Oxidative Stress and Pathways of Molecular Hydrogen Effects in Medicine

Potential role of molecular hydrogen therapy on oxidative stress and redox signaling in chronic kidney disease

Oxidative stress plays a key role in chronic kidney disease (CKD) development and progression, inducing kidney cell damage, inflammation, and fibrosis. However, effective therapeutic interventions to slow down CKD advancement are currently lacking. The multifaceted pharmacological effects of molecular hydrogen (H2) have made it a promising therapeutic avenue. H2 is capable of capturing harmful •OH and ONOO- while maintaining the crucial reactive oxygen species (ROS) involved in cellular signaling. The NRF2-KEAP1 system, which manages cell redox balance, could be used to treat CKD. H2 activates this pathway, fortifying antioxidant defenses and scavenging ROS to counteract oxidative stress. H2 can improve NRF2 signaling by using the Wnt/β-catenin pathway and indirectly activate NRF2-KEAP1 in mitochondria. Additionally, H2 modulates NF-κB activity by regulating cellular redox status, inhibiting MAPK pathways, and maintaining Trx levels. Treatment with H2 also attenuates HIF signaling by neutralizing ROS while indirectly bolstering HIF-1α function. Furthermore, H2 affects FOXO factors and enhances the activity of antioxidant enzymes. Despite the encouraging results of bench studies, clinical trials are still limited and require further investigation. The focus of this review is on hydrogen's role in treating renal diseases, with a specific focus on oxidative stress and redox signaling regulation, and it discusses its potential clinical applications.

Hydrogen Attenuates Cognitive Impairment in Rat Models of Vascular Dementia by Inhibiting Oxidative Stress and NLRP3 Inflammasome Activation

Vascular dementia (VaD) is the second most common form of dementia worldwide. Oxidative stress and neuroinflammation are important factors contributing to cognitive dysfunction in patients with VaD. The antioxidant and anti-inflammatory properties of hydrogen are increasingly being utilized in neurological disorders, but conventional hydrogen delivery has the disadvantage of inefficiency. Therefore, magnesium silicide nanosheets (MSNs) are used to release hydrogen in vivo in larger quantities and for longer periods of time to explore the appropriate dosage and regimen. In this study, it is observed that hydrogen improved learning and working memory in VaD rats in the Morris water maze and Y-maze, which elicits improved cognitive function. Nissl staining of neurons shows that hydrogen treatment significantly improves edema in neuronal cells. The expression and activation of reactive oxygen species (ROS), Thioredoxin-interacting protein (TXNIP), NOD-like receptor protein 3 (NLRP3), caspase-1, and IL-1β in the hippocampus are measured via ELISA, Western blotting, real-time qPCR, and immunofluorescence. The results show that oxidative stress indicators and inflammasome-related factors are significantly decreased after 7dMSN treatment. Therefore, it is concluded that hydrogen can ameliorate neurological damage and cognitive dysfunction in VaD rats by inhibiting ROS/NLRP3/IL-1β-related oxidative stress and inflammation.

The Therapeutic Potential of Harpagophytum procumbens and Turnera subulata and Advances in Nutraceutical Delivery Systems in Neurodegenerative Diseases

This review article covers the therapeutic potential of the plants Harpagophytum procumbens and Turnera subulata in the treatment of neurodegenerative diseases. Despite the recognition of their beneficial properties, there is notable shortage of specific clinical and in vitro studies on these species regarding neurodegenerative diseases. Compounds such as harpagosides and vite-xin-2-O-rhamnoside, found in Harpagophytum procumbens and Turnera subulata, respectively, as well as other antioxidants and anti-inflammatory agents, are associated with mechanisms of action that involve reducing oxidative stress and modulating the inflammatory response, indicating their therapeutic potential in these pathologies. Additionally, the use of nutraceuticals derived from medicinal plants has emerged as a promising approach, offering natural therapeutic alternatives. However, the pressing need for studies focusing on the pharmacokinetics, safety, and pharmacological interactions of these extracts for the treatment of neurodegenerative diseases is emphasized. This review also evaluated advances in nutraceutical delivery systems, highlighting technological innovations that can optimize the precise delivery of these compounds to patients. Such findings highlight the gaps in the study of these plants for the treatment of neurodegenerative diseases and, at the same time, the potential for opening new perspectives in the treatment of neurodegenerative diseases, providing expectations for innovative solutions in this critical domain of medicine.

