scholarly journals Engineering and Monitoring 3D Cell Constructs with Time-Evolving Viscoelasticity for the Study of Liver Fibrosis In Vitro

2021 ◽  
Vol 8 (8) ◽  
pp. 106
Author(s):  
Ludovica Cacopardo ◽  
Arti Ahluwalia
Keyword(s):  
Mechanical Properties ◽  
Liver Fibrosis ◽  
Progressive Increase ◽  
Cell Stress ◽  
Matrix Proteins ◽  
Hepatic Tissue ◽  
3D Microenvironment ◽  
Mechanical Microenvironment ◽  
Over Time

Liver fibrosis is generally associated with an over-production and crosslinking of extracellular matrix proteins, causing a progressive increase in both the elastic and viscous properties of the hepatic tissue. We describe a strategy for mimicking and monitoring the mechano-dynamics of the 3D microenvironment associated with liver fibrosis. Cell-laden gelatin hydrogels were crosslinked with microbial transglutaminase using a purpose-designed cytocompatible two-step protocol, which allows for the exposure of cells to a mechanically changing environment during culturing. A bioreactor was re-engineered to monitor the mechanical properties of cell constructs over time. The results showed a shift towards a more elastic (i.e., solid-like) behaviour, which is likely related to an increase in cell stress. The method effectively mimics the time-evolving mechanical microenvironment associated with liver fibrosis and could provide novel insights into pathophysiological processes in which both elastic and viscous properties of tissues change over time.

scholarly journals WNT-5A regulates TGF-β-related activities in liver fibrosis

2017 ◽  
Vol 312 (3) ◽  
pp. G219-G227 ◽  
Author(s):  
Leonie Beljaars ◽  
Sara Daliri ◽  
Christa Dijkhuizen ◽  
Klaas Poelstra ◽  
Reinoud Gosens
Keyword(s):  
Liver Fibrosis ◽  
Functional Role ◽  
Collagen Type ◽  
Collagen Type I ◽  
Matrix Proteins ◽  
Type I ◽  
Human Livers

WNT-5A is a secreted growth factor that belongs to the noncanonical members of the Wingless-related MMTV-integration family. Previous studies pointed to a connection between WNT-5A and the fibrogenic factor TGF-β warranting further studies into the functional role of WNT-5A in liver fibrosis. Therefore, we studied WNT-5A expressions in mouse and human fibrotic livers and examined the relation between WNT-5A and various fibrosis-associated growth factors, cytokines, and extracellular matrix proteins. WNT-5A gene and protein expressions were significantly increased in fibrotic mouse and human livers compared with healthy livers. Regression or therapeutic intervention in mice resulted in decreased hepatic WNT-5A levels paralleled by lower collagen levels. Immunohistochemical analysis showed WNT-5A staining in fibrotic septa colocalizing with desmin staining indicating WNT-5A expression in myofibroblasts. In vitro studies confirmed WNT-5A expression in this cell type and showed that TGF-β significantly enhanced WNT-5A expression in contrast to PDGF-BB and proinflammatory cytokines IL-1β and TNF-α. Additionally, TGF-β induces the expression of the WNT receptors FZD2 and FZD8. After silencing of WNT-5A, reduced levels of collagen type I, vimentin, and fibronectin in TGF-β-stimulated myofibroblasts were measured compared with nonsilencing siRNA-treated controls. Interestingly, the antifibrotic cytokine IFNγ suppressed WNT-5A in vitro and in vivo. IFNγ-treated fibrotic mice showed significantly less WNT-5A expression compared with untreated fibrotic mice. In conclusion, WNT-5A paralleled collagen I levels in fibrotic mouse and human livers. WNT-5A expression in myofibroblasts is induced by the profibrotic factor TGF-β and plays an important role in TGF-β-induced regulation of fibrotic matrix proteins, whereas its expression can be reversed upon treatment, both in vitro and in vivo. NEW & NOTEWORTHY This study describes the localization and functional role of WNT-5A in human and mouse fibrotic livers. Hepatic WNT-5A expression parallels collagen type I expression. In vivo and in vitro, the myofibroblasts were identified as the key hepatic cells producing WNT-5A. WNT-5A is under control of TGF-β and its activities are primarily profibrotic.

