Velocity Measurements Inside a Hemodialysis Graft In Vitro Model

2004 ◽  
Author(s):  
David S. Smith ◽  
Francis Loth ◽  
Hisham S. Bassiouny ◽  
Paul Fischer ◽  
Jennifer K. Grogan ◽  
...  
Keyword(s):  
In Vitro Model ◽  
Laser Doppler Anemometry ◽  
In Vitro Models ◽  
Venous Anastomosis ◽  
Rate Environment ◽  
Plastic Cast ◽  
Computational Fluid Dynamics Cfd ◽  
Vitro Model ◽  
Good Agreement

Arteriovenous (AV) grafts, which provide an access site for hemodialysis, typically produce a high flow rate environment with pressure and velocity fluctuations; high and low wall shear stress, and vibration. Laser Doppler anemometry (LDA) was performed at Reynolds number (Re) 1200 on an in vitro model, which was constructed from computerized tomography (CT) images of a perfusion fixed plastic cast of a canine venous anastomosis. The results obtained were compared to numerical results and to results previously obtained with idealized in vitro models. This study showed the importance of an accurate geometry in characterizing the flow environment inside an AV graft. Good agreement between the computational fluid dynamics (CFD) and LDA was observed although differences were clearly present.

The Effect of Angle and Flow Rate Upon Hemodynamics in Distal Vascular Graft Anastomoses: An In Vitro Model Study

1991 ◽  
Vol 113 (4) ◽  
pp. 458-463 ◽  
Author(s):  
R. S. Keynton ◽  
S. E. Rittgers ◽  
M. C. S. Shu
Keyword(s):  
Stagnation Point ◽  
Flow Rate ◽  
In Vitro Model ◽  
Laser Doppler Anemometry ◽  
Bypass Graft ◽  
Outer Wall ◽  
Model Study ◽  
Vitro Model ◽  
Junction Angle

A steady flow, in vitro model of distal arterial bypass graft junctions was used to examine the effects of junction angle and flow rate on the local velocity field. Three test sections were fabricated from Plexiglas™ tubing having anastomotic junction angles of either 30, 45, or 60 deg. Flow visualization revealed velocity profiles skewed toward the outer wall with a flow split around a clear stagnation point along the outer wall. Laser Doppler anemometry [LDA] measurements confirmed a distinct stagnation point at the outer wall and both reverse and forward shear were detected immediately upstream and downstream, respectively, of this site. Axial velocities and shear rates along the outer wall were higher than along the inner wall and occurred in the junction angle order: 45, 60, and 30 deg. This study clearly identified changes in wall shear which varied with the anastomotic angle and flow rate.

Abstract TP492: Novel in vitro Model of Arteriovenous Malformation for Endovascular Embolization and Flow Analysis

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Naoki Kaneko ◽  
Henrik Ullman ◽  
Fadil Ali ◽  
Philipp Berg ◽  
Yinn Cher Ooi ◽  
...  
Keyword(s):  
Arteriovenous Malformation ◽  
In Vitro Model ◽  
Flow Analysis ◽  
Real Life ◽  
In Vitro Models ◽  
Endovascular Embolization ◽  
Experimental Models ◽  
Cfd Analysis ◽  
Vitro Model