Hydrogen-rich water supplementation promotes muscle recovery after two strenuous training sessions performed on the same day in elite fin swimmers: randomized, double-blind, placebo-controlled, crossover trial

Purpose: Molecular hydrogen has been shown to possess antioxidant, anti-inflammatory, ergogenic, and recovery-enhancing effects. This study aimed to assess the effect of molecular hydrogen administration on muscle performance, damage, and perception of soreness up to 24 h of recovery after two strenuous training sessions performed on the same day in elite fin swimmers. Methods: Eight females (mean ± SD; age 21.5 ± 5.0 years, maximal oxygen consumption 45.0 ± 2.5 mL.kg-1.min-1) and four males (age 18.9 ± 1.3 years, maximal oxygen consumption 52.2 ± 1.7 mL.kg-1.min-1) performed 12 × 50 m sprints in the morning session and a 400 m competitive performance in the afternoon session. Participants consumed hydrogen-rich water (HRW) or placebo 3 days before the sessions (1,260 mL/day) and 2,520 mL on the experimental day. Muscle performance (countermovement jump), muscle damage (creatine kinase), and muscle soreness (100 mm visual analogue scale) were measured during the experimental day and at 12 and 24 h after the afternoon session. Results: HRW compared to placebo reduced blood activity of creatine kinase (156 ± 63 vs. 190 ± 64 U.L-1, p = 0.043), muscle soreness perception (34 ± 12 vs. 42 ± 12 mm, p = 0.045), and improved countermovement jump height (30.7 ± 5.5 cm vs. 29.8 ± 5.8 cm, p = 0.014) at 12 h after the afternoon session. Conclusion: Four days of HRW supplementation is a promising hydration strategy for promoting muscle recovery after two strenuous training sessions performed on the same day in elite fin swimmers. Clinical Trial Registration: clinicaltrials.gov, identifier NCT05799911.

Prospects of molecular hydrogen in cancer prevention and treatment

Gas signaling molecules, including carbon monoxide (CO), nitric oxide (NO), and hydrogen sulfide (H2S), have been shown to have cancer therapeutic potential, pointing to a new direction for cancer treatment. In recent years, a series of studies have confirmed that hydrogen (H2), a weakly reductive gas, also has therapeutic effects on various cancers and can mitigate oxidative stress caused by radiation and chemotherapy, reducing tissue damage and immunosuppression to improve prognosis. Meanwhile, H2 also has immunomodulatory effects, inhibiting T cell exhaustion and enhancing T cell anti-tumor function. It is worth noting that human intestinal flora can produce large amounts of H2 daily, which becomes a natural barrier to maintaining the body's resistance to diseases such as tumors. Although the potential anti-tumor mechanisms of H2 are still to be investigated, previous studies have shown that H2 can selectively scavenge highly toxic reactive oxygen species (ROS) and inhibit various ROS-dependent signaling pathways in cancer cells, thus inhibiting cancer cell proliferation and metastasis. The ROS scavenging ability of H2 may also be the underlying mechanism of its immunomodulatory function. In this paper, we review the significance of H2 produced by intestinal flora on the immune homeostasis of the body, the role of H2 in cancer therapy and the underlying mechanisms, and the specific application of H2 to provide new ideas for the comprehensive treatment of cancer patients.

Hydrogen inhalation: in vivo rat genotoxicity tests

Preclinical and clinical studies have shown that molecular hydrogen (H2) has anti-oxidant, anti-inflammatory, and anti-apoptotic properties. Safety data are available in the literature and acute toxicity has been tested in isolated cells and laboratory animals. We have evaluates the genotoxicity of H2 in vivo in rats after 72 h exposure, following the International Council for Harmonization guidelines ICH S2 (R1). The study was conducted on three groups of male Wistar rats: a negative control group, a positive control group receiving methyl methanesulfonate, and a H2-treated group receiving a 3.1% H2 gas mixture for 72 h. Alkaline comet, formamidopyrimidine DNA glycosylase (Fpg)-modified comet and bone marrow micronucleus assays were performed. H2 exposure increased neither comet-tail DNA intensity (DNA damage) nor frequency of "hedgehogs" in blood, liver, lungs, or bronchoalveolar lavage fluid. No increase in Fpg-sensitive sites in lungs, no induction of micronucleus formation, and no imbalance of immature erythrocyte to total erythrocyte ratio (IME%) was observed in rats exposed to H2. The ICH S2 (R1) test-battery revealed no in vivo genotoxicity in Wistar rats after 72 h inhalation of a mixture containing 3.1% H2.

