scholarly journals pH AND POPULATION DENSITY IN THE REGULATION OF ANIMAL CELL MULTIPLICATION

1971 ◽  
Vol 51 (3) ◽  
pp. 686-702 ◽  
Author(s):  
H. Rubin
Keyword(s):  
Cell Migration ◽  
Cell Density ◽  
Plasma Membranes ◽  
High Cell Density ◽  
Low Ph ◽  
Cell Multiplication ◽  
High Cell ◽  
High Ph ◽  
Cell Densities ◽  
Very High

Sparse and dense cultures of chick embryo cells were affected differently by pH. The rates of cell multiplication and of thymidine-3H incorporation into DNA of dense cultures were increased as the pH was increased from 6.6 to 7.6. At pH higher than 7.6 the rate of multiplication decreased slightly in the dense cultures, but the rate of thymidine-3H incorporation continued to increase. The discrepancy was due in part to cell death and detachment at very high pH, and in part to a more rapid uptake of thymidine-3H at very high pH. Sparse cultures were much less sensitive to pH reduction and, when a suitably conditioned medium was used to minimize cell damage, very sparse cultures grew almost as well at pH 6.7 as at higher pH. The rates of cell multiplication and thymidine-3H incorporation at low pH decreased in the initially sparse cultures before they reached confluent cell densities. There was no microscope evidence of direct contact between plasma membranes of cells at these densities although the parallel orientation indicated that the cells were influencing locally each other's behavior. Even at much higher cell densities, electron microscopy revealed large intercellular gaps partly filled with a fragmentary electron-opaque material suspected to be glycoprotein. Wounding experiments showed that pH affected cell migration in a manner similar to its effects on cell multiplication. Low pH inhibited cell migration, but those cells which migrated into the denuded region multiplied as rapidly at low pH as at high pH. The effects of pH on growth were correlated with effects on the uptake of 2-deoxyglucose-3H. Dense populations of cells inhibited by low pH were stimulated to incorporate thymidine-3H by the addition of small amounts of diethylaminoethyl-dextran. Rous sarcoma cells at high cell density were less sensitive to pH than were normal cells at the same density, but were more sensitive than sparse normal cultures. The results suggest that cell growth is inhibited through the combined effects of both lowered pH and high cell density on cell surface permeability.

Preparation of Very-High-Yield Recombinant Proteins Using Novel High-Cell-Density Bacterial Expression Methods

2010 ◽  
Vol 2010 (8) ◽  
pp. pdb.prot5475 ◽  
Author(s):  
Victoria Murray ◽  
Jianglei Chen ◽  
Yuefei Huang ◽  
Qianqian Li ◽  
Jianjun Wang
Keyword(s):  
Cell Density ◽  
Recombinant Proteins ◽  
High Cell Density ◽  
Bacterial Expression ◽  
High Yield ◽  
High Cell ◽  
Very High

scholarly journals Very high cell density perfusion of CHO cells anchored in a non-woven matrix-based bioreactor

2015 ◽  
Vol 213 ◽  
pp. 28-41 ◽  
Author(s):  
Ye Zhang ◽  
Per Stobbe ◽  
Christian Orrego Silvander ◽  
Véronique Chotteau
Keyword(s):  
Cell Density ◽  
Cho Cells ◽  
High Cell Density ◽  
High Cell ◽  
Very High

scholarly journals 3D bioprinting of high cell-density heterogeneous tissue models through spheroid fusion within self-healing hydrogels

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrew C. Daly ◽  
Matthew D. Davidson ◽  
Jason A. Burdick
Keyword(s):  
Cell Density ◽  
Spatial Organization ◽  
High Cell Density ◽  
Self Healing ◽  
High Cell ◽  
Cellular Models ◽  
Functional Features ◽  
Cell Densities ◽  
Tissue Models

AbstractCellular models are needed to study human development and disease in vitro, and to screen drugs for toxicity and efficacy. Current approaches are limited in the engineering of functional tissue models with requisite cell densities and heterogeneity to appropriately model cell and tissue behaviors. Here, we develop a bioprinting approach to transfer spheroids into self-healing support hydrogels at high resolution, which enables their patterning and fusion into high-cell density microtissues of prescribed spatial organization. As an example application, we bioprint induced pluripotent stem cell-derived cardiac microtissue models with spatially controlled cardiomyocyte and fibroblast cell ratios to replicate the structural and functional features of scarred cardiac tissue that arise following myocardial infarction, including reduced contractility and irregular electrical activity. The bioprinted in vitro model is combined with functional readouts to probe how various pro-regenerative microRNA treatment regimes influence tissue regeneration and recovery of function as a result of cardiomyocyte proliferation. This method is useful for a range of biomedical applications, including the development of precision models to mimic diseases and the screening of drugs, particularly where high cell densities and heterogeneity are important.

