Does brain death induce a pro-inflammatory response at the organ level in a porcine model?

H2S-Enriched Flush out Does Not Increase Donor Organ Quality in a Porcine Kidney Perfusion Model

Kidney extraction time has a detrimental effect on post-transplantation outcome. This study aims to improve the flush-out and potentially decrease ischemic injury by the addition of hydrogen sulphide (H2S) to the flush medium. Porcine kidneys (n = 22) were extracted during organ recovery surgery. Pigs underwent brain death induction or a Sham operation, resulting in four groups: donation after brain death (DBD) control, DBD H2S, non-DBD control, and non-DBD H2S. Directly after the abdominal flush, kidneys were extracted and flushed with or without H2S and stored for 13 h via static cold storage (SCS) +/− H2S before reperfusion on normothermic machine perfusion. Pro-inflammatory cytokines IL-1b and IL-8 were significantly lower in H2S treated DBD kidneys during NMP (p = 0.03). The non-DBD kidneys show superiority in renal function (creatinine clearance and FENa) compared to the DBD control group (p = 0.03 and p = 0.004). No differences were seen in perfusion parameters, injury markers and histological appearance. We found an overall trend of better renal function in the non-DBD kidneys compared to the DBD kidneys. The addition of H2S during the flush out and SCS resulted in a reduction in pro-inflammatory cytokines without affecting renal function or injury markers.

Integrative omics reveals subtle molecular perturbations following ischemic conditioning in a porcine kidney transplant model

BACKGROUND

Remote Ischemic Conditioning (RIC) has been proposed as a therapeutic intervention to circumvent the ischemia/reperfusion injury (IRI) that is inherent to organ transplantation. Using a porcine kidney transplant model, we aimed to decipher the subclinical molecular effects of a RIC regime, compared to non-RIC controls.

METHODS

Kidney pairs (n = 8 + 8) were extracted from brain dead donor pigs and transplanted in juvenile recipient pigs following a period of cold ischemia. One of the two kidney recipients in each pair was subjected to RIC prior to kidney graft reperfusion, while the other served as non-RIC control. We designed an integrative Omics strategy combining transcriptomics, proteomics, and phosphoproteomics to deduce molecular signatures in kidney tissue that could be attributed to RIC.

RESULTS

In kidney grafts taken out 10 h after transplantation we detected minimal molecular perturbations following RIC compared to non-RIC at the transcriptome level, which was mirrored at the proteome level. In particular, we noted that RIC resulted in suppression of tissue inflammatory profiles. Furthermore, an accumulation of muscle extracellular matrix assembly proteins in kidney tissues was detected at the protein level, which may be in response to muscle tissue damage and/or fibrosis. However, the majority of these protein changes did not reach significance (p < 0.05).

CONCLUSIONS

Our data identifies subtle molecular phenotypes in porcine kidneys following RIC, and this knowledge could potentially aid optimization of remote ischemic conditioning protocols in renal transplantation.

Brain stem death induces pro-inflammatory cytokine production and cardiac dysfunction in sheep model

Introduction

Organs procured following brain stem death (BSD) are the main source of organ grafts for transplantation. However, BSD is associated with inflammatory responses that may damage the organ and affect both the quantity and quality of organs available for transplant. Therefore, we aimed to investigate plasma and bronchoalveolar lavage (BAL) pro-inflammatory cytokine profiles and cardiovascular physiology in a clinically relevant 6-h ovine model of BSD.

Methods

Twelve healthy female sheep (37–42 Kg) were anaesthetized and mechanically ventilated prior to undergoing BSD induction and then monitored for 6 h. Plasma and BAL endothelin-1 and cytokines (IL-1β, 6, 8 and tumour necrosis factor alpha (TNF-α)) were assessed by ELISA. Differential white blood cell counts were performed. Cardiac function during BSD was also examined using echocardiography, and cardiac biomarkers (A-type natriuretic peptide and troponin I were measured in plasma.

Results

Plasma concentrations big ET-1, IL-6, IL-8, TNF-α and BAL IL-8 were significantly (p < 0.01) increased over baseline at 6 h post-BSD. Increased numbers of neutrophils were observed in the whole blood (3.1 × 10⁹ cells/L [95% confidence interval (CI) 2.06–4.14] vs. 6 × 10⁹ cells/L [95%CI 3.92–7.97]; p < 0.01) and BAL (4.5 × 10⁹ cells/L [95%CI 0.41–9.41] vs. 26 [95%CI 12.29–39.80]; p = 0.03) after 6 h of BSD induction vs baseline. A significant increase in ANP production (20.28 pM [95%CI 16.18–24.37] vs. 78.68 pM [95%CI 53.16–104.21]; p < 0.0001) and cTnI release (0.039 ng/mL vs. 4.26 [95%CI 2.69–5.83] ng/mL; p < 0.0001), associated with a significant reduction in heart contractile function, were observed between baseline and 6 h.

