Deferoxamine improves early postresuscitation reperfusion after prolonged cardiac arrest in rats

No-reflow phenomenon following stroke recanalization therapy: Clinical assessment advances: A narrative review

The no-reflow phenomenon (NRP) after successful vascular recanalization in acute ischemic stroke (AIS) has become a major cause of poor clinical prognosis and ineffective recanalization. However, there is currently no clear definition or unified clinical assessment method for the NRP. Therefore, it is urgent to clarify the clinical evaluation criteria for the NRP and develop new no-reflow evaluation techniques so that remedial treatment can be applied to AIS patients suffering from the NRP. In this brief review, a variety of NRP assessment methods and defining criteria for clinical practice are presented.

Iron Neurotoxicity and Protection by Deferoxamine in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a subtype of stroke that is characterized by high morbidity and mortality, for which clinical outcome remains poor. An extensive literature indicates that the release of ferrous iron from ruptured erythrocytes in the hematoma is a key pathogenic factor in ICH-induced brain injury. Deferoxamine is an FDA-approved iron chelator that has the capacity to penetrate the blood-brain barrier after systemic administration and binds to iron. Previous animal studies have shown that deferoxamine attenuates ICH-induced brain edema, neuronal death, and neurological deficits. This review summarizes recent progress of the mechanisms by which deferoxamine may alleviate ICH and discusses further studies on its clinical utility.

UAMC-3203 or/and Deferoxamine Improve Post-Resuscitation Myocardial Dysfunction Through Suppressing Ferroptosis in a Rat Model of Cardiac Arrest

ABSTRACT

Blocking ferroptosis reduces ischemia-reperfusion injury in some pathological contexts. However, there is no evidence that ferroptosis contributes to post-resuscitation myocardial dysfunction (PRMD). Here, we evaluated the therapeutic performance of ferroptosis inhibitors (UAMC-3203 or/and Deferoxamine) on the PRMD in a rat model of cardiac arrest and surveyed the changes of essential ferroptosis markers in the myocardium. Remarkably, all treatments reduce the severity of cardiac dysfunction and microcirculation hypoperfusion after resuscitation compared with control. Consistently, we observe that the ferroptosis marker Glutathione peroxidase 4, 4-hydroxynonenal and non-heme iron altered (1 ± 0.060 vs. 0.021 ± 0.016, 1 ± 0.145 vs. 3.338 ± 0.221, 52.010 ± 3.587 ug/g vs. 70.500 ± 3.158 ug/g, all P < 0.05) in the myocardium after resuscitation. These changes were significantly suppressed by UAMC-3203 [(0.187 ± 0.043, 2.848 ± 0.169, all P < 0.05), (72.43 ± 4.920 ug/g, P  > 0.05)], or Deferoxamine (0.203 ± 0.025, 2.683 ± 0.273, 55.95 ± 2.497 ug/g, all P < 0.05). Briefly, UAMC-3203 or/and Deferoxamine improve post-resuscitation myocardial dysfunction and provide evidence of ferroptosis involvement, suggesting that ferroptosis inhibitors could potentially provide an innovative therapeutic approach for mitigating the myocardial damage caused by cardiopulmonary resuscitation.

Brain Hypoxia Is Associated With Neuroglial Injury in Humans Post-Cardiac Arrest

Supplemental Digital Content is available in the text.

Secondary brain hypoxia portends significant mortality in ischemic brain diseases; yet, our understanding of hypoxic ischemic brain injury (HIBI) pathophysiology in humans remains rudimentary.

