Changes in the mitochondrial membrane potential in endothelial cells can be detected by Raman microscopy 2022 Pieczara et al

[Andy]

Highlights

• Visualization of mitochondria and tracking of functional changes in live cells was shown.
• Subcellular mitochondrial activity was tested using labeled and unlabeled Raman imaging, the latter improved sensitivity.
• The MitoBADY Raman probe was used to detect subtle changes in mitochondrial membrane potential as an indicator of mitochondrial activity.
• A semi-quantitative approach was used to estimate mitochondrial activity in live cells.

Abstract

The role of mitochondria goes beyond their capacity to create molecular fuel and includes e.g. the production of reactive oxygen species and the regulation of cell death. In endothelial cells, mitochondria have a significant impact on cellular function under both healthy and pathological conditions. Endothelial dysfunction contributes to the development of various lifestyle diseases and the key players in their pathogenesis are among others vascular inflammation and oxidative stress. The latter is very closely related to mitochondrial dysfunction; however, it is not straightforward. First, because mitochondria are small cellular structures, and second, it requires a sensitive method to follow the subtle biochemical changes. For this purpose, Raman microscopy (RM) was used here, which is considered a high-resolution method and can be applied in situ, usually as a non-labeled technique.

In this work, we show that RM can not only locate mitochondria in the cell but also track their functional changes. Moreover, we test if labeling cells with Raman probes (Rp) can improve the specificity and sensitivity of RM (compared to conventional labeled techniques such as fluorescence, and the non-labeled Raman technique). MitoBADY Rp was used to detect changes in mitochondrial membrane potential as an indicator of mitochondrial activity, e.g. hyperpolarization or distortion of the proton gradient in the intermembrane space (depolarization). Thus, we show and compare RM, in the form of a label and non-labeled, to such a subtle cellular analysis.

Open access, https://www.sciencedirect.com/science/article/pii/S138614252201126X

 

[Creekside]

Another potentially useful tool for figuring just what's going on in bodies. Even if this sort of testing shows no differences between PWME and PWithoutME, that would at least reduce wastage of research resources and direct them along other paths.

It takes many steps to reach Bones' tricorder.

 

[SNT Gatchaman]

I found the following paragraphs interesting, given background assertions that stress can lead to ME or analogues and that abnormalities of cortisol were evidenced in LC cohorts.

Mitochondria are both targets and mediators of stress. Due to stress caused by various factors, the level of hormones in the body changes. It is known that chronic stress is a significant risk factor for [cardiovascular disease], what is more, the endothelium emerges as a primary target for excessive glucocorticoid and catecholamine action. The mechanism underlying the stress-induced ED is still elusive. It is described that mitochondria sense changes in energy demand and rapidly respond to energy-mobilizing glucocorticoids (e.g. cortisol) and catecholamines (adrenaline and noradrenaline). Cortisol directly decreases nitric oxide (NO) availability and potentially induces the production of proinflammatory cytokines and adhesion molecules. Excessive catecholamines in the bloodstream may induce ROS production and lipid peroxidation as well as increased production of angiotensin II.

Here, we attempt to understand the effect of stress hormones such as adrenaline, noradrenaline, cortisol, and the equimolar mixture (EM) of these three hormones on the MMP by looking at the cytochrome c Raman signal.

Adrenaline and noradrenaline affected the mitochondria, which can be seen as an increase in the intensity of the cytochrome c band. [...] It was reported that adrenaline stimulates the production of cyclic adenosine monophosphate (cAMP), which is converted from ATP, while the other catecholamine hormone, i.e. noradrenaline, was not that potent

in the case of adrenaline, noradrenaline, and the [equimolar mixture of adrenaline, noradrenaline and cortisol], a higher ratio is observed than in the case of the control, which indicates membrane hyperpolarization, where it should be noted that with the sample incubated with all hormones, hyperpolarization is the highest, which may indicate interdependent effects of stress hormones.

It can be postulated that the influence of hormones on the potential of the mitochondrial membrane is much weaker and more intricate than in the case of the other compounds discussed in this paper