A review of experimental studies of hydrogen as a new therapeutic agent in emergency and critical care medicine

Molecular hydrogen promotes wound healing by inducing early epidermal stem cell proliferation and extracellular matrix deposition

BACKGROUND

Despite progress in developing wound care strategies, there is currently no treatment that promotes the self-tissue repair capabilities. H₂ has been shown to effectively protect cells and tissues from oxidative and inflammatory damage. While comprehensive effects and how H₂ functions in wound healing remains unknown, especially for the link between H₂ and extracellular matrix (ECM) deposition and epidermal stem cells (EpSCs) activation.

METHODS

Here, we established a cutaneous aseptic wound model and applied a high concentration of H₂ (66% H₂) in a treatment chamber. Molecular mechanisms and the effects of healing were evaluated by gene functional enrichment analysis, digital spatial profiler analysis, blood perfusion/oxygen detection assay, in vitro tube formation assay, enzyme-linked immunosorbent assay, immunofluorescent staining, non-targeted metabonomic analysis, flow cytometry, transmission electron microscope, and live-cell imaging.

RESULTS

We revealed that a high concentration of H₂ (66% H₂) greatly increased the healing rate (3 times higher than the control group) on day 11 post-wounding. The effect was not dependent on O₂ or anti-reactive oxygen species functions. Histological and cellular experiments proved the fast re-epithelialization in the H₂ group. ECM components early (3 days post-wounding) deposition were found in the H₂ group of the proximal wound, especially for the dermal col-I, epidermal col-III, and dermis-epidermis-junction col-XVII. H₂ accelerated early autologous EpSCs proliferation (1-2 days in advance) and then differentiation into myoepithelial cells. These epidermal myoepithelial cells could further contribute to ECM deposition. Other beneficial outcomes include sustained moist healing, greater vascularization, less T-helper-1 and T-helper-17 cell-related systemic inflammation, and better tissue remodelling.

CONCLUSION

We have discovered a novel pattern of wound healing induced by molecular hydrogen treatment. This is the first time to reveal the direct link between H₂ and ECM deposition and EpSCs activation. These H₂-induced multiple advantages in healing may be related to the enhancement of cell viability in various cells and the maintenance of mitochondrial functions at a basic level in the biological processes of life.

Molecular Hydrogen: From Molecular Effects to Stem Cells Management and Tissue Regeneration

It is known that molecular hydrogen is a relatively stable, ubiquitous gas that is a minor component of the atmosphere. At the same time, in recent decades molecular hydrogen has been shown to have diverse biological effects. By the end of 2022, more than 2000 articles have been published in the field of hydrogen medicine, many of which are original studies. Despite the existence of several review articles on the biology of molecular hydrogen, many aspects of the research direction remain unsystematic. Therefore, the purpose of this review was to systematize ideas about the nature, characteristics, and mechanisms of the influence of molecular hydrogen on various types of cells, including stem cells. The historical aspects of the discovery of the biological activity of molecular hydrogen are presented. The ways of administering molecular hydrogen into the body are described. The molecular, cellular, tissue, and systemic effects of hydrogen are also reviewed. Specifically, the effect of hydrogen on various types of cells, including stem cells, is addressed. The existing literature indicates that the molecular and cellular effects of hydrogen qualify it to be a potentially effective agent in regenerative medicine.

Incorporation of hydrogen into the packaging atmosphere protects the nutritional, textural and sensorial freshness notes of strawberries and extends shelf life

Strawberries are known for their high perishability and short shelf life. The effects of incorporating hydrogen gas into sealed packaging on the quality and shelf life of strawberries were evaluated. Fruits were packaged under reducing atmosphere [RAP1 (5% CO 2 , 4% H 2 , 91% N 2 ) and RAP2 (10% CO 2 , 4% H 2 , 86% N 2 )], modified atmosphere [MAP1 (5% CO 2 , 95% N 2 ) and MAP2 (10% CO 2 , 90% N 2 )], and control, followed by 12 weeks storage at 4 °C. At the end of storage, RAPs exhibited higher total soluble solids (TSS), firmness, L* and a*, phenolic and anthocyanin contents, and antioxidant activity followed by MAPs when compared with control. RAP2 was more potent in protecting the freshness indices than RAP1, and MAP2 outperformed MAP1, with the best protection characteristic attributed to RAP2. RAP technique extended the shelf life by 3-5 times the control, and 1.5-3.0 times the MAP. RAP should be recommended as a green and healthy preservation technique for the long storage of fresh fruits.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05427-y.

