicators and the stochastic nature of the event of rupture combined with limited knowledge on the microscopic determinants motivate the development of such an analysis. Moreover, this study will advance the study of coupling microscopic mechanisms to rupture of the artery as a whole.


Assuntos
Túnica Adventícia/fisiologia , Colágenos Fibrilares/química , Modelos Cardiovasculares , Algoritmos , Animais , Fenômenos Biomecânicos , Simulação por Computador , Análise de Elementos Finitos , Masculino , Dinâmica não Linear , Porosidade , Probabilidade , Coelhos , Reprodutibilidade dos Testes , Estresse Mecânico , Resistência à Tração
13.
PLoS One ; 14(5): e0216537, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31091287

RESUMO

Aligned collagen architecture is a characteristic feature of the tumor extracellular matrix (ECM) and has been shown to facilitate cancer metastasis using 3D in vitro models. Additional features of the ECM, such as pore size and stiffness, have also been shown to influence cellular behavior and are implicated in cancer progression. While there are several methods to produce aligned matrices to study the effect on cell behavior in vitro, it is unclear how the alignment itself may alter these other important features of the matrix. In this study, we have generated aligned collagen matrices and characterized their pore sizes and mechanical properties at the micro- and macro-scale. Our results indicate that collagen alignment can alter pore-size of matrices depending on the polymerization temperature of the collagen. Furthermore, alignment does not affect the macro-scale stiffness but alters the micro-scale stiffness in a temperature independent manner. Overall, these results describe the manifestation of confounding variables that arise due to alignment and the importance of fully characterizing biomaterials at both micro- and macro-scales.


Assuntos
Matriz Extracelular/patologia , Colágenos Fibrilares/metabolismo , Neoplasias/diagnóstico por imagem , Algoritmos , Movimento Celular , Progressão da Doença , Matriz Extracelular/metabolismo , Humanos , Microscopia de Força Atômica , Neoplasias/metabolismo
16.
Cardiovasc Eng Technol ; 10(2): 344-353, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30949919

RESUMO

PURPOSE: Atherosclerotic plaques are highly heterogeneous, nonlinear materials with uncharacteristic structural behaviors. It is well known that mechanics of atherosclerotic plaques significantly depend on plaque geometry, location, composition, and loading conditions. There is no question that atherosclerotic plaques are viscoelastic. Plaques are characterized as the buildup of low-density lipoprotein cholesterol, macrophages, monocytes, and foam cells at a place of inflammation inside arterial walls. Lipid core and fibrous cap are the two major ingredients that are frequently used for the identification of main constituting quantities of atherosclerotic plaques. The lipid core contains of debris from dead cells, esterified cholesterol and cholesterol crystals. The fibrous cap contains smooth muscle cells and collagen fibers. All these materials contribute to the viscoelastic properties of atherosclerotic plaques. Computational studies have shown great potential to characterize this mechanical behavior. Different types of plaque morphologies and mechanical properties have been used in a computational platform to estimate the stability of rupture-prone plaques and detect their locations. In this study for the first time to the best of authors' knowledge, we hypothesize that heart rate is also one of the major factors that should be taken into account while mechanics of plaques is studied. METHOD: We propose a tunable viscoelastic constitutive material model for the fibrous cap tissue in order to calculate the peak cap stress in normal physiological (dynamic) conditions while heart rate changes from 60 bpm to 150 bpm in 2D plane stress models. A critical discussion on stress distribution in the fibrous cap area is made with respect to heart rate for the first time. RESULTS: Results strongly suggest the viscoelastic properties of the fibrous cap tissue and heart rate together play a major role in the estimation of the pick cap stress values. CONCLUSIONS: The results of current study may provide a better understanding on the mechanics of vulnerable atherosclerotic plaques and that any experimental methods assessing the viscoelasticity of plaque composition during progression are highly desirable.


