Methylene blue attenuates ischemia–reperfusion injury in lung transplantation

Background

Ischemia–reperfusion injury (IRI) is one of the principal obstacles for the lung transplantation (LTx) success. Several strategies have been adopted to minimize the effects of IRI in lungs, including ex vivo conditioning of the grafts and the use of antioxidant drugs, such as methylene blue (MB). We hypothesized that MB could minimize the effects of IRI in a LTx rodent model.

Methods

Forty rats were divided into four groups (n = 10) according to treatment (saline solution or MB) and graft cold ischemic time (3 or 6 h). All animals underwent unilateral LTx. Recipients received 2 mL of saline or MB intraperitoneally before transplantation. After 2 h of reperfusion, arterial blood and exhaled nitric oxide samples were collected and bronchoalveolar lavage performed. Then animals were euthanized, and histopathology analysis as well as cell counts and cytokine levels measurements in bronchoalveolar lavage fluid were performed.

Results

There was a significant decrease in exhaled nitric oxide, neutrophils, interleukin-6, and tumor necrosis factor-α in MB-treated animals. PaO₂ and uric acid levels were higher in MB group.

Conclusions

MB was able in attenuating IRI in this LTx model.     

Taurine attenuates lung ischemia–reperfusion injury after lung transplantation in rats

Purpose

Taurine, the major intracellular free amino acid found in high concentrations in mammalian cells, is known to be an endogenous antioxidant and a membrane-stabilizing agent. It was hypothesized that taurine may be effective in reducing ischemia–reperfusion injury after lung transplantation and an experimental study was conducted in a rat model.

Methods

The number of Sprague–Dawley rats used in the study was 35. Animals were randomized into five groups of 7 rats each, including control, donor I, donor II, ischemia–reperfusion injury, and treatment groups. All animals were exposed to the same experimental conditions in the preoperative period. Rats were fixed in a supine position after the induction. After the rats were shaved, a left pneumonectomy was performed following sternotomy in control, donor I, and donor II groups. The harvested grafts in donor I and donor II groups were transplanted to the rats of the ischemia–reperfusion group and treatment group, respectively. However, taurine was administered intraperitoneally for 3 days before the harvesting procedure in donor II. All harvested lungs were kept in a Euro-Collins solution at +4 °C for 24 h in a half-inflated manner. After harvesting and transplantation, lungs were sampled for histopathological and biochemical analysis.

Results

Malondialdehyde and superoxide dismutase, glutathione peroxidase, and catalase levels were lower in the treatment group than the other groups (p < 0.05). Histopathological findings were better in treatment group than the ischemia–reperfusion group (p < 0.05).

Conclusion

It was demonstrated that donor treatment with taurine resulted in preservation of transplanted lung tissue in respect to histopathological and biochemical findings.     

Mesenchymal stem cells attenuate ischemia–reperfusion injury after prolonged cold ischemia in a mouse model of lung transplantation: a preliminary study

Purpose

Mesenchymal stem cells (MSCs) suppress inflammation and immune responses. We conducted this study to find out if MSCs attenuate ischemia–reperfusion injury in a mouse model of lung transplantation.

Methods

C57BL/6J mouse lungs perfused with low-potassium dextran glucose solution were preserved at 4 °C for 18 h. Human MSCs were slowly injected into the left pulmonary artery of the lung grafts, and orthotopic left lung transplantation was then performed. The lung isografts were reperfused for 6 h, and bronchoalveolar lavage fluid (BALF) from the left lung graft was collected. We measured the protein concentration, cell count, and proinflammatory cytokine concentrations in the BALF.

Results

The protein concentration and cell count in the BALF were significantly lower in the MSC-administered grafts than in the PBS-administered controls. Concentrations of proinflammatory cytokines, including IL-1β, IL-17A, and TNF-α, in BALF tended to be lower in the MSC-administered grafts than in the controls, but the difference was not significant.

Conclusion

The pre-transplant administration of MSCs via the pulmonary artery of the lung graft attenuated ischemia–reperfusion injury after prolonged cold ischemia in this mouse model of lung transplantation.