Exosomes derived from mmu_circ_0000623-modified ADSCs prevent liver fibrosis via activating autophagy

2020 ◽  
Vol 39 (12) ◽  
pp. 1619-1627 ◽  
Author(s):  
M Zhu ◽  
X Liu ◽  
W Li ◽  
L Wang
Keyword(s):  
Liver Fibrosis ◽  
Expression Profiles ◽  
Parenchymal Cell ◽  
Hepatic Tissue ◽  
Circular Rnas ◽  
In Vivo Experiments ◽  
Matrix Accumulation ◽  
Inhibitor Treatment

Prolonged parenchymal cell death leads to activation of fibrogenic cells, extracellular matrix accumulation, and eventually liver fibrosis. Increasing evidence shows that exosomes (Exos) secreted by adipose-derived mesenchymal stem cells (ADSCs) can be used to deliver circular RNAs (circRNAs) to treat liver fibrosis. To explore the uses of circRNA, circRNA expression profiles of hepatic tissue from normal and CCl4-induced mice were analyzed using high-throughput circRNA microarrays. The result showed that mmu_circ_0000623 expression was downregulated in CCl4-induced mice. Bioinformatics analysis and luciferin reporter experiments showed that mmu_circ_0000623 interacted with and regulated miR-125/ATG4D. In vitro and in vivo experiments showed that Exos from ADSCs, especially from mmu_circ_0000623-modified ADSCs, significantly suppressed CCl4-induced liver fibrosis by promoting autophagy activation. Autophagy inhibitor treatment significantly reversed the treatment effects of Exos. Proteins involved in autophagy and autophagy plaques positive for ATG4D expression were regulated by mmu_circ_0000623/miR-125. Our study found that Exos derived from mmu_circ_0000623-modified ADSCs prevented liver fibrosis via activating autophagy.

Surface Changes of Fluoride-Releasing Composites: a Comparison of in Vivo and in Vitro Results

1995 ◽  
Vol 9 (4) ◽  
pp. 348-354 ◽  
Author(s):  
G.E.H.M. Dijkman ◽  
J. De Vries ◽  
W.L. Jongebloed ◽  
J. Arends
Keyword(s):  
Mechanical Properties ◽  
Outer Surface ◽  
Tap Water ◽  
Surface Microhardness ◽  
Vitro Experiment ◽  
In Vitro Experiment ◽  
Over Time ◽  
Surface Changes

Fluoride-releasing composites lose fluoride very slowly over time. An interesting question is the possible change in mechanical properties related to the F release. If this happens, it might be expected that the mechanical properties of the outer surface of a fluoridating composite are affected first. The purpose of this study was to investigate in vivo and in vitro the changes in surface microhardness and surface structure of three fluoride-releasing composites and a non-F-containing control after 28 days. In the in vitro experiment, the composites were stored in tap water at 37°C. The results show that all composites stored in water were significantly softened after 28 days. In vivo, however, a very different picture emerged: The surface microhardness of the fluoride-releasing composites did not change significantly. In vitro, the data indicate that the amount of softening of the fluoridating composites is related to the amount of fluoride released. No relation was found between the amount of F released in one month in vitro and the microhardness changes in vivo. SEM micrographs of fluoridating composites do not reflect the microhardness changes mentioned.

Degradation Behaviour of Zeolite Filled Polyurethanes under In Vitro Aging Process

2015 ◽  
Vol 812 ◽  
pp. 83-88
Author(s):  
Peter Kaali ◽  
György Czél
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Artificial Aging ◽  
Surface Pattern ◽  
Degradation Behaviour ◽  
Total Exposure Time ◽  
Polyurethane Composites ◽  
Over Time ◽  
Release Processes

In this study the degradation and ion/zeolite release processes of in vitro aged zeolite loaded polyurethane composites were evaluated. Two in vitro artificial aging solutions were used; artificial lysosomal fluid (ALF) and Gamble ́s solution and the total exposure time was 12 weeks. Periodically, SEM micrographs were taken of the surface of polyester type polyurethane-zeolite composites. After exposure to ALF solution the samples showed round holes and a rougher surface in general over time. Micrographs of the samples immersed in Gamble’s solution exhibited different signs of degradation with damage features on the surfaces, understood as black holes and a rougher surface pattern. In addition varying amount of salt was also observed on the surfaces that might influence the ion/zeolite release. Furthermore, the zeolite filler caused remarkable changes in mechanical properties after the aging process, which could not be discerned.

scholarly journals Evaluation of Cardiac Thrombus Stability based on Contrast-Enhanced Echocardiography：Research Protocol and Preliminary Results