Mitochondria: one of the vital hubs for molecular hydrogen's biological functions

As a novel antioxidant, a growing body of studies has documented the diverse biological effects of molecular hydrogen (H2) in a wide range of organisms, spanning animals, plants, and microorganisms. Although several possible mechanisms have been proposed, they cannot fully explain the extensive biological effects of H2. Mitochondria, known for ATP production, also play crucial roles in diverse cellular functions, including Ca2+ signaling, regulation of reactive oxygen species (ROS) generation, apoptosis, proliferation, and lipid transport, while their dysfunction is implicated in a broad spectrum of diseases, including cardiovascular disorders, neurodegenerative conditions, metabolic disorders, and cancer. This review aims to 1) summarize the experimental evidence on the impact of H2 on mitochondrial function; 2) provide an overview of the mitochondrial pathways underlying the biological effects of H2, and 3) discuss H2 metabolism in eukaryotic organisms and its relationship with mitochondria. Moreover, based on previous findings, this review proposes that H2 may regulate mitochondrial quality control through diverse pathways in response to varying degrees of mitochondrial damage. By combining the existing research evidence with an evolutionary perspective, this review emphasizes the potential hydrogenase activity in mitochondria of higher plants and animals. Finally, this review also addresses potential issues in the current mechanistic study and offers insights into future research directions, aiming to provide a reference for future studies on the mechanisms underlying the action of H2.

Therapeutic Potential of Hydrogen-Rich Water on Muscle Atrophy Caused by Immobilization in a Mouse Model

Skeletal muscle atrophy is associated with poor quality of life and disability. Thus, finding a new strategy for the prevention and treatment of skeletal muscle atrophy is very crucial. This study aimed to investigate the therapeutic potential of hydrogen-rich water (HRW) on muscle atrophy in a unilateral hind limb immobilization model. Thirty-six male Balb/C mice were divided into control (without immobilization), atrophy, and atrophy + hydrogen-rich water (HRW). Unilateral hind limb immobilization was induced using a splint for 7 days (atrophy) and removed for 10 days (recovery). At the end of each phase, gastrocnemius and soleus muscle weight, limb grip strength, skeletal muscle histopathology, muscle fiber size, cross-section area (CSA), serum troponin I and skeletal muscle IL-6, TNF-α and Malondialdehyde (MDA), and mRNA expression of NF-κB, BAX and Beclin-1 were evaluated. Muscle weight and limb grip strength in the H2-treated group were significantly improved during the atrophy phase, and this improvement continued during the recovery period. Treatment by HRW increased CSA and muscle fiber size and reduced muscle fibrosis, serum troponin I, IL-6, TNF-α and MDA which was more prominent in the atrophy phase. These data suggest that HRW could improve muscle atrophy in an immobilized condition and could be considered a new strategy during rehabilitation.

Molecular hydrogen: prospective treatment strategy of kidney damage after cardiac surgery

Cardiac surgery-associated acute kidney injury is a common post-operative complication, mostly due to increasing oxidative stress. Recently, molecular hydrogen (H2 gas) has also been applied to cardiac surgery due to its ability to reduce oxidative stress. We evaluated the potential effect of H2 application on the kidney in an in vivo model of simulated heart transplantation. Pigs underwent cardiac surgery within 3 h while connected to extracorporeal circulation (ECC) and subsequent 60 min of spontaneous reperfusion of the heart. We used two experimental groups: T-pigs after transplantation and TH-pigs after transplantation treated with 4% H2 mixed with air during inhalation of anesthesia and throughout oxygenation of blood in ECC. The levels of creatinine, urea and phosphorus were measured in plasma. Renal tissue samples were analyzed by Western blot method for protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap-1), and superoxide dismutase (SOD1). After cardiac surgery, selected plasma biomarkers were elevated. However, H2 therapy was followed by the normalization of all these parameters. Our results suggest activation of Nrf2/Keap1 pathway as well as increased SOD1 protein expression in the group treated with H2. The administration of H2 had a protective effect on the kidneys of pigs after cardiac surgery, especially in terms of normalization of plasma biomarkers to control levels.

Effect and mechanism of hydrogen-rich bath on mice with imiquimod-induced psoriasis

The purpose of this study was to investigate whether hydrogen-rich bath has therapeutic effect on psoriasis and its molecular mechanism. Mice with imiquimod-induced psoriasis were established and divided into groups. The mice were respectively treated with hydrogen-rich water bath and distilled water bath. The changes of skin lesions and PSI scores of mice were compared after their treatments. HE staining was used to observe the pathological feature. The changes of inflammatory indexes and immune factors were analysed by ELISA and immunohistochemical staining. Malondialdehyde (MDA) content was measured by the thiobarbituric assay (TBA) method. By naked eye, the severity of skin lesions in hydrogen-rich water bath group was lower than that in distilled water bath group, and the psoriasis severity index (PSI) was lower (p < 0.01). The results of HE staining showed that the mice with distilled water bath had more abnormal keratosis, thickening of the spinous layer and prolongation of the dermal process, and more Munro abscess than the mice with hydrogen-rich water bath. During the course of disease, the overall levels and peaks of IL-17, IL-23, TNF-α, CD3+ and MDA in mice with hydrogen-rich bath were lower than those in mice with distilled water bath (p < 0.05). In the skin, the mice treated with the hydrogen-rich water bath also had lower peak of proliferating cell nuclear antigen (PCNA) levels. It is concluded that hydrogen-rich water bath can inhibit psoriasis inflammation and oxidative stress, relieve psoriasis skin lesions and accelerate the end of abnormal skin proliferation state, which shows a therapeutic and improving effect on psoriasis.