Future of Hydrogen as an Alternative Fuel for Next-Generation Industrial Applications; Challenges and Expected Opportunities

A general rise in environmental and anthropogenically induced greenhouse gas emissions has resulted from worldwide population growth and a growing appetite for clean energy, industrial outputs, and consumer utilization. Furthermore, well-established, advanced, and emerging countries are seeking fossil fuel and petroleum resources to support their aviation, electric utilities, industrial sectors, and consumer processing essentials. There is an increasing tendency to overcome these challenging concerns and achieve the Paris Agreement’s priorities as emerging technological advances in clean energy technologies progress. Hydrogen is expected to be implemented in various production applications as a fundamental fuel in future energy carrier materials development and manufacturing processes. This paper summarizes recent developments and hydrogen technologies in fuel refining, hydrocarbon processing, materials manufacturing, pharmaceuticals, aircraft construction, electronics, and other hydrogen applications. It also highlights the existing industrialization scenario and describes prospective innovations, including theoretical scientific advancements, green raw materials production, potential exploration, and renewable resource integration. Moreover, this article further discusses some socioeconomic implications of hydrogen as a green resource.

Mechanisms Underlying the Biological Effects of Molecular Hydrogen

Aberrant redox-sensitive reactions and accumulation of oxidative damage can impair body functions and contribute to the development of various pathologies and aging. Although antioxidant substances have long been recognized as a measure of alleviating oxidative stress and restoring redox balance, the arsenal of effective means of preventing the development of various disorders, is still limited. There is an emerging field that utilizes molecular hydrogen (H₂) as a scavenger of free radicals and reactive oxygen species (ROS). Among the remarkable characteristics of H₂ is its ability to counteract the harmful effects of hydroxyl radical and peroxynitrite without affecting the activity of functionally important ROS, such as hydrogen peroxide and nitric oxide. The beneficial effects of H₂ have been documented in numerous clinical studies and studies on animal models and cell cultures. However, the established scavenging activity of H₂ can only partially explain its beneficial effects because the effects are achieved at very low concentrations of H₂. Given the rate of H₂ diffusion, such low concentrations may not be sufficient to scavenge continuously generated ROS. H₂ can also act as a signaling molecule and induce defense responses. However, the exact targets and mechanism(s) by which H₂ exerts these effects are unknown. Here, we analyzed both positive and negative effects of the endogenous H₂, identified the redox-sensitive components of the pathways affected by molecular hydrogen, and also discussed the potential role of molecular hydrogen in regulating cellular redox.

Inhaled Gases as Therapies for Post-Cardiac Arrest Syndrome: A Narrative Review of Recent Developments

Despite recent advances in the management of post-cardiac arrest syndrome (PCAS), the survival rate, without neurologic sequelae after resuscitation, remains very low. Whole-body ischemia, followed by reperfusion after cardiac arrest (CA), contributes to PCAS, for which established pharmaceutical interventions are still lacking. It has been shown that a number of different processes can ultimately lead to neuronal injury and cell death in the pathology of PCAS, including vasoconstriction, protein modification, impaired mitochondrial respiration, cell death signaling, inflammation, and excessive oxidative stress. Recently, the pathophysiological effects of inhaled gases including nitric oxide (NO), molecular hydrogen (H₂), and xenon (Xe) have attracted much attention. Herein, we summarize recent literature on the application of NO, H₂, and Xe for treating PCAS. Recent basic and clinical research has shown that these gases have cytoprotective effects against PCAS. Nevertheless, there are likely differences in the mechanisms by which these gases modulate reperfusion injury after CA. Further preclinical and clinical studies examining the combinations of standard post-CA care and inhaled gas treatment to prevent ischemia-reperfusion injury are warranted to improve outcomes in patients who are being failed by our current therapies.