scholarly journals Antibody capture process based on magnetic beads from very high cell density suspension

2021 ◽  
Author(s):  
Nils A. Brechmann ◽  
Hubert Schwarz ◽  
Per‐Olov Eriksson ◽  
Kristofer Eriksson ◽  
Atefeh Shokri ◽  
...  
Keyword(s):  
Cell Density ◽  
Magnetic Beads ◽  
High Cell Density ◽  
High Cell ◽  
Capture Process ◽  
Antibody Capture ◽  
Very High

scholarly journals 3D bioprinting of high cell-density heterogeneous tissue models through spheroid fusion within self-healing hydrogels

2020 ◽  
Author(s):  
Andrew C. Daly ◽  
Matthew D. Davidson ◽  
Jason A. Burdick
Keyword(s):  
Cell Density ◽  
Spatial Organization ◽  
High Cell Density ◽  
Self Healing ◽  
High Cell ◽  
Cellular Models ◽  
Functional Features ◽  
Cell Densities ◽  
Tissue Models

AbstractCellular models are needed to study human development and disease in vitro, including the screening of drugs for toxicity and efficacy. However, current approaches are limited in the engineering of functional tissue models with requisite cell densities and heterogeneity to appropriately model cell and tissue behaviors. Here, we develop a new bioprinting approach to transfer spheroids into self-healing support hydrogels at high resolution, which enables their patterning and fusion into high-cell density microtissues of prescribed spatial organization. As an example application, we bioprint induced pluripotent stem cell-derived cardiac microtissue models with spatially controlled cardiomyocyte and fibroblast cell ratios to replicate the structural and functional features of scarred cardiac tissue that arise following myocardial infarction, including reduced contractility and irregular electrical activity. The bioprinted in vitro model is combined with functional readouts to probe how various pro-regenerative microRNA treatment regimes influence tissue regeneration and recovery of function as a result of cardiomyocyte proliferation. This method is useful for a range of biomedical applications, including the development of precision models to mimic diseases and for the screening of drugs, particularly where high cell densities and heterogeneity are important.

What’s in the Offing?

Bioprinting ◽  
2021 ◽  
pp. 202-218
Author(s):  
Kenneth Douglas
Keyword(s):  
3D Printing ◽  
Cell Density ◽  
Cardiac Tissue ◽  
High Cell Density ◽  
High Density ◽  
High Cell ◽  
Hierarchical Network ◽  
Native Tissue ◽  
Vascular Channels ◽  
Cell Densities

Abstract: This chapter attempts to peer into the possible future of bioprinting to consider two conceivable directions that bioprinting might take while also contemplating what we may be able to learn about bioprinting’s trajectory by reflecting on another biomedical quest—the twentieth-century’s attempt to conquer polio. In one study that might offer a route for bioprinting, a team created bioconstructs with cell densities approaching that of native tissue (about 108 cells/gram). The group used embedded 3D printing to create a branched, hierarchical network of vascular channels within a large, high cell density bioconstruct and perfused media through the channels that they created using fugitive ink. This was to provide nutrient support for the cells. They also built a high-density cardiac construct in which the cells beat synchronously and showed functional contractility. They quantitatively measured the deformation of the cardiac tissue during contraction.

scholarly journals Chemotactic behaviour of Escherichia coli at high cell density

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Remy Colin ◽  
Knut Drescher ◽  
Victor Sourjik
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Collective Motion ◽  
High Cell Density ◽  
Environmental Gradients ◽  
Model Organism ◽  
High Density ◽  
Intermediate Cell ◽  
High Cell ◽  
Cell Densities

AbstractAt high cell density, swimming bacteria exhibit collective motility patterns, self-organized through physical interactions of a however still debated nature. Although high-density behaviours are frequent in natural situations, it remained unknown how collective motion affects chemotaxis, the main physiological function of motility, which enables bacteria to follow environmental gradients in their habitats. Here, we systematically investigate this question in the model organism Escherichia coli, varying cell density, cell length, and suspension confinement. The characteristics of the collective motion indicate that hydrodynamic interactions between swimmers made the primary contribution to its emergence. We observe that the chemotactic drift is moderately enhanced at intermediate cell densities, peaks, and is then strongly suppressed at higher densities. Numerical simulations reveal that this suppression occurs because the collective motion disturbs the choreography necessary for chemotactic sensing. We suggest that this physical hindrance imposes a fundamental constraint on high-density behaviours of motile bacteria, including swarming and the formation of multicellular aggregates and biofilms.

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