The Effect of Adjuvant Therapy with Molecular Hydrogen on Endogenous Coenzyme Q10 Levels and Platelet Mitochondrial Bioenergetics in Patients with Non-Alcoholic Fatty Liver Disease

Molecular hydrogen (H2) has been recognized as a novel medical gas with antioxidant and anti-inflammatory effects. Non-alcoholic fatty liver disease (NAFLD) is a liver pathology with increased fat accumulation in liver tissue caused by factors other than alcohol consumption. Platelet mitochondrial function is considered to reflect systemic mitochondrial health. We studied the effect of adjuvant therapy with hydrogen-rich water (HRW) on coenzyme Q10 (CoQ10) content and platelet mitochondrial bioenergetics in patients with NAFLD. A total of 30 patients with NAFLD and 15 healthy volunteers were included in this clinical trial. A total of 17 patients (H2 group) drank water three × 330 mL/day with tablets producing HRW (>4 mg/L H2) for 8 weeks, and 13 patients (P group) drank water with placebo tablets producing CO2. The concentration of CoQ10-TOTAL was determined by the HPLC method, the parameter of oxidative stress, thiobarbituric acid reactive substances (TBARS), by the spectrophotometric method, and mitochondrial bioenergetics in platelets isolated from whole blood by high-resolution respirometry. The patients with NAFLD had lower concentrations of CoQ10-TOTAL in the blood, plasma, and platelets vs. the control group. Mitochondrial CI-linked LEAK respiration was higher, and CI-linked oxidative phosphorylation (OXPHOS) and CII-linked electron transfer (ET) capacities were lower vs. the control group. Plasma TBARS concentrations were higher in the H2 group. After 8 weeks of adjuvant therapy with HRW, the concentration of CoQ10 in platelets increased, plasma TBARS decreased, and the efficiency of OXPHOS improved, while in the P group, the changes were non-significant. Long-term supplementation with HRW could be a promising strategy for the acceleration of health recovery in patients with NAFLD. The application of H2 appears to be a new treatment strategy for targeted therapy of mitochondrial disorders. Additional and longer-term studies are needed to confirm and elucidate the exact mechanisms of the mitochondria-targeted effects of H2 therapy in patients with NAFLD.

Hydrogen gas ameliorates acute alcoholic liver injury via anti-inflammatory and antioxidant effects and regulation of intestinal microbiota

Alcoholic liver disease (ALD) is a globally prevalent liver-related disorder characterized by severe oxidative stress and inflammatory liver damage, for which no effective treatment is currently available. Hydrogen gas (H₂) has been demonstrated to be an efficient antioxidant in various diseases in animals as well as humans. However, the protective effects of H₂ on ALD and its underlying mechanisms remain to be elucidated. The present study demonstrated that H₂ inhalation ameliorated liver injury, and attenuated liver oxidative stress, inflammation, and steatosis in an ALD mouse model. Moreover, H₂ inhalation improved gut microbiota, including increasing the abundance of Lachnospiraceae and Clostridia, and decreasing the abundance of Prevotellaceae and Muribaculaceae, and also improved intestinal barrier integrity. Mechanistically, H₂ inhalation blocked activation of the LPS/TLR4/NF-κB pathway in liver. Notably, it was further demonstrated that the reshaped gut microbiota may accelerate alcohol metabolism, regulate lipid homeostasis and maintain immune balance by bacterial functional potential prediction (PICRUSt). Fecal microbiota transplantation from mice that had undergone H₂ inhalation significantly alleviated acute alcoholic liver injury. In summary, the present study showed that H₂ inhalation alleviated liver injury by reducing oxidative stress and inflammation, while also improving intestinal flora and enhancing the intestinal barrier. H₂ inhalation may serve as an effective intervention for preventing and treating ALD in a clinical context.

Protective Effect of Hydrogen-Rich Saline on Spinal Cord Damage in Rats

The anti-inflammatory and anti-apoptotic effects of molecular hydrogen, delivered as hydrogen-rich saline (HRS), on spinal cord injury was investigated. Four-month-old male Sprague Dawley rats (n = 24) were classified into four groups: (1) control—laminectomy only at T7-T10; (2) spinal injury—dura left intact, Tator and Rivlin clip compression model applied to the spinal cord for 1 min, no treatment given; (3) HRS group—applied intraperitoneally (i.p.) for seven days; and (4) spinal injury—HRS administered i.p. for seven days after laminectomy at T7–T10 level, leaving the dura intact and applying the Tator and Rivlin clip compression model to the spinal cord for 1 min. Levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were measured in blood taken at day seven from all groups, and hematoxylin–eosin (H & E) and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) were used to stain the tissue samples. IL-6 and TNF-α levels were significantly lower in the group treated with HRS following the spinal cord injury compared to the group whose spinal cord was damaged. A decrease in apoptosis was also observed. The anti-inflammatory and anti-apoptotic effect of IL-6 may be a clinically useful adjuvant therapy after spinal cord injury.

