scholarly journals Integrated Microscopy and Metabolomics to Test an Innovative Fluid Dynamic System for Skin Explants In Vitro

2021 ◽  
pp. 1-12
Author(s):  
Enrica Cappellozza ◽  
Serena Zanzoni ◽  
Manuela Malatesta ◽  
Laura Calderan
Keyword(s):  
Dynamic System ◽  
Fluid Dynamic ◽  
Skin Explants

Abstract

A Numerical Investigation of the Fluid Flow in a Chandler Loop for Thrombus Studies

2013 ◽  
Author(s):  
Hisham Touma ◽  
Iskender Sahin ◽  
Tidimogo Gaamangwe ◽  
Maud B. Gorbet ◽  
Sean D. Peterson
Keyword(s):  
Laminar Flow ◽  
Stress Field ◽  
Strain Rate ◽  
Rotation Rate ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Straight Tube ◽  
Dean Number ◽  
Chandler Loop

The Chandler loop is an artificial circulatory platform for in vitro hemodynamic experiments. In most experiments, the working fluid is subjected to a stress field via rotation of the Chandler loop, which, in turn, induces biochemical responses of the suspended cells. For very low rotation rates, the stress field can be approximated using laminar flow in a straight tube as a model. However, as the rotation rate increases, while still maintaining laminar flow, the effect of the tube curvature causes the stress field to deviate considerably from the straight tube approximation. In this manuscript, we investigate the flow and associated strain rate field of an incompressible Newtonian fluid in a Chandler loop as a function of the governing non-dimensional fluid dynamic parameters. We find that the Dean number, which is proportional to the rotation rate, is the dominant parameter in determining the fluid strain rate. We propose an empirical formula for predicting the average fluid strain rate magnitude in the working fluid that is valid over a wide parameter space to be used in lieu of the common, yet restrictive, straight tube-based prediction.

Exogenous glycosaminoglycans (GAG) are able to modulate avian skin differentiation (epithelial keratinization and feather formation

Development ◽  
1984 ◽  
Vol 82 (1) ◽  
pp. 25-40
Author(s):  
E. Becchetti ◽  
G. Stabellini ◽  
A. Caruso ◽  
P. Carinci
Keyword(s):  
Hyaluronic Acid ◽  
Chick Embryo ◽  
Synthetic Medium ◽  
Calf Serum ◽  
Epithelial Differentiation ◽  
Dermal Fibroblasts ◽  
Conditioned Media ◽  
Lung Fibroblasts ◽  
Skin Explants

Several reports have suggested that mesenchymal glycosaminoglycans (GAG) may be involved in the regulatory role of epithelial differentiation. Some researchers have pointed out that exogenousGAG affects extracellular GAG accumulation. We have therefore examined the effect of added GAG on two typical processes of avian skin differentiation: keratinization and feather formation. Glycosaminoglycans, either obtained from fibroblasts cultures (conditioned media) or purified commercially available GAG were administered to 5/6-day chick embryo back skin explants. Control cultures were supported with 199 synthetic medium, chick embryo extract or calf serum. Explants have been examined by histological and histochemical procedures. Skin explants maintained in vitro for 7 days exhibited an epithelial differentiation and a dermal histochemical reactivity which were related to the composition of the culture medium. In conditioned media from dermal fibroblasts, but not from heart or lung fibroblasts, explants always exhibited keratinization. In purified-GAG-containing media, keratinization was observed with condroitinsulphates and not with hyaluronic acid. Keratinization was always related toprevalent accumulation of hyaluronic acid in the underlying mesenchyme whereas feather formation was in relation to deposits of condroitinsulphates in dermis pulp. The above findings demonstrate that exogenous GAG is able to modulate avian skin differentiation and that this regulation is linked to an influence on the mesenchymal GAG pattern.

scholarly journals 3D Perfusable Hydrogel Recapitulating the Cancer Dynamic Environment to in Vitro Investigate Metastatic Colonization

