02061nas a2200145   4500008004100000245011800041210006900159260000800228300001400236490000700250520149600257100001701753700001901770856012601789       2016                        eng d00aShear stress increases cytotoxicity and reduces transfection efficiency of liposomal gene delivery to CHO-S cells0 aShear stress increases cytotoxicity and reduces transfection eff  cDEC  a2529-25380 v683 aAnimal cells in suspension experience shear stress in different situations such as in vivo due to hemodynamics, or in vitro due to agitation in large-scale bioreactors. Shear stress is known to affect cell physiology, including binding and uptake of extracellular cargo. In adherent cells the effects of exposure to shear stress on particle binding kinetics and uptake have been studied. There are however no reports on the effect of shear stress on extracellular cargo delivery to suspension cells. In this study, we have evaluated the effect of shear stress on transfection of CHO-S cells using Lipofectamine 2000 in a simple flow apparatus. Our results show decreased cell growth and transfection efficiency upon lipoplex assisted transfection of CHO-S while being subjected to shear stress. This effect is not seen to the same extent when cells are exposed to shear stress in absence of the lipoplex complex and subsequently transfected, or if the lipoplex is subjected to shear stress and subsequently used to transfect the cells. It is also not seen to the same extent when cells are exposed to shear stress in presence of liposome alone, suggesting that the observed effect is dependent on interaction of the lipoplex with cells in the presence of shear stress. These results suggest that studies involving liposomal DNA delivery in presence of shear stress such as large scale transient protein expression should account for the effect of shear during lipoplex assisted DNA delivery.1 aRawat, Jyoti1 aGadgil, Mugdha  uhttps://library.ncl.res.in/content/shear-stress-increases-cytotoxicity-and-reduces-transfection-efficiency-liposomal-gene02699nas a2200277   4500008004100000022001400041245019500055210006900250260001200319300001500331490000700346520166900353653002502022653001402047653002502061653002502086653001102111653001102122653004002133653001102173100003702184700002602221700003102247700001902278856012402297       2019                        eng d  a8756-793800aSuperfluous glutamine synthetase activity in Chinese Hamster Ovary cells selected under glutamine limitation is growth limiting in glutamine-replete conditions and can be inhibited by serine0 aSuperfluous glutamine synthetase activity in Chinese Hamster Ova  cSEP-OCT  aUNSP e28560 v353 a<p>Passaging and expansion of animal cells in lean maintenance medium could result in periods of limitation of some nutrients. Over time, such stresses could possibly result in selection of cells with metabolic changes and contribute to heterogeneity. Here, we investigate whether selection of Chinese Hamster Ovary (CHO) cells under glutamine limitation results in changes in growth under glutamine-replete conditions. In glutamine-limiting medium, compared to control cells passaged in glutamine-rich medium, the selected cells showed higher glutamine synthetase (GS) activity and attained a higher peak viable cell density (PVCD). Surprisingly, in glutamine-replete conditions, selected cells still showed a higher GS activity but a lower PVCD. We show that in glutamine-replete medium, PVCD of selected cells was restored on (a) inhibition of GS activity with methionine sulfoximine, (b) supplementation of aspartate-without affecting GS activity, and (c) supplementation of serine, which is reported to inhibit GS in vitro. Consistent with the reported effect of serine, inhibition of GS activity was observed upon serine supplementation along with reduced growth of cells under glutamine-limiting conditions. The latter observation is important for the design of glutamine-free culture medium and feed used for GS-CHO and GS-NS0. In summary, we show that CHO cells selected under glutamine limitation have superfluous GS activity in glutamine-replete medium, which negatively affects their PVCD. This may be due to its effect on availability of aspartate which was the limiting nutrient for the growth of selected cells in glutamine-replete conditions.</p>
10aC-13 tracer analysis10aCHO cells10aglutamine limitation10aGlutamine synthetase10aGS-CHO10aGS-NS010aselection under nutrient limitation10aserine1 aMaralingannavar, Vishwanathgouda1 aParmar, Dharmeshkumar1 aPanchagnula, Venkateswarlu1 aGadgil, Mugdha  uhttps://library.ncl.res.in/content/superfluous-glutamine-synthetase-activity-chinese-hamster-ovary-cells-selected-under