Conclusions

BSD induced systemic pro-inflammatory responses, characterized by increased neutrophil infiltration and cytokine production in the circulation and BAL fluid, and associated with reduced heart contractile function in ovine model of BSD.

Compromised right ventricular contractility in an ovine model of heart transplantation following 24 h donor brain stem death

BACKGROUND

Heart failure is an inexorably progressive disease with a high mortality, for which heart transplantation (HTx) remains the gold standard treatment. Currently, donor hearts are primarily derived from patients following brain stem death (BSD). BSD causes activation of the sympathetic nervous system, increases endothelin levels, and triggers significant inflammation that together with potential myocardial injury associated with the transplant procedure, may affect contractility of the donor heart. We examined peri-transplant myocardial catecholamine sensitivity and cardiac contractility post-BSD and transplantation in a clinically relevant ovine model.

METHODS

Donor sheep underwent BSD (BSD, n = 5) or sham (no BSD) procedures (SHAM, n = 4) and were monitored for 24h prior to heart procurement. Orthotopic HTx was performed on a separate group of donor animals following 24h of BSD (BSD-Tx, n = 6) or SHAM injury (SH-Tx, n = 5). The healthy recipient heart was used as a control (HC, n = 11). A cumulative concentration-effect curve to (-)-noradrenaline (NA) was established using left (LV) and right ventricular (RV) trabeculae to determine β₁-adrenoceptor mediated potency (-logEC₅₀ [(-)-noradrenaline] M) and maximal contractility (Emax).

RESULTS

Our data showed reduced basal and maximal (-)-noradrenaline induced contractility of the RV (but not LV) following BSD as well as HTx, regardless of whether the donor heart was exposed to BSD or SHAM. The potency of (-)-noradrenaline was lower in left and right ventricles for BSD-Tx and SH-Tx compared to HC.

CONCLUSION

These studies show that the combination of BSD and transplantation are likely to impair contractility of the donor heart, particularly for the RV. For the donor heart, this contractile dysfunction appears to be independent of changes to β₁-adrenoceptor sensitivity. However, altered β₁-adrenoceptor signalling is likely to be involved in post-HTx contractile dysfunction.

Peritransplant Cardiometabolic and Mitochondrial Function: The Missing Piece in Donor Heart Dysfunction and Graft Failure

Primary graft dysfunction is an important cause of morbidity and mortality after cardiac transplantation. Donor brain stem death (BSD) is a significant contributor to donor heart dysfunction and primary graft dysfunction. There remain substantial gaps in the mechanistic understanding of peritransplant cardiac dysfunction. One of these gaps is cardiac metabolism and metabolic function. The healthy heart is an "omnivore," capable of utilizing multiple sources of nutrients to fuel its enormous energetic demand. When this fails, metabolic inflexibility leads to myocardial dysfunction. Data have hinted at metabolic disturbance in the BSD donor and subsequent heart transplantation; however, there is limited evidence demonstrating specific metabolic or mitochondrial dysfunction. This review will examine the literature surrounding cardiometabolic and mitochondrial function in the BSD donor, organ preservation, and subsequent cardiac transplantation. A more comprehensive understanding of this subject may then help to identify important cardioprotective strategies to improve the number and quality of donor hearts.

Cytochrome b5 Interacts With Cytochrome C and Inhibits Hepatocyte Apoptosis in Brain-dead Rabbit Donors

BACKGROUND

Donation after brain death (BD) liver grafts undergo the process of hypoxia-ischemia, which induces hepatocyte apoptosis, but the underlying mechanisms remain unclear. Cytochrome (Cyt) b5 expression was shown to be low in BD rabbits. This study aimed to investigate if Cyt b5 and Cyt c are involved in liver apoptosis after BD.

METHODS AND RESULTS

Liver tissue samples were obtained from donors after BD and from BD rabbit models. Tissues were analyzed by immunofluorescence, western blotting, and reverse-transcriptase polymerase chain reaction to detect Cyt b5 and Cyt c protein expressions and mRNA. Normal liver cells (LO-2) were cultured under serum deprivation and hypoxia, and analyzed as above. Cyt b5 protein and mRNA levels had decreased, while Cyt c levels had increased in BD liver donors and rabbits. Similar results were obtained in LO-2 cells cultured under hypoxia. After 6 and 12 hours of serum deprivation and hypoxia, apoptosis was increased, the levels of Cyt b5 gradually decreased, and the levels of Cyt c gradually increased over time; meanwhile, the Cyt b5-Cyt c combination was gradually reduced. A negative linear correlation between Cyt b5 and Cyt c was also observed.