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2467
Author(s):  
Chiara Vitale ◽  
Arianna Fedi ◽  
Alessandra Marrella ◽  
Gabriele Varani ◽  
Marco Fato ◽  
...  
Keyword(s):  
Single Channel ◽  
Fluid Dynamic ◽  
Dynamic Environment ◽  
Metastatic Breast ◽  
Polymeric Matrix ◽  
The Body ◽  
Secondary Site ◽  
Circulation System ◽  
Metastatic Cascade

Metastasis is a dynamic process involving the dissemination of circulating tumor cells (CTCs) through blood flow to distant tissues within the body. Nevertheless, the development of an in vitro platform that dissects the crucial steps of metastatic cascade still remains a challenge. We here developed an in vitro model of extravasation composed of (i) a single channel-based 3D cell laden hydrogel representative of the metastatic site, (ii) a circulation system recapitulating the bloodstream where CTCs can flow. Two polymers (i.e., fibrin and alginate) were tested and compared in terms of mechanical and biochemical proprieties. Computational fluid-dynamic (CFD) simulations were also performed to predict the fluid dynamics within the polymeric matrix and, consequently, the optimal culture conditions. Next, once the platform was validated through perfusion tests by fluidically connecting the hydrogels with the external circuit, highly metastatic breast cancer cells (MDA-MB-231) were injected and exposed to physiological wall shear stress (WSS) conditions (5 Dyn/cm2) to assess their migration toward the hydrogel. Results indicated that CTCs arrested and colonized the polymeric matrix, showing that this platform can be an effective fluidic system to model the first steps occurring during the metastatic cascade as well as a potential tool to in vitro elucidate the contribution of hemodynamics on cancer dissemination to a secondary site.

Fluid dynamic factors in tracheal pressure measurement

1981 ◽  
Vol 51 (1) ◽  
pp. 218-225 ◽  
Author(s):  
H. K. Chang ◽  
J. P. Mortola
Keyword(s):  
Endotracheal Tube ◽  
Pressure Measurement ◽  
Fluid Dynamic ◽  
Theoretical Explanation ◽  
Apparent Paradox ◽  
Cross Sectional ◽  
Tracheal Cannula ◽  
Dynamic Factors ◽  
Tracheal Pressure

Because tracheal pressure measurement generally involves the use of a cannula or an endotracheal tube, fluid dynamic factors may cause a considerable artifact. We present a theoretical explanation of the observed apparent paradox in which the resistance of a tracheal cannula or an endotracheal tube is isolation was found to exceed the resistance of the airways plus the cannula or the tube in situ. By estimating the viscous dissipation and the kinetic energy change in a conduit with sudden variation of cross-sectional area, a predictive model is derived. The predictions are verified by a series of in vitro experiments with both steady and oscillatory flows. The experiments showed that the pressure recorded from the sidearm of a tracheal cannula or endotracheal tube contains an error which, in general, increased with the mean Reynolds' number of the through flow and also depends on the diameter ratio between the trachea and the tube or cannula, the position of the pressure tap, and the frequency of ventilation. When feasible, direct measurement with a needle in the trachea is suggested as a way to avoid the possible artifacts arising from the use fo a side tap of the cannula. Theoretical considerations, as well as in vitro and animal experiments, indicate that adding a properly chosen expansion to the tracheal cannula makes it possible to alter inspiratory and expiratory pressures selectively. This device may prove useful in control of breathing studies.

Assessment of the biochemical effects of percutaneous exposure of sulphur mustard in an in vitro human skin system

1996 ◽  
Vol 15 (3) ◽  
pp. 237-244 ◽  
Author(s):  
CD Lindsay ◽  
P. Rice
Keyword(s):  
Inflammatory Response ◽  
Human Skin ◽  
Serine Proteases ◽  
Inflammatory Cells ◽  
Chemical Warfare Agent ◽  
Skin Damage ◽  
Sulphur Mustard ◽  
Nuclear Pyknosis ◽  
Skin Explants

