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
- DOI
- 10.4240/wjgs.v14.i12.1329
- PMC
- PMC9827576
Tags
Delivery context
In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.
Safety notes
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