# Hydrogen gas and preservation of intestinal stem cells in mesenteric ischemia and reperfusion.
> 腸間膜虚血再灌流における水素ガス吸入と腸管幹細胞保護効果の検討


## Abstract

Using a rat model of mesenteric ischemia-reperfusion, this study investigated the effects of continuous 3% hydrogen gas inhalation on intestinal tissue. Three experimental groups were compared: ischemia alone (60-min mesenteric artery occlusion), ischemia followed by reperfusion, and ischemia-reperfusion with concurrent hydrogen inhalation. Ischemia primarily damaged villous tip epithelium, while reperfusion caused extensive apoptosis at the crypt base, where LGR5-positive intestinal stem cells reside. Hydrogen inhalation markedly reduced crypt-base apoptosis and maintained higher LGR5 and OLFM4 mRNA levels compared with the reperfusion-only group. Tissue 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, was elevated in the reperfusion group and substantially reduced by hydrogen, particularly at the crypt base. Systemic plasma 8-OHdG showed a non-significant trend toward elevation in both reperfusion groups. These findings indicate that hydrogen gas inhalation preserves intestinal stem cell viability by attenuating local oxidative stress during mesenteric ischemia-reperfusion.

### Mechanism

Hydrogen gas scavenges reactive oxygen species, reducing oxidative DNA damage (measured by 8-OHdG) at the intestinal crypt base and thereby suppressing apoptosis of LGR5-positive intestinal stem cells during reperfusion.

## Bibliographic

- **Authors**: Yamamoto R, Suzuki S, Homma K, Yamaguchi S, Sujino T, Sasaki J
- **Journal**: World J Gastrointest Surg
- **Year**: 2022 (2022-12-27)
- **PMID**: [36632117](https://pubmed.ncbi.nlm.nih.gov/36632117/)
- **DOI**: [10.4240/wjgs.v14.i12.1329](https://doi.org/10.4240/wjgs.v14.i12.1329)
- **PMC**: [PMC9827576](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9827576/)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 3%

## Delivery context

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

## Safety notes

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 36632117. https://h2-papers.org/en/papers/36632117
> **Source**: PubMed PMID [36632117](https://pubmed.ncbi.nlm.nih.gov/36632117/)