     

The effect of U-74389G on pancreas ischemia–reperfusion injury in a swine model

Background

Oxidative stress is a crucial factor in the pathophysiology of acute pancreatitis and its systemic complications. Lazaroids are a novel class of antioxidants that potently protect pancreatic acinar cells against oxidant attack. The aim of our study was to evaluate the therapeutic potential of 21-aminosteroid U-74389G in pancreatic injury after ischemia and reperfusion of the organ in a swine model.

Materials and methods

Twelve pigs (weighing 28–35 kg) were randomized into the following two experimental groups: group A (control group, n = 6): ischemia of pancreas (30 min) followed by reperfusion for 120 min; and group B (n = 6): ischemia of pancreas (30 min), U-74389G intravenous injection (10 mg/kg) in the inferior vena cava, and reperfusion for 120 min. Tissue and blood sampling was conducted at 0, 30, 60, 90 and 120 min after reperfusion. Repeated measures analysis of variance was performed for the evaluation of differences between the two groups.

Results

Histopathologic evaluation did not reveal a statistically significant difference concerning hemorrhage (P = 0.193), leukocyte infiltration (P = 0.838), acinar necrosis (P = 0.183), and vacuolization (P = 0.185) in the pancreatic tissue between the two groups; nevertheless, edema seemed to be more pronounced in the U-74389G group (P = 0.020). Serum metabolic data in the control and therapy groups were not significantly different; accordingly, tissue malondialdehyde levels (P = 0.705) and tumor necrosis factor α values (P = 0.863) did not differ between the two groups.

Conclusions

On the basis of the histologic data and the absence of reduction in the malondialdehyde and tumor necrosis factor α levels, it is concluded that the administration of U-74389G does not seem to exert a sizable therapeutic effect in attenuating pancreatic damage from ischemia–reperfusion injury.     

Thiopental improves renal ischemia–reperfusion injury

Ischemia/reperfusion (I/R) occurs in a number of pathological conditions, including myocardial infarction, stroke, aortic surgery, cardiopulmonary bypass surgery, organ transplantation, resuscitation, and critical care. Massive and abrupt release of oxygen-free radicals after reperfusion triggers oxidative damage. Before critical operations or after resuscitation, it would be wise to find a suitable prophylactic treatment to avoid I/R damage. We aimed to determine whether several commonly used intravenous anesthetics protect against renal I/R injury. Methods: Animals were randomly divided into seven groups, each consisting of six animals: sham group, control group, thiopental group, propofol group, intralipid group, etomidate group, and ketamine group. At the end of the 60-min ischemic period, 60 min reperfusion was established and the materials administered 15 min before the reperfusion. At the end of the reperfusion period, the samples of blood and tissue were reaped for biochemical and serological evaluation. Results: I/R procedure significantly increased malondialdehyde (MDA) levels, decreased catalase (CAT) activities, and superoxide dismutase (SOD) levels. The lowest MDA mean level was in the thiopental group and the highest MDA mean level was in control group. The lowest CAT mean level was in the intralipid group and the highest CAT mean level was in the etomidate group. The lowest SOD mean level was in the control group and the highest SOD mean level was in the propofol group. Conclusion: Thiopental and propofol, especially thiopental, are more effective to protect renal I/R injury.     

Hind limb ischemia–reperfusion injury in diet-induced obese mice

Background

Obesity is a major risk factor for the development of diabetes. Limb ischemia–reperfusion injury (IR) is a common clinical problem in diabetics who have compromised lower extremity perfusion. This study compared the histologic, metabolic, and functional outcomes after hind limb IR in diet-induced obese (DIO) and non-diabetic (ND) mice during the acute and the regenerative phases of IR.

Methods

DIO and ND mice were subjected to 1.5 h unilateral hind limb ischemia followed by 1- or 28-d IR. Muscle morphology, metabolic, and genomic stress were evaluated at days 1 and 28 IR; Acute inflammation and thrombosis were only measured at day-1 IR. At day 28, IR, skeletal muscle contractility, and maturation were also assessed.