CONCLUSIONS

Cyt b5 might be an anti-apoptotic protein that could protect the liver after BD and this protective effect might involve increased binding to Cyt c. This study provides some clues for improving the quality of donor livers.

A porcine model to study the effect of brain death on kidney genomic responses

Introduction

A majority of transplanted organs come from donors after brain death (BD). Renal grafts from these donors have higher delayed graft function and lower long-term survival rates compared to living donors. We designed a novel porcine BD model to better delineate the incompletely understood inflammatory response to BD, hypothesizing that adhesion molecule pathways would be upregulated in BD.

Methods

Animals were anesthetized and instrumented with monitors and a balloon catheter, then randomized to control and BD groups. BD was induced by inflating the balloon catheter and animals were maintained for 6 hours. RNA was extracted from kidneys, and gene expression pattern was determined.

Results

In total, 902 gene pairs were differently expressed between groups. Eleven selected pathways were upregulated after BD, including cell adhesion molecules.

Conclusions

These results should be confirmed in human organ donors. Treatment strategies should target involved pathways and lessen the negative effects of BD on transplantable organs.

Organ-specific responses during brain death: increased aerobic metabolism in the liver and anaerobic metabolism with decreased perfusion in the kidneys

Hepatic and renal energy status prior to transplantation correlates with graft survival. However, effects of brain death (BD) on organ-specific energy status are largely unknown. We studied metabolism, perfusion, oxygen consumption, and mitochondrial function in the liver and kidneys following BD. BD was induced in mechanically-ventilated rats, inflating an epidurally-placed Fogarty-catheter, with sham-operated rats as controls. A 9.4T-preclinical MRI system measured hourly oxygen availability (BOLD-related R2*) and perfusion (T1-weighted). After 4 hrs, tissue was collected, mitochondria isolated and assessed with high-resolution respirometry. Quantitative proteomics, qPCR, and biochemistry was performed on stored tissue/plasma. Following BD, the liver increased glycolytic gene expression (Pfk-1) with decreased glycogen stores, while the kidneys increased anaerobic- (Ldha) and decreased gluconeogenic-related gene expression (Pck-1). Hepatic oxygen consumption increased, while renal perfusion decreased. ATP levels dropped in both organs while mitochondrial respiration and complex I/ATP synthase activity were unaffected. In conclusion, the liver responds to increased metabolic demands during BD, enhancing aerobic metabolism with functional mitochondria. The kidneys shift towards anaerobic energy production while renal perfusion decreases. Our findings highlight the need for an organ-specific approach to assess and optimise graft quality prior to transplantation, to optimise hepatic metabolic conditions and improve renal perfusion while supporting cellular detoxification.

A Good Death? Report of the Second Newcastle Meeting on Laboratory Animal Euthanasia

Simple Summary

Millions of laboratory animals are killed each year worldwide. However, there is a lack of consensus regarding what methods of killing are humane for many species and stages of development. This report summarises research findings and discussions from an international meeting of experts and stakeholders, with recommendations to inform good practice for humane killing of mice, rats and zebrafish. It provides additional guidance and perspectives for researchers designing projects that involve euthanasing animals, researchers studying aspects of humane killing, euthanasia device manufacturers, regulators, and institutional ethics or animal care and use committees that wish to review local practice.

Abstract

Millions of laboratory animals are killed each year worldwide. There is an ethical, and in many countries also a legal, imperative to ensure those deaths cause minimal suffering. However, there is a lack of consensus regarding what methods of killing are humane for many species and stages of development. In 2013, an international group of researchers and stakeholders met at Newcastle University, United Kingdom to discuss the latest research and which methods could currently be considered most humane for the most commonly used laboratory species (mice, rats and zebrafish). They also discussed factors to consider when making decisions about appropriate techniques for particular species and projects, and priorities for further research. This report summarises the research findings and discussions, with recommendations to help inform good practice for humane killing.

Circulation stabilizing therapy and pulmonary high-resolution computed tomography in a porcine brain-dead model

BACKGROUND

Currently 80% of donor lungs are not accepted for transplantation, often due to fluid overload. Our aim was to investigate if forced fluid infusion may be replaced by a new pharmacological therapy to stabilize circulation after brain death in an animal model, and to assess therapy effects on lung function and morphology trough blood gas parameters and state-of-the-art High-resolution CT (HRCT).