2021 ◽  
Author(s):  
Ying Li ◽  
Xin Wang ◽  
Weidong Ren ◽  
Yangjie Xiao ◽  
Xiaona Yu ◽  
...  
Keyword(s):  
Scoring System ◽  
Shear Wave Elastography ◽  
Progressive Increase ◽  
Cardiac Thrombus ◽  
Contrast Enhanced ◽  
Study Results ◽  
Time Changes ◽  
The Stability ◽  
Over Time

Abstract Objective: This study attempted to test a new scoring system for evaluating the stability of cardiac thrombi using contrast-enhanced ultrasound (CEUS). Methods: We used human whole blood to make the thrombus model in vitro which were divided into 2 groups, the 1-hour (T1h) and 7-day (T7d) group. The T1h group was monitored for 1 hour continuously to observe for the formation of a new thrombus on the original thrombus base. Over time, changes in CEUS images and pathology and shear wave elastography (SWE) of thrombus were observed in theT1h and T7 groups. Twenty-eight adult patients diagnosed with a cardiac thrombus were selected and examined by transthoracic echocardiography (TTE) and CEUS. Thrombi were scored for substrate (Ts) and hardness (Th) based on the visualized degree of contrast penetration into the thrombus. The Ts and Th were statistically analyzed for thrombolytic time and the risk of embolism to other organs. Results: In vitro, pathology revealed a decreased pore structure; further, the average Young’s modulus of the thrombi over time indicated a progressive increase in hardness. Contrast-enhancing agents were able to enter a fresh, loose thrombus, but were not able to enter a chronic, stable thrombus. With increasing Ts and Th, thrombolytic time was prolonged, and the risk of embolism to other organs was increased. Conclusions: Our study results suggest that this new CEUS scoring system can evaluate the hardness of a cardiac thrombus and the quality of its underlying substrate; this allows for quantitative evaluation of thrombus stability.

scholarly journals Cardiac thrombotic stability determined by contrast-enhanced echocardiography: investigative protocol and preliminary results

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ying Li ◽  
Xin Wang ◽  
Weidong Ren ◽  
Yangjie Xiao ◽  
Xiaona Yu ◽  
...  
Keyword(s):  
Shear Wave Elastography ◽  
Progressive Increase ◽  
Contrast Enhanced Ultrasound ◽  
Human Whole Blood ◽  
Contrast Enhanced ◽  
Contrast Enhanced Echocardiography ◽  
New System ◽  
Over Time

Abstract Objective This study’s intent was to test a new system for scoring cardiac thrombotic stability, based on contrast-enhanced ultrasound (CEUS). Methods We used human whole blood for an in vitro thrombotic model involving 1-h (T1h) and 7-day (T7d) subsets. The T1h group was monitored for 1 h continuously to observe for the formation of a new thrombus on the original thrombus base. Changes in thrombotic CEUS images, histologic features, and shear wave elastography were recorded over time. We also studied 28 patients diagnosed with cardiac thrombi, each examined by transthoracic echocardiography and CEUS.Thrombi were scored for substrate (Ts) and hardness (Th) based on the visualized degree of contrast penetration into the thrombi. Statistical analyses of Ts and Th reflected thrombolytic time and risk of embolism to other organs. Results Histologically, the loosely constructed ends of in vitro thrombi solidified over time. In addition, the average Young’s modulus of thrombi over time indicated a progressive increase in hardness. Contrast-enhancing agents were able to penetrate fresh, loose thrombi only, not chronic, stable thrombi. As Ts and Th increased, prolonged thrombolytic time and greater risk of embolism to other organs were apparent. Conclusions Our data suggest that this new CEUS scoring system correlates well with cardiac thrombotic hardness and the quality of its underlying substrate, serving to quantify thrombotic stability.

MECHANICAL PROPERTIES OF ELECTROSPUN PCL SCAFFOLD UNDER IN VITRO AND ACCELERATED DEGRADATION CONDITIONS

2014 ◽  
Vol 26 (03) ◽  
pp. 1450043 ◽  
Author(s):  
Alexandra Løvdal ◽  
Jakob Vange ◽  
Lene Feldskov Nielsen ◽  
Kristoffer Almdal
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Molecular Weight ◽  
Elastic Modulus ◽  
No Reduction ◽  
Biodegradable Scaffold ◽  
Accelerated Degradation ◽  
Degradation Time ◽  
Over Time

Within recent years, researchers have looked into using polycaprolactone (PCL) as a synthetic biodegradable scaffold for tissue engineering purposes. This study investigated the mechanical properties of an electrospun PCL, while being exposed to physiological fluids at 37°C (in vitro conditions) with and without the influence of cell in-growth. The molecular weight and mechanical properties were monitored during the degradation. Incubation in physiological fluids for 3–16 weeks showed an improvement in mechanical properties and no reduction in molecular weight. It was also shown that cells did not deteriorate the mechanical properties of PCL after 16 weeks. The viability of the cells decreased over time, however, without influencing the mechanical properties of the scaffold. A relation between reduction in molecular weight and the mechanical properties of electrospun PCL was seen between 2–29 days in buffer (pH 12). The accelerated study showed a linear decrease in both elastic modulus and yield stress as a function of degradation time.

