Renoprotective effects of the 21-aminosteroid U74389G in ischemia-reperfusion injury and cold storage preservation

Lazaroid U-74389G in liver ischemia-reperfusion injury: A swine model

Reactive oxygen species have a key role in liver ischemia-reperfusion (I/R) injury. In the present study, the effect of the anti-oxidant compound lazaroid U-74389G in preventing liver I/R injury was investigated in a swine model. Ischemia was produced by portal vein occlusion. Two sets of experiments were performed, each with two groups (n=7 per group). In the first group, the potential protective effect of an intracaval injection of U-74389G after a 30-min ischemia, followed by a 60-min reperfusion period was assessed (biopsies at 0, 15, 30 and 90 min experimental time). In the second set, the effect of intracaval U-74389G injection after 30 min of ischemia, followed by a longer reperfusion period of 120 min was determined (biopsies at 0, 15, 30 and 150 min experimental time). Liver malondialdehyde, hepatocyte vacuolation-degeneration, venous congestion, inflammatory cell infiltration, sinus congestion-dilation and Chiu score of intestinal damage were determined at up to 150 min of reperfusion. In the second set of experiments, the Chiu score of intestinal damage was improved by the administration of U-74389G (3.17±0.40 vs. 4.33±0.21; P=0.030). However, in the two sets of experiments, the liver inflammatory reaction was more pronounced in the U-74389G groups (P=0.017 for the first set, P=0.021 for the second set). No significant effect of U-74389G on any other parameters was detected. In conclusion, intestinal damage due to portal venous congestion and reflow appears to be mitigated by the lazaroid U-74389G; however, intracaval administration of U-74389G does not appear to exert any protective effects against liver I/R-induced inflammation.

Contribution of large pig for renal ischemia-reperfusion and transplantation studies: the preclinical model

Animal experimentation is necessary to characterize human diseases and design adequate therapeutic interventions. In renal transplantation research, the limited number of in vitro models involves a crucial role for in vivo models and particularly for the porcine model. Pig and human kidneys are anatomically similar (characterized by multilobular structure in contrast to rodent and dog kidneys unilobular). The human proximity of porcine physiology and immune systems provides a basic knowledge of graft recovery and inflammatory physiopathology through in vivo studies. In addition, pig large body size allows surgical procedures similar to humans, repeated collections of peripheral blood or renal biopsies making pigs ideal for medical training and for the assessment of preclinical technologies. However, its size is also its main drawback implying expensive housing. Nevertheless, pig models are relevant alternatives to primate models, offering promising perspectives with developments of transgenic modulation and marginal donor models facilitating data extrapolation to human conditions.

A radical scavenger, edaravone, protects canine kidneys from ischemia-reperfusion injury after 72 hours of cold preservation and autotransplantation

BACKGROUND

Cold ischemia-reperfusion (I/R) injury is a prominent cause of delayed graft function after kidney transplantation. Reactive oxygen species play a crucial role in I/R injury. Edaravone is a synthetic radical scavenger that has been used in acute stroke. Some animal experiments have revealed its beneficial effects against I/R injury, but its effects after cold preservation and transplantation of canine kidneys are unknown.

METHODS

Female hybrid dogs weighing 11 to 13 kg were used. Under anesthesia, the left kidney was harvested. After 72 hr of preservation in cold histidine-tryptophan-ketoglutarate solution, autotransplantation was performed in the right iliac fossa, with contralateral nephrectomy. Animals were divided into control and treatment groups (n=6 per group). In the treatment group, edaravone was administered intravenously at harvest and at reperfusion (3 mg/kg) and in addition was added to the preservation solution (50 microM).

RESULTS

Animal survival at 2 weeks was four of six in the control group and six of six in the treatment group. Compared with controls, treated animals had higher mean urine output, higher mean glomerular filtration rate, improved tubular cell function, lower mean serum creatinine, and lower renal vascular resistance. Biopsy specimens from treated animals showed less tubular cell damage and decreased P-selectin expression in endothelial cells. Lipid peroxidation of renal tissue and urinary excretion of 8-hydroxy-2'-deoxyguanosine were suppressed by the treatment.