METHODS

Brain death was caused by surgical decapitation. To maintain mean aortic pressure > 60 mmHg, pigs were treated with forced electrolyte solution infusion (GI; n = 6) or the pharmacological therapy (GII; n = 11). GIII (n = 11) were non-decapitated controls. Lung function was investigated with blood gases and lung morphology with HRCT.

RESULTS

GI pigs became circulatory instable 4-6 h after brain death in spite of forced fluid infusion, five pigs showed moderate to severe pulmonary edema on HRCT and median final PaO2 /FiO2 was 29 kPa (Q1; Q3; range 26; 40; 17-76). GII and GIII were circulatory stable (mean aortic pressure > 80 mmHg) and median final PaO2 /FiO2 after 24 h was 72 kPa (Q1; Q3; range 64; 76; 53-91) (GII) and 66 kPa (55; 78; 43-90) (GIII). On HRCT, only two pigs in GII had mild pulmonary edema and none in GIII. More than 50% of HRCT exams revealed unexpected lung disease even in spite of PaO2 /FiO2 > 40 kPa.

CONCLUSION

Pharmacological therapy but not forced fluid infusion prevented circulatory collapse and extensive HRCT verified pulmonary edema after acute brain death. HRCT was useful to evaluate lung morphology and revealed substantial occult parenchymal changes justifying efforts toward a more intense use of HRCT in the pre-transplant evaluation.

Peroxiredoxin 6 attenuates ischemia‑ and hypoxia‑induced liver damage of brain‑dead donors

Oxidative stress induced by ischemia and hypoxia in the livers of donors after brain death (DBD) is associated with poor organ function and low patient survival rates in those receiving DBD liver transplants. Peroxiredoxin 6 (Prdx6) can defend cells against liver damage induced by oxidative stress. The present study aimed to investigate the role of Prdx6 in ischemia‑ and hypoxia‑induced liver damage in DBD livers. Liver tissue samples from ten DBD patients were collected. The control group constituted of six liver samples from patients with liver hemangioma that had accepted tumor excision surgery. Protein expression levels were determined by western blotting, cell viability was assessed using a CCK‑8 assay, intracellular reactive oxygen species (ROS) levels were measured using a ROS assay kit, and phospholipase A2 (PLA2) activity was measured using a PLA2 assay kit. In DBD liver samples, Prdx6 expression was downregulated and the nuclear factor‑κB (NF‑κB) signaling pathway was activated. Furthermore, when human liver L02 cells were exposed to ischemia and hypoxia, the expression of Prdx6 was reduced, causing an increase in reactive oxygen species (ROS); this in turn activated NF‑κB signaling and lowered cell viability (P<0.01). In agreement, overexpression of Prdx6 reduced ROS levels and improved cell viability. It was also demonstrated that inhibition of NF‑κB increased Prdx6 expression, while inhibition of Prdx6 limited PLA2 activity, exacerbating ischemia‑ and hypoxia‑induced cell damage. This data suggests that Prdx6 and its PLA2 activity have a protective role in DBD livers, the expression of which is regulated by NF‑κB. Thus, Prdx6 may be a novel target to alleviate liver damage in DBD.

Physiologic Measures of Animal Stress during Transitional States of Consciousness

Determination of the humaneness of methods used to produce unconsciousness in animals, whether for anesthesia, euthanasia, humane slaughter, or depopulation, relies on our ability to assess stress, pain, and consciousness within the contexts of method and application. Determining the subjective experience of animals during transitional states of consciousness, however, can be quite difficult; further, loss of consciousness with different agents or methods may occur at substantially different rates. Stress and distress may manifest behaviorally (e.g., overt escape behaviors, approach-avoidance preferences [aversion]) or physiologically (e.g., movement, vocalization, changes in electroencephalographic activity, heart rate, sympathetic nervous system [SNS] activity, hypothalamic-pituitary axis [HPA] activity), such that a one-size-fits-all approach cannot be easily applied to evaluate methods or determine specific species applications. The purpose of this review is to discuss methods of evaluating stress in animals using physiologic methods, with emphasis on the transition between the conscious and unconscious states.

A standardized model of brain death, donor treatment, and lung transplantation for studies on organ preservation and reconditioning

BACKGROUND

We set a model of brain death, donor management, and lung transplantation for studies on lung preservation and reconditioning before transplantation.

