Mitochondrial ROS production, oxidative stress and aging within and between species: Evidences and recent advances on this aging effector

Arctiin Inhibits Hyperglycemia-Induced Oxidative Stress by Activating the Nrf2/HO-1 Signaling Pathway to Treat Type 2 Diabetic Osteoporosis

Arctiin (ARC), a primary component of burdock (Arctium lappa L.), is widely recognized as a traditional herb and nutritional supplement in Asia. This study set out to explore its potential impact on type 2 diabetic osteoporosis (T2DOP). MC3T3-E1 cells were exposed to a high-glucose environment to simulate diabetic conditions. Treatment with ARC increased the expression of crucial osteogenic transcription factor genes, such as RUNX2, Osterix, and COL1A1. Moreover, ARC mitigated the production of ROS induced by high glucose levels. For in vivo experimentation, db/db mice were used as models for T2DOP. ARC supplementation decreased bone loss and improved bone structural integrity. Collectively, our findings indicate that ARC holds promise as a nutritional intervention for the treatment of T2DOP. By activating the Nrf2/HO-1 signaling pathway, ARC could help counteract oxidative stress and impaired bone differentiation associated with diabetes, thus offering a potential dietary strategy to support bone health. Incorporating ARC-containing foods or supplements into the diet could be a beneficial approach to enhance overall bone quality and potentially reduce the risk of fractures and other bone-related problems in patients with diabetes, highlighting the importance of considering natural compounds for the nutritional management of chronic diseases.

Revitalising Aging Oocytes: Echinacoside Restores Mitochondrial Function and Cellular Homeostasis Through Targeting GJA1/SIRT1 Pathway

As maternal age increases, the decline in oocyte quality emerges as a critical factor contributing to reduced reproductive capacity, highlighting the urgent need for effective strategies to combat oocyte aging. This study investigated the protective effects and underlying mechanisms of Echinacoside (ECH) on aging oocytes. ECH significantly improved cytoskeletal stability and chromosomal integrity, as demonstrated by restored spindle morphology and reinforced F-actin structures, essential for meiotic progression. It also preserved mitochondrial function by restoring membrane potential and dynamics, reducing ROS levels, and downregulating the DNA damage marker γ-H2AX, thereby alleviating oxidative stress and enhancing genomic stability. Furthermore, ECH promoted cellular homeostasis through modulation of lipid metabolism, autophagy and lysosomal function. Transcriptomic analyses identified GJA1 as a pivotal mediator of ECH's effects, validated through molecular docking and bio-layer interferometry. Functional studies showed that inhibiting GJA1 significantly reduced ECH's ability to enhance first polar body extrusion rates, mitochondrial function and antioxidant capacity, validating the critical role of the GJA1/SIRT1 pathway in combating oocyte aging. This study provides novel insights into the mechanisms of oocyte rejuvenation and highlights ECH as a promising therapeutic candidate for addressing age-related reproductive challenges.

Nanocomposite TiO2/ZnO/chitosan by method sol-gel for self-cleaning application

TiO2/ZnO/Chitosan coated cotton fabric as a self-cleaning, which has been synthesized by various concentrations of TiO2: 0.5 g, 1 g, and 2 g through the sol-gel method at pH 9. The self-cleaning test was conducted on TiO2/ZnO/Chitosan-coated cotton fabric samples by irradiating for 15 h using UVA-UVB lamps with clothing stain dye. TiO2/ZnO/Chitosan composite's structural properties were analyzed from X-ray diffraction (XRD) spectra, chemical bonding by Fourier Transform Infrared (FTIR), and bandgap by quantitative analysis from UV-visible spectroscopy. The XRD diffraction peaks showed a slight shift to the right, except for the sample with the highest TiO2 concentration, which showed a more significant shift. FTIR spectra showed the presence of Ti-O-Ti bonds at wavenumbers 500 cm-1 - 700 cm-1, which identified the presence of TiO2, and at wavenumber 3485 cm-1, which was used for stretching-OH and -NH2 of chitosan. The band gaps were 5.64 eV, 5.63 eV, and 5.58 eV for TiO2: 0.5 g, 1 g, and 2 g, respectively. The self-cleaning test showed that the best results were in the TiO2 sample with a concentration of 2 g at pH 9, where the dye successfully disappeared after exposure to UVA-UVB lamps for 15 h of irradiation.