CONCLUSIONS

Edaravone reduced cold I/R injury in canine renal transplantation. The agent has the potential to ameliorate preservation injury in clinical transplantation.

Protection against ischemia/reperfusion injury by the cavitary two-layer method in canine small intestinal transplantation with reduction of reactive oxygen species

BACKGROUND

Ischemia and reperfusion (I/R) injury is a major determinant of early graft dysfunction and long-term graft survival in small intestinal transplantation. The cavitary two-layer method (TLM) has been reported to be superior to the University of Wisconsin cold storage method (UWM) in long-term preservation of canine small intestine. This study was designed to evaluate the protective effect of the cavitary TLM against I/R injury in canine small intestinal transplantation.

METHODS

Intestinal grafts harvested from beagles were allotransplanted after 24-hour preservation by UWM (group 1) or the cavitary TLM (group 2). The graft in the controls (group 3) was immediately allotransplanted without preservation. I/R injury was assessed by functional success rates, biochemical assay, graft adenosine triphosphate (ATP) and lipid peroxidation (LPO) concentrations, and histopathologic examination including TUNEL staining for apoptosis.

RESULTS

In group 1, ATP recovery was delayed after reperfusion, and most recipients died with hemorrhage of the grafts and lungs. In group 2, graft ATP concentrations recovered rapidly, and I/R injury was prevented with reduced LPO production, resulting in good outcome.

CONCLUSIONS

The cavitary TLM protected intestinal grafts against I/R injury evidenced by maintenance of graft ATP levels and reduction of LPO production compared with UWM in canine small intestinal transplantation.

Lazaroid (U74389G)-supplemented cardioplegia: results of a double-blind, randomized, controlled trial in a porcine model of orthotopic heart transplantation

BACKGROUND

U74389G (16-desmethyl tirilazad), a 21-aminosteroid or "lazaroid," inhibits lipid peroxidation, which is an important element of ischemia-reperfusion injury. The aim of this study was to determine whether the addition of U74389G to the cardioplegic preservation solution could improve early cardiac allograft function.

METHODS

A porcine model of donor brain death and orthotopic cardiac transplantation was used. Hearts were arrested and preserved for 6 hours in an aspartate-enriched extracellular cardioplegia that had been supplemented with either U74389G and its carrier (n = 7) or the carrier alone (n = 9). Epicardial sonomicrometry and transmyocardial micromanometry were used to obtain pressure-volume loops before and after transplantation. Left ventricular wall volume was measured by volume displacement.

RESULTS

A higher proportion of U74389G-treated hearts were weaned successfully from cardiopulmonary bypass, but this difference did not achieve statistical significance (86% [6 of 7] vs 56% [5 of 9]; p = 0.308). In the hearts that were weaned successfully, preservation of left ventricular contractility, as judged by the pre-load recruitable stroke work relationship, was significantly better in the U74389G-treated hearts (p = 0.0271). In contrast, left ventricular compliance, as judged by the end-diastolic pressure-volume relationship, was significantly better preserved in the control group (p < 0.0001). U74389G-treated hearts developed less myocardial edema, as judged by the post-transplant left ventricular wall volume/baseline steady-state epicardial end-diastolic volume ratio (64 +/- 9% vs 76 +/- 11%; p = 0.045).

CONCLUSIONS

The benefit obtained from U74389G-supplemented cardioplegic preservation solution was marginal for hearts stored for 6 hours. After longer ischemic times, the benefit may be clearer.

Geranylgeranylacetone, a heat shock protein inducer, prevents primary graft nonfunction in rat liver transplantation

BACKGROUND

Heat shock proteins (HSPs) are well known as cytoprotective proteins. Geranylgeranylacetone (GGA), a nontoxic anti-ulcer drug, was recently shown to have HSP-inducing capacity. In the present study, the activity of GGA was tested in a rat orthotopic liver transplantation (OLT) model to determine whether the compound has beneficial effects in warm ischemia-reperfusion injury.