METHODS

Ten pigs (39.7 ± 5.9 Kg) were investigated. Five animals underwent brain death and were treated as organ donors; the lungs were then procured and cold stored (Ischemia). Five recipients underwent left lung transplantation and post-reperfusion follow-up (Graft). Cardiorespiratory and metabolic parameters were collected. Lung gene expression of cytokines (tumor necrosis factor alpha (TNFα), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interferon gamma (IFNγ), high mobility group box-1 (HMGB-1)), chemokines (chemokine CC motif ligand-2 (CCL2-MCP-1), chemokine CXC motif ligand-10 (CXCL-10), interleukin-8 (IL-8)), and endothelial activation markers (endothelin-1 (EDN-1), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), selectin-E (SELE)) was assessed by real-time polymerase chain reaction (PCR).

RESULTS

Tachycardia and hypertension occurred during brain death induction; cardiac output rose, systemic vascular resistance dropped (P < 0.05), and diabetes insipidus occurred. Lung-protective ventilation strategy was applied: 9 h after brain death induction, PaO2 was 192 ± 12 mmHg at positive end-expiratory pressure (PEEP) 8.0 ± 1.8 cmH2O and FiO2 of 40%; wet-to-dry ratio (W/D) was 5.8 ± 0.5, and extravascular lung water (EVLW) was 359 ± 80 mL. Procured lungs were cold-stored for 471 ± 24 min (Ischemia) at the end of which W/D was 6.1 ± 0.9. Left lungs were transplanted and reperfused (warm ischemia 98 ± 14 min). Six hours after controlled reperfusion, PaO2 was 192 ± 23 mmHg (PEEP 8.7 ± 1.5 cmH2O, FiO2 40%), W/D was 5.6 ± 0.4, and EVLW was 366 ± 117 mL. Levels of IL-8 rose at the end of donor management (BD, P < 0.05); CCL2-MCP-1, IL-8, HMGB-1, and SELE were significantly altered after reperfusion (Graft, P < 0.05).

CONCLUSIONS

We have set a standardized, reproducible pig model resembling the entire process of organ donation that may be used as a platform to test in vivo and ex vivo strategies of donor lung optimization before transplantation.

α-Melanocyte stimulating hormone treatment in pigs does not improve early graft function in kidney transplants from brain dead donors

Delayed graft function and primary non-function are serious complications following transplantation of kidneys derived from deceased brain dead (DBD) donors. α-melanocyte stimulating hormone (α-MSH) is a pleiotropic neuropeptide and its renoprotective effects have been demonstrated in models of acute kidney injury. We hypothesized that α-MSH treatment of the recipient improves early graft function and reduces inflammation following DBD kidney transplantation. Eight Danish landrace pigs served as DBD donors. After four hours of brain death both kidneys were removed and stored for 18 hours at 4°C in Custodiol preservation solution. Sixteen recipients were randomized in a paired design into two treatment groups, transplanted simultaneously. α-MSH or a vehicle was administered at start of surgery, during reperfusion and two hours post-reperfusion. The recipients were observed for ten hours following reperfusion. Blood, urine and kidney tissue samples were collected during and at the end of follow-up. α-MSH treatment reduced urine flow and impaired recovery of glomerular filtration rate (GFR) compared to controls. After each dose of α-MSH, a trend towards reduced mean arterial blood pressure and increased heart rate was observed. α-MSH did not affect expression of inflammatory markers. Surprisingly, α-MSH impaired recovery of renal function in the first ten hours following DBD kidney transplantation possibly due to hemodynamic changes. Thus, in a porcine experimental model α-MSH did not reduce renal inflammation and did not improve short-term graft function following DBD kidney transplantation.

Brain death increases COX-1 and COX-2 expression in the renal medulla in a pig model

BACKGROUND

Brain death is linked to a systemic inflammatory response that includes prostaglandins and cytokines among its mediators. The levels of cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2) affect graft survival, but it remains unknown whether these enzymes are modified during brain death. The aims of this study were to investigate the organ expression of COX and to analyse the cytokine response in the plasma, cerebrospinal fluid (CSF), and organs in a porcine model of intracerebral haemorrhage and brain death.

METHODS

Twenty pigs were randomly assigned to either a brain death group or a control group. Brain death was induced by an intracerebral injection of blood, and the animals were observed over the next 8 h. Tissue samples were tested for COX-1, COX-2 messenger RNA (mRNA) expression (heart, lung, and kidney), haeme oxygenase-1 (HO-1) (kidney), interleukin-1β (IL-1β), IL-6, IL-8, IL-10, and tumour necrosis factor-α. These cytokines were also measured at eight time points in the plasma and CSF.

RESULTS

At the organ level, the levels of COX-1 and COX-2 mRNA expression were increased only in the renal medulla (P = 0.03 and P = 0.02, respectively). The cytokine levels in the tissue, plasma, and CSF revealed no differences between the groups. HO-1 expression decreased (P = 0.0088).