The 7436-bp mitochondrial DNA deletion as a risk factor for ulcerative colitis in the Iranian population

Ulcerative colitis (UC) is a chronic condition characterized by inflammation in the colon. Free radicals and oxidative stress play a significant role in the pathophysiology of UC. Excessive production of reactive oxygen species can damage the mitochondrial genome, leading to mutations such as the7436-bp deletion. The aim of this study was to identify the presence of the 7436-bp mtDNA deletion in patients with UC and its association with susceptibility to colon inflammation. This case-control study, included 195 patients with UC and 250 healthy individuals from the Iranian population. The Multiplex PCR method was used to detect the 7436-bp mtDNA deletion. Statistical analysis was performed using SPSS software. The frequency of 7436-bp mtDNA deletion in patients was 41.5% and 6.8% in healthy individuals. Statistical analysis showed a significant association between the frequency of the 7436-bp mtDNA deletion and UC (p = 0.016). Furthermore, a significant difference was found between the presence of this deletion and an increased risk of severe (p = 0.003) and extensive (p = 0.002) forms of UC. There was no statistically significant difference in the frequency of this deletion between younger patients and the control group. This study suggests that the presence of the 7436-bp mtDNA deletion is a risk factor for UC and plays a significant role in the pathogenesis of the disease. Further research involving larger and more diverse populations is necessary to validate or challenge these findings. Identifying these mutations can enhance our understanding of genetic factors influencing UC.

Norharmane prevents muscle aging via activation of SKN-1/NRF2 stress response pathways

Sarcopenia, the age-related decline in muscle mass and function, is a significant contributor to increased frailty and mortality in the elderly. Currently, no FDA-approved treatment exists for sarcopenia. Here, we identified norharmane (NR), a β-carboline alkaloid, as a potential therapeutic agent for mitigating muscle aging. We aimed to determine the ability of NR to delay muscle aging in Caenorhabditis elegans (C. elegans), mouse, and muscle cells in mice and humans. NR treatment improved swimming ability and increased the maximum velocity in aged C. elegans. Transcriptomic analysis revealed that NR upregulated detoxification genes in C. elegans, including cytochrome P450, UGT, and GST enzymes. NR-induced benefits were dependent on the SKN-1/Nrf2 stress response pathway. In mammalian models, NR delayed cellular senescence in human skeletal muscle myoblasts and enhanced myogenesis in C2C12 cells and primary aged myoblasts. NR supplementation in aged mice prevented muscle loss, improved muscle function, and reduced markers of cellular senescence. We found that the p38 MAPK pathway mediated NR activation of Nrf2 by disrupting the Nrf2-Keap1 interaction. NR also improved oxygen consumption rates and promoted mitochondrial biogenesis. These findings suggest that NR is a promising candidate for preventing sarcopenia and improving muscle health.

The Anti-Aging Mechanism of Metformin: From Molecular Insights to Clinical Applications

