Impact of donor age on the growth of young recipient rats after liver transplantation

Mitochondrial Autophagy in Ischemic Aged Livers

Mitochondrial autophagy (mitophagy) is a central catabolic event for mitochondrial quality control. Defective or insufficient mitophagy, thus, can result in mitochondrial dysfunction, and ultimately cell death. There is a strong causal relationship between ischemia/reperfusion (I/R) injury and mitochondrial dysfunction following liver resection and transplantation. Compared to young patients, elderly patients poorly tolerate I/R injury. Accumulation of abnormal mitochondria after I/R is more prominent in aged livers than in young counterparts. This review highlights how altered autophagy is mechanistically involved in age-dependent hypersensitivity to reperfusion injury.

Aging-associated oxidative stress inhibits liver progenitor cell activation in mice

Recent studies have discovered aging-associated changes of adult stem cells in various tissues and organs, which potentially contribute to the organismal aging. However, aging-associated changes of liver progenitor cells (LPCs) remain elusive. Employing young (2-month-old) and old (24-month-old) mice, we found diverse novel alterations in LPC activation during aging. LPCs in young mice could be activated and proliferate upon liver injury, whereas the counterparts in old mice failed to respond and proliferate, leading to the impaired liver regeneration. Surprisingly, isolated LPCs from young and old mice did not exhibit significant difference in their clonogenic and proliferative capacity. Later, we uncovered that the decreased activation and proliferation of LPCs were due to excessive reactive oxygen species produced by neutrophils infiltrated into niche, which was resulted from chemokine production from activated hepatic stellate cells during aging. This study demonstrates aging-associated changes in LPC activation and reveals critical roles for the stem cell niche, including neutrophils and hepatic stellate cells, in the negative regulation of LPCs during aging.

Aging and its impact onthe quality of grafts: an experimental study in rats livers

CONTEXT: There are consistent clues of worse results with grafts from older donors, especially in hepatitis C. University of Wisconsin (UW) solution is adopted for liver preservation, but other solutions are being studied, as fructose-1,6-bisphosphate (FBP). OBJECTIVE: To determinate the impact of aging of the donor on the cold ischemia injury in rat livers and compare UW and FBP. METHODS: Twenty male Wistar rats were studied - 10, aging 20 weeks: 5 to preservation with UW (C-UW) and 5, FBP (C-FBP); and other 10, aging 50 weeks: 5 to UW (E-UW) and 5 to FBP (E-FBP). Rats were anesthesized, submitted to hepatectomy, and graft was kept under 2-4ºC for 8 hours. Liquid samples were taken at 2, 4, 6, and 8 hours, to determine AST and LDH. At the end, in the liver tissue thiobarbituric acid reactive substances and catalase were determined. RESULTS: Average liver weight was similar between controls and the others (12.5 g ± 1.8 and 13.4 g ± 2.0). AST and LDH levels were higher in C-UW group (P<0.05). In the older group, there was a difference between UW and FBP preserved livers related to LDH, but not to AST. Thiobarbituric acid reactive substances were superior in control group than in the older one (P = 0.001). Catalase activity was similar between these groups (P = 0.11), but it was superior in UW preserved animals (P = 0.02). CONCLUSION: Livers from older rats were similar to the controls regarding cold ischemia injury in FBP group. Surprisingly, with UW solution there was less cold ischemia injury in the elderly group. When comparing both solutions, FBP provided significantly more protection than UW in the controls. There was a trend to FBP to being better than UW in the elderly group. Further studies with liver from older donors and ischemia and reperfusion are needed.