Argon Delays Initiation of Liver Regeneration after Partial Hepatectomy in Rats

Abstract

Background: The liver can heal up to restitutio ad integrum following damage resulting from various causes. Different studies have demonstrated the protective effect of argon on various cells and organs. To the best of our knowledge, the organ-protective effects of the noble gas argon on the liver have not yet been investigated, although argon appears to influence signal paths that are well-known mediators of liver regeneration. We hypothesized that argon inhalation prior to partial hepatectomy (70%) has a positive effect on the initiation of liver regeneration in rats. Methods: Partial hepatectomy (70%) with or without inhaled argon (50 vol%) was performed for 1 h. Liver tissue was harvested after 3, 36, and 96 h to analyze the mRNA and protein expression of hepatocyte growth factor (HGF), interleukin-6 (IL-6), tumor necrosis factor-α, and extracellular signal-regulated kinase 1/2. Histological tissue samples were prepared for immunohistochemistry (bromodeoxyuridine [BrdU], Ki-67, and TUNEL) and blood was analyzed regarding the effects of argon on liver function. Statistical analyses were performed using 1-way ANOVA followed by the post hoc Tukey-Kramer test. Results: After 3 h, the primary outcome parameter of hepatocyte proliferation was significantly reduced with argon 50 vol% inhalation in comparison to nitrogen inhalation (BrdU: 15.7 ± 9.7 vs. 7.7 ± 3.1 positive cells/1,000 hepatocytes, p = 0.013; Ki-67: 17.6 ± 13.3 vs. 4.7 ± 5.4 positive cells/1,000 hepatocytes, p = 0.006). This was most likely mediated by significant downregulation of HGF (after 3 h: 5.2 ± 3.2 vs. 2.3 ± 1.0 fold, p = 0.032; after 96 h: 2.1 ± 0.5 vs. 1.3 ± 0.3 fold, p = 0.029) and IL-6 (after 3 h: 43.7 ± 39.6 vs. 8.5 ± 9.2 fold, p = 0.032). Nevertheless, we could detect no significant effect on the weight of the residual liver, liver-body weight ratio, or liver blood test results after argon inhalation. Conclusion: Impairment of liver regeneration was apparent after argon 50 vol% inhalation that was most probably mediated by downregulation of HGF and IL-6 in the initial phase. However, the present study was not adequately powered to prove that argon has detrimental effects on the liver. Further studies are needed to evaluate the effects of argon on livers with preexisting conditions as well as on ischemia-reperfusion models.

A complete review of preclinical and clinical uses of the noble gas argon: Evidence of safety and protection

“…[13171845] Nine studies focused on the preservation of other organs and tissues, such as ex vivo perfused kidney and lung, and culture of human airway epithelium, kidney tubular, and osteosarcoma cells. [192123324647485253] A single study evaluated the influence of Ar inhalation on liver regeneration after partial hepatectomy. [53] Three in vivo studies investigated the effects and the mechanisms of action of Ar under hyperbaric condition.…”

“…[192123324647485253] A single study evaluated the influence of Ar inhalation on liver regeneration after partial hepatectomy. [53] Three in vivo studies investigated the effects and the mechanisms of action of Ar under hyperbaric condition. [424344] Five studies specifically focused on the safety: In 2, Ar was administered as respiratory mixture to pigs;[3652] while, in 3 studies, Ar was used to induce pneumoperitoneum for surgical laparoscopic procedures in place of CO 2 .…”

“…[14] Only in 3 studies specifically focused on myocardial I/R, EVLP, and liver regeneration, Ar was employed as a preconditioning agent, before induction of the insult. [455253]…”

Inhaled Argon Impedes Hepatic Regeneration after Ischemia/Reperfusion Injury in Rats

“…Rats were sacrificed after 3, 36 or 96 h after the operation. Survival times were determined according to a previously performed experiment [25].…”

“…Prior to the operation, animals were exposed to either 50 Vol% argon (argon group) or 50 Vol% nitrogen (control group) balanced with 48 Vol% oxygen and 2 Vol% Isoflurane for 60 min (preconditioning). Concentrations were based on the findings of a previous study [25]. Directly thereafter, surgery was performed under isoflurane anesthesia (1.5 Vol%) and the argon inhalation was stopped.…”