Introduction: 3D printed human vascular in vitro models of aneurysms and acute stroke have been utilized for training, simulation and device development. However, there are no realistic in vitro arteriovenous malformation (AVM) models. Current experimental models analyzing the efficacy of embolic materials or flow conditions are limited by their simplistic design, lacking complex AVM nidus anatomic features. The purpose of this study is to develop a new in vitro AVM model for embolic material testing and flow analysis. Methods: 3D images of the AVM nidus were extracted from 3D rotational angiography from a patient. Artificial feeders and drainers were added to the nidus and an inner vascular mold was printed using a 3D printer. The inner mold was coated with polydimethylsiloxanes. The inner plastic mold was removed by acetone, leaving a hollow AVM model. ONYX injection and 4DFlow MRI (Phase Contrast MRA) were performed using the AVM models. In addition, computational fluid dynamics (CFD) analysis was performed to compare flow rate with 4DFlow MRI. Results: An in vitro AVM model with realistic representation of nidus vasculature and complexity was successfully created. Liquid onyx injection performed in the in vitro model successfully replicated real-life treatment conditions. The model effectively simulated plug and push technique before penetration of the ONYX into the AVM nidus. 4DFlow MRI flow rates were similar to the CFD analysis. Conclusions: An in vitro AVM model using 3D printing technology was successfully created. The model demonstrated realistic pliability during ONYX injection. This in vitro AVM model may represent a useful tool for training and development of new materials, and have potential of highly-resolved flow quantifications.

scholarly journals 3D Bioprinting of In Vitro Models Using Hydrogel-Based Bioinks

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 366
Author(s):  
Yeong-Jin Choi ◽  
Honghyun Park ◽  
Dong-Heon Ha ◽  
Hui-Suk Yun ◽  
Hee-Gyeong Yi ◽  
...  
Keyword(s):  
In Vitro Model ◽  
Therapeutic Agents ◽  
In Vitro Models ◽  
Human Society ◽  
3D Bioprinting ◽  
Global Pandemic ◽  
The Social ◽  
Vitro Model ◽  
Pathological Behavior

Coronavirus disease 2019 (COVID-19), which has recently emerged as a global pandemic, has caused a serious economic crisis due to the social disconnection and physical distancing in human society. To rapidly respond to the emergence of new diseases, a reliable in vitro model needs to be established expeditiously for the identification of appropriate therapeutic agents. Such models can be of great help in validating the pathological behavior of pathogens and therapeutic agents. Recently, in vitro models representing human organs and tissues and biological functions have been developed based on high-precision 3D bioprinting. In this paper, we delineate an in-depth assessment of the recently developed 3D bioprinting technology and bioinks. In particular, we discuss the latest achievements and future aspects of the use of 3D bioprinting for in vitro modeling.

scholarly journals 54 Substrate and inoculum composition affect in vitro model of ruminal acidosis

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 151-151
Author(s):  
Natalie Shaw ◽  
Sara Tondini ◽  
Daniel W Shike ◽  
Joshua C McCann
Keyword(s):  
In Vitro Model ◽  
Rumen Fluid ◽  
In Vitro Models ◽  
Feedlot Cattle ◽  
Ruminal Acidosis ◽  
Time Interaction ◽  
Rumen Ph ◽  
Randomized Design ◽  
Vitro Model

Abstract The objective was to create an in vitro model of ruminal acidosis. Ruminal acidosis is a prevalent metabolic disorder in beef feedlot cattle characterized by low rumen pH. Experiment 1 was a 3×3 factorial design testing the interaction between inoculum composition and quantity of substrate. Eighteen flasks containing 150 mL of inoculum were used to evaluate treatments in duplicate. Treatments evaluated inoculum ratios (buffer: rumen fluid) 2:1, 4:1, and 6:1 in combination with substrate levels 5 g, 7.5 g, and 10 g. Manual pH was collected every 4 h for 36 h. Experiment 2 was a completely randomized design with 5 treatments evaluated in triplicate. Treatments consisted of a 4:1 inoculum ratio (150 mL) with the substrate (7.5 g) consisting of 70% corn (PCON), 40% corn (NCON), or increasing inclusions (10, 20, and 30%) of wheat in place of corn (W10, W20, and W30). Flasks were incubated at 39°C for 36 h with continual pH measurement. In exp. 1, 7.5 g of substrate remained between a pH of 5.6 and 5.0 (P ≤ 0.01) for a longer period (880 min) than 10 g of substrate (520 min). In experiment 2, a treatment by time interaction (P ≤ 0.05) was observed for pH with NCON having the greatest pH over 8-36 h and PCON having the lowest pH over 4-8 h. A treatment by time interaction (P = 0.02) was observed for lactate at 20 h with PCON having the greatest and W30 having the lowest concentration. Treatment PCON had the greatest (P < 0.01) acetate and propionate concentration. The W20 treatment remained between a pH of 5.6 and 5.0 (P < 0.01) for a longer period than PCON. Results suggest W20 and PCON may be the most useful in vitro models of ruminal acidosis.

