Investigation of a primary requirement of organ preservation solutions: supplemental buffering agents improve hepatic energy production during cold storage

BACKGROUND

This study was designed to investigate the effects of a modified University of Wisconsin (UW) solution supplemented with one of four buffering agents (histidine, bicine [N,N-bis(2-hydroxyethyl)glycine], tricine [N-tris(hydroxymethyl)methylglycine], and Tris) on liver metabolism during cold ischemic storage.

METHODS

Rat livers were flushed and stored for a maximum period of 24 hr at 4 degrees C, and tissue energetics, substrate, and anaerobic end-products were assessed; the group exhibiting the best results during storage was recovered in a 60-min period of warm reperfusion. Relative buffering capacities of the experimental solutions (measured over physiological pH range, in mM H+/L) were: UW, 4.1; histidine+UW, 9.8; Tris+UW, 19.0; bicine+UW, 22.5; tricine+UW, 26.8.

RESULTS

In the UW group, ATP levels dropped rapidly over the first 4 hr; 1.0 micromol/g (40% of initial) remained after 4 hr of storage. By 2 hr, ATP levels in bicine- and tricine-treated groups were 0.5 and 1.1 micromol/g greater than in the UW-stored livers and by 10 hr, ATP in bicine-treated livers was twofold that of the control (UW) group. Total adenylate levels also reflected a superior elevation of cellular energetics; even after 24 hr, quantities were 1.4 and 2.0 micromol/g higher than the UW group in bicine- and histidine-supplemented organs. The increase in energetics occurred as a result of increased flux through the major anaerobic energy-producing pathway, glycolysis. The glycolytic rate was significantly greater at storage times > 10 hr with solutions supplemented with bicine, histidine, and tricine. Final values for net lactate accumulation over the entire 24-hr storage period were: UW, 10.1 micromol/g; histidine, 14.3 micromol/g; bicine, 15.2 micromol/g; tricine, 13.8 micromol/g. Activities of glycogen phosphorylase revealed that the activity of this enzyme dropped by 50% within 2 hr of storage in UW. However, histidine and bicine supplementation resulted in a substantial elevation of phosphorylase "a" over 4 hr and 10 hr, respectively. The best buffer of the four examined in this study was bicine; energetics, glycolytic flux, and patterns of adenylate regeneration upon reperfusion were markedly superior to modified UW solution.

CONCLUSION

The results of this study suggest that supplementing the "gold standard" UW solution with an additional buffering agent (in order of efficacy: bicine>tricine>histidine) may improve the metabolic status of livers during clinical organ retrieval/storage.

[The anatomy, surgical technic, preservation and reperfusion of the rat liver in an experiment]

Preservation of hepar of 86 rats using Euro-Collins' and Bretschneider preservation solutions was realized in experiment. The animals hepar anatomy was studied thoroughly, the hepar preservation pattern was improved, the modified pattern of the hepar isolated perfusion was used. Morphologic, cytologic and biochemical investigations were conducted to estimate the viability of hepar.

Effect of inline filtration on ViaSpan cold-storage solution

The effect of filtration on the particulate load in ViaSpan cold-storage solution was studied. Commercially available inline blood transfusion filters (SQ40S, Pall Biomedical) were inserted into the delivery-set port of polyvinyl chloride bags of ViaSpan (DuPont Merck Pharmaceutical). Particles in samples collected in particle-free vials before and after filtration were counted by a light-obscuration technique. The compatibility of key ViaSpan ingredients and of three commonly used additives (penicillin G potassium, dexamethasone sodium phosphate, and human insulin) with the inline filter was also investigated. Filtration removed 56% of particles 5-10 microm in diameter, 71% of particles of > 10-25 microm, and > 99% of particles measuring > 25 microm. Flow rates with the filters were more than adequate for clinical use. Concentrations of constituent hydroxyethyl starch, glutathione, adenosine, allopurinol, raffinose pentahydrate, and lactobionic acid were not significantly affected by filtration, nor were the concentrations of any of the drug additives. Inline filtration of ViaSpan effectively reduced fatty acid salt particulates in the solution and had no deleterious effect on flow rate, ingredient concentrations, or concentrations of commonly added drugs.

The effects of the hypothermic management of brain dead dogs on preserving graft viability in heart transplantation

The effect of hypothermic management for brain dead dogs on preserving graft viability was evaluated through preservation and transplantation. After the occurrence of brain death, 43 dogs were divided into two groups; the normothermic group (37.2+/-0.3 degrees C) and the hypothermic group (31.8+/-0.3 degrees C) according to the esophageal temperature. After the 6-hour management of brain dead donors, the heart beat was arrested using a cardioplegic solution followed by coronary vascular bed washout. The donor heart was then harvested and preserved for 12 hours with simple immersion into the University of Wisconsin solution. Following preservation, orthotopic transplantation was performed in six grafts randomly selected from each group. During the 6-hour management of brain dead dogs; 1) heart rates, rate-pressure products, and the total amount of catecholamine were significantly (p<0.05) lower in the hypothermic group than in the normothermic group, and 2) lactate contents collected from the coronary sinus blood and O2-extraction rates of the heart tended to be lower in the hypothermic group than in the normothermic group. During 12 hours of preservation, intracellular pH and creatine phosphate contents were higher in the hypothermic group than in the normothermic group. Following orthotopic transplantation, the animals in the hypothermic group showed a significantly (p<0.05) higher recovery rate of left ventricular (LV) pressure and the maximum rate of the rise of LV pressure compared with normothermic group animals. We conclude that the hypothermic management of brain dead dogs may be effective in preserving graft viability and may provide a clinical application for heart transplantation with acceptable outcomes.