Aging represents a complex biological phenomenon marked by the progressive deterioration of physiological functions over time, reduced resilience, and increased vulnerability to age-related diseases, ultimately culminating in mortality. Recent research has uncovered diverse molecular mechanisms through which metformin extends its benefits beyond glycemic control, presenting it as a promising intervention against aging. This review delves into the anti-aging properties of metformin, highlighting its role in mitochondrial energy modulation, activation of the AMPK-mTOR signaling pathway, stimulation of autophagy, and mitigation of inflammation linked to cellular aging. Furthermore, we discuss its influence on epigenetic modifications that underpin genomic stability and cellular homeostasis. Metformin's potential in addressing age-associated disorders including metabolic, cardiovascular, and neurodegenerative diseases is also explored. The Targeting Aging with Metformin (TAME) trial aims to provide key evidence on its efficacy in delaying aging in humans. Despite these promising insights, significant challenges persist in gaining a more comprehensive understanding into its underlying mechanisms, determining optimal dosing strategies, and evaluating long-term safety in non-diabetic populations. Addressing these challenges is crucial to fully realizing metformin's potential as an anti-aging therapeutic.

Hallmarks of aging: A user's guide for comparative biologists

Since the first description of a set of characteristics of aging as so-called hallmarks or pillars in 2013/2014, these characteristics have served as guideposts for the research in aging biology. They have been examined in a range of contexts, across tissues, in response to disease conditions or environmental factors, and served as a benchmark for various anti-aging interventions. While the hallmarks of aging were intended to capture generalizable characteristics of aging, they are derived mostly from studies of rodents and humans. Comparative studies of aging including species from across the animal tree of life have great promise to reveal new insights into the mechanistic foundations of aging, as there is a great diversity in lifespan and age-associated physiological changes. However, it is unclear how well the defined hallmarks of aging apply across diverse species. Here, we review each of the twelve hallmarks of aging defined by Lopez-Otin in 2023 with respect to the availability of data from diverse species. We evaluate the current methods used to assess these hallmarks for their potential to be adapted for comparative studies. Not unexpectedly, we find that the data supporting the described hallmarks of aging are restricted mostly to humans and a few model systems and that no data are available for many animal clades. Similarly, not all hallmarks can be easily assessed in diverse species. However, for at least half of the hallmarks, there are methods available today that can be employed to fill this gap in knowledge, suggesting that these studies can be prioritized while methods are developed for comparative study of the remaining hallmarks.

Curcumin Improves Hippocampal Cell Bioenergetics, Redox and Inflammatory Markers, and Synaptic Proteins, Regulating Mitochondrial Calcium Homeostasis

Mitochondria produces energy through oxidative phosphorylation (OXPHOS), maintaining calcium homeostasis, survival/death cell signaling mechanisms, and redox balance. These mitochondrial functions are especially critical for neurons. The hippocampus is crucial for memory formation in the brain, which is a process with high mitochondrial function demand. Loss of hippocampal function in aging is related to neuronal damage, where mitochondrial impairment is critical. Synaptic and mitochondrial dysfunction are early events in aging; both are regulated reciprocally and contribute to age-associated memory loss together. We previously showed that prolonged treatment with Curcumin or Mitoquinone (MitoQ) improves mitochondrial functions in aged mice, exerting similar neuroprotective effects. Curcumin has been described as an anti-inflammatory and antioxidant compound, and MitoQ is a potent antioxidant directly targeting mitochondria; however, whether Curcumin exerts a direct impact on the mitochondria is unclear. In this work, we study whether Curcumin could have a mechanism similar to MitoQ targeting the mitochondria. We utilized hippocampal slices of 4-6-month-old C57BL6 mice to assess the cellular changes induced by acute Curcumin treatment ex-vivo compared to MitoQ. Our results strongly suggest that both compounds improve the synaptic structure, oxidative state, and energy production in the hippocampus. Nevertheless, Curcumin and MitoQ modify mitochondrial function differently; MitoQ improves the mitochondrial bioenergetics state, reducing ROS production and increasing ATP generation. In contrast, Curcumin reduces mitochondrial calcium levels and prevents calcium overload related to mitochondrial swelling. Thus, Curcumin is described as a new regulator of mitochondrial calcium homeostasis and could be used in pathological events involving calcium deregulation and excitotoxicity, such as aging and neurodegenerative diseases.

