2019 · Kobayashi — Organ Preservation Solution Containing Dissolved Hydrogen Gas from a Hydrogen-Absorbing Alloy Canister Improves Function of Transplanted Ischemic Kidneys in Miniature Pigs
Super-Abstract
Adding dissolved molecular hydrogen (H₂) to the organ preservation solution — via a rapid, practical canister method — significantly improved kidney function after transplantation from donors with circulatory arrest in miniature pigs. Kidneys stored in H₂-containing solution produced urine and showed blood flow on day 6 post-transplant, while those stored in standard solution without H₂ did not. This is an animal study; direct human applicability requires further research. (PLoS ONE, 2019.)
Commentary
Organ preservation during transplantation is a critical window in which ischemia-reperfusion injury (IRI) causes lasting damage. Kobayashi et al. tackle both a scientific question (does H₂ protect kidneys from warm ischemic injury?) and an engineering challenge (how to rapidly dissolve H₂ in cold preservation solution at the bedside?). Their solution is a portable hydrogen-absorbing alloy canister that saturates cold ETK solution in just 2–3 minutes to ≥ 1.0 mg/L H₂ — a concentration maintained for at least 4 hours after bag opening. In the miniature pig donor-after-circulatory-death model, H₂-containing preservation solution produced a striking functional difference: kidneys recovered urinary output and perfusion by day 6, while standard-solution kidneys showed neither. The practical implications are potentially significant for transplant medicine, but the study is animal-level proof-of-concept, not a clinical trial.
Key quotes
- „The time required for dissolution of hydrogen gas was only 2-3 minutes.“ — the practical advantage of the alloy-canister method over cumbersome cylinder or electrolysis approaches
- „after storage of the kidney in hydrogen-free preservation solution for 1 hour before transplantation, no urine production was observed and blood flow was not detected in the transplanted kidney at sacrifice on postoperative day 6“ — stark functional failure in the control group — kidney non-functional
- „after storage in hydrogen-containing preservation solution for either 1 or 4 hours, urine was detected in the bladder and blood flow was confirmed in the transplanted kidney“ — H₂ group: kidney function preserved even after 4 h storage
Our assessment
A well-designed animal study (miniature pig) with a clear, clinically relevant question. The functional endpoint (urine production + blood flow at day 6) is meaningful and the results are striking. Honest limitations: (1) this is a pig model, not a human trial — direct transfer is not warranted; (2) the sample sizes are not detailed in the abstract, making statistical evaluation impossible; (3) only one cold ischemia time series was tested; (4) longer follow-up and rejection/fibrosis outcomes are not assessed. If confirmed in larger trials, H₂-enriched preservation solution could be a practical, low-cost addition to transplant protocols — but clinical validation is needed.
Study design
- Type: controlled animal experiment · Model: miniature pig kidney transplantation from donors with circulatory arrest (30 min warm ischemia) · H₂ delivery: dissolved H₂ (≥ 1.0 mg/L) in cold ETK organ preservation solution via hydrogen-absorbing alloy canister
- Groups: H₂-containing ETK solution (1 h or 4 h storage) vs. hydrogen-free ETK solution (1 h storage)
- Result: H₂ groups: urine present in bladder + blood flow confirmed in transplanted kidney on day 6; control group: no urine production, no blood flow detected — kidney functionally failed
Abstract
Various methods have been devised to dissolve hydrogen gas in organ preservation solutions, including use of a hydrogen gas cylinder, electrolysis, or a hydrogen-generating agent. However, these methods require considerable time and effort for preparation. We investigated a practical technique for rapidly dissolving hydrogen gas in organ preservation solutions by using a canister containing hydrogen-absorbing alloy. The efficacy of hydrogen-containing organ preservation solution created by this method was tested in a miniature pig model of kidney transplantation from donors with circulatory arrest. The time required for dissolution of hydrogen gas was only 2-3 minutes. When hydrogen gas was infused into a bag containing cold ETK organ preservation solution at a pressure of 0.06 MPa and the bag was subsequently opened to the air, the dissolved hydrogen concentration remained at 1.0 mg/L or more for 4 hours. After warm ischemic injury was induced by circulatory arrest for 30 minutes, donor kidneys were harvested and perfused for 5 minutes with hydrogen-containing cold ETK solution or hydrogen-free cold ETK solution. The perfusion rate was faster from the initial stage with hydrogen-containing cold ETK solution than with hydrogen-free ETK solution. After storage of the kidney in hydrogen-free preservation solution for 1 hour before transplantation, no urine production was observed and blood flow was not detected in the transplanted kidney at sacrifice on postoperative day 6. In contrast, after storage in hydrogen-containing preservation solution for either 1 or 4 hours, urine was detected in the bladder and blood flow was confirmed in the transplanted kidney. This method of dissolving hydrogen gas in organ preservation solution is a practical technique for potentially converting damaged organs to transplantable organs that can be used safely in any clinical setting where organs are removed from donors.
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