A study on continuous low-flow perfusion with low-potassium dextran for donor isolated lung preservation

OBJECTIVE

To test the validity of continuous low-flow perfusion with low-potassium dextran (LPD) to preserve rabbit lung.

METHODS

Isolated rabbit lungs were preserved for eight hours either in Ringer's solution by simple storage (Group I) or in continuous low-flow perfusion with LPD (Group II). After preservation, lung functions were assessed to compare these two methods.

RESULTS

The water gain in Group I was higher than that in Group II. During reperfusion, the functional test values for the immersed lungs were lower than those for the perfused lungs. The lipid peroxidation product (MDA) was significantly decreased in perfused lungs during reperfusion.

CONCLUSIONS

Low-flow perfusion with LPD is better than immersion for the lung preservation.

Mitochondrial activity after cold preservation of pancreatic islet cells treated with pefloxacin (PFX)

Mitochondrial energetic and oxidative dysfunctions caused by free radical production trigger release of proinflammatory cytokines involved in organ rejection. The aim of this study was to investigate the role of a fluoroquinolone drug, pefloxacin (PFX) and those of various cold preservation solutions on pancreatic beta cell viability. Our data clearly demonstrate that islet cell viability, as determined by glucose-stimulated insulin secretion, is directly correlated with reduced expression of microsomal cytochrome P-450IIIA. Moreover, IL-2, a known mediator of apoptosis was found to be downregulated, whereas TNF-alpha had been upregulated for the first 18 hours after pefloxacin administration. These results demonstrate that pefloxacin downregulates the expression of cytochrome P-450IIIA isozyme and regulates the production of TNF-alpha and IL-2. Thus, we postulate that the presence of pefloxacin in the pancreatic islet cells before organ preservation facilitates increased cell viability.

High-Na+ low-K+ UW cold storage solution reduces reperfusion injuries of the rat liver graft

The isolated perfused rat liver model was used to assess graft viability after 24 h of cold preservation. Two solutions were compared for liver preservation: Belzer's original UW solution (high-K+ UW) and a solution containing the same components but with inverted concentrations of sodium and potassium (high-Na+ UW). During the 120 min of normothermic reperfusion, livers preserved in the high-Na+ UW solution released lower levels of creatine kinase-BB isoenzyme, transaminases (ALT and AST), and potassium than those preserved in the high-K+ UW solution. Bile flow and biliary excretion of indocyanine green increased when livers were preserved in the high-Na+ UW solution. We found no statistical differences for oxygen consumption and tissue ATP concentration. The results of this study support the concept that a high-Na+ UW solution is a more effective means of preserving rat livers, at least after 24 h of cold-storage and 120 min of reperfusion in the isolated perfused model, than the original high-K+ UW solution. Liver preservation in the high-Na+ UW solution reduces damage to sinusoidal endothelial and hepatocellular cells. The use of an extracellular-like Belzer cold storage solution eliminates potassium-related problems in cold preservation and subsequent normothermic reperfusion while keeping all the qualities of the original UW solution.

Organ preservation with EC, HTK, and UW solutions in orthotopic liver transplantation in syngeneic rats. Part I: Functional parameters

Ischemic injury to the liver is known to influence the outcome of liver transplantation. In this study the efficacy of Euro-Collins (EC), histidine-tryptophan-ketoglutarate (HTK), and University of Wisconsin (UW) preservation solution was analyzed in the model of orthotopic liver transplantation in syngeneic rats. The study design was as follows: Group I, Euro-Collins solution (n = 11); Group II, Histidine-Tryptophan-Ketoglutarate solution (n = 11); Group III, University of Wisconsin solution (n = 11). The rat liver transplantation was performed with arterialization of the graft as described by Engemann. The postoperative follow-up was 28 days. The perfusion flow rate of the preservation solution measured during organ perfusion revealed lowest levels in the UW group and comparable levels in Groups I and II. Postoperative graft function was monitored by measuring liver enzymes (aspartate amino-transferase, ASAT, alanine aminotransferase, ALAT), bilirubin and bile production. The survival rate was 10/11 in each group. Liver enzymes and bilirubin increased postoperatively and went back to normal within 2 or 3 weeks. In contrast to bilirubin, the liver enzymes showed a biphasic increase with maxima on the 1st and 5th days (range: ALAT, 220-264 U/L; ASAT, 145-177 U/L). Bile production was observed in all groups, but was significantly higher after UW-preservation (P < .005). Analysis of inflammatory cells revealed high concentrations of intrasinusoidal leukocytes and lymphocytes in the graft with a maximum on the 5th day.

