Low pH value of pericellular medium as a factor limiting cell proliferation in dense cultures

Акатов, В. С.; Lezhnev, E. I.; Vexler, Akiva; Kublik, L. N.

doi:10.1016/0014-4827(85)90188-0

Cited by 28 publications

(16 citation statements)

References 5 publications

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“…Since the cells are concentrated at a single layer, diffusion limitations may create a local microenvironment that is significantly different from the bulk liquid conditions. This effect was demonstrated in measurements by Akatov et al (1985), who showed that Chinese hamster fibroblast cells at 1 × 10 6 cells/cm 2 had a local pH of 6·5 within 6 h of feeding, even though the bulk pH remained at 7·6. Thus, in designing appropriate ex vivo expansion systems, it is important to take into account the effect of pH on the differentiation of haemopoietic cells, because even though the bulk pH may not change, the local pH may be significantly different.…”

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confidence: 88%

Variations in culture pH affect the cloning efficiency and differentiation of progenitor cells in ex vivo haemopoiesis

1997

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Summary.Haemopoietic cultures may experience pH variations of as much as 0·5 units depending on culture duration and cell density. Since pH is a potent modulator of cellular proliferation and differentiation, we examined its effects on the performance of both semisolid and liquid haemopoietic cultures. Culture pH was found to have substantial effects both on progenitor cloning efficiency (as measured in liquid cultures) and on progenitor cell differentiation (as measured in methylcellulose cultures). Liquid cultures were conducted with both peripheral blood (PB) mononuclear cells (MNCs) and cord blood (CB) MNCs using growth factor combinations that promote either erythroid expansion (IL-3/IL-6/SCF/ Epo) or granulocyte/macrophage expansion (IL-3/IL-6/SCF/ G-CSF/GM-CSF). Reduced pH was found to have either a positive or neutral effect on the expansion and cloning efficiency of progenitors in ex vivo liquid cultures. Cloning efficiencies of PB BFU-E in the erythroid combination were 9-fold higher at low pH (7·1) when compared to high pH (7·6). A small pH increase of 0·2 units over physiological values consistently produced significant reductions (42-85%) in cloning efficiencies for all cell types and cytokine combinations tested. Methylcellulose cultures conducted using CB MNC and PB MNC indicated that differentiation of CFU-GM into progeny was optimal between pH 7·2 and 7·4. The differentiation of erythroid progenitors (BFU-E) progressively increased as pH was increased from 6·95 (no colonies detected) to 7·4 (maximum colonies detected), to 7·6 (maximum haemoglobin content). Methylcellulose cultures using PB CD34 + cells exhibited similar patterns to the MNC cultures. We conclude that even small variations in pH substantially affected the performance of human haemopoietic cultures. The erythroid lineage was particularly sensitive, with its extent of differentiation increasing with increasing pH. PB progenitors are more sensitive to pH variations than CB progenitors.

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confidence: 88%

Variations in culture pH affect the cloning efficiency and differentiation of progenitor cells in ex vivo haemopoiesis

1997

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“…Currently, the majority of clinical trial protocols make use of static culture vessels such as T-flasks or gas permeable tissue culture bags (Levine et al, 1998;Robinet et al, 1998). These systems may be suboptimal for a number of reasons, including formation of nonuniform culture conditions due to gradients in nutrient and metabolic byproduct concentrations, and inefficient usage of working culture volumes due to the relatively low cell densities attainable under static conditions (Akatov et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

Culture of human T cells in stirred bioreactors for cellular immunotherapy applications: Shear, proliferation, and the IL-2 receptor

Carswell

Papoutsakis

2000

Biotechnol. Bioeng.

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“…This preponderance leads to a shift to an acidic pH. Studies by Akatov et al [23] showed that a low pH of the pericellular medium can limit cell proliferation. On the other hand, colony growth had clearly deteriorated when perfu sion tube volumes greater than 12 ml or an early onset of continuous perfusion were used.…”

Section: Discussionmentioning

confidence: 99%

Effect of Medium Exchange Rate on Colony Growth of the Human Tumor Cell Line MDA-231 Cloned within the Perfused Capillary Cloning System

Weisser¹,

Witzel²,

Lathan³

1994

Tumor Biol

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The conventional human tumor stem cell assay is limited by the lack of flexibility for drug scheduling with single agents and its inability to test drug combinations. Recently, we described the cloning of tumor cell lines within porous glass capillary tubes which allow free exchange of substances. The present study describes the influence of various perfusion modalities on the colony growth of the human tumor cell line MDA-231 cloned within the perfused capillary cloning system (PCCS). Colony growth of tumor cells within the PCCS is strongly dependent on perfusion tube volume, flow rate and duration of perfusion with growth medium. Best colony growth was achieved using a perfusion tube volume of 12 ml resulting in a cloning efficiency of 36.3%. Continuous perfusion with fresh medium did not improve the cloning efficiency; in fact, colony growth was hampered compared to colony growth within unperfused porous capillaries. However, cloning efficiency was acceptable when continuous perfusion was started at day 6 (26.4%) instead of day 0 (17.2%), or when a short perfusion with high volume (12 ml/h) was discontinued after 1 h at day 0. In contrast to the conventional capillary cloning system the PCCS has the potential for investigating secretion and kinetics of tumor-specific factors and the effect of growth-stimulating or growth-inhibiting drugs.

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Low pH value of pericellular medium as a factor limiting cell proliferation in dense cultures

Cited by 28 publications

References 5 publications

Variations in culture pH affect the cloning efficiency and differentiation of progenitor cells in ex vivo haemopoiesis

Variations in culture pH affect the cloning efficiency and differentiation of progenitor cells in ex vivo haemopoiesis

Culture of human T cells in stirred bioreactors for cellular immunotherapy applications: Shear, proliferation, and the IL-2 receptor

Effect of Medium Exchange Rate on Colony Growth of the Human Tumor Cell Line MDA-231 Cloned within the Perfused Capillary Cloning System

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