Early dysregulation of GSK3β impairs mitochondrial activity in Fragile X Syndrome

The finely tuned regulation of mitochondria activity is essential for proper brain development. Fragile X Syndrome (FXS), the leading cause of inherited intellectual disability, is a neurodevelopmental disorder in which mitochondrial dysfunction has been increasingly implicated. This study investigates the role of Glycogen Synthase Kinase 3β (GSK3β) in FXS. Several studies have reported the dysregulation of GSK3β in FXS, and its role in mitochondrial function is also well established. However, the link between disrupted GSK3β activity and mitochondrial dysfunction in FXS remains unexplored. Utilizing Fmr1 knockout (KO) mice and human cell lines from individuals with FXS, we uncovered a developmental window where dysregulated GSK3β activity disrupts mitochondrial function. Notably, a partial inhibition of GSK3β activity in FXS fibroblasts from young individuals rescues the observed mitochondrial defects, suggesting that targeting GSK3β in the early stages may offer therapeutic benefits for this condition.

Metallic and metallic oxide nanoparticles toxicity primarily targets the mitochondria of hepatocytes and renal cells

Nanoparticles (NPs) are utilized in various applications, posing potential risks to human health, tissues, cells, and macromolecules. This study aimed to investigate the ultrastructural alterations in hepatocytes and renal tubular cells induced by metallic and metal oxide NPs. Adult healthy male Wistar albino rats (Rattus norvegicus) were divided into 6 (n = 7) control and 6 treated groups (n = 7). The rats in the treated groups exposed daily to silver NPs, gold NPs, zinc oxide NPs, silicon dioxide NPs, copper oxide NPs, and ferric oxide NPs for 35 days. The members of the control group for each corresponding NPs received the respective vehicle. Liver and kidney tissue blocks from all rats were processed for Transmission Electron Microscopy (TEM) examinations. The hepatocytes and renal tubular cells of all NPs-treated rats demonstrated mitochondrial ultrastructural alterations mainly cristolysis, swelling, membrane disruption, lucent matrices, matrices lysis, and electron-dense deposits. However, other organelles demonstrated injury but to a lesser extent in the form of shrunken nuclei, nuclear membrane indentation, endoplasmic reticulum fragmentation, cellular membranes enfolding, brush border microvilli disruption, lysosomal hyperplasia, ribosomes dropping, and peroxisome formation. One may conclude from the findings that the hepatocytes and the renal tubular cells mitochondria are the main targets for nanoparticles toxicity ending in mitochondrial disruption and cell injury. Further studies taking into account the relation of mitochondrial ultrastructural damage with a weakened antioxidant defense system induced by chronic exposure to nanomaterials are needed.

Tiron enhances the anti-cancer activity of doxorubicin in DMBA-induced breast cancer: Role of Notch signaling/apoptosis/autophagy/oxidative stress

Existing work intended to investigate the outcomes of the localized mitochondrial antioxidant tiron (TR) alone or in combination with doxorubicin (DOX) in 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis in rats and the mechanistic pathways behind these effects. Also, to examine the preventive role of TR against DOX-related cardiotoxicity. 64 female Sprague-Dawley rats were randomly assigned into 8 groups: CTRL, DOX, TR, DMBA, DMBA + DOX, DMBA + TR100, DMBA + TR200, and DMBA + DOX + TR200. Rats received TR (100 and 200 mg/kg), DOX (2mg/kg), and DMBA (7.5 mg/kg) for four consecutive weeks. TR alone or combined with DOX not only inhibited oxidative status-related parameters and Notch pathway proteins but also attenuated proliferation markers, and enhanced apoptosis, and autophagy-related genes. Consistently, the histopathological analysis showed better scores in mammary tissues isolated from groups treated with TR only or combined with DOX. Additionally, TR dramatically decreased relative heart weight, myocardial injury biomarkers, and heart oxidative stress parameters while maintaining the myocardial histological integrity. Here we provided evidence that TR acts via modulating Notch signaling/apoptosis/autophagy/oxidative stress to elicit anti-tumor activity and combination with DOX revealed a higher efficacy as a novel anticancer strategy. Moreover, TR could be a potential cardio-protective candidate during DOX-chemotherapy, possibly via its antioxidant activity.