CONCLUSION

Brain death increases the expression of COX-1 and COX-2 mRNA in the renal medulla. The release of cytokines into the plasma and CSF did not vary between the groups.

Pharmacological normalization of circulation after acute brain death

BACKGROUND

Circulatory instability is a serious problem after brain death in organ donors. The hypotension is often counteracted with infusion of large amounts of crystalloid solutions, which may impair lung function leading to rejection of the lungs as donor organs. The aim was to show that the circulation can be normalized pharmacologically for 24 h in pigs after total removal of the brain and brainstem by decapitation (between C2 and C3).

METHODS

Twenty-four 40-kg pigs (n = 8 × 3) were included: non-decapitated, decapitated, and decapitated with pharmacological treatment. All animals got the same basal fluid supply and ventilation. The pharmacological treatment consisted of the neuronal monoamine reuptake blocker cocaine and low doses of noradrenaline and adrenaline. Desmopressin, triiodothyroxine, thyroxine and cortisol were also given.

RESULTS

After decapitation, a catecholamine storm occurred, with an increase of noradrenaline and adrenaline by a factor of 79 and 298, respectively. Thirty minutes later, the pigs were hypotensive. The median time to the aortic pressure that was less than 40 mmHg was 9:09 h (range 5:50 to 22:01). After 6 h, the concentration of thyroid hormones and cortisol was significantly reduced. With pharmacological treatment of decapitated animals, the aortic pressure, renal blood flow, creatinine, urine production, liver function and blood gases did not differ significantly from the non-decapitated control animals.

CONCLUSION

Pharmacological substitution of pituitary gland function, blockade of peripheral catecholamine neuronal reuptake and low doses of catecholamines normalize circulation in decapitated pigs throughout a 24-h observation period, whereas untreated decapitated pigs all develop severe circulatory collapse within 12 h.

Early outcome in renal transplantation from large donors to small and size-matched recipients - a porcine experimental model

Kidney transplantation from a large donor to a small recipient, as in pediatric transplantation, is associated with an increased risk of thrombosis and DGF. We established a porcine model for renal transplantation from an adult donor to a small or size-matched recipient with a high risk of DGF and studied GFR, RPP using MRI, and markers of kidney injury within 10 h after transplantation. After induction of BD, kidneys were removed from ∼63-kg donors and kept in cold storage for ∼22 h until transplanted into small (∼15 kg, n = 8) or size-matched (n = 8) recipients. A reduction in GFR was observed in small recipients within 60 min after reperfusion. Interestingly, this was associated with a significant reduction in medullary RPP, while there was no significant change in the size-matched recipients. No difference was observed in urinary NGAL excretion between the groups. A significant higher level of HO-1 mRNA was observed in small recipients than in donors and size-matched recipients indicating cortical injury. Improvement in early graft perfusion may be a goal to improve short- and long-term GFR and avoid graft thrombosis in pediatric recipients.

Brain death induced by cerebral haemorrhage - a new porcine model evaluated by CT angiography

BACKGROUND

Brain death and complications to brain death affects the function of organs in the potential donor. Previous animal models of brain death have not been able to fully elucidate the mechanisms behind this organ dysfunction, and none of the available animal models mimic the most common insult prior to brain death: intracerebral haemorrhage. The objective of this study was to develop a large animal model of brain death based on a controlled intracerebral haemorrhage and verified by computerised tomographic angiography (CTA).

METHODS

Twenty pigs (range: 26.6-31.2 kg) were randomised to brain death or control. Brain death was induced by infusion of blood through a stereotaxically placed needle in the internal capsule. Brain death was confirmed by the measured intracranial pressure (ICP), lack of corneal and pupillary light reflexes, and atropine test. CTA was performed 120-180 min after brain death. The pigs were observed for 8 h after brain death.

RESULTS

Brain death was declared when the ICP exceeded mean arterial pressure after a median of 36 min (range: 28-51 min). Significant increases in heart rate, and mean arterial pressure (MAP) were followed by a steep decrease. With fluid therapy, the animals demonstrated haemodynamic stability. Reflexes disappeared, and atropine did not induce an increase in heart rate in the brain dead animals. CTA confirmed loss of cerebral circulation.

CONCLUSION

This study offers a standardised, clinically relevant porcine model of brain death induced by a haemorrhagic attack. Brain death was verified by the disappearance of corneal and pupil reflex, atropine test, and CTA.

