Intracellular water‐specific MR of microbead‐adherent cells: the HeLa cell intracellular water exchange lifetime

Abstract

Quantitative characterization of the intracellular water 1 H magnetic resonance (MR) signal from cultured cells will provide critical biophysical insight into the MR signal from tissues in vivo. Microbeads provide a robust immobilization substrate for the many mammalian cell lines that adhere to surfaces and also provide sufficient cell density for observation of the intracellular water MR signal. However, selective observation of the intracellular water MR signal from perfused, microbead-adherent mammalian cells requires highly effective suppression of the extracellular water MR signal. We describe herein how high velocity perfusion of microbead-adherent cells results in short apparent 1 H MR longitudinal and transverse relaxation times for the extracellular water in a thin slice selected orthogonal to the direction of flow. When combined with a spin echo pulse sequence, this phenomenon provides highly effective suppression of the extracellular water MR signal. This new method is exploited herein to quantify the kinetics of water exchange from the intracellular to extracellular spaces for HeLa cells. The time constant describing water exchange from intracellular to extracellular spaces, also known as the exchange lifetime for intracellular water, is 119 ± 14 ms.

Time-Dependent Influence of Cell Membrane Permeability on MR Diffusion Measurements

“…This is consistent with previous results showing that ADC is mainly determined by membrane density and permeability at long diffusion times . When Δ eff decreased from 100 ms to 1 ms, ADC changed dramatically for typical cell sizes (2.5 μm < R < 10 μm) with typical cell membrane permeabilities (0 < P m < 0.05 μm/ms) . Moreover, the ADC differences between groups became smaller with decreasing Δ eff .…”

Time-Dependent Influence of Cell Membrane Permeability on MR Diffusion Measurements

“…This is consistent with previous results showing that ADC is mainly determined by membrane density and permeability at long diffusion times . When Δ eff decreased from 100 ms to 1 ms, ADC changed dramatically for typical cell sizes (2.5 μm < R < 10 μm) with typical cell membrane permeabilities (0 < P m < 0.05 μm/ms) . Moreover, the ADC differences between groups became smaller with decreasing Δ eff .…”

Intracellular water specific MR of microbead‐adherent cells: Hela cell intracellular water diffusion

“…[5] that in is 129 Ϯ 19 ms. This is consistent with a more accurate lifetime estimate of 119 Ϯ 14 ms provided by an inversionrecovery experiment (11).…”

Label-Free and Substrate-Free Potentiometric Aptasensing Using Polycation-Sensitive Membrane Electrodes

“…The cellular ATP level was calculated as [ATP-(cellular)] = ATP(total)/(total cell population × cell volume). By using the cell volume of 2.6 × 10 −12 L, 49 the concentration of the cellular ATP was measured as 0.71 ± 0.06 mM, which is consistent with the ATP concentrations that are typically found in cells (0.1−3.0 mM). 50 Recently, various fluorescent and electrochemical apatsensors have been developed for cellular ATP assays based on nanoflares, 50 graphene oxide nanocomplexes, 51 redox tags, 31 and copper nanoparticles.…”

Time-Dependent Influence of Cell Membrane Permeability on MR Diffusion Measurements

“…This is consistent with previous results showing that ADC is mainly determined by membrane density and permeability at long diffusion times . When Δ eff decreased from 100 ms to 1 ms, ADC changed dramatically for typical cell sizes (2.5 μm < R < 10 μm) with typical cell membrane permeabilities (0 < P m < 0.05 μm/ms) . Moreover, the ADC differences between groups became smaller with decreasing Δ eff .…”

Intracellular water specific MR of microbead‐adherent cells: Hela cell intracellular water diffusion

“…[5] that in is 129 Ϯ 19 ms. This is consistent with a more accurate lifetime estimate of 119 Ϯ 14 ms provided by an inversionrecovery experiment (11).…”

Label-Free and Substrate-Free Potentiometric Aptasensing Using Polycation-Sensitive Membrane Electrodes

“…The cellular ATP level was calculated as [ATP-(cellular)] = ATP(total)/(total cell population × cell volume). By using the cell volume of 2.6 × 10 −12 L, 49 the concentration of the cellular ATP was measured as 0.71 ± 0.06 mM, which is consistent with the ATP concentrations that are typically found in cells (0.1−3.0 mM). 50 Recently, various fluorescent and electrochemical apatsensors have been developed for cellular ATP assays based on nanoflares, 50 graphene oxide nanocomplexes, 51 redox tags, 31 and copper nanoparticles.…”

Time-Dependent Influence of Cell Membrane Permeability on MR Diffusion Measurements

“…This is consistent with previous results showing that ADC is mainly determined by membrane density and permeability at long diffusion times . When Δ eff decreased from 100 ms to 1 ms, ADC changed dramatically for typical cell sizes (2.5 μm < R < 10 μm) with typical cell membrane permeabilities (0 < P m < 0.05 μm/ms) . Moreover, the ADC differences between groups became smaller with decreasing Δ eff .…”

Intracellular water specific MR of microbead‐adherent cells: Hela cell intracellular water diffusion

“…[5] that in is 129 Ϯ 19 ms. This is consistent with a more accurate lifetime estimate of 119 Ϯ 14 ms provided by an inversionrecovery experiment (11).…”

Label-Free and Substrate-Free Potentiometric Aptasensing Using Polycation-Sensitive Membrane Electrodes

“…The cellular ATP level was calculated as [ATP-(cellular)] = ATP(total)/(total cell population × cell volume). By using the cell volume of 2.6 × 10 −12 L, 49 the concentration of the cellular ATP was measured as 0.71 ± 0.06 mM, which is consistent with the ATP concentrations that are typically found in cells (0.1−3.0 mM). 50 Recently, various fluorescent and electrochemical apatsensors have been developed for cellular ATP assays based on nanoflares, 50 graphene oxide nanocomplexes, 51 redox tags, 31 and copper nanoparticles.…”