scholarly journals EWSR1-WT1 Target Genes and Therapeutic Options Identified in a Novel DSRCT In Vitro Model

Cancers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 6072
Author(s):  
Margit Bleijs ◽  
Corine Pleijte ◽  
Sem Engels ◽  
Femke Ringnalda ◽  
Friederike Meyer-Wentrup ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
In Vitro Model ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Treatment Options ◽  
Chromosomal Translocation ◽  
In Vitro Models ◽  
Therapeutic Options ◽  
Vitro Model

Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive soft tissue sarcoma with a lack of effective treatment options and a poor prognosis. DSRCT is characterized by a chromosomal translocation, resulting in the EWSR1-WT1 gene fusion. The molecular mechanisms driving DSRCT are poorly understood, and a paucity of preclinical models hampers DSRCT research. Here, we establish a novel primary patient-derived DSRCT in vitro model, recapitulating the original tumor. We find that EWSR1-WT1 expression affects cell shape and cell survival, and we identify downstream target genes of the EWSR1-WT1 fusion. Additionally, this preclinical in vitro model allows for medium-throughput drug screening. We discover sensitivity to several drugs, including compounds targeting RTKs. MERTK, which has been described as a therapeutic target for several malignancies, correlates with EWSR1-WT1 expression. Inhibition of MERTK with the small-molecule inhibitor UNC2025 results in reduced proliferation of DSRCT cells in vitro, suggesting MERTK as a therapeutic target in DSRCT. This study underscores the usefulness of preclinical in vitro models for studying molecular mechanisms and potential therapeutic options.

scholarly journals In Vitro Model of Bartonella henselae-Induced Angiogenesis

2004 ◽  
Vol 72 (12) ◽  
pp. 7315-7317 ◽  
Author(s):  
James E. Kirby
Keyword(s):  
In Vitro Model ◽  
Type I Collagen ◽  
Bartonella Henselae ◽  
Collagen Matrix ◽  
In Vitro Models ◽  
Type I ◽  
Blood Vessel Formation ◽  
Vitro Model

ABSTRACT Bartonella henselae is a gram-negative pathogen that causes angiogenesis. Here, I establish in vitro models to study Bartonella-induced blood vessel formation. I found that B. henselae induces long-term endothelial survival and tubular differentiation within type I collagen matrix.

scholarly journals Hepato(Geno)Toxicity Assessment of Nanoparticles in a HepG2 Liver Spheroid Model

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 545 ◽  
Author(s):  
Elisabeth Elje ◽  
Espen Mariussen ◽  
Oscar H. Moriones ◽  
Neus G. Bastús ◽  
Victor Puntes ◽  
...  
Keyword(s):  
Laser Doppler Anemometry ◽  
Animal Experiments ◽  
Toxicity Assessment ◽  
In Vitro Models ◽  
Substantial Part ◽  
Ag Nps ◽  
Zno Nps ◽  
Vis Spectroscopy ◽  
Vitro Model