Recent advances in studies of molecular hydrogen in the treatment of pancreatitis

Pancreatitis is an inflammatory disease of the pancreas characterized by acinar cell injury and is associated with the abnormal release of trypsin, which results in high mortality due to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). The inflammatory response, impaired autophagic flux, endoplasmic reticulum stress (ERS) and their interactions are involved in the development of pancreatitis. Molecular hydrogen (H₂) is a novel antioxidant that possesses the features of selective scavenging of oxygen free radicals and nontoxic metabolites and has been shown to be efficacious for treating infection, injury, tumors, ischemia-reperfusion organ injury, metabolic disease and several other diseases. Recent studies have found that H₂ is also useful in the treatment of pancreatitis, which may be related to the mechanism of antioxidative stress, anti-inflammation, anti-apoptosis, regulation of immunity and regulation of molecular pathways. This review focuses on the pathogenesis of pancreatitis and the research progress and potential mechanisms of H₂ against pancreatitis to provide theoretical bases for future research and clinical application of H₂ therapy for pancreatitis.

Amelioration of Coagulation Disorders and Inflammation by Hydrogen-Rich Solution Reduces Intestinal Ischemia/Reperfusion Injury in Rats through NF-κB/NLRP3 Pathway

Intestinal ischemia/reperfusion (I/R) injury often causes inflammatory responses and coagulation disorders, which is further promoting the deterioration of the disease. Hydrogen has anti-inflammatory, antioxidative, and antiapoptotic properties against various diseases. However, the effect of hydrogen on coagulation dysfunction after intestinal I/R and the underlying mechanism remains unclear. The purpose of this study was to explore whether hydrogen-rich solution (HRS) could attenuate coagulation disorders and inflammation to improve intestinal injury and poor survival following intestinal I/R. The rat model of intestinal I/R injury was established by clamping the superior mesenteric artery for 90 min and reperfusion for 2 h. HRS (10 or 20 mL/kg) or 20 mL/kg 0.9% normal saline was intravenously injected at 10 min before reperfusion, respectively. The samples were harvested at 2 h after reperfusion for further analyses. Moreover, the survival rate was observed for 24 h. The results showed that HRS improved the survival rate and alleviated serum diamine oxidase activities, intestinal injury, edema, and apoptosis. Interestingly, HRS markedly improved intestinal I/R-mediated coagulation disorders as evidenced by abnormal conventional indicators of coagulation and thromboelastography. Additionally, HRS attenuated inflammatory responses and the elevated tissue factor (TF) and inhibited nuclear factor kappa beta (NF-κB) and nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation in peripheral blood mononuclear cells. Moreover, inflammatory factors and myeloperoxidase were closely associated with TF level. This study thus emphasized upon the amelioration of coagulation disorders and inflammation by HRS as a mechanism to improve intestinal I/R-induced intestinal injury and poor survival, which might be partially related to inhibition of NF-κB/NLRP3 pathway.

Hydrogen gas therapy improves survival rate and neurological deficits in subarachnoid hemorrhage rats: a pilot study

The high morbidity, high mortality, and significant shortage of effective therapies for subarachnoid hemorrhage (SAH) have created an urgency to discover novel therapies. Human studies in Asia have established the safety of hydrogen gas in the treatment of hepatic, renal, pulmonary, and cardiac diseases. Mechanistically, hydrogen gas has been shown to affect oxidative stress, inflammation, and apoptosis. We hypothesized that hydrogen therapy would improve neurological function and increase survival rate in SAH. High dose hydrogen gas (66% at 3 L/min) was administered for 2 hours at 0.5, 8, and 18 hours after SAH. This treatment increased 72-hour survival rate and provided 24-hour neuroprotection after SAH in rats. To our knowledge, this is the first report demonstrating that high dose hydrogen gas therapy reduces mortality and improves outcome after SAH. Our results correlate well with the proposed mechanisms of hydrogen gas therapy within the literature. We outline four pathways and downstream targets of hydrogen gas potentially responsible for our results. A potentially complex network of pathways responsible for the efficacy of hydrogen gas therapy, along with a limited mechanistic understanding of these pathways, justifies further investigation to provide a basis for clinical trials and the advancement of hydrogen gas therapy in humans. This study was approved by the Institutional Animal Care and Use Committee of Loma Linda University, USA (Approval No. 8160016) in May 2016.

