Background: Massive hepatectomy (MHX) leads to failure of remnant livers. Excessive metabolic burden in remnant livers may cause mitochondrial dysfunction. This study investigated whether blockade of the mitochondrial permeability transition (MPT) with N-methyl-4-isoleucine cyclosporine (NIM811) improves the outcome of MHX.
Methods: Mice were gavaged with NIM811 (10 mg/kg before surgery and 5 mg/kg daily afterward) and underwent sham-operation or approximately 90% partial hepatectomy.
Results: Serum alanine aminotransferase, necrosis, and apoptosis increased, respectively, to approximately 1200 U/L, 6.1%, and 7% after MHX. NIM811 decreased peak alanine aminotransferase release, necrosis, and apoptosis by 70%, 100%, and 42%, respectively. 5-Bromo-2'-deoxyuridine incorporation, proliferating cell nuclear antigen expression, and the remnant liver weights were all increased significantly by NIM811 treatment, indicating improved liver regeneration. NIM811 also blunted hyperbilirubinemia by 54%, increased serum albumin by 51%, and improved survival from 6% to 40% after MHX. Hepatic mitochondrial depolarization, cell death, and MPT were detected by intravital confocal/multiphoton microscopy of rhodamine 123, propidium iodide, and calcein. Mitochondrial depolarization occurred in many viable hepatocytes (13 cells/high-power field), and nonviable hepatocytes increased slightly to approximately 1 cell/high-power field at 3 hr after MHX. Entry of calcein into mitochondria after MHX indicated MPT onset. Importantly, NIM811 decreased mitochondria depolarization by more than 60%, blocked MPT onset, and prevented cell death. Decreases of hepatic ATP, mitochondrial cytochrome c release, and caspase-3 activation after MHX were also partially blocked by NIM811.
Conclusions: NIM811 minimized liver injury and improved liver regeneration after MHX, at least in part, by preventing MPT onset and subsequent compromised energy supply and proapoptotic cytochrome c release.