Determination of a Pressure Drop in the Arteriovenous Fistula With Fluid Structure Interaction Simulations and In Vitro Methods

2017 ◽  
Author(s):  
Daniel Jodko ◽  
Tomasz Palczynski ◽  
Piotr Reorowicz ◽  
Kacper Miazga ◽  
Damian Obidowski ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Blood Vessel ◽  
Arteriovenous Fistula ◽  
In Vitro Model ◽  
Experimental Methods ◽  
Measurement Methods ◽  
Patient Specific ◽  
Vessel Walls ◽  
Vitro Model

A pressure drop and its oscillations occurring in the arteriovenous fistula due to sudden changes in the velocity vector direction or the transitional or turbulent flow, related to its complicated geometry, can exert a significant impact on the blood vessel wall behaviour. On the other hand, the pressure drop cannot be precisely measured in vivo with non-invasive measurement methods. The aim of this study is to assess the pressure drop with numerical and experimental methods in the patient-specific fistula model taking into account a pulsating nature of the flow and the elasticity of blood vessel walls. An additional target is to find a correlation between these two methods. FSI and in vitro simulations of the blood flow were performed for a patient-specific model of the fistula. Basic geometrical data of the correctly functioning mature fistula were obtained with angio-computed tomography. Those data were applied to develop a spatial CAD model of the fistula, which allowed for creating a virtual model for computer simulations and an analogous in vitro model made with rapid prototyping techniques. The material used to build the in vitro model is characterised by mechanical properties similar to the arterial tissue. A non-stationary computer simulation was carried out with an ANSYS software package, keeping as many flow similarities to the experiments carried out on the test stand as possible, and where the blood mimicking fluid was a water solution of glycerine. During the experiments, the static pressure was measured downstream and upstream of the anastomosis with precise pressure transducers. The pressure drop was determined with the numerical and experimental methods, which take into account the elasticity of blood vessels. This is a novel approach, since most of similar studies were conducted on the assumption of rigid blood vessel walls. The obtained results show that the pressure drop within the fistula is not so high as reported in the literature, which is correlated with the precision of measurement methods and the fact that a large portion of the fluid energy is accumulated by the elastic walls.

In Vitro Pressure Flow Relationship in Model of Significant Coronary Artery Stenosis

2004 ◽  
Author(s):  
Abhijit Sinha Roy ◽  
Lloyd H. Back ◽  
Ronald W. Millard ◽  
Saeb Khoury ◽  
Rupak K. Banerjee
Keyword(s):  
Coronary Artery ◽  
Pressure Drop ◽  
Power Law ◽  
Flow Rate ◽  
In Vitro Model ◽  
Maximum Pressure ◽  
Vitro Model ◽  
Maximum Pressure Drop

Simultaneous measurement of pressure and flow rate has been found to be helpful in evaluating the physiologic significance of obstructive coronary artery disease and in the diagnosis of microvascular disease. This experimental study seeks to find important pressure-flow relationship in an in-vitro model of significant coronary artery stenoses using a non-Newtonian liquid, similar to blood showing a shear thinning behavior, using significant stenotic in-vitro model (minimal area stenosis = 90%). The geometry for the stenotic model is based on data provided in an in vivo study by Wilson et al., (1988). For 90% area stenosis, the maximum recorded pressure drop for steady flow rate of 55, 79 and 89 are 14, ~24 and ~32 mmHg respectively. The maximum pressure drop at flow rate of 115 ml/min (the physiological limit) is 50.3 mmHg respectively. Using a power law curve fit, the maximum pressure drop (in mmHg) related with flow rate (in ml/min) provided a power law index of 1.72. Shorter distal length than required in the in-vitro model did not allow the recording of complete pressure recovery. This preliminary data provides reference values for further experimentation both in vitro with pulsatile flow as in physiological conditions, and in vivo.