An NIR-Driven Upconversion/C3N4/CoP Photocatalyst for Efficient Hydrogen Production by Inhibiting Electron-Hole Pair Recombination for Alzheimer's Disease Therapy

Redox imbalance and abnormal amyloid protein (Aβ) buildup are key factors in the etiology of Alzheimer's disease (AD). As an antioxidant, the hydrogen molecule (H₂) has the potential to cure AD by specifically scavenging highly harmful reactive oxygen species (ROS) such as ^•OH. However, due to the low solubility of H₂ (1.6 ppm), the traditional H₂ administration pathway cannot easily achieve long-term and effective accumulation of H₂ in the foci. Therefore, how to achieve the continuous release of H₂ in situ is the key to improve the therapeutic effect on AD. As a corollary, we designed a rare earth ion doped g-C₃N₄ upconversion photocatalyst, which can respond to NIR and realize the continuous production of H₂ by photocatalytic decomposition of H₂O in biological tissue, which avoids the problem of the poor penetration of visible light. The introduction of CoP cocatalyst accelerates the separation and transfer of photogenerated electrons in g-C₃N₄, thus improving the photocatalytic activity of hydrogen evolution reaction. The morphology of the composite photocatalyst was shown by transmission electron microscopy, and the crystal structure was studied by X-ray diffractometry and Raman analysis. In addition, the ability of g-C₃N₄ to chelate metal ions and the photothermal properties of CoP can inhibit Aβ and reduce the deposition of Aβ in the brain. Efficient in situ hydrogen production therapy combined with multitarget synergism solves the problem of a poor therapeutic effect of a single target. In vivo studies have shown that UCNP@CoP@g-C₃N₄ can reduce Aβ deposition, improve memory impairment, and reduce neuroinflammation in AD mice.

Electrolyzed-Reduced Water: Review I. Molecular Hydrogen Is the Exclusive Agent Responsible for the Therapeutic Effects

Numerous benefits have been attributed to alkaline-electrolyzed-reduced water (ERW). Sometimes these claims are associated with easily debunked concepts. The observed benefits have been conjectured to be due to the intrinsic properties of ERW (e.g., negative oxidation-reduction potential (ORP), alkaline pH, H₂ gas), as well enigmatic characteristics (e.g., altered water structure, microclusters, free electrons, active hydrogen, mineral hydrides). The associated pseudoscientific marketing has contributed to the reluctance of mainstream science to accept ERW as having biological effects. Finally, through many in vitro and in vivo studies, each one of these propositions was examined and refuted one-by-one until it was conclusively demonstrated that H₂ was the exclusive agent responsible for both the negative ORP and the observed therapeutic effects of ERW. This article briefly apprised the history of ERW and comprehensively reviewed the sequential research demonstrating the importance of H₂. We illustrated that the effects of ERW could be readily explained by the known biological effects of H₂ and by utilizing conventional chemistry without requiring any metaphysical conjecture (e.g., microclustering, free electrons, etc.) or reliance on implausible notions (e.g., alkaline water neutralizes acidic waste). The H₂ concentration of ERW should be measured to ensure it is comparable to those used in clinical studies.

Electrolyzed-Reduced Water: Review II: Safety Concerns and Effectiveness as a Source of Hydrogen Water

Many studies demonstrate the safety of alkaline-electrolyzed-reduced water (ERW); however, several animal studies have reported significant tissue damage and hyperkalemia after drinking ERW. The mechanism responsible for these results remains unknown but may be due to electrode degradation associated with the production of higher pH, in which platinum nanoparticles and other metals that have harmful effects may leach into the water. Clinical studies have reported that, when ERW exceeds pH 9.8, some people develop dangerous hyperkalemia. Accordingly, regulations on ERW mandate that the pH of ERW should not exceed 9.8. It is recommended that those with impaired kidney function refrain from using ERW without medical supervision. Other potential safety concerns include impaired growth, reduced mineral, vitamin, and nutrient absorption, harmful bacterial overgrowth, and damage to the mucosal lining causing excessive thirst. Since the concentration of H₂ in ERW may be well below therapeutic levels, users are encouraged to frequently measure the H₂ concentration with accurate methods, avoiding ORP or ORP-based H₂ meters. Importantly, although, there have been many people that have used high-pH ERW without any issues, additional safety research on ERW is warranted, and ERW users should follow recommendations to not ingest ERW above 9.8 pH.

