scholarly journals Embryonic nodal flow and the dynamics of nodal vesicular parcels

2006 ◽  
Vol 4 (12) ◽  
pp. 49-56 ◽  
Author(s):  
Julyan H.E Cartwright ◽  
Nicolas Piro ◽  
Oreste Piro ◽  
Idan Tuval
Keyword(s):  
Fluid Flow ◽  
Closed System ◽  
Biochemical Mechanism ◽  
Numerical Techniques ◽  
Biophysical Properties ◽  
Nodal Flow ◽  
Dynamical Simulations ◽  
Mechanical Rupture

We address with fluid-dynamical simulations using direct numerical techniques three important and fundamental questions with respect to fluid flow within the mouse node and left–right development. First, we consider the differences between what is experimentally observed when assessing cilium-induced fluid flow in the mouse node in vitro and what is to be expected in vivo . The distinction is that in vivo , the leftward fluid flow across the mouse node takes place within a closed system and is consequently confined, while this is no longer the case on removing the covering membrane and immersing the embryo in a fluid-filled volume to perform in vitro experiments. Although there is a central leftward flow in both instances, we elucidate some important distinctions about the closed in vivo situation. Second, we model the movement of the newly discovered nodal vesicular parcels (NVPs) across the node and demonstrate that the flow should indeed cause them to accumulate on the left side of the node, as required for symmetry breaking. Third, we discuss the rupture of NVPs. Based on the biophysical properties of these vesicles, we argue that the morphogens they contain are likely not delivered to the surrounding cells by their mechanical rupture either by the cilia or the flow, and rupture must instead be induced by an as yet undiscovered biochemical mechanism.

scholarly journals O23: CHARACTERISING PATIENT-DERIVED COLORECTAL CANCER TISSUE-ORIGINATED ORGANOIDAL SPHEROIDS FOR HIGH-THROUGHPUT MICROFLUIDIC APPLICATIONS

2021 ◽  
Vol 108 (Supplement_1) ◽  
Author(s):  
MI Khot ◽  
M Levenstein ◽  
R Coppo ◽  
J Kondo ◽  
M Inoue ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Fluid Flow ◽  
High Throughput ◽  
Microfluidic Devices ◽  
In Vitro Models ◽  
Fluorescent Imaging ◽  
Cancer Tissue ◽  
Cell Models

Abstract Introduction Three-dimensional (3D) cell models have gained reputation as better representations of in vivo cancers as compared to monolayered cultures. Recently, patient tumour tissue-derived organoids have advanced the scope of complex in vitro models, by allowing patient-specific tumour cultures to be generated for developing new medicines and patient-tailored treatments. Integrating 3D cell and organoid culturing into microfluidics, can streamline traditional protocols and allow complex and precise high-throughput experiments to be performed with ease. Method Patient-derived colorectal cancer tissue-originated organoidal spheroids (CTOS) cultures were acquired from Kyoto University, Japan. CTOS were cultured in Matrigel and stem-cell media. CTOS were treated with 5-fluorouracil and cytotoxicity evaluated via fluorescent imaging and ATP assay. CTOS were embedded, sectioned and subjected to H&E staining and immunofluorescence for ABCG2 and Ki67 proteins. HT29 colorectal cancer spheroids were produced on microfluidic devices using cell suspensions and subjected to 5-fluorouracil treatment via fluid flow. Cytotoxicity was evaluated through fluorescent imaging and LDH assay. Result 5-fluorouracil dose-dependent reduction in cell viability was observed in CTOS cultures (p<0.01). Colorectal CTOS cultures retained the histology, tissue architecture and protein expression of the colonic epithelial structure. Uniform 3D HT29 spheroids were generated in the microfluidic devices. 5-fluorouracil treatment of spheroids and cytotoxic analysis was achieved conveniently through fluid flow. Conclusion Patient-derived CTOS are better complex models of in vivo cancers than 3D cell models and can improve the clinical translation of novel treatments. Microfluidics can streamline high-throughput screening and reduce the practical difficulties of conventional organoid and 3D cell culturing. Take-home message Organoids are the most advanced in vitro models of clinical cancers. Microfluidics can streamline and improve traditional laboratory experiments.

scholarly journals mTORC1 controls phase-separation and the biophysical properties of the cytoplasm by tuning crowding

2017 ◽  
Author(s):  
M. Delarue ◽  
G.P. Brittingham ◽  
S. Pfeffer ◽  
I.V. Surovtsev ◽  
S. Ping-lay ◽  
...  
Keyword(s):  
Phase Separation ◽  
Fluorescent Protein ◽  
Effective Diffusion ◽  
Reaction Rates ◽  
Biophysical Properties ◽  
Cell Interior ◽  
Profound Impact ◽  
Mtorc1 Pathway

Summary (Abstract)Macromolecular crowding has a profound impact on reaction rates and the physical properties of the cell interior, but the mechanisms that regulate crowding are poorly understood. We developed Genetically Encoded Multimeric nanoparticles (GEMs) to dissect these mechanisms. GEMs are homomultimeric scaffolds fused to a fluorescent protein. GEMs self-assemble into bright, stable fluorescent particles of defined size and shape. By combining tracking of GEMs with genetic and pharmacological approaches, we discovered that the mTORC1 pathway can tune the effective diffusion coefficient of macromolecules ≥15 nm in diameter more than 2-fold without any discernable effect on the motion of molecules ≥5 nm. These mTORCI-dependent changes in crowding and rheology affect phase-separation both in vitro and in vivo. Together, these results establish a role for mTORCI in controlling both the biophysical properties of the cytoplasm and the phase-separation of biopolymers.

scholarly journals ATP:Mg2+ shapes condensate properties of rRNA-NPM1 in vitro nucleolus model and its partitioning of ribosomes