METHODS

Either GGA or a control vehicle was orally administered to donor rats before graft harvest. Harvested livers were subjected to 45-min warm ischemia (37 degrees C) followed by OLT. HSP mRNA expressions and HSP syntheses in the graft livers were evaluated by reverse transcriptase polymerase chain reaction and Western blot analysis, respectively.

RESULTS

When the donors were treated with a vehicle, all recipients died of primary nonfunction within 2 days after OLT. In contrast, when the donors were treated with GGA (200 mg/kg per day) for 4 weeks, the 7-day survival rate of recipients was dramatically improved (90%). By giving a high dose of GGA (600 mg/kg per day) for 1 week, a similar improvement in recipient survival was seen (83.3%). GGA administration accumulated mRNA for both HSP72 and HSP90 in the livers even before warm ischemia and facilitated the syntheses of HSP72 and HSP90 after warm ischemia. In addition, GGA pretreatment also significantly reduced the serum levels of tumor necrosis factor-alpha (TNF-alpha) after reperfusion.

CONCLUSIONS

These findings indicate that both the enhanced induction of HSPs and the suppression of a cytotoxic mediator (TNF-alpha) might be involved in the beneficial effects of GGA on ischemia-reperfusion injury. Thus, oral administration of GGA would be a useful tool for preventing primary nonfunction in liver transplantation.

Antioxidants in the prevention of renal disease

In view of the role of oxidative processes in inflicting damage that leads to glomerulosclerosis and renal medullary interstitial fibrosis, more attention could be paid to the use of antioxidant food constituents and the usage of drugs with recognized antioxidant potential. In any case atherosclerosis is an important component of chronic renal diseases. There is a wide choice of foods and drugs that could confer benefit. Supplementation with vitamins E and C, use of soy protein diets and drinking green tea could be sufficient to confer remarkable improvements.

Effects of tetrodotoxin and OKY-046 in renal ischemia reperfusion

Ischemia reperfusion injury (IRI) contributes significantly to posttransplant graft dysfunction. An emphasis, therefore, has been directed toward the identification of novel renoprotective agents. In this study, the renoprotective effect of tetrodotoxin (TTX) alone, or in combination with a thromboxane synthetase inhibitor (OKY-046), was investigated in a 60-min warm ischemia, 72-h reperfusion, IRI rodent model. Unilateral nephrectomized rats were treated with the test vehicle alone, 1, 2, or 4 microgram/kg of TTX or 2 mg/kg of OKY-046 intravenously, either 15 min pre- or postischemia, or 2 microgram/kg TTX administered simultaneously with OKY-046 (2 mg/kg), following the ischemic interval. Baseline, 24, and 72 h mean plasma creatinine (Cr) and urea nitrogen (BUN) were compared. Maximal renoprotection was demonstrated by significantly improved 72-h Cr and BUN levels with the 2 microgram/kg of TTX or with 2 mg/kg of OKY-046, each administered after ischemia (ischemic control Cr = 8. 01 +/- 1.07 mg/dl vs TTX = 3.84 +/- 0.80 mg/dl, P = 0.008; vs OKY-046 = 4.0 +/- 1.5, P + 0.008; ischemic control BUN = 241.3 mg/dl +/- 32.8 vs TTX = 85.7 mg/dl +/- 18.7, P < 0.008; vs OKY-046 = 52.6 +/- 22.5, P = 0.008). The combination therapy utilizing TTX with OKY-046 resulted in reduced animal survival, demonstrating no renoprotection as measured with the biochemical parameters. These results support the renoprotective effects of TTX in a severe, rodent IRI model. The exact mechanism of action, as well as the therapeutic potential of TTX in preservation/transplantation, warrants further study.