Results

At day-1 IR, similar levels of acute muscle fiber necrosis were seen in both groups. DIO mice demonstrated substantially greater inflammatory, prothrombotic, and genomic stress responses, which were also associated with a greater reduction in energy substrates and Akt phosphorylation. At 28d, there was no difference in the peak forces generated in the hind limbs for the two groups. DIO mice had reduced fatigue resistance compared with ND and larger areas of fat accumulation although there was no significant difference in muscle fiber maturation.

Conclusions

DIO mice had an exacerbated acute response to IR with enhanced metabolic deficit, fat accumulation, and defective functional recovery during the regenerative phase of IR. These changes in fatigue resistance reflect compromised functional recovery after IR injury and have relevance for the functional recovery of patients with metabolic syndrome and insulin resistance.     

Penehyclidine hydrochloride ameliorates renal ischemia–reperfusion injury in rats

Background

Renal ischemia–reperfusion (I/R) injury is a major cause of acute kidney failure by mechanisms that involve oxidative stress, inflammation, and apoptosis. Penehyclidine hydrochloride (PHC), a selective anticholinergic agent, possesses anti-inflammatory, antioxidative stress, and antiapoptotic effects. Therefore, we investigated the ability of PHC to ameliorate renal I/R injury in Sprague–Dawley rats.

Materials and methods

Rats were randomly assigned to three groups (35 rats per group): sham operated, saline-treated I/R, and PHC-treated I/R. After removing the right kidney, renal I/R injury was induced by clamping the left renal artery for 45 min followed by reperfusion. The rats were administered PHC (0.45 mg/kg, intravenously) or saline 30 min before renal ischemia. The blood and kidneys were harvested at 1, 3, 6, 12, or 24 h after reperfusion. Renal function and histologic changes were assessed. Markers of oxidative stress, inflammation, and apoptosis in the kidneys were also measured.

Results

PHC treatment significantly attenuated renal dysfunction and histologic damage caused by I/R injury. The treatment also decreased malondialdehyde level and attenuated the reduction in superoxide dismutase activity in the kidney. Moreover, the levels of activated p38 mitogen-activated protein kinase, nuclear factor kappa B, and caspase 3 were lower in the PHC-treated animals.

Conclusions

PHC protected rat kidneys from I/R injury by attenuating oxidative stress, inflammatory response, and apoptosis. Thus, PHC may represent a novel practical strategy for the treatment of renal I/R injury.     

Combination antioxidant effect of α-tocoferol and erdosteine in ischemia–reperfusion injury in rat model

Introduction  

Renal ischemia/reperfusion (I/R) which is an important cause of renal dysfunction is inevitable in renal transplantation, surgical revascularization of the renal artery, partial nephrectomy and treatment of suprarenal aortic aneurysms.     

Dexamethasone pretreatment alleviates intestinal ischemia–reperfusion injury

Background

Activated mast cells are involved in the pathogenesis of intestinal ischemia–reperfusion (I/R)-related injury. Dexamethasone has been widely used to protect organs from I/R injury. This study was conducted to investigate the impact of treatment with dexamethasone at different stages of the II/R process on mast cell infiltration and activity and intestinal injury.

Methods

Kunming mice were randomized and subjected to a sham surgery or the II/R induction by clamping the superior mesenteric artery for 30 min and then reperfusion. During the II/R induction, the mice were treated intravenously with dexamethasone (10 mg/kg) for 30 min before ischemia (pretreatment group), at 5 min after clamping the superior mesenteric artery (isc-treatment group), or at the beginning of perfusion (rep-treatment group), respectively. The levels of intestinal injury, mast cell infiltration and activity, tumor necrosis factor α (TNFα) and myeloperoxidase (MPO) activity in the intestines, and mouse survival rates were measured.

Results

The death rates, levels of intestinal injury, mast cell infiltration and activity, and tumor necrosis factor α and myeloperoxidase activity in the intestinal tissues from the II/R group were similar to those from the isc-treatment and rep-treatment groups of mice and were significantly higher than those from the sham group. In contrast, pretreatment with dexamethasone significantly mitigated the II/R-induced mast cell infiltration and activity, inflammation, and intestinal injury and reduced the death rates in mice.

