Reactive Oxygen Species Imaging in U937 Cells.

Ankush Prasad,Pavel Pospíšil,Shigenobu Kasai,Michaela Sedlářová,Michal Křupka,Marek Rác,Alina Ovsii,Anastasiia Balukova

doi:10.3389/fphys.2020.552569

Abstract

The U937 cell culture is a pro-monocytic, human histiocytic lymphoma cell line. These monocytes can differentiate into either macrophages or dendritic cells (antigen-presenting cells) depending on the initiators. The U937 cells activated in the presence of phorbol 12-myristate 13-acetate (PMA) change their morphology into macrophage-like cells creating pseudopodia and adhering generously. Macrophages are known to produce reactive oxygen species (ROS) mostly during phagocytosis of foreign particles, an important non-specific immune response. Recently, we have focused on the role of hydroxyl radical (HO∙) and provide evidence on its importance for differentiation in U937 cells. Based on electron paramagnetic resonance (EPR) spectroscopy combined with confocal laser scanning microscopy (CLSM), formation of HO∙ was confirmed within the cells undergoing differentiation and/or apoptosis during the PMA treatment. This study aims to increase our knowledge of ROS metabolism in model cell lines used in human research.

Highlights

Human myeloid leukemia cell line U937 has been isolated already in the year 1976 from the histiocytic lymphoma of a 37-year-old male (Sundstrom and Nilsson, 1976)
It is important to mention that the effect of dimethyl sulfoxide (DMSO) on cells and tissues, in general, cannot be ignored as it can have a detrimental effect on the cell morphology and viability, not to mention the preceding finer physiological processes
It can be seen that the addition of superoxide dismutase (SOD) prior to PMA treatment led to significant suppression of electron paramagnetic resonance (EPR) signal (∼50%) (Figure 5B, trace b) which is in agreement with the results presented by Zeng et al (2018)

Summary

Introduction

Human myeloid leukemia cell line U937 has been isolated already in the year 1976 from the histiocytic lymphoma of a 37-year-old male (Sundstrom and Nilsson, 1976). The U937 cells grown in suspension are characterized by a round shape, short microvilli, and a large beam-shaped nucleus (Pagliara et al, 2005; Tenuzzo et al, 2008). These monocytic cells bear the potential of differentiating into macrophages or dendritic cells; in response to a number of stimuli adopt the morphology and physiological characteristic of macrophages and represent a precursor of mononuclear phagocyte system (Kigerl et al, 2009; Italiani and Boraschi, 2014; Nemati et al, 2019). The mature differentiated U937 cells attain all the features of a macrophage-like cell which include flat irregular shape, presence of pseudopodia, Abbreviations: ROS, reactive oxygen species; EPR spectroscopy, electron paramagnetic resonance spectroscopy; CLSM, confocal laser scanning microscopy; PMA, phorbol 12-myristate 13-acetate

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