Cardioprotective effects of Lazaroid U-74389G on ischemia-reperfusion injury in canine hearts

BACKGROUND

Lazaroid, an inhibitor of iron-mediated lipid peroxidation, has been shown to reduce free radical-mediated injury after ischemia and reperfusion. The effect of Lazaroid U-74389G was investigated on ischemia-reperfusion injury of the heart through preservation and transplantation (Tx) in dogs.

METHODS

Eleven pairs of adult mongrel dogs weighing 8.5 to 12 kg formed the recipient-donor combinations. Following electromechanical arrest of the heart using cardioplegia, the coronary vascular beds were washed out with a cold University of Wisconsin solution followed by 12-hour preservation and orthotopic Tx. Experimental animals were divided into 2 groups; 6 pairs formed the control group, and 5 formed the Lazaroid-treated group in which Lazaroid U-74389G at 10 mg/kg was administered intravenously 30 minutes before reperfusion of the heart. The cardiac function including cardiac output, left ventricular (LV) pressure, and LV dp/dt was assessed 2 hours after Tx by comparing it with the recovery rates (%) from cardiac function of donor dogs. Each transplanted heart was harvested for histological study.

RESULTS

The recovery of cardiac function after Tx was significantly better in the Lazaroid-treated group than in the control group. Histologically, myocardial damage, evaluated by both light and transmission electron microscopy, was less evident in the Lazaroid-treated group than in the control group.

CONCLUSION

Early cardiac function following Tx was significantly better and histological damage was less in the Lazaroid-treated group than in the control group, suggesting that Lazaroid U-74389G is effective in preventing ischemia-reperfusion injury after preservation and Tx.

Protective effects of lazaroid U74389G on intestinal graft after heterotopic small bowel transplantation in rats

BACKGROUND

Experimental studies have shown that 21-aminosteroids (21-A) are powerful inhibitors of superoxide-mediated iron-dependent lipid peroxidation. This study was aimed at determining how far the blocking effect of one of these substances (lazaroid U74389G) on lipid peroxidation protects intestinal grafts morphologically and biologically in a heterotopic transplant model (SBT) in rats.

ANIMALS AND METHODS

Heterotopic LEW were performed using Ringer lactate (4 degrees C) as preservation solution. In Group 1 (n = 7) the donor and recipient animals received 3 and 6 mg/kg of the 21-A U74389G, respectively. Group 2 (n = 7) received the same doses of the vehicle of the drug. Sham group underwent only a laparotomy. Bacterial translocation (BT) was determined in mesenteric lymph nodes (MLN), liver (L), and spleen (S) 60 min after reperfusion. Tissue myeloperoxidase (MPO), malondialdehyde (MDA), and percentage conversion xanthine dehydrogenase/xanthine oxidase (XD/XO) were also determined in the ileal graft. Histological damage was graded according to Park's classification.

RESULTS

Tissue MDA (nmol/mg prot) was significantly lower in Group 1 (0.53 +/- 0.09) than in Group 2 (3.66 +/- 1, P < 0.05) and showed levels similar to those of the sham-operated group (0.40 +/- 0.05). Injury grades were also significantly different in both study groups (Group 1, 0-1; Group 2, 2-3, P < 0.05). BT (log CFU/g tissue) in Group 1 were MLN, 0; L, 0.36; and S, 0. In Group 2, MLN, 1.07; L, 0.81; and S, 1.49 (P < 0.05 in MLN). Increase in MPO activity (U/g prot) in comparison with sham-operated animals was similar in the two study groups (Group 1, 1.49 +/- 0.58; Group 2, 1.22 +/- 0.46; Sham, 0.34 +/- 0.37 (P < 0.05 1,2 vs sham). Conversion of XD to XO was unaffected by the supplementation of the drug.

CONCLUSION

21A U74389G inhibits lipid peroxidation, protects intestinal graft, and reduces BT after heterotopic SBT in rats.