Nitric oxide donors attenuate increase in pressure drop across membrane oxygenators

Perfusion ◽  
1999 ◽  
Vol 14 (5) ◽  
pp. 331-336 ◽  
Author(s):  
F De Somer ◽  
L Foubert ◽  
E Schacht ◽  
G Van Nooten
Keyword(s):  
Nitric Oxide ◽  
Pressure Drop ◽  
In Vitro Model ◽  
Membrane Oxygenator ◽  
In Vivo Models ◽  
Initial Resistance ◽  
Membrane Oxygenators ◽  
Vitro Model

We have evaluated the effect of nitric oxide (NO) on the pressure drop across a membrane oxygenator in one in vitro model and two in vivo models (using four dogs and five pigs). In all the experiments sodium nitroprusside (SNP) was used as a NO source, whereas gaseous NO was only used in the in vitro model. The drugs were given when the pressure drop or resistance across the device increased to at least twice the baseline values. In the in vitro model, both SNP and gaseous NO decreased the pressure drop to 75% of its peak value after 10 min and to 67% after 20 min. In the dog model, resistance decreased from 390 to 153 mmHg/l/min after 5 min and to 85 mmHg/l/min after 20 min for a baseline value of 75 mmHg/l/min. The initial resistance across the membrane oxygenator in the pig model increased from 6.6 ± 1.3 to 74 ± 38 mmHg/l/min. An infusion of 10 μg/kg/min SNP reduced the resistance to 16 ± 5 mmHg/l/min.

A patient-specific intracranial aneurysm model with endothelial lining: a novel in vitro approach to bridge the gap between biology and flow dynamics

2017 ◽  
Vol 10 (3) ◽  
pp. 306-309 ◽  
Author(s):  
Naoki Kaneko ◽  
Toshihiro Mashiko ◽  
Katsunari Namba ◽  
Satoshi Tateshima ◽  
Eiju Watanabe ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
In Vitro Model ◽  
Patient Specific ◽  
Parent Artery ◽  
Complex Flow ◽  
Endothelial Lining ◽  
Vascular Model ◽  
Vitro Model ◽  
Aneurysm Model

ObjectivesTo develop an in vitro model for studying the biological effect of complex-flow stress on endothelial cells in three-dimensional (3D) patient-specific vascular geometry.Materials and methodsA vessel replica was fabricated with polydimethylsiloxanes using 3D printing technology from vascular image data acquired by rotational angiography. The vascular model was coated with fibronectin and immersed in a tube filled with a cell suspension of endothelium, and then cultured while being slowly rotated in three dimensions. Culture medium with viscosity was perfused in the circulation with the endothelialized vascular model. A computational fluid dynamics (CFD) study was conducted using perfusion conditions used in the flow experiment. The morphology of endothelial cells was observed under a confocal microscope.ResultsThe CFD study showed low wall shear stress and circulating flow in the apex of the basilar tip aneurysm, with linear flow in the parent artery. Confocal imaging demonstrated that the inner surface of the vascular model was evenly covered with monolayer endothelial cells. After 24 h of flow circulation, endothelial cells in the parent artery exhibited a spindle shape and aligned with the flow direction. In contrast, endothelial cells in the aneurysmal apex were irregular in shape and size.ConclusionsA geometrically realistic intracranial aneurysm model with live endothelial lining was successfully developed. This in vitro model enables a new research approach combining study of the biological impact of complex flow on endothelial cells with CFD analysis and patient information, including the presence of aneurysmal growth or rupture.

scholarly journals Patient-specific organotypic blood vessels as an in vitro model for anti-angiogenic drug response testing in renal cell carcinoma

EBioMedicine ◽  
2019 ◽  
Vol 42 ◽  
pp. 408-419 ◽  
Author(s):  
José A. Jiménez-Torres ◽  
María Virumbrales-Muñoz ◽  
Kyung E. Sung ◽  
Moon Hee Lee ◽  
E. Jason Abel ◽  
...  
Keyword(s):  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Blood Vessels ◽  
Renal Cell ◽  
Drug Response ◽  
In Vitro Model ◽  
Patient Specific ◽  
Vitro Model ◽  
Response Testing

scholarly journals A Novel In Vitro Model of Trophoblast-Mediated Decidual Blood Vessel Remodeling