2021 ◽  
Author(s):  
N. Amy Yewdall ◽  
Alain A. M. André ◽  
Merlijn H. I. van Haren ◽  
Frank H. T. Nelissen ◽  
Aafke Jonker ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Enzymatic Reaction ◽  
Atp Depletion ◽  
Gel Point ◽  
Dependent Manner ◽  
Biophysical Properties ◽  
Temperature Dependent ◽  
Quantitative Fluorescence

Nucleoli have viscoelastic gel-like condensate dynamics that are not well represented in vitro. Nucleoli models, such as those formed by nucleophosmin 1 (NPM1) and ribosomal RNA (rRNA), exhibit condensate dynamics orders of magnitude faster than in vivo nucleoli. Here we show that an interplay between magnesium ions (Mg2+) and ATP governs rRNA dynamics, and this ultimately shapes the physical state of these condensates. Using quantitative fluorescence microscopy, we demonstrate that increased RNA compaction occurs in the condensates at high Mg2+ concentrations, contributing to the slowed RNA dynamics. At Mg2+ concentrations above 7 mM, rRNA is fully arrested and the condensates are gels. Below the critical gel point, NPM1-rRNA droplets age in a temperature-dependent manner, suggesting that condensates are viscoelastic materials, undergoing maturation driven by weak multivalent interactions. ATP addition reverses the dynamic arrest of rRNA, resulting in liquefaction of these gel-like structures. Surprisingly, ATP and Mg2+ both act to increase partitioning of NPM1-proteins as well as rRNA, which influences the partitioning of small client molecules. By contrast, larger ribosomes form a halo around NPM1-rRNA coacervates when Mg2+ concentrations are higher than ATP concentrations. Within cells, ATP levels fluctuate due to biomolecular reactions, and we demonstrate that a dissipative enzymatic reaction can control the biophysical properties of in vitro condensates through depletion of ATP. This enzymatic ATP depletion also reverses the formation of the ribosome halos. Our results illustrate how cells, by changing local ATP concentrations, may regulate the state and client partitioning of RNA-containing condensates such as the nucleolus.

In Vitro Experimental Investigation of the Integrity of the Stem–Cement Interface

2013 ◽  
Vol 647 ◽  
pp. 53-56
Author(s):  
Hong Yu Zhang ◽  
Leigh Fleming ◽  
Liam Blunt
Keyword(s):  
Experimental Investigation ◽  
Fluid Flow ◽  
Hip Replacement ◽  
Hip Prosthesis ◽  
Vitro Experiment ◽  
Cement Interface ◽  
In Vitro Experiment ◽  
Mechanical Bonding

The rationale behind failure of cemented total hip replacement is still far from being well understood in a mechanical and molecular perspective. In the present study, the integrity of the stem–cement interface was investigated through an in vitro experiment monitoring fluid flow along this interface. The results indicated that a good mechanical bonding formed at the stem–cement interface before debonding of this interface was induced by physiological loadings during the in vivo service of the hip prosthesis.

In vivo and in vitro study of enamel fluid flow in human premolars

2020 ◽  
Vol 117 ◽  
pp. 104795 ◽  
Author(s):  
Rathirach Tanapitchpong ◽  
Ekachai Chunhacheevachaloke ◽  
Orapin Ajcharanukul
Keyword(s):  
Fluid Flow ◽  
In Vitro Study ◽  
Vitro Study

Review of the fluid flow within intervertebral discs - How could in vitro measurements replicate in vivo?

2016 ◽  
Vol 49 (14) ◽  
pp. 3133-3146 ◽  
Author(s):  
Hendrik Schmidt ◽  
Sandra Reitmaier ◽  
Friedmar Graichen ◽  
Aboulfazl Shirazi-Adl
Keyword(s):  
Fluid Flow ◽  
Intervertebral Discs ◽  
In Vitro Measurements

scholarly journals Finite element study of stem cells under fluid flow for mechanoregulation toward osteochondral cells

2021 ◽  
Vol 32 (7) ◽  
Author(s):  
Mehdi Moradkhani ◽  
Bahman Vahidi ◽  
Bahram Ahmadian
Keyword(s):  
Stem Cells ◽  
Shear Stress ◽  
Fluid Flow ◽  
Computational Simulation ◽  
Hydrodynamic Pressure ◽  
Mechanical Stimuli ◽  
Pore Architecture ◽  
Proliferation And Differentiation

AbstractInvestigating the effects of mechanical stimuli on stem cells under in vitro and in vivo conditions is a very important issue to reach better control on cellular responses like growth, proliferation, and differentiation. In this regard, studying the effects of scaffold geometry, steady, and transient fluid flow, as well as influence of different locations of the cells lodged on the scaffold on effective mechanical stimulations of the stem cells are of the main goals of this study. For this purpose, collagen-based scaffolds and implicit surfaces of the pore architecture was used. In this study, computational fluid dynamics and fluid-structure interaction method was used for the computational simulation. The results showed that the scaffold microstructure and the pore architecture had an essential effect on accessibility of the fluid to different portions of the scaffold. This leads to the optimization of shear stress and hydrodynamic pressure in different surfaces of the scaffold for better transportation of oxygen and growth factors as well as for optimized mechanoregulative responses of cell–scaffold interactions. Furthermore, the results indicated that the HP scaffold provides more optimizer surfaces to culture stem cells rather than Gyroid and IWP scaffolds. The results of exerting oscillatory fluid flow into the HP scaffold showed that the whole surface of the HP scaffold expose to the shear stress between 0.1 and 40 mPa and hydrodynamics factors on the scaffold was uniform. The results of this study could be used as an aid for experimentalists to choose optimist fluid flow conditions and suitable situation for cell culture.

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