Hydrogen Flush After Cold Storage as a New End‐Ischemic Ex Vivo Treatment for Liver Grafts Against Ischemia/Reperfusion Injury

Abstract

Cold storage (CS) remains the gold standard for organ preservation worldwide, although it is inevitably associated with ischemia/reperfusion injury (IRI). Molecular hydrogen (H ) is well known to have antioxidative properties. However, its unfavorable features, ie, inflammability, low solubility, and high tissue/substance permeability, have hampered its clinical application. To overcome such obstacles, we developed a novel reconditioning method for donor organs named hydrogen flush after cold storage (HyFACS), which is just an end-ischemic H flush directly to donor organs ex vivo, and, herein, we report its therapeutic impact against hepatic IRI. Whole liver grafts were retrieved from Wistar rats. After 24-hour CS in UW solution, livers were cold-flushed with H solution (1.0 ppm) via the portal vein (PV), the hepatic artery (HA), or both (PV + HA). Functional integrity and morphological damages were then evaluated by 2-hour oxygenated reperfusion at 37°C. HyFACS significantly lowered portal venous pressure, transaminase, and high mobility group box protein 1 release compared with vehicle-treated controls (P < 0.01). Hyaluronic acid clearance was significantly higher in the HyFACS-PV and -PV + HA groups when compared with the others (P < 0.01), demonstrating the efficacy of the PV route to maintain the sinusoidal endothelia. In contrast, bile production and lactate dehydrogenase leakage therein were both significantly improved in HyFACS-HA and -PV + HA (P < 0.01), representing the superiority of the arterial route to attenuate biliary damage. Electron microscopy consistently revealed that sinusoidal ultrastructures were well maintained by portal HyFACS, while microvilli in bile canaliculi were well preserved by arterial flush. As an underlying mechanism, HyFACS significantly lowered oxidative damages, thus improving the glutathione/glutathione disulfide ratio in liver tissue. In conclusion, HyFACS significantly protected liver grafts from IRI by ameliorating oxidative damage upon reperfusion in the characteristic manner with its route of administration. Given its safety, simplicity, and cost-effectiveness, end-ischemic HyFACS may be a novel pretransplant conditioning for cold-stored donor organs.

Organ preservation solution containing dissolved hydrogen gas from a hydrogen-absorbing alloy canister improves function of transplanted ischemic kidneys in miniature pigs

“…Previous methods for dissolving hydrogen in organ preservation solutions have involved generation of hydrogen by electrolysis [18,20,21,22] or by use of a hydrogen-generating agent [17], after which the hydrogen gas undergoes passive diffusion into the organ preservation solution. However, these methods are complicated and are unsuitable for clinical use Dissolving hydrogen gas in organ preservation solution with a hydrogen-absorbing alloy canister since it requires 24-48 hours for the hydrogen gas concentration in the solution to reach 1 mg/L.…”

“…Use of hydrogen gas has been reported to be effective in transplantation models of various organs, including the small intestine [6][7], lung [8][9][10][11][12][13][14], liver [15][16][17][18], heart [19,20], osteochondral tissue [21], and kidney [22]. It is possible to expose the excised organ to hydrogen gas ex vivo without the donor and/or recipient inhaling the gas, and various methods have been devised to dissolve hydrogen gas in organ preservation solutions, including use of a hydrogen gas cylinder [6], electrolysis [18,20,21,22], or a hydrogen-generating agent [17]. However, these methods require bulky equipment and dangerous high-pressure cylinders with strict regulations for handling, resulting in the need to expend considerable time and effort for preparation.…”

Hydrogen: A Novel Option in Human Disease Treatment

“…In a human study, HW also significantly reduced liver fat accumulation in twelve overweight outpatients with NAFLD [ 111 ]. Another in vivo study revealed that oral HW significantly attenuated oxidative stress in patients with chronic hepatitis B [ 112 ]. In recent years, it has become widely accepted that bile acids are a nutrient signaling hormone [ 113 ].…”

Pharmacokinetics of a single inhalation of hydrogen gas in pigs

“…Oxygen is supplied by the PV and the hepatic artery in half each. Therefore, in contrast to the brain, the liver has been regarded as the organ where inhaled H 2 is least likely to reach [16]. The liver is the largest organ in the body, performing a number of functions that are essential for life, such as metabolism, detoxification, and excretion, so protecting it with H 2 is considered to be a great advantage.…”