Comparison of the effects of nimodipine and deferoxamine on brain injury in rat with subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) may lead to brain atrophy and cognitive dysfunction. This study aimed to compare the efficacy of nimodipine and deferoxamine on these sequelae of SAH. A rat model of SAH was established by the double-hemorrhage method. These rats were injected with saline (intraperitoneal, IP), nimodipine (IP), or deferoxamine (IP and intranasal) every 12 h for 5 days after SAH. The MRI scanning, including magnetic resonance angiography, diffusion tensor imaging, T_2-weighted imaging, was performed to detect the brain structure. The levels of iron metabolism-related proteins were examined by Western blot analysis. The Morris water maze (MWM) test was used to assess the cognitive function. Then, then neurons in the cortex and hippocampus were counted on hematoxylin and eosin-stained brain sections. Significant cerebral vasospasm (CVS) was found in the saline and deferoxamine groups, but not in the nimodipine group. Cerebral peduncle injury was detected in the saline and nimodipine groups, but not significantly in the deferoxamine group. Compared with nimodipine, deferoxamine reduced transferrin (Tf), Tf receptor, and ferritin levels after SAH. The MWM performances were significantly worse in the saline and nimodipine groups than that in the deferoxamine group. Brain atrophy and neuronal losses were more significant in the saline and nimodipine groups than in the deferoxamine group. Nimodipine significantly ameliorated CVS, but it did not improve the late changes in brain structure and cognitive function. Deferoxamine effectively reduced neuronal cell death and ameliorated cognitive function after SAH.

Invasion of Peripheral Immune Cells into Brain Parenchyma after Cardiac Arrest and Resuscitation

Although a direct link has long been suspected between systemic immune responses and neuronal injuries after stroke, it is unclear which immune cells play an important role. A question remains as to whether the blood brain barrier (BBB) is transiently disrupted after circulatory arrest to allow peripheral immune cells to enter brain parenchyma. Here, we developed a clinically relevant cardiac arrest and resuscitation model in mice to investigate the BBB integrity using noninvasive magnetic resonance imaging. Changes in immune signals in the brain and periphery were assayed by immunohistochemistry and flow cytometry. Quantitative variance maps from T1-weighted difference images before and after blood-pool contrast clearance revealed BBB disruptions immediately after resuscitation and one day after reperfusion. Time profiles of hippocampal CA1 neuronal injuries correlated with the morphological changes of microglia activation. Cytotoxic T cells, CD11b⁺CD11c⁺ dendritic cells, and CD11b⁺CD45^+hi monocytes and macrophages were significantly increased in the brain three days after cardiac arrest and resuscitation, suggesting direct infiltration of these cells following the BBB disruption. Importantly, these immune cell changes were coupled with a parallel increase in the same subset of immune cell populations in the bone marrow and blood. We conclude that neurovascular breakdown during the initial reperfusion phase contributes to the systemic immune cell invasion and subsequent neuropathogenesis affecting the long-term outcome after cardiac arrest and resuscitation.

Significance of oxygen free radicals in the pathophysiology of hemorrhagic shock - A protocol

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Free radicals can cause significant tissue damage.

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Scavengers of free radicals are a useful way to reduce reperfusion injury.

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Electron Paramagnetic Resonance (EPR) spectroscopy is the best way to detect free radicals.

Oxygen free radicals have been implicated as the deleterious agent in a variety of organ systems undergoing ischemia and subsequent reperfusion. Hemorrhagic shock represents a clinical situation that carries a high rate of morbidity and mortality despite adequate fluid resuscitation. Since this entity represents, in its most simplified sense, total body ischemia followed by reperfusion, it is likely that the generation of oxygen free radicals has some significance in the pathophysiology of this delayed morbidity. This is a research protocol, where rabbits will be subjected to severe hemorrhagic shock followed by adequate fluid resuscitation. In the first part of the experiment, free radical generation will be measured directly by Electron Paramagnetic Resonance (EPR) spectroscopy in various organ systems in rabbits before and during shock, and following resuscitation. In the second part, free radical scavengers will be introduced as an adjunct to fluid resuscitation in a group of rabbits subjected to hemorrhagic shock to see if mortality rates are affected. By acquiring a better understanding of the molecular mechanisms that may be responsible for the delayed morbidity in reperfusion injury in general, and hemorrhagic shock in particular, we will be able to better address the long-standing problem of multi system organ failure (MSOF) that often follows a successful resuscitation.

Imaging PEG-like nanoprobes in tumor, transient ischemia, and inflammatory disease models

The iron chelator deferoxamine (DFO), approved for the treatment of iron overload, has been examined as a therapeutic in a variety of conditions which iron may exacerbate. To evaluate