Selection for Late Reproduction Leads to Loss of Complex I Mitochondrial Capacity and Associated Increased Longevity in Seed Beetles

Mitochondria play a key role in aging. Here, we measured integrated mitochondrial functions in experimentally evolved lines of the seed beetle Acanthoscelides obtectus that were selected for early (E) or late (L) reproduction for nearly 4 decades. The 2 lines have markedly different lifespans (8 days and 13 days in the E and L lines, respectively). The contribution of the NADH pathway to maximal flux was lower in the L compared to the E beetles at young stages, associated with increased control by complex I. In contrast, the contribution of the Succinate pathway was higher in the L than in the E line, whereas the Proline pathway showed no differences between the lines. Our data suggest that selection of age at reproduction leads to a modulation of complex I activity in mitochondria and that mitochondria are a functional link between evolutionary and mechanistic theories of aging.

Enhancing healthy aging with small molecules: A mitochondrial perspective

The pursuit of enhanced health during aging has prompted the exploration of various strategies focused on reducing the decline associated with the aging process. A key area of this exploration is the management of mitochondrial dysfunction, a notable characteristic of aging. This review sheds light on the crucial role that small molecules play in augmenting healthy aging, particularly through influencing mitochondrial functions. Mitochondrial oxidative damage, a significant aspect of aging, can potentially be lessened through interventions such as coenzyme Q10, alpha-lipoic acid, and a variety of antioxidants. Additionally, this review discusses approaches for enhancing mitochondrial proteostasis, emphasizing the importance of mitochondrial unfolded protein response inducers like doxycycline, and agents that affect mitophagy, such as urolithin A, spermidine, trehalose, and taurine, which are vital for sustaining protein quality control. Of equal importance are methods for modulating mitochondrial energy production, which involve nicotinamide adenine dinucleotide boosters, adenosine 5'-monophosphate-activated protein kinase activators, and compounds like metformin and mitochondria-targeted tamoxifen that enhance metabolic function. Furthermore, the review delves into emerging strategies that encourage mitochondrial biogenesis. Together, these interventions present a promising avenue for addressing age-related mitochondrial degradation, thereby setting the stage for the development of innovative treatment approaches to meet this extensive challenge.

Effects of chronic hydrogen peroxide exposure on mitochondrial oxidative stress genes, ROS production and lipid peroxidation in HL60 cells

Hydrogen peroxide (H2O2) is a reactive species that is also involved in the redox regulation of cells because of it is relative stability. In numerous pathological situations, a chronic increase in the production of reactive species is observed, which is related to oxidative stress and cellular damage. This study aimed to evaluate the effects of long-term exposure to different H2O2 concentrations on oxidative stress biomarkers and mitochondrial dynamics in HL60 cells. HL60 cells were treated with a sustained production (0.1, 1.0 and 10.0 nM/s) of H2O2 for one hour. H2O2 production and malondialdehyde (MDA) levels, as a lipid peroxidation marker, increased progressively in HL60 cells in accordance with higher H2O2 exposure, with significant differences between the 10 nM/s H2O2 group and the control and 0.1 nM/s groups. Similarly, progressive increased expression in genes related to the mitochondrial antioxidant defences and mitochondrial dynamics were also observed. Significantly increased gene expression in the 10 nM/s H2O2 with respect to the control group was observed for manganese superoxide dismutase (MnSOD), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PCG1α), nuclear respiratory factor 2 (Nrf2), mitochondrial transcription factor A (Tfam), mitofusins 1 and 2 (Mfn1 and Mfn2) and uncoupling protein 3 (UCP3), whereas no significant changes were observed in the cytochrome c oxidase subunit IV (COXIV) gene expression. In conclusion, exposure to different sustained production of H2O2 is related to a progressive increase in the gene expression of mitochondrial dynamics and redox processes in HL60 cells, but also to oxidative damage at higher H2O2 production levels.