Biological Effects of Hydrogen Water on Subjects with NAFLD: A Randomized, Placebo-Controlled Trial

Non-alcoholic fatty liver disease (NAFLD) is a liver pathology affecting around 25% of the population worldwide. Excess oxidative stress, inflammation and aberrant cellular signaling can lead to this hepatic dysfunction and eventual carcinoma. Molecular hydrogen has been recognized for its selective antioxidant properties and ability to attenuate inflammation and regulate cellular function. We administered hydrogen-rich water (HRW) to 30 subjects with NAFLD in a randomized, double-blinded, placebo-controlled manner for eight weeks. Phenotypically, we observed beneficial trends (p > 0.05) in decreased weight (≈1 kg) and body mass index in the HRW group. HRW was well-tolerated, with no significant changes in liver enzymes and a trend of improved lipid profile and reduced lactate dehydrogenase levels. HRW tended to non-significantly decrease levels of nuclear factor kappa B, heat shock protein 70 and matrix metalloproteinase-9. Interestingly, there was a mild, albeit non-significant, tendency of increased levels of 8-hydroxy-2’-deoxyguanosine and malondialdehyde in the HRW group. This mild increase may be indicative of the hormetic effects of molecular hydrogen that occurred prior to the significant clinical improvements reported in previous longer-term studies. The favorable trends in this study in conjunction with previous animal and clinical findings suggest that HRW may serve as an important adjuvant therapy for promoting and maintaining optimal health and wellness. Longer term studies focused on prevention, maintenance, or treatment of NAFLD and early stages of NASH are warranted.

Role of Molecular Hydrogen in Ageing and Ageing-Related Diseases

Ageing is a physiological process of progressive decline in the organism function over time. It affects every organ in the body and is a significant risk for chronic diseases. Molecular hydrogen has therapeutic and preventive effects on various organs. It has antioxidative properties as it directly neutralizes hydroxyl radicals and reduces peroxynitrite level. It also activates Nrf2 and HO-1, which regulate many antioxidant enzymes and proteasomes. Through its antioxidative effect, hydrogen maintains genomic stability, mitigates cellular senescence, and takes part in histone modification, telomere maintenance, and proteostasis. In addition, hydrogen may prevent inflammation and regulate the nutrient-sensing mTOR system, autophagy, apoptosis, and mitochondria, which are all factors related to ageing. Hydrogen can also be used for prevention and treatment of various ageing-related diseases, such as neurodegenerative disorders, cardiovascular disease, pulmonary disease, diabetes, and cancer. This paper reviews the basic research and recent application of hydrogen in order to support hydrogen use in medicine for ageing prevention and ageing-related disease therapy.

Molecular hydrogen is a potential protective agent in the management of acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome, which is a more severe form of ALI, are life-threatening clinical syndromes observed in critically ill patients. Treatment methods to alleviate the pathogenesis of ALI have improved to a great extent at present. Although the efficacy of these therapies is limited, their relevance has increased remarkably with the ongoing pandemic caused by the novel coronavirus disease 2019 (COVID-19), which causes severe respiratory distress syndrome. Several studies have demonstrated the preventive and therapeutic effects of molecular hydrogen in the various diseases. The biological effects of molecular hydrogen mainly involve anti-inflammation, antioxidation, and autophagy and cell death modulation. This review focuses on the potential therapeutic effects of molecular hydrogen on ALI and its underlying mechanisms and aims to provide a theoretical basis for the clinical treatment of ALI and COVID-19.

Molecular Hydrogen Positively Affects Physical and Respiratory Function in Acute Post-COVID-19 Patients: A New Perspective in Rehabilitation

Molecular hydrogen (H₂) is potentially a novel therapeutic gas for acute post-coronavirus disease 2019 (COVID-19) patients because it has antioxidative, anti-inflammatory, anti-apoptosis, and antifatigue properties. The aim of this study was to determine the effect of 14 days of H₂ inhalation on the respiratory and physical fitness status of acute post-COVID-19 patients. This randomized, single-blind, placebo-controlled study included 26 males (44 ± 17 years) and 24 females (38 ± 12 years), who performed a 6-min walking test (6 MWT) and pulmonary function test, specifically forced vital capacity (FVC) and expiratory volume in the first second (FEV1). Symptomatic participants were recruited between 21 and 33 days after a positive polymerase chain reaction test. The experiment consisted of H₂/placebo inhalation, 2 × 60 min/day for 14 days. Results showed that H₂ therapy, compared with placebo, significantly increased 6 MWT distance by 64 ± 39 m, FVC by 0.19 ± 0.24 L, and, in FEV1, by 0.11 ± 0.28 L (all p ≤ 0.025). In conclusion, H₂ inhalation had beneficial health effects in terms of improved physical and respiratory function in acute post-COVID-19 patients. Therefore, H₂ inhalation may represent a safe, effective approach for accelerating early function restoration in post-COVID-19 patients.

