Single cell versus large population analysis: cell variability in elemental intracellular concentration and distribution

Abstract

The quantification of elemental concentration in cells is usually performed by analytical assays on large populations missing peculiar but important rare cells. The present article aims at comparing the elemental quantification in single cells and cell population in three different cell types using a new approach for single cells elemental analysis performed at sub-micrometer scale combining X-ray fluorescence microscopy and atomic force microscopy. The attention is focused on the light element Mg, exploiting the opportunity to compare the single cell quantification to the cell population analysis carried out by a highly Mg-selective fluorescent chemosensor. The results show that the single cell analysis reveals the same Mg differences found in large population of the different cell strains studied. However, in one of the cell strains, single cell analysis reveals two cells with an exceptionally high intracellular Mg content compared with the other cells of the same strain. The single cell analysis allows mapping Mg and other light elements in whole cells at sub-micrometer scale. A detailed intensity correlation analysis on the two cells with the highest Mg content reveals that Mg subcellular localization correlates with oxygen in a different fashion with respect the other sister cells of the same strain. Graphical abstract Single cells or large population analysis this is the question!

TRPM7 and MagT1 in the osteogenic differentiation of human mesenchymal stem cells in vitro

“…Silencing TRPM7 in different cell types, among which colon carcinoma cells, thymocytes and human endothelial cells, does not influence intracellular Mg content 30 – 32 , while knocking down MagT1 in mammalian cell lines lowered the levels of intracellular Mg 33 . We did not detect differences in intracellular Mg content in hMSC silencing TRPM7 or MagT1 , suggesting that either TRPM7 or MagT1 is sufficient to maintain intracellular Mg homeostasis in hMSC.…”

“…Total Mg content was measured on sonicated hMSC using the fluorescent chemosensor DCHQ5 (kindly donated by Prof. S. Iotti, Università di Bologna) as described 31 , 32 . Fluorescence intensities were acquired at 510 nm.…”

3D Quantitative and Ultrastructural Analysis of Mitochondria in a Model of Doxorubicin Sensitive and Resistant Human Colon Carcinoma Cells

“…We have previously shown that silencing the channel/enzyme TRPM7 switches the phenotype of LoVo-S to one more similar to LoVo-R [17]. Moreover, in LoVo-R we have demonstrated a higher concentration of total intracellular magnesium (Mg) than in LoVo-S [26,27], and this is associated with a different spatial distribution and, specifically, a significant accumulation in proximity to the plasma membrane [28,29]. These findings hint to a direct relationship between Mg homeostasis and subcellular localization and efflux pump function, considering that: (i) MDR proteins belong to the family of ATP-binding cassette which transports a substrates across biological membranes in an energy-dependent manner [30] and (ii) MgATP 2– is the active species in enzyme binding, in the cellular active transport and the form responsible for the energy production [31].…”

Assessment and Imaging of Intracellular Magnesium in SaOS-2 Osteosarcoma Cells and Its Role in Proliferation

“…Figure 1 shows that in cells grown in a medium without magnesium, the total intracellular content of the ion was about 50% with respect to cells cultured in the presence of magnesium, ranging from 31 to 16.7 nmol/10 6 cells, respectively. Thus, considering the SaOS-2 volume [23], the intracellular magnesium content was 13.7 mM in cells grown with magnesium and 8.4 mM in cells grown without magnesium. The dynamic of intracellular magnesium involves changes in its total amount and in cellular compartmentalization.…”

“…Magnesium concentration was normalized for the amount of cells mL −1 used during analysis, and reported as nmoles/10 6 cells. To obtain the mM concentration of magnesium, the detected nmoles are divided by the cell volume (µL) calculated according to Malucelli et al [23].…”