Oxidase enzyme genes are differentially expressed during Acanthamoeba castellanii encystment

Acanthamoeba castellanii, a ubiquitous protozoan, is responsible for significant diseases such as Acanthamoeba keratitis and granulomatous amoebic encephalitis. A crucial survival strategy of A. castellanii involves the formation of highly resistant cysts during adverse conditions. This study delves into the cellular processes underpinning encystment, focusing on gene expression changes related to reactive oxygen species (ROS) balance, with a particular emphasis on mitochondrial processes. Our findings reveal a dynamic response within the mitochondria during encystment, with the downregulation of key enzymes involved in oxidative phosphorylation (COX, AOX, and NADHalt) during the initial 48 h, followed by their overexpression at 72 h. This orchestrated response likely creates a pro-oxidative environment, facilitating encystment. Analysis of other ROS processing enzymes across the cell reveals differential expression patterns. Notably, antioxidant enzymes, such as catalases, glutaredoxins, glutathione S-transferases, peroxiredoxins, and thioredoxins, mirror the mitochondrial trend of downregulation followed by upregulation. Additionally, glycolysis and gluconeogenesis are downregulated during the early stages in order to potentially balance the metabolic requirement of the cyst. Our study underscores the importance of ROS regulation in Acanthamoeba encystment. Understanding these mechanisms offers insights into infection control and identifies potential therapeutic targets. This work contributes to unraveling the complex biology of A. castellanii and may aid in combatting Acanthamoeba-related infections. Further research into ROS and oxidase enzymes is warranted, given the organism's remarkable respiratory versatility.

High-Fat Diet-Induced Obesity Increases Brain Mitochondrial Complex I and Lipoxidation-Derived Protein Damage

Obesity is a risk factor for highly prevalent age-related neurodegenerative diseases, the pathogenesis of whichinvolves mitochondrial dysfunction and protein oxidative damage. Lipoxidation, driven by high levels of peroxidizable unsaturated fatty acids and low antioxidant protection of the brain, stands out as a significant risk factor. To gain information on the relationship between obesity and brain molecular damage, in a porcine model of obesity we evaluated (1) the level of mitochondrial respiratory chain complexes, as the main source of free radical generation, by Western blot; (2) the fatty acid profile by gas chromatography; and (3) the oxidative modification of proteins by mass spectrometry. The results demonstrate a selectively higher amount of the lipoxidation-derived biomarker malondialdehyde-lysine (MDAL) (34% increase) in the frontal cortex, and positive correlations between MDAL and LDL levels and body weight. No changes were observed in brain fatty acid profile by the high-fat diet, and the increased lipid peroxidative modification was associated with increased levels of mitochondrial complex I (NDUFS3 and NDUFA9 subunits) and complex II (flavoprotein). Interestingly, introducing n3 fatty acids and a probiotic in the high-fat diet prevented the observed changes, suggesting that dietary components can modulate protein oxidative modification at the cerebral level and opening new possibilities in neurodegenerative diseases' prevention.

Phenotypic molecular features of long-lived animal species

One of the challenges facing science/biology today is uncovering the molecular bases that support and determine animal and human longevity. Nature, in offering a diversity of animal species that differ in longevity by more than 5 orders of magnitude, is the best 'experimental laboratory' to achieve this aim. Mammals, in particular, can differ by more than 200-fold in longevity. For this reason, most of the available evidence on this topic derives from comparative physiology studies. But why can human beings, for instance, reach 120 years whereas rats only last at best 4 years? How does nature change the longevity of species? Longevity is a species-specific feature resulting from an evolutionary process. Long-lived animal species, including humans, show adaptations at all levels of biological organization, from metabolites to genome, supported by signaling and regulatory networks. The structural and functional features that define a long-lived species may suggest that longevity is a programmed biological property.