Molecular Hydrogen Mitigates Performance Decrement during Repeated Sprints in Professional Soccer Players

Hydrogen-rich water (HRW) supplementation has been shown to have an antifatigue effect across different modes of exercise. However, its effect on repeated sprint performance is unknown. The aim of this study was to assess the effect of pre-exercise HRW consumption on repeated sprint performance, lactate, and perceptual responses using a repeated sprint protocol. This randomized, double blinded, placebo controlled, crossover study included 16 professional, male soccer players aged 18.8 ± 1.2 years. Athletes performed two indoor tests, particularly 15 × 30 m track sprints interspersed by 20 s of recovery, separated by a 1-week washout period. Sprint time was measured at 15 m and 30 m. Ratings of perceived exertion were assessed immediately after each sprint, and post-exercise blood lactate concentration was measured after the last sprint. There were significantly faster sprint times after HRW consumption compared with placebo at 15 m for the 14th and 15th sprints, representing improvements in time of 3.4% and 2.7%, respectively. Sprint time at 30 m also significantly improved by 1.9% in the HRW group in the last sprint. However, neither lactate concentrations nor ratings of perceived exertion were significantly different between HRW and placebo. Pre-exercise HRW supplementation is associated with an increased ability to reduce fatigue, especially during the later stages of repeated sprint exercise.

Quantification of dissolved H2 and continuous monitoring of hydrogen-rich water for haemodialysis applications: An experimental study

The prevalence of oxidative and inflammatory stress in end-stage renal disease (ESRD) patients has often been associated with chronic haemodialysis therapies. Over the past decades, several reports have shown the potential of hydrogen molecule as an antioxidant in the treatment of various medical conditions in animal models, as well as in pilot studies with human patients. Recently, a hydrogen-enriched dialysate solution has been introduced, holding promise in reducing the oxidative and/or inflammatory complications arising during haemodialysis. To this end, a standardised measuring method to determine the levels of hydrogen in dialysate and subsequently in blood is required. This study explores the possibility of quantifying hydrogen concentration using a novel contactless sensor that detects dissolved hydrogen in liquids. An experimental circuit is assembled to validate the sensitivity and accuracy of the hydrogen monitoring system (Pureron Japan Co., Ltd) through in vitro investigations with physiological solutions. Measurements of dissolved molecular hydrogen concentration are corroborated by an established oxygen sensor providing continuous partial pressure readings. The relationship between the applied H₂ content in the gaseous mixture and the H₂ concentration value at equilibrium is linear. At the same time, the hydrogen monitoring system has a rather long response time, and its readings seem to slightly diverge from sensor to sensor as well as at different temperatures. For this reason, a sensor recalibration might be necessary, which could become part of the product's ongoing development. Nevertheless, the aforementioned minor deficiencies can be mostly considered negligible in applications such as haemodialysis.

Molecular Hydrogen as Medicine: An Assessment of Administration Methods

Since the late 18th century, molecular hydrogen (H2) has been shown to be well tolerated, firstly in animals, and then in humans. However, although research into the beneficial effects of molecular hydrogen in both plant and mammalian physiology is gaining momentum, the idea of utilising this electrochemically neutral and non-polar diatomic compound for the benefit of health has yet to be widely accepted by regulatory bodies worldwide. Due to the precise mechanisms of H2 activity being as yet undefined, the lack of primary target identification, coupled with difficulties regarding administration methods (e.g., dosage and dosage frequencies, long-term effects of treatment, and the patient’s innate antioxidant profile), there is a requirement for H2 research to evidence how it can reasonably and most effectively be incorporated into medical practice. This review collates and assesses the current information regarding the many routes of molecular hydrogen administration in animals and humans, whilst evaluating how targeted delivery methods could be integrated into a modern healthcare system.