Conclusions

Pretreatment with dexamethasone inhibits II/R injury by reducing mast cell–related inflammation in mice.     

Atrial natriuretic peptide reduces hepatic ischemia–reperfusion injury in rabbits

Purpose

Atrial natriuretic peptide (ANP) has been known to be protective against hepatic ischemia/reperfusion injury. The purpose of this study was to verify the hypothesis that ANP conserves microvascular circulation and reduces ischemia–reperfusion injury in the in vivo rabbit model.

Methods

With IRB approval, 30 male Japanese white rabbits under pentobarbital anesthesia were studied. These animals were randomly assigned to the following three groups (n = 10 each): control, ANP, and sham group. Animals in the ANP group received continuous infusion of ANP at 0.1 μg/kg/min throughout the study period. Animals in control and ANP groups underwent 90 min of partial hepatic ischemia by clamping the right hepatic artery and portal vein. Descending aortic blood flow (AoF) was monitored with a transit-time ultrasound flowmeter. Hepatic tissue microvascular blood flow (HTBF) at both right (ischemic) and left (nonischemic) lobe was intermittently evaluated with the hydrogen clearance method. After 180 min of reperfusion, hepatic injury was determined with serum AST and ALT. Galactose clearance of reperfused right lobe was also measured as an indicator of hepatic metabolic function. Histopathological change and the number of apoptotic hepatocytes were also evaluated.

Results

Systemic hemodynamic data including mean arterial pressure, heart rate, and AoF did not differ among the three groups during the study period. ANP attenuated ischemia-induced right HTBF decrease. ANP also suppressed histopathological degeneration, apoptosis, and decline in galactose clearance after reperfusion.

Conclusions

ANP attenuated hepatic microvascular dysfunction and hepatocyte injury after reperfusion without significant hemodynamic change.     

Mast cell degranulation promotes ischemia–reperfusion injury in rat liver

Background

Mast cells (MCs) play a role in ischemia–reperfusion (I/R) injury in many organs. However, a recent study found that MCs are not involved in I/R injury in isolated rat livers that were perfused only for 1 h. The purpose of this study is to reevaluate the role of MCs in hepatic I/R injury in rat.

Materials and methods

A warm hepatic I/R injury model of 1 h ischemia followed by 24 h of reperfusion was used. MC modulation was induced via cromolyn injection or a method called MC depletion using compound 48/80. The effects of MC modulation were evaluated by toluidine blue staining and assessment of mast cell tryptase in sera. The role of MCs in I/R injury was evaluated by hematoxylin and eosin staining graded by Suzuki criteria, alanine aminotransferase and aspartate aminotransferase levels in sera, and malondialdehyde levels in liver homogenates.

Results

First, MC degranulation peaked after 2 h of reperfusion and liver damage peaked after approximately 6 h of reperfusion. Second, a method called MC depletion previously used in the skin with repeated injections of compound 48/80 worked similarly in the hepatic setting. Third, stabilization of MCs with cromolyn or depletion of MCs with compound 48/80 each decreased hepatic I/R injury. The most noticeable effects of cromolyn and compound 48/80 treatment were observed after approximately 6 h of reperfusion.

Conclusions

MC degranulation promotes hepatic I/R injury in rats.     

Dexmedetomidine protects against ischemia–reperfusion injury in rat skeletal muscle

Background

Dexmedetomidine (DEX) has been shown to decrease ischemia–reperfusion (I/R) injury in kidney and brain tissues. In this study, the effects of DEX were evaluated in skeletal muscle during I/R injury.

Materials and methods

Animals were divided into four groups: sham-operated (sham group), saline + I/R, DEX + I/R, and α-tocopherol + I/R groups. Hind limb ischemia was induced by clamping the common femoral artery and vein. After 4 h of ischemia, the clamp was removed and the animals underwent 2 h of reperfusion. Animals in the drug treatment group received DEX or α-tocopherol by intraperitoneal injection 1 h before reperfusion. We measured plasma concentrations of interleukin 1β and tumor necrosis factor α levels using an enzyme-linked immunosorbent assay. The right gastrocnemius muscle was harvested and immediately stored at −80°C for the assessment of superoxide dismutase (SOD) and catalase (CAT) activities as well as glutathione (GSH), malondialdehyde (MDA), and protein oxidation (PO) levels. DEX (25 μg/kg) and normal saline (10 mL/kg) were administered by intraperitoneal injection 1 h before reperfusion.