1 Sulphur mustard (HD) is a potent chemical warfare agent which causes incapacitating blisters on human skin. There is no specific pretreatment nor therapy against this agent and the mechanism of dermo-epidermal cleavage is unclear. The aim of this study was to use a human skin explant system to determine the consequences of percuta neous exposure to HD. 2 Increased activities of serine proteases associated with blistering disorders in humans were detected from human skin explants after exposure to HD. The most consistent response and the highest protease activities measured were found for trypsin. This class of enzyme is therefore implicated in the dermo-epidermal separation which is associated with blistering in humans following exposure to HD. 3 An inflammatory response was observed in the skin explants exposed to HD. At low doses of HD it was characterised by the presence of neutrophils in the papillary dermis, culminating in the infiltration of the epidermis by these inflammatory cells at higher concen trations of HD. A variety of other histopathological changes in the explants was found such as focal dermo- epidermal separation, nuclear pyknosis and perinuclear vacuolation. 4 The study indicates that full thickness human skin explants can be used to investigate various aspects of the possible pathogenesis of HD-induced skin damage, in cluding the associated inflammatory response.

scholarly journals Osteogenic differentiation and mineralization in fibre-reinforced tubular scaffolds: theoretical study and experimental evidences

2012 ◽  
Vol 9 (74) ◽  
pp. 2201-2212 ◽  
Author(s):  
Vincenzo Guarino ◽  
Francesco Urciuolo ◽  
Marco A. Alvarez-Perez ◽  
Benedetto Mele ◽  
Paolo A. Netti ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Mechanical Response ◽  
Fluid Dynamic ◽  
Human Mesenchymal Stem Cells ◽  
Filament Winding ◽  
Long Bone ◽  
Design Strategies ◽  
Dynamic Simulations ◽  
Scale Properties

The development of composite scaffolds with well-organized architecture and multi-scale properties (i.e. porosity, degradation) represents a valid approach for achieving a tissue-engineered construct capable of reproducing the medium- and long-term in vitro behaviour of hierarchically complex tissues such as spongy bone. To date, the implementation of scaffold design strategies able to summarize optimal scaffold architecture as well as intrinsic mechanical, chemical and fluid transport properties still remains a challenging issue. In this study, poly ɛ -caprolactone/polylactid acid (PCL/PLA) tubular devices (fibres of PLA in a PCL matrix) obtained by phase inversion/salt leaching and filament winding techniques were proposed as cell instructive scaffold for bone osteogenesis. Continuous fibres embedded in the polymeric matrix drastically improved the mechanical response as confirmed by compression elastic moduli, which vary from 0.214 ± 0.065 to 1.174 ± 0.143 MPa depending on the relative fibre/matrix and polymer/solvent ratios. Moreover, computational fluid dynamic simulations demonstrated the ability of composite structure to transfer hydrodynamic forces during in vitro culture, thus indicating the optimal flow rate conditions that, case by case, enables specific cellular events—i.e. osteoblast differentiation from human mesenchymal stem cells (hMSCs), mineralization, etc. Hence, we demonstrate that the hMSC differentiation preferentially occurs in the case of higher perfusion rates—over 0.05 ml min –1 —as confirmed by the expression of alkaline phosphate and osteocalcin markers. In particular, the highest osteopontin values and a massive mineral phase precipitation of bone-like phases detected in the case of intermediate flow rates (i.e. 0.05 ml min –1 ) allows us to identify the best condition to stimulate the bone extracellular matrix in-growth, in agreement with the hydrodynamic model prediction. All these results concur to prove the succesful use of tubular composite as temporary device for long bone treatment.

Formulation of survival acceptor medium able to maintain the viability of skin explants over in vitro dermal experiments

2019 ◽  
Vol 41 (6) ◽  
pp. 617-623 ◽  
Author(s):  
M. Tarnowska ◽  
S. Briançon ◽  
J. Resende Azevedo ◽  
Y. Chevalier ◽  
C. Barratier ◽  
...  
Keyword(s):  
Skin Explants
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