(1) In compliance with the 3Rs policy to reduce, refine and replace animal experiments, the development of advanced in vitro models is needed for nanotoxicity assessment. Cells cultivated in 3D resemble organ structures better than 2D cultures. This study aims to compare cytotoxic and genotoxic responses induced by titanium dioxide (TiO2), silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) in 2D monolayer and 3D spheroid cultures of HepG2 human liver cells. (2) NPs were characterized by electron microscopy, dynamic light scattering, laser Doppler anemometry, UV-vis spectroscopy and mass spectrometry. Cytotoxicity was investigated by the alamarBlue assay and confocal microscopy in HepG2 monolayer and spheroid cultures after 24 h of NP exposure. DNA damage (strand breaks and oxidized base lesions) was measured by the comet assay. (3) Ag-NPs were aggregated at 24 h, and a substantial part of the ZnO-NPs was dissolved in culture medium. Ag-NPs induced stronger cytotoxicity in 2D cultures (EC50 3.8 µg/cm2) than in 3D cultures (EC50 > 30 µg/cm2), and ZnO-NPs induced cytotoxicity to a similar extent in both models (EC50 10.1–16.2 µg/cm2). Ag- and ZnO-NPs showed a concentration-dependent genotoxic effect, but the effect was not statistically significant. TiO2-NPs showed no toxicity (EC50 > 75 µg/cm2). (4) This study shows that the HepG2 spheroid model is a promising advanced in vitro model for toxicity assessment of NPs.

scholarly journals Best Practices and Progress in Precision-Cut Liver Slice Cultures

2021 ◽  
Vol 22 (13) ◽  
pp. 7137
Author(s):  
Liza Dewyse ◽  
Hendrik Reynaert ◽  
Leo A. van Grunsven
Keyword(s):  
Liver Disease ◽  
In Vitro Model ◽  
Liver Slice ◽  
In Vitro Models ◽  
Promising Tool ◽  
Cell Matrix ◽  
Vitro Model ◽  
Cell Matrix Interactions

Thirty-five years ago, precision-cut liver slices (PCLS) were described as a promising tool and were expected to become the standard in vitro model to study liver disease as they tick off all characteristics of a good in vitro model. In contrast to most in vitro models, PCLS retain the complex 3D liver structures found in vivo, including cell–cell and cell–matrix interactions, and therefore should constitute the most reliable tool to model and to investigate pathways underlying chronic liver disease in vitro. Nevertheless, the biggest disadvantage of the model is the initiation of a procedure-induced fibrotic response. In this review, we describe the parameters and potential of PCLS cultures and discuss whether the initially described limitations and pitfalls have been overcome. We summarize the latest advances in PCLS research and critically evaluate PCLS use and progress since its invention in 1985.

An Ultrastructural Evaluation of the SKIN2™ ZK1200 System as an in Vitro Model of the Human Oral Mucosa

1997 ◽  
Vol 25 (3) ◽  
pp. 263-270
Author(s):  
Dorthe Arenholt-Bindslev ◽  
Lis Andersen Torpet ◽  
Kaj Josephsen
Keyword(s):  
Oral Mucosa ◽  
Structural Changes ◽  
In Vitro Model ◽  
Dental Materials ◽  
In Vitro Models ◽  
Experimental Models ◽  
Histological Evaluation ◽  
Fissure Sealant ◽  
Vitro Model

At present, there are no validated experimental models for the preclinical oral mucosa irritancy screening of dental materials and oral hygiene products. Standardised in vitro models for the assessment of skin irritancy have been marketed, and have made possible the application of such models in preclinical skin irritancy testing. Some of these are currently undergoing international interlaboratory validation. The aim of the present study was to evaluate the histology of the commercially available SKIN2™ ZK1200 system as a potential in vitro model of the human oral mucosa. Histological evaluation by light microscopy and transmission electron microscopy over 6 days revealed a fibroblast-rich matrix covered by an 8–12 cell layer of stratifying epithelium, which shared a number of basic characteristics with non-keratinised human oral mucosa (for example, desmosomes, dispersed tonofilaments, glycogen deposits, membrane-coating granules, and keratohyalin granules, both the spherical and ribosome-associated types). Exposure to a methacrylate-based dental fissure sealant for 24 hours caused structural changes in the epithelium which were not reflected by a cytochemical cytotoxicity assay (MTT).

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