Effect of pressure on myocardial function after 6-hour preservation with blood cardioplegia

BACKGROUND

This study examined the return of cardiac function in pig hearts after 6 hours' preservation by continuous perfusion with blood cardioplegia at two perfusion pressures compared with preservation with crystalloid solutions.

METHODS

Isolated pig hearts were randomly divided into five groups (n = 8 per group) according to the following treatments: group 1 = fresh hearts (control); group 2 = hearts arrested with Queen's cocktail cardioplegia and then immersion in 0 degrees C saline solution (QS group); group 3 = hearts arrested with (5 degrees C) and simple immersion in 0 degrees C University of Wisconsin solution (UW group); and groups 4 and 5 = hearts arrested with blood cardioplegia at 10 degrees C and then continuously perfused at a pressure of 80 cm H2O or 40 cm H2O, respectively (groups BC80 and BC40). After preservation for 6 hours, donor hearts were reperfused by a cross-circulation support pig. Thereafter, cardiac function and metabolism were examined every half hour for 2 hours. A three-way mixed general linear model was used to analyze data with repeated measures. Bonferroni test was used to determine differences (p < or = 0.05) between groups.

RESULTS

Only 4 hearts recovered electric activity in the BC80 group (p < or = 0.05 versus other groups). There was poor recovery of left ventricular work in the BC80 group compared with the other groups (p < 0.001). Left ventricular work in the QS and UW groups was also lower than in the control and BC40 groups. Left ventricular work in the BC40 group fully recovered. Maximum elastance did not differ between groups. Compliance was reduced in the QS, BC80, and BC40 groups versus controls after preservation (p < 0.006). Coronary flow decreased and coronary vascular resistance increased in the BC80 group versus the other groups (p < or = 0.001). Coronary flow in the QS, UW, and BC40 groups was lower than in the control group (p < 0.001). The magnitude of lactate release was much higher in the BC80 group than in the other groups (p < or = 0.001).

CONCLUSIONS

Continuous perfusion with 10 degrees C blood cardioplegia at 40 cm H2O pressure for 6 hours provided adequate preservation of systolic function in this model. University of Wisconsin solution provided the best protection of diastolic function.

Efficacy of prostaglandin I2 analog on liver grafts subjected to 30 minutes of warm ischemia

Due to the fact that no effective conditioning agent for hemodynamically unstable donors exists, the number of suitable donors is limited. The efficacy of OP-41483, a stable analog of prostaglandin I2, as a conditioning agent of the liver was investigated in this study using pigs. OP-41483 was administered via the portal tributary for 10 min before 30 min of warm ischemia. Graft livers were procured after perfusion with OP-41483 in cold normal saline, then flushed with OP-41483 in Euro-Collins solution and placed in cold storage prior to orthotopic transplantation. OP-41483 was also administered intraportally for 120 min after reperfusion. Biochemical and histological studies, and survival rates were compared with a control group not given OP-41483 in an otherwise similar experimental protocol. The graft function recovered better in the OP group than in the control group, shown by the lactate values and lactate-to-pyruvate ratios. The marked congestion noted in the parenchyma of the control group livers was minimal in the OP group, verifying the microcirculatory effect of prostaglandin I2 by its vasodilatory and antithrombotic actions. These findings suggest that OP-41483 has some protective effect as a conditioning agent in liver transplantation, with timing of administration being crucial.

The effect of trehalose on human lung fibroblasts stored in euro-collins and low potassium dextran solutions

BACKGROUND

The research on lung preservation for transplantation is directed to synthesize a solution, in order to prolong the preservation period, thus avoiding the damage to lung tissues caused by ischemia. In recent years some in vivo experimental papers have been published, in which good results were obtained by adding trehalose, a non-reducing disaccharide able to stabilize the cell membrane, to the storage solutions.

MATERIALS AND METHODS

In this study we have evaluated the effects on human lung fibroblasts of commonly used storage solutions like Euro-Collins (EC) and Low Potassium Dextran (LPD), in which trehalose has respectively replaced glucose (T-EC) or was added (LPD-T). The cultures were incubated for 8 hours at 10 degrees C in standard and modified solutions.

RESULTS

The data relative to EC compared to EC-T showed that the total protein content and the rate of protein synthesis, that is in other words cell viability, are drastically compromised. Concerning LPD-T, compared to standard LPD, a slightly decrease of the total protein content and of the rate of protein synthesis in the cells incubated in the modified solution were observed. The reasons for these unexpected data are related to the hypothesis that during the ischemic period membrane stabilization is neither the main nor the only factor responsible for the cellular damage. Moreover the role of trehalose in preservation solutions, is still not clear and should be further investigated.

CONCLUSIONS

With the limits of the study of single cells in vitro, the advantages of trehalose containing solutions proved ineffective and toxic especially as for as EC-T is concerned.