2003 ◽  
Vol 83 (12) ◽  
pp. 1821-1828 ◽  
Author(s):  
Caroline Dunk ◽  
Ljiljana Petkovic ◽  
Dora Baczyk ◽  
Janet Rossant ◽  
Elke Winterhager ◽  
...  
Keyword(s):  
Blood Vessel ◽  
In Vitro Model ◽  
Vessel Remodeling ◽  
Vitro Model

scholarly journals Modeling congenital cataract in vitro using patient-specific induced pluripotent stem cells

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Danni Lyu ◽  
Lifang Zhang ◽  
Zhenwei Qin ◽  
Shuang Ni ◽  
Jiayong Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Induced Pluripotent Stem Cells ◽  
Pluripotent Stem Cells ◽  
Congenital Cataract ◽  
In Vitro Model ◽  
Patient Specific ◽  
Congenital Cataracts ◽  
Vitro Model ◽  
Induced Pluripotent

AbstractCongenital cataracts are the leading cause of childhood blindness. To date, surgical removal of cataracts is the only established treatment, but surgery is associated with multiple complications, which often lead to visual impairment. Therefore, mechanistic studies and drug-candidate screening have been intrigued by the aims of developing novel therapeutic strategies. However, these studies have been hampered by a lack of an appropriate human-disease model of congenital cataracts. Herein, we report the establishment of a human congenital cataract in vitro model through differentiation of patient-specific induced pluripotent stem cells (iPSCs) into regenerated lenses. The regenerated lenses derived from patient-specific iPSCs with known causative mutations of congenital cataracts (CRYBB2 [p. P24T] and CRYGD [p. Q155X]) showed obvious opacification that closely resembled that seen in patients’ cataracts in terms of opacification severity and disease course accordingly, as compared with lentoid bodies (LBs) derived from healthy individuals. Increased protein aggregation and decreased protein solubility corresponding to the patients’ cataract severity were observed in the patient-specific LBs and were attenuated by lanosterol treatment. Taken together, the in vitro model described herein, which recapitulates patient-specific clinical manifestations of congenital cataracts and protein aggregation in patient-specific LBs, provides a robust system for research on the pathological mechanisms of cataracts and screening of drug candidates for cataract treatment.

An in vitro model for investigation of vitamin A effects on wound healing

2021 ◽  
pp. 1-6
Author(s):  
Hoda Keshmiri Neghab ◽  
Mohammad Hasan Soheilifar ◽  
Gholamreza Esmaeeli Djavid
Keyword(s):  
Wound Healing ◽  
Endothelial Cell ◽  
Vitamin A ◽  
In Vitro Model ◽  
Cellular Proliferation ◽  
Endothelial Cell Migration ◽  
Normal Fibroblast ◽  
Anti Inflammatory ◽  
Vitro Model

Abstract. Wound healing consists of a series of highly orderly overlapping processes characterized by hemostasis, inflammation, proliferation, and remodeling. Prolongation or interruption in each phase can lead to delayed wound healing or a non-healing chronic wound. Vitamin A is a crucial nutrient that is most beneficial for the health of the skin. The present study was undertaken to determine the effect of vitamin A on regeneration, angiogenesis, and inflammation characteristics in an in vitro model system during wound healing. For this purpose, mouse skin normal fibroblast (L929), human umbilical vein endothelial cell (HUVEC), and monocyte/macrophage-like cell line (RAW 264.7) were considered to evaluate proliferation, angiogenesis, and anti-inflammatory responses, respectively. Vitamin A (0.1–5 μM) increased cellular proliferation of L929 and HUVEC (p < 0.05). Similarly, it stimulated angiogenesis by promoting endothelial cell migration up to approximately 4 fold and interestingly tube formation up to 8.5 fold (p < 0.01). Furthermore, vitamin A treatment was shown to decrease the level of nitric oxide production in a dose-dependent effect (p < 0.05), exhibiting the anti-inflammatory property of vitamin A in accelerating wound healing. These results may reveal the therapeutic potential of vitamin A in diabetic wound healing by stimulating regeneration, angiogenesis, and anti-inflammation responses.

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