Reversible mitochondrial uncoupling in the cold phase during liver preservation/reperfusion reduces oxidative injury in the rat model.

Reversible uncoupling of the mitochondrial electron-transport chain may be one strategy to prevent intracellular oxidative stress during liver cold preservation/warm reperfusion (CP/WR) injury. 2,4-Dinitrophenol (DNP) is a potent water-soluble uncoupling agent for supplementation of the hepatic CP solution. The aim of this work was to investigate the possible influence of DNP in the CP solution on the isolated rat liver state during CP/WR. Livers were subjected to CP at 4 degrees C in sucrose-phosphate based solution (SPS) for 18 h, followed by WR for 60 min in vitro. The final concentration of DNP was 100 microM. DNP presence during the CP stage led to partial ATP level decrease accompanied by a significant diminution in liver TBARS and a prevention of antioxidant enzyme activity decrease (catalase, GSH-PO, GSH-Red) when compared with livers stored without DNP. After DNP wash-out during WR, an improvement in the mitochondrial functional state (higher respiratory control indices and ATP levels, and a decrease in V(4) respiration rates) were observed. This was concurrent with lower TBARS levels, higher antioxidant enzyme activities and significant increase of bile production. The results suggest that reversible uncoupling may be one way to influence oxidative stress associated with hepatic cold preservation.

Bioregulators of stem and progenitor cells in preservation solution reduce cold ischemia-reperfusion injury of isolated rat livers.

The effects of bioregulators of stem and progenitor cells (BSPC) of fetal tissue cytosol on rat liver during 24h hypothermic storage (HS) and following normothermic reperfusion (NR) were investigated. It was shown that BSPC presence in the preservation medium stabilized pro-oxidant-antioxidant balance impaired in liver after HS and NR, prevented the uncoupling of mitochondrial oxidative phosphorylation and ATP level decline. These consequences led to significant improvement of hepatic morphological integrity and functional state. Powerful protective effect of BSPC on liver at sub-zero temperatures can serve as basis for new approaches to extend safe time for organ preservation and foster understanding of pathways of stem and progenitor cell paracrine action. © 2016 BioFactors, 42(3):287-295, 2016.

Capacity of bioregulators of stem and progenitor cells to strongly affect liver redox-dependent processes.

Abstract Effects of stem and progenitor cells or their compounds on recipient cells are investigated intensively today. In spite of this, their ability to interact with native cells and the final targets affected by them, particularly biochemical parameters that characterize cell redox-dependent processes, remain little studied. We have studied how bioregulators of stem and progenitor cells affect these processes in freshly isolated liver after animal pretreatment in vivo. Cytosol of human fetal mesenchymal-mesodermal tissues (8-10 weeks gestation) was administered intravenously; the control group was treated with Hanks' solution. After 4 hr, rats were sacrificed and their livers were isolated. To evaluate liver redox-dependent state, mitochondrial respiratory activity and nitroxyl radical and Alamar Blue™ reduction rates, mitochondrial and cytosolic glycerol kinase and nicotinamide adenine dinucleotide (NADH)-dependent malate dehydrogenase activities were studied. The results obtained demonstrate that bioregulators strongly affect liver redox-dependent processes, increasing mitochondrial respiration in state III and spin probe reduction rate and enhancing Alamar Blue™ reduction by glycolytic and nonglycolytic postmitochondrial enzymes. In addition, mitochondrial glycerol kinase and both isoforms of NADH-dependent malate dehydrogenase were inhibited. These data bring us closer to understanding stem and progenitor cell effects via directed regulation of metabolic redox-dependent processes.

Positive effects of cryopreserved adult or fetal liver cell transplants on hypercholesterolemia and hepatic antioxidant defenses in cholesterol-fed rabbits.

The liver plays a central role in lipid metabolism and the pathophysiology of many lipid disorders leads in turn to liver cell injury. Adult hepatocyte transplants provide well-recognized metabolic support, whilst hepatic stem cells may promote liver regeneration and repair, but in both cases, any clinical application would require low temperature banking of the cells. A model of dietary hypercholesterolemia was established in rabbits over 5 months, and transplants of cryopreserved adult hepatocytes (CH) and cryopreserved fetal liver cells (CFLC) were compared to Sham transplants. Cryopreservation was performed by a two-step freezing protocol using 1.5mol/l dimethyl sulfoxide (Me(2)SO). Serum contents of cholesterol lipid classes were measured during the subsequent 4 weeks, in addition to markers of serum and liver oxidative stress. Both CH and CFLC transplantation resulted in a decrease of serum lipids during the 1st week after transplantation. The effect of CH was limited to the 1st week, but CFLC provided a sustained lipid-lowering effect over the 4 weeks. The ultimate outcome of CFLC transplantation by the end of 4 weeks was more pronounced and statistically significant for both serum total cholesterol (0.15+/-0.05 versus 3.65+/-1.4mmol/l) and high-density lipoprotein-cholesterol (0.04+/-0.01 versus 0.56+/-0.06mmol/l) compared to Sham transplants (p<0.05 in both cases). CFLC transplantation also normalized hepatic tissue antioxidant defenses, namely an increase in reduced glutathione content, and enzyme activities for catalase and glutathione reductase (all significantly higher at p<0.05 than in Sham transplants) by 4 weeks.