Zavadskis, S. (2021). Comparative study of reactive oxygen species in mesenchymal stem and osteoblast-like MG-63 cells [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2021.76466
reactive oxygen species - mitochondria - NADPH oxidase
en
Abstract:
Reactive oxygen species (ROS) are biological molecules known for their high chemical reactivity caused by an unpaired electron on the outer shell of the oxygen atom. For a long time ROS were considered as a toxic byproduct of the cellular metabolism. However, in the last decade, the view on ROS had shifted from being a deleterious metabolic side product to an important molecule playing asignificant role in numerous regulatory cell processes. At low physiological concentrations, ROS areengaged in proliferative and regenerative cellular pathways and cellular homeostasis, however, their overproduction is known to cause oxidative stress associated with various diseases. Therefore, a better understanding of ROS metabolism can be implicated in the development of novel drugs and therapies, particularly for tissue regeneration.The aim of this study was to investigate metabolic pathways of ROS in non-differentiated (human amniotic mesenchymal stromal cells (hAMSC) and differentiated (MG-63 osteoblast-like) cells withemphasis on NOX(NADPH-Oxidase) and mitochondria-derived ROS and possible therapeutic potential of the NOX inhibitor diphenyliodonium (DPI).By utilizing laser scanning confocal microscopy with ROS-sensitive fluorescent probes in conjunction with specific chemical treatments targeting well defined segments of ROS metabolism, we examined the turnover of cellular ROS in both cell types. In hAMSC, DPI decreased the levels of cytoplasmic ROS. Different concentrations of DPI manifested similar effects in this type of cells. MitoTEMPO, a specific inhibitor of mitochondrial ROS (mtROS), decreased ROS levels in cytoplasm suggesting occurrence of a crosstalk between NOX and mitochondria mediated by ROS.In contrast to hAMSC, MG-63 did not show any decrease in ROS levels in response to low concentration of DPI, but high concentration of DPI acutely increased the concentration of cytoplasmic ROS. The increased levels of ROS were accompanied by a drop in mitochondrial membrane potential, suggesting mitochondria as a predominant ROS source in MG63. The latter was supported by the fact that the release of ROS into the cytoplasm was prevented by mitoTEMPO.The determination of nitric oxide in cytoplasm of MG-63 indirectly suggested the involvement of ONOO- in the damage of mitochondria.Our data suggest that metabolism of ROS is different in non-differentiated and differentiated cells. In non-differentiated cells, NOX and the crosstalk between NOX and mitochondria predominantly define ROS metabolism, while in differentiated cells ROS is regulated predominantly by mitochondria. DPI potentially can be used to modulate activity of human amniotic mesenchymal stromal cells. Modulation of cellular activity can increase the applicability of hAMSC in tissue regeneration