Effect of oxidative stress and endotoxin on human serum albumin in brain-dead organ donors

Albumin, among other molecules, binds and detoxifies endotoxin in healthy people. Oxidative stress leads to protein oxidation and thus to the impaired binding properties of albumin. This property, in combination with increased gut permeability, leads to the appearance of endotoxin in the systemic circulation and to impaired organ function. We hypothesize that these processes occur in the serum of brain-dead organ donors. Endotoxin was determined with an adapted Limulus amoebocyte lysate assay. The albumin fractions and binding capacity were determined by high-performance liquid chromatography (HPLC). FlowCytomix (eBioscience, San Diego, Calif) was used to determine the cytokine levels. Carbonylated proteins (CPs) and myeloperoxidase (MPO) were measured by an enzyme-linked immunosorbent assay (ELISA). Eighty-four brain-dead organ donors were enrolled and categorized by the duration of intensive care unit (ICU) stay. The albumin-binding capacity for dansylsarcosine was reduced in brain-dead patients compared with controls. Endotoxin positivity in 16.7% of donors was associated with decreased binding capacity in donors and worse survival of recipients. The CP and MPO levels of organ donors were significantly higher than in healthy controls. The durations of ICU stay increased albumin oxidation. In addition, interleukin-6 (IL-6), IL-8, IL-10, and IL-1β levels were increased in patients, whereas the interferon-γ (IFN-γ) levels were within the normal range. We conclude that oxidative stress and systemic endotoxemia are present in brain-dead organ donors, which might affect recipient survival. High endotoxin levels might be caused by increased gut permeability and decreased binding capacity of albumin influenced not just by higher albumin oxidation.

Fluoro-D-glucose-micro positron emission tomography as a diagnostic tool to confirm brain death in a murine donor lung injury model

PURPOSE

Because brain death (BD)-related donor lung injury is still poorly understood, a reliable mouse model can help in understanding the immunologic mechanisms behind this lung injury. The purpose of our study was to validate BD in mice using small-animal positron emission tomography.

PROCEDURES

BD was induced in male Balb/c mice (27.1 ± 0.9 g) with an intracranial balloon catheter inflated rapidly (<1 min) [BD](R) or gradually (36 ± 5 min) [BD](G), and compared with sham-operated [SH] and control animals [C] (n = 6/group). Ten minutes after balloon insertion 10.4 ± 1.0 MBq 2-deoxy-2-[(18)F]-fluoro-D-glucose ((18)FDG) was administered intravenously and static images were performed and quantified.

RESULTS

Coronal, sagittal, and transaxial sections of cerebral (18)FDG activity revealed significant differences when comparing [BD](R) and [BD](G) with [C] and [SH] animals. No significant (18)FDG uptake was visually detectable in [BD](R) and [BD](G). The percentage injected dose showed significant differences between BD groups and [C] and [SH] (P < 0.0001). No significant difference was seen between [C] versus [SH] nor between [BD](R)versus [BD](G) (P > 0.05).

CONCLUSIONS

(18)FDG micro positron emission tomography imaging is a valuable tool to demonstrate brain functionality and can therefore be used as a surrogate test to confirm BD in mice.

Paradoxical effects of brain death and associated trauma on rat mesenteric microcirculation: an intravital microscopic study

OBJECTIVE

Experimental findings support clinical evidence that brain death impairs the viability of organs for transplantation, triggering hemodynamic, hormonal, and inflammatory responses. However, several of these events could be consequences of brain death-associated trauma. This study investigated microcirculatory alterations and systemic inflammatory markers in brain-dead rats and the influence of the associated trauma.

METHOD

Brain death was induced using intracranial balloon inflation; sham-operated rats were trepanned only. After 30 or 180 min, the mesenteric microcirculation was observed using intravital microscopy. The expression of Pselectin and ICAM-1 on the endothelium was evaluated using immunohistochemistry. The serum cytokine, chemokine, and corticosterone levels were quantified using enzyme-linked immunosorbent assays. White blood cell counts were also determined.

RESULTS

Brain death resulted in a decrease in the mesenteric perfusion to 30%, a 2.6-fold increase in the expression of ICAM-1 and leukocyte migration at the mesentery, a 70% reduction in the serum corticosterone level and pronounced leukopenia. Similar increases in the cytokine and chemokine levels were seen in the both the experimental and control animals.

CONCLUSION

The data presented in this study suggest that brain death itself induces hypoperfusion in the mesenteric microcirculation that is associated with a pronounced reduction in the endogenous corticosterone level, thereby leading to increased local inflammation and organ dysfunction. These events are paradoxically associated with induced leukopenia after brain damage.