Results

Plasma tumor necrosis factor α or interleukin 1β levels increased significantly in the I/R group (P < 0.01 compared with sham group) and decreased significantly in the DEX group (P < 0.01 compared with I/R group). Muscle tissues of the I/R group had significantly decreased SOD, GSH, and CAT activities and increased levels of MDA and PO content compared with the sham group. The activity of antioxidant enzymes in the DEX + I/R group was greatly elevated compared with that in the I/R group (SOD, 1.068 ± 0.120 versus 0.576 ± 0.072 U/mg protein; GSH, 2.436 ± 0.144 versus 1.128 ± 0.132 μmol/g; and CAT, 69.240 ± 6.456 versus 31.884 ± 6.312 U/mg protein; P < 0.01), whereas the levels of MDA and PO content were clearly reduced (23.268 ± 3.708 versus 53.604 ± 5.972 nmol/g protein and 1.908 ± 0.192 versus 5.208 ± 0.612 nmol/mg protein, respectively; P < 0.01). Moreover, DEX exhibited more potent antioxidant activity than vitamin E in the skeletal muscle I/R.

Conclusions

We found that DEX exhibits protective effects against skeletal muscle I/R injury. These results underscore the necessity of human studies with DEX to determine if it is beneficial for preventing skeletal muscle I/R injury.     

Inhibition of Na-K-Cl cotransporter isoform 1 reduces lung injury induced by ischemia–reperfusion

Objectives

Ischemia–reperfusion acute lung injury is characterized by increased vascular permeability, lung edema, and neutrophil sequestration. Ischemia–reperfusion acute lung injury occurs in lung transplantation and other major surgical procedures. Effective regulation of alveolar fluid balance is critical for pulmonary edema. Sodium-potassium-chloride co-transporter regulates alveolar fluid and is associated with inflammation. We hypothesized that sodium-potassium-chloride co-transporter is important in ischemia–reperfusion acute lung injury. Bumetanide, a sodium-potassium-chloride co-transporter inhibitor, is used to treat pulmonary edema clinically. We studied the effect of bumetanide in ischemia–reperfusion acute lung injury.

Osthole prevents intestinal ischemia-reperfusion–induced lung injury in a rodent model

Background

Intestinal ischemia–reperfusion (II/R) is associated with high morbidity and mortality. The aim of this study was to investigate the effects of osthole on lung injury and mortality induced by II/R.

Methods

A rat model of II/R was induced by clamping the superior mesenteric artery for 90 min followed by reperfusion for 240 min. Osthole was administrated intraperitoneally at 30 min before intestinal ischemia (10 or 50 mg/kg). The survival rate and mean arterial pressure were observed. Blood samples were obtained for blood gas analyses. Lung injury was assessed by the histopathologic changes (hematoxylin and eosin staining), lung wet-to-dry weight ratio, and pulmonary permeability index. The levels of reactive oxygen species, malondialdehyde, interleukin 6, and tumor necrosis factor α, as well as the activities of superoxide dismutase and myeloperoxidase in lung were measured.

Results

The survival rate, ratio of arterial oxygen tension to fraction of inspired oxygen, and mean arterial pressure decreased significantly after II/R. Results also indicated that II/R-induced severe lung injury evidenced by increase in pathologic scores, lung wet-to-dry weight ratio, and pulmonary permeability index, which was accompanied by increases in the levels of pulmonary reactive oxygen species, malondialdehyde, interleukin 6, tumor necrosis factor α, and the pulmonary myeloperoxidase activity and a decrease in superoxide dismutase activity. Osthole could significantly ameliorate lung injury and improve the previously mentioned variables.

Conclusions

These findings indicated that osthole could attenuate the lung injury induced by II/R in rats, at least in part, by inhibiting inflammatory response and oxidative stress.