Assuntos
Doença da Artéria Coronariana/patologia , Doença da Artéria Coronariana/fisiopatologia , Circulação Coronária , Vasos Coronários/patologia , Vasos Coronários/fisiopatologia , Frequência Cardíaca , Modelos Cardiovasculares , Placa Aterosclerótica , Colesterol/metabolismo , Simulação por Computador , Doença da Artéria Coronariana/metabolismo , Vasos Coronários/metabolismo , Elasticidade , Colágenos Fibrilares/metabolismo , Fibrose , Humanos , Análise Numérica Assistida por Computador , Ruptura Espontânea , Estresse Mecânico , Viscosidade
17.
Am J Respir Crit Care Med ; 200(4): 431-443, 2019 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-30950644

RESUMO

Rationale: Histologic stains have been used as the gold standard to visualize extracellular matrix (ECM) changes associated with airway remodeling in asthma, yet they provide no information on the biochemical and structural characteristics of the ECM, which are vital to understanding alterations in tissue function.Objectives: To demonstrate the use of nonlinear optical microscopy (NLOM) and texture analysis algorithms to image fibrillar collagen (second harmonic generation) and elastin (two-photon excited autofluorescence), to obtain biochemical and structural information on the remodeled ECM environment in asthma.Methods: Nontransplantable donor lungs from donors with asthma (n = 13) and control (n = 12) donors were used for the assessment of airway collagen and elastin fibers by NLOM, and extraction of lung fibroblasts for in vitro experiments.Measurements and Main Results: Fibrillar collagen is not only increased but also highly disorganized and fragmented within large and small asthmatic airways compared with control subjects, using NLOM imaging. Furthermore, such structural alterations are present in pediatric and adult donors with asthma, irrespective of fatal disease. In vitro studies demonstrated that asthmatic airway fibroblasts are deficient in their packaging of fibrillar collagen-I and express less decorin, important for collagen fibril packaging. Packaging of collagen fibrils was found to be more disorganized in asthmatic airways compared with control subjects, using transmission electron microscopy.Conclusions: NLOM imaging enabled the structural assessment of the ECM, and the data suggest that airway remodeling in asthma involves the progressive accumulation of disorganized fibrillar collagen by airway fibroblasts. This study highlights the future potential clinical application of NLOM to assess airway remodeling in vivo.


Assuntos
Remodelação das Vias Aéreas/fisiologia , Asma/metabolismo , Elastina/metabolismo , Colágenos Fibrilares/metabolismo , Fibroblastos/metabolismo , Pulmão/metabolismo , Adolescente , Adulto , Asma/patologia , Criança , Colágeno Tipo I/metabolismo , Decorina/metabolismo , Elastina/ultraestrutura , Matriz Extracelular , Feminino , Colágenos Fibrilares/ultraestrutura , Humanos , Técnicas In Vitro , Pulmão/citologia , Pulmão/ultraestrutura , Masculino , Microscopia Eletrônica de Transmissão , Microscopia Óptica não Linear , Adulto Jovem
18.
Biofabrication ; 11(3): 035017, 2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-30995622

RESUMO

The microenvironments of tissues or organs are complex architectures comprised of structural proteins including collagen. Particularly, the cornea is organized in a lattice pattern of collagen fibrils which play a significant role in its transparency. This paper introduces a transparent bioengineered corneal structure for transplantation. The structure is fabricated by inducing shear stress to a corneal stroma-derived decellularized extracellular matrix bioink based on a 3D cell printing technique. The printed structure recapitulates the native macrostructure of the cornea with aligned collagen fibrils which results in the construction of a highly matured and transparent cornea stroma analog. The level of shear stress, controlled by the various size of the printing nozzle, manipulates the arrangement of the fibrillar structure. With proper parameter selection, the printed cornea exhibits high cellular alignment capability, indicating a tissue-specific structural organization of collagen fibrils. In addition, this structural regulation enhances critical cellular events in the assembly of collagen over time. Interestingly, the collagen fibrils that remodeled along with the printing path create a lattice pattern similar to the structure of native human cornea after 4 weeks in vivo. Taken together, these results establish the possibilities and versatility of fabricating aligned collagen fibrils; this represents significant advances in corneal tissue engineering.