Development of an in vitro Model for the Study of the Response of Equine Tendon Fibroblasts to Injury and Medication

1997 ◽  
Vol 10 (01) ◽  
pp. 6-11 ◽  
Author(s):  
R. F. Rosenbusch ◽  
L. C. Booth ◽  
L. A. Dahlgren
Keyword(s):  
Electron Microscopy ◽  
Extracellular Matrix ◽  
Light Microscopy ◽  
Light And Electron Microscopy ◽  
Tendon Healing ◽  
Matrix Proteins ◽  
Isolated Cells ◽  
Superficial Digital Flexor Tendon ◽  
Vitro Model

SummaryEquine tendon fibroblasts were isolated from explants of superficial digital flexor tendon, subcultured and maintained in monolayers. The cells were characterized by light microscopy, electron microscopy and radiolabel studies for proteoglycan production. Two predominant cell morphologies were identified. The cells dedifferentiated toward a more spindle shape with repeated subcultures. Equine tendon fibroblasts were successfully cryopreserved and subsequently subcultured. The ability to produce proteoglycan was preserved.The isolated cells were identified as fibroblasts, based on their characteristic shape by light microscopy and ultrastructure and the active production of extracellular matrix proteins. Abundant rough endoplasmic reticulum and the production of extracellular matrix products demonstrated active protein production and export. Proteoglycans were measurable via liquid scintillation counting in both the cell-associated fraction and free in the supernatant. This model is currently being utilized to study the effects of polysulfated glycosaminoglycan on tendon healing. Future uses include studying the effects of other pharmaceuticals, such as hyaluronic acid, on tendon healing.A model was developed for in vitro investigations into tendon healing. Fibroblasts were isolated from equine superficial digital flexor tendons and maintained in monolayer culture. The tenocytes were characterized via light and electron microscopy. Proteoglycan production was measured, using radio-label techniques. The fibroblasts were cryopreserved and subsequently subcultured. The cells maintained their capacity for proteoglycan production, following repeated subculturing and cryopreservation.

The Development of Homologous (Canine/Anti-Canine) Antibodies in Dogs with Haemophilia A (Factor VIII Deficiency): A Ten-Year Longitudinal Study

1993 ◽  
Vol 69 (01) ◽  
pp. 021-024 ◽  
Author(s):  
Shawn Tinlin ◽  
Sandra Webster ◽  
Alan R Giles
Keyword(s):  
Factor Viii ◽  
Canine Model ◽  
Significant Inhibition ◽  
Human Condition ◽  
Haemophilia A ◽  
Variable Expression ◽  
The Family ◽  
Over Time

SummaryThe development of inhibitors to factor VIII in patients with haemophilia A remains as a serious complication of replacement therapy. An apparently analogous condition has been described in a canine model of haemophilia A (Giles et al., Blood 1984; 63:451). These animals and their relatives have now been followed for 10 years. The observation that the propensity for inhibitor development was not related to the ancestral factor VIII gene has been confirmed by the demonstration of vertical transmission through three generations of the segment of the family related to a normal (non-carrier) female that was introduced for breeding purposes. Haemophilic animals unrelated to this animal have not developed functionally significant factor VIII inhibitors despite intensive factor VIII replacement. Two animals have shown occasional laboratory evidence of factor VIII inhibition but this has not been translated into clinical significant inhibition in vivo as assessed by clinical response and F.VIII recovery and survival characteristics. Substantial heterogeneity of inhibitor expression both in vitro and in vivo has been observed between animals and in individual animals over time. Spontaneous loss of inhibitors has been observed without any therapies designed to induce tolerance, etc., being instituted. There is also phenotypic evidence of polyclonality of the immune response with variable expression over time in a given animal. These observations may have relevance to the human condition both in determining the pathogenetic factors involved in this condition and in highlighting the heterogeneity of its expression which suggests the need for caution in the interpretation of the outcome of interventions designed to modulate inhibitor activity.

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