Insulin and aging - a disappointing relationship

Experimental studies in animal models of aging such as nematodes, fruit flies or mice have observed that decreased levels of insulin or insulin signaling promotes longevity. In humans, hyperinsulinemia and concomitant insulin resistance are associated with an elevated risk of age-related diseases suggestive of a shortened healthspan. Age-related disorders include neurodegenerative diseases, hypertension, cardiovascular disease, and type 2 diabetes. High ambient insulin concentrations promote increased lipogenesis and fat storage, heightened protein synthesis and accumulation of non-functional polypeptides due to limited turnover capacity. Moreover, there is impaired autophagy activity, and less endothelial NO synthase activity. These changes are associated with mitochondrial dysfunction and oxidative stress. The cellular stress induced by anabolic activity of insulin initiates an adaptive response aiming at maintaining homeostasis, characterized by activation of the transcription factor Nrf2, of AMP activated kinase, and an unfolded protein response. This protective response is more potent in the long-lived human species than in short-lived models of aging research resulting in a stronger pro-aging impact of insulin in nematodes and fruit flies. In humans, resistance to insulin-induced cell stress decreases with age, because of an increase of insulin and insulin resistance levels but less Nrf2 activation. These detrimental changes might be contained by adopting a lifestyle that promotes low insulin/insulin resistance levels and enhances an adaptive response to cellular stress, as observed with dietary restriction or exercise.

The Reduction in the Mitochondrial Membrane Potential in Aging: The Role of the Mitochondrial Permeability Transition Pore

It is widely reported that the mitochondrial membrane potential, ∆Ψm, is reduced in aging animals. It was recently suggested that the lower ∆Ψm in aged animals modulates mitochondrial bioenergetics and that this effect is a major cause of aging since artificially increased ∆Ψm in C. elegans increased lifespan. Here, I critically review studies that reported reduction in ∆Ψm in aged animals, including worms, and conclude that many of these observations are best interpreted as evidence that the fraction of depolarized mitochondria is increased in aged cells because of the enhanced activation of the mitochondrial permeability transition pore, mPTP. Activation of the voltage-gated mPTP depolarizes the mitochondria, inhibits oxidative phosphorylation, releases large amounts of calcium and mROS, and depletes cellular NAD+, thus accelerating degenerative diseases and aging. Since the inhibition of mPTP was shown to restore ∆Ψm and to retard aging, the reported lifespan extension by artificially generated ∆Ψm in C. elegans is best explained by inhibition of the voltage-gated mPTP. Similarly, the reported activation of the mitochondrial unfolded protein response by reduction in ∆Ψm and the reported preservation of ∆Ψm in dietary restriction treatment in C. elegans are best explained as resulting from activation or inhibition of the voltage-gated mPTP, respectively.

Endothelial Cells and Mitochondria: Two Key Players in Liver Transplantation

Building the inner layer of our blood vessels, the endothelium forms an important line communicating with deeper parenchymal cells in our organs. Previously considered passive, endothelial cells are increasingly recognized as key players in intercellular crosstalk, vascular homeostasis, and blood fluidity. Comparable to other cells, their metabolic function strongly depends on mitochondrial health, and the response to flow changes observed in endothelial cells is linked to their mitochondrial metabolism. Despite the direct impact of new dynamic preservation concepts in organ transplantation, the impact of different perfusion conditions on sinusoidal endothelial cells is not yet explored well enough. This article therefore describes the key role of liver sinusoidal endothelial cells (LSECs) together with their mitochondrial function in the context of liver transplantation. The currently available ex situ machine perfusion strategies are described with their effect on LSEC health. Specific perfusion conditions, including perfusion pressure, duration, and perfusate oxygenation are critically discussed considering the metabolic function and integrity of liver endothelial cells and their mitochondria.