Assuntos
Substância Própria/fisiologia , Colágenos Fibrilares/química , Impressão Tridimensional , Engenharia Tecidual/métodos , Animais , Bovinos , Forma Celular , Ceratócitos da Córnea/citologia , Humanos , Masculino , Coelhos
19.
Nat Commun ; 10(1): 1850, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015429

RESUMO

Macrophage (Mϕ)-fibroblast interactions coordinate tissue repair after injury whereas miscommunications can result in pathological healing and fibrosis. We show that contracting fibroblasts generate deformation fields in fibrillar collagen matrix that provide far-reaching physical cues for Mϕ. Within collagen deformation fields created by fibroblasts or actuated microneedles, Mϕ migrate towards the force source from several hundreds of micrometers away. The presence of a dynamic force source in the matrix is critical to initiate and direct Mϕ migration. In contrast, collagen condensation and fiber alignment resulting from fibroblast remodelling activities or chemotactic signals are neither required nor sufficient to guide Mϕ migration. Binding of α2ß1 integrin and stretch-activated channels mediate Mϕ migration and mechanosensing in fibrillar collagen ECM. We propose that Mϕ mechanosense the velocity of local displacements of their substrate, allowing contractile fibroblasts to attract Mϕ over distances that exceed the range of chemotactic gradients.


Assuntos
Movimento Celular/imunologia , Matriz Extracelular/metabolismo , Colágenos Fibrilares/metabolismo , Fibroblastos/imunologia , Macrófagos/imunologia , Animais , Adesão Celular/imunologia , Células Cultivadas , Fibroblastos/metabolismo , Microscopia Intravital , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Vídeo , Cultura Primária de Células
20.
Nutr Metab Cardiovasc Dis ; 29(6): 621-632, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31005375

RESUMO

BACKGROUND AND AIMS: The vascular remodeling plays a crucial role in pathogenesis of diabetic cardiovascular complications. In this study, we intended to explore the effects and potential mechanisms of microRNA-24 (miR-24) on vascular remodeling under diabetic conditions. METHODS AND RESULTS: MiR-24 recombinant adenovirus (Ad-miR-24-GFP) was used to induce miR-24 overexpression either in carotid arteries or high glucose (HG)-induced vascular smooth muscle cells (VSMCs). Cell proliferation was analyzed using CCK-8 method. Cell migration was examined using wound-healing and transwell assay. mRNA and protein expressions of critical factors were, respectively, measured by real-time PCR and western blot as follows: qRT-PCR for the levels of miR-24, PIK3R1; western blot for the protein levels of PI3K (p85α), Akt, p-Akt, mTOR, p-mTOR, 4E-BP1, p-4E-BP1, p70s6k, p-p70s6k, MMP 2, MMP 9, collagen Ⅰ, as well as collagen Ⅲ. Carotid arteries in diabetic rats suffered balloon injury were harvested and examined by HE, immunohistochemical and Masson trichrome staining. The expression of miR-24 was decreased in HG-stimulated VSMCs and balloon-injured carotid arteries of diabetic rats, accompanied by increased mRNA expression of PIK3R1. The up-regulation of miR-24 suppressed VSMCs proliferation, migration, collagen deposition not only induced by HG in vitro, but also in balloon-injured diabetic rats, which were related to inactivation of PI3K/Akt signaling pathway. CONCLUSION: The up-regulation of miR-24 significantly attenuated vascular remodeling both in balloon-injured diabetic rats and HG-stimulated VSMCs via suppression of proliferation, migration and collagen deposition by acting on PIK3R1 gene that modulated the PI3K/Akt/mTOR axes.


Assuntos
Lesões das Artérias Carótidas/enzimologia , Diabetes Mellitus Experimental/enzimologia , MicroRNAs/metabolismo , Músculo Liso Vascular/enzimologia , Miócitos de Músculo Liso/enzimologia , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Remodelação Vascular , Animais , Artérias Carótidas/enzimologia , Artérias Carótidas/patologia , Lesões das Artérias Carótidas/genética , Lesões das Artérias Carótidas/patologia , Movimento Celular , Proliferação de Células , Células Cultivadas , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/patologia , Colágenos Fibrilares/metabolismo , Masculino , MicroRNAs/genética , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/patologia , Neointima , Ratos Sprague-Dawley , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo
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