Role of oxidative stress versus lipids in monocrotaline-induced pulmonary hypertension and right heart failure

Pulmonary hypertension (PH) is a global health issue with a prevalence of 10% in ages >65 years. Right heart failure (RHF) is the main cause of death in PH. We have previously shown that monocrotaline (MCT)-induced PH and RHF are due to an increase in oxidative stress. In this study, probucol (PROB), a strong antioxidant with a lipid-lowering property, versus lovastatin (LOV), a strong lipid-lowering drug with some antioxidant effects, were evaluated for their effects on the MCT-induced RHF. Rats were treated (I.P.) with PROB (10 mg/kg ×12) or LOV (4 mg/kg ×12), daily 6 days before and 6 days after a single MCT injection (60 mg/kg). Serial echocardiography was performed and at 4-week post-MCT, lung wet-to-dry weight, hemodynamics, RV glutathione peroxidase (GSHPx), superoxide dismutase (SOD), catalase, lipid peroxidation, and myocardial as well as plasma lipids were examined. MCT increased RV systolic and diastolic pressures, wall thickness, RV end diastolic diameter, mortality, and decreased ejection fraction as well as pulmonary artery acceleration time. These changes were mitigated by PROB while LOV had no effect. Furthermore, PROB prevented lipid peroxidation, lowered lipids, and increased GSHPx and SOD in RV myocardium. LOV did decrease the lipids but had no effect on antioxidants and lipid peroxidation. A reduction in oxidative stress and not the lipid-lowering effect of PROB may explain the prevention of MCT-induced PH, RHF, and mortality. Thus targeting of oxidative stress as an adjuvant therapy is suggested.

Molecular Hydrogen: Is This a Viable New Treatment for Plants in the UK?

Despite being trialed in other regions of the world, the use of molecular hydrogen (H₂) for enhanced plant growth and the postharvest storage of crops has yet to be widely accepted in the UK. The evidence that the treatment of plants and plant products with H₂ alleviates plant stress and slows crop senescence continues to grow. Many of these effects appear to be mediated by the alteration of the antioxidant capacity of plant cells. Some effects seem to involve heme oxygenase, whilst the reduction in the prosthetic group Fe³⁺ is also suggested as a mechanism. Although it is difficult to use as a gaseous treatment in a field setting, the use of hydrogen-rich water (HRW) has the potential to be of significant benefit to agricultural practices. However, the use of H₂ in agriculture will only be adopted if the benefits outweigh the production and application costs. HRW is safe and relatively easy to use. If H₂ gas or HRW are utilized in other countries for agricultural purposes, it is tempting to suggest that they could also be widely used in the UK in the future, particularly for postharvest storage, thus reducing food waste.

Molecular Hydrogen Attenuated N-methyl-N-Nitrosourea Induced Corneal Endothelial Injury by Upregulating Anti-Apoptotic Pathway

Purpose

Previous work by our group has demonstrated the value of N-methyl-N-nitrosourea (MNU)-induced corneal endothelial decompensation in animal models. The aim of this study was to investigate the effect of molecular hydrogen (H2) on MNU-induced corneal endothelial cell (CEC) injury and the underlying mechanism.

Methods

MNU-induced animal models of CEC injury were washed with hydrogen-rich saline (HRS) for 14 days. Immunofluorescence staining, immunohistochemical staining, and corneal endothelial assessment were applied to determine architectural and cellular changes on the corneal endothelium following HRS treatment. MNU-induced cell models of CEC injury were co-cultured with H2. The effect of H2 was examined using morphological and functional assays.

Results

It was shown that MNU could inhibit the proliferation and specific physiological functions of CECs by increasing apoptosis and decreasing the expression of ZO-1 and Na+/K+-ATPase, whereas H2 improved the proliferation and physiological function of CECs by anti-apoptosis. Cell experiments further confirmed that H2 could reverse MNU damage to CECs by decreasing oxidative stress injury, interfering with the NF-κB/NLRP3 pathway and the FOXO3a/p53/p21 pathway.

Conclusions

This study suggests that topical application of H2 could protect CECs against corneal damage factors through anti-apoptotic effect, reduce the incidence and severity of corneal endothelial decompensation, and maintain corneal transparency.

Mitochondria at Work: New Insights into Regulation and Dysregulation of Cellular Energy Supply and Metabolism

Mitochondria are of great relevance to health, and their dysregulation is associated with major chronic diseases. Research on mitochondria-156 brand new publications from 2019 and 2020-have contributed to this review. Mitochondria have been fundamental for the evolution of complex organisms. As important and semi-autonomous organelles in cells, they can adapt their function to the needs of the respective organ. They can program their function to energy supply (e.g., to keep heart muscle cells going, life-long) or to metabolism (e.g., to support hepatocytes and liver function). The capacity of mitochondria to re-program between different options is important for all cell types that are capable of changing between a resting state and cell proliferation, such as stem cells and immune cells. Major chronic diseases are characterized by mitochondrial dysregulation. This will be exemplified by cardiovascular diseases, metabolic syndrome, neurodegenerative diseases, immune system disorders, and cancer. New strategies for intervention in chronic diseases will be presented. The tumor microenvironment can be considered a battlefield between cancer and immune defense, competing for energy supply and metabolism. Cancer cachexia is considered as a final stage of cancer progression. Nevertheless, the review will present an example of complete remission of cachexia via immune cell transfer. These findings should encourage studies along the lines of mitochondria, energy supply, and metabolism.