Early activation of the inflammatory response in the liver of brain-dead non-human primates

BACKGROUND

Donor brain death (BD) triggers a systemic inflammatory response that reduces organ quality and increases immunogenicity of the graft. We characterized the early innate immune response induced by BD in the liver and peripheral blood of hemodinamically stable non-human primates (NHP).

METHODS

Rhesus macaques were assigned to either brain death or control group. BD was induced by inflation of a subdurally placed catheter and confirmed clinically and by cerebral angiography. Animals were monitored for 6 h after BD and managed to maintain hemodynamic stability.

RESULTS

Cortisol, epinephrine, nor-epinephrine, and IL-6 levels were elevated immediately after BD induction. Neutrophils and monocytes significantly increased in circulation following BD induction, while dendritic cells were decreased at 6 h post-induction. Flow cytometry revealed increased expression of chemokine receptors CxCR1, CxCR2, CCR2, and CCR5 in peripheral blood leukocytes from NHP subjected to BD. Microarray analysis demonstrated a significant up-regulation of genes related to innate inflammatory responses, toll-like receptor signaling, stress pathways, and apoptosis/cell death in BD subjects. Conversely, pathways related to glucose, lipid, and protein metabolism were down-regulated. In addition, increased expression of SOCS3, S100A8/A9, ICAM-1, MHC class II, neutrophil accumulation, and oxidative stress markers (carboxy-methyl-lysine and hydroxynonenal) were detected by immunoblot and immunohistochemistry.

CONCLUSIONS

Activation of the innate immune response after BD in association with a down-regulation of genes associated with cell metabolism pathways in the liver. These findings may provide a potential explanation for the reduced post-transplant function of organs from brain dead donors. In addition, this work suggests potential novel targets to improve donor management strategies.

Simultaneous detection of porcine cytokines by multiplex analysis: development of magnetic bioplex assay

Multiplex assays for analysis of human and rodent cytokines are highly developed, while development of porcine cytokine assays needs further attention. In order to follow the cytokine response in consecutive porcine samples, in which the sample volume may be limited, we have developed multiplex immunoassays for simultaneous detection of porcine cytokines interleukin (IL)-1beta, IL-6, IL-8, IL-10, tumour necrosis factor alpha (TNF-alpha), and heat shock protein 32 (Hsp32). Antibodies against porcine cytokines were coupled to magnetic microspheres. Quantification was obtained with biotinylated antibodies followed by PE-labelled streptavidin and measurements by Luminex(100). Validation and cross-reaction experiments revealed detection limits below 5-20 ng/L, recovery of recombinant cytokines in spiked plasma between 80 and 110%, and intra- and inter-assay variation between 5 and 15%. No cross-reaction between assays was found. However, for optimal sensitivity the assays were performed as a 2-plex (IL-1beta and Hsp32) and a 4-plex (IL-6, IL-8, IL-10, and TNF-alpha). Cytokine levels were determined in plasma samples from a porcine model of acute endotoxaemia and the levels correlated to previously published concentrations.

Insulin alters cytokine content in two pivotal organs after brain death: a porcine model

BACKGROUND

To optimize the quantity and quality of organs available for transplantation, it is crucial to gain further insight into the treatment of brain dead organ donors. In the current study we hypothesized that insulin treatment after brain death alters cytokine content in the heart, liver, and kidney.

METHODS

Sixteen brain dead pigs (35-40 kg) were treated with either (1) no insulin [brain dead without insulin treatment treatment (BD)], or (2) insulin infusion intravenously (i.v.) at a constant rate of 0.6 mU/kg/min during 360 min [brain dead with insulin treatment (BD+I)]. Blood glucose was clamped at 4.5 mmol/l by infusion of 20% glucose. Blood samples for insulin, glucose, catecholamines, free fatty acids, and glucagon were obtained during the experimental period. Six hours after brain death biopsies were taken from the heart, liver, and kidney. These were analyzed for cytokine mRNA and proteins [tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, and IL-10].

RESULTS

The BD+I compared with the BD animals had lower IL-6 concentrations in the right ventricle of the heart (P=0.001), in the renal cortex (P=0.04) and in the renal medulla (P=0.05), and lower IL-6 mRNA in the renal medulla (P=0.0002). Furthermore, the BD+I animals had lower concentrations in the renal medulla of IL-10 (P=0.01), and tended to have lower TNF-alpha in the renal cortex (P=0.06) than the BD animals. In the right ventricle of the heart TNF-alpha mRNA and IL-10 mRNA were higher in the BD+I than in the BD group (P=0.002 and 0.004).

CONCLUSION

Insulin has anti-inflammatory effects on cytokine concentration in the heart and kidney after brain death.