Inhalation of molecular hydrogen prevents ischemia-reperfusion liver damage during major liver resection

Background

Liver resection is a surgical procedure associated with a high risk of hepatic failure that can be fatal. One of the key mechanisms involves ischemia-reperfusion damage. Building on the well-known positive effects of hydrogen at mitigating this damage, the goal of this work was to demonstrate the antioxidant, anti-inflammatory, and anti-apoptotic effects of inhaled hydrogen in domestic pigs during major liver resection.

Methods

The study used a total of 12 domestic pigs, 6 animals underwent resection with inhaled hydrogen during general anesthesia, and 6 animals underwent the same procedure using conventional, unsupplemented, general anesthesia. Intraoperative preparation of the left branch of the hepatic portal vein and the left hepatic artery was performed, and a tourniquet was applied. Warm ischemia was induced for 120 minutes and then followed by liver reperfusion for another 120 minutes. Samples from the ischemic and non-ischemic halves of the liver were then removed for histological and biochemical examinations.

Results

An evaluation of histological changes was based on a numerical expression of damage based on the Suzuki score. Liver samples in the group with inhaled hydrogen showed a statistically significant reduction in histological changes compared to the control group. Biochemical test scores showed no statistically significant difference in hepatic transaminases, alkaline phosphatase (ALP), lactate dehydrogenase (LD), and lactate. However, a surprising result was a statistically significant difference in gamma-glutamyl-transferase (GMT). Marker levels of oxidative damage varied noticeably in plasma samples.

Conclusions

In this experimental study, we showed that inhaled hydrogen during major liver resection unquestionably reduced the level of oxidative stress associated with ischemia-reperfusion damage. We confirmed this phenomenon both histologically and by direct measurement of oxidative stress in the organism.

Comparative study on protective effect of hydrogen rich saline and adipose-derived stem cells on hepatic ischemia-reperfusion and hepatectomy injury in swine

AIM

To compare and evaluate the hepatoprotective effect of liver parenchyma injection of ADSCs and portal vein injection of HRS in laparoscopic hepatic ischemia reperfusion combined with hepatectomy injury in miniature pigs.

METHODS

Eighteen miniature pigs were randomly assigned to IRI group, HRS group and ADSCs group. HRS was injected through the portal vein 10 min before reperfusion, 1 d, 2 d, and 3 d after surgery. ADSCs were injected into liver parenchyma after hepatectomy. The serum and liver tissue samples were collected at different time points (preoperative, and postoperative at 1 d, 3 d and 7 d).

RESULTS

Compared with the IRI group, both ADSCs and HRS groups can promote liver function recovery, reduce oxidative stress, reduce inflammation, and promote liver regeneration. Compared with HRS, ALT and TBIL in ADSCs group were significantly decreased at 3 d, and AST was significantly reduced at 1 d. The activities of SOD and GSH-Px in ADSCs group were significantly higher than that in HRS group, but the MDA level in HRS group was markedly lower than that in ADSCs group at 1 d. IL-1β was significantly lower in the ADSCs group than in the HRS group at 1 day after operation. The expressions of HGF and PCNA were significantly higher than that in the HRS group at 3 day after surgery.

CONCLUSION

Our study has demonstrated that HRS and ADSCs have significant hepatoprotective effects in miniature pigs after HIRI and hepatectomy injury. However, liver parenchyma injection of ADSCs is more beneficial to the recovery of liver function than portal vein injection of HRS.

Recent Advances in Studies of Molecular Hydrogen against Sepsis

Sepsis is a syndrome comprised of a series of life-threatening organ dysfunctions caused by a maladjusted body response to infection with no effective treatment. Molecular hydrogen is a new type of antioxidant with strong free radical scavenging ability, which has been demonstrated to be effective for treating various diseases, such as infection, trauma, poisoning, organ ischemia-reperfusion, metabolic diseases, and tumors. Molecular hydrogen exerts multiple biological effects involving anti-inflammation, anti-oxidation, anti-apoptosis, anti-shock, and autophagy regulation, which may attenuate the organ and barrier damage caused by sepsis. However, the underlying molecular mechanisms remain elusive, but are likely related to the signaling pathways involved. This review focuses on the research progress and potential mechanisms of molecular hydrogen against sepsis to provide a theoretical basis for clinical treatment.

Transcriptome analysis of radish sprouts hypocotyls reveals the regulatory role of hydrogen-rich water in anthocyanin biosynthesis under UV-A

BACKGROUND

Hydrogen gas (H2) is the most abundant element in the universe, and has been reported to act as a novel beneficial gaseous molecule in plant adaptive responses. Radish sprouts are popular because they contain substantial amounts of antioxidants and health-promoting compounds, such as anthocyanin and glucosinolates. Although radish sprouts accumulated more anthocyanin under UV-A after treatment with hydrogen-rich water (HRW), the molecular mechanism responsible is still elusive. To explore these mechanisms, RNA-seq analysis was used.

RESULTS

Four cDNA libraries from radish sprout hypocotyls were constructed, and a total of 14,564 differentially expressed genes (DEGs) were identified through pairwise comparisons. By Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, these unigenes were found to be implicated in light signal perception and transduction, starch and sucrose metabolism, photosynthesis, nitrogen metabolism and biosynthesis of secondary metabolites. The MYB-bHLH-WD40 complex accounted for the majority of the transcription factors found to be involved in anthocyanin biosynthesis, and levels of transcripts for this complex were in accordance with the anthocyanin concentrations observed. In addition, other transcription factors (such as NAC, bZIP and TCP) might participate in HRW-promoted anthocyanin biosynthesis. Furthermore, the signaling processes of plant hormones, MAPKs and Ca2+ might be involved in HRW-promoted anthocyanin biosynthesis under UV-A. The expression patterns of 16 selected genes were confirmed using qRT-PCR analysis.

CONCLUSIONS

Taken together, the results of this study may expand our understanding of HRW-promoted anthocyanin accumulation under UV-A in radish sprouts.

Effects of hydrogen-rich saline on endotoxin-induced uveitis

The therapeutic effects of hydrogen-rich saline (HRS) have been reported for a wide range of diseases mainly via selectively reducing the amount of reactive oxygen species. Oxidative stress plays an important role in the pathogenesis of uveitis and endotoxin-induced uveitis (EIU). In this study, we investigated whether HRS can mitigate EIU in rats. Sprague-Dawley rats were randomly divided into Norm group, Model group, HRS group, dexamethasone (DEX) group, and rats in the latter three groups were injected with equal amount of lipopolysaccharide (LPS) to induce EIU of different severities (by 1 mg/kg of LPS, or 1/8 mg/kg of LPS). Rats in HRS group were injected with HRS intraperitoneally at three different modes to purse an ameliorating effect of EIU (10 mL/kg of HRS immediately after injection of 1 mg/kg of LPS, 20 mL/kg of HRS once a day for 1 week before injection of 1 mg/kg of LPS and at 0, 0.5, 1, 2, 6, 8, 12 hours after LPS administration, or 20 mL/kg of HRS once a day for 1 week before injection of 1/8 mg/kg of LPS, and at 0, 0.5, 1, 2, 6, 8, 12, 24 hours and once a day for 3 weeks after LPS administration). Rats of DEX group were injected with 1 mL/kg of DEX solution intraperitoneally immediately after LPS administration. Rats in Norm and Model groups did not receive any treatment. All rats were examined under slit lamp microscope and graded according to the clinical signs of uveitis. Electroretinogram, quantitative analysis of protein in aqueous humor (AqH) and histological examination of iris and ciliary body were also carried out. Our results showed that HRS did not obviously ameliorate the signs of uveitis under slit lamp examination and the inflammatory cells infiltration around iris and cilliary body of EIU induced by 1 mg/kg or 1/8 mg/kg of LPS (P > 0.05), while DEX significantly reduced the inflammation reflected by the above two indicators (P < 0.05). The impaired retinal function of mild EIU induced by 1/8 mg/kg of LPS, showed by delay of peak time of b-wave of Dark adapted 3.0 electroretinogram, was not significantly restored by HRS (P > 0.05), while DEX had an obvious therapeutic effect (P < 0.05). However, HRS exerted an inhibition trend on elevation of protein in AqH of EIU induced by 1 mg/kg of LPS, and significantly reduced the increasing amount of protein in AqH of mild EIU induced by 1/8 mg/kg of LPS (P < 0.05). In conclusion, HRS could not obviously mitigate EIU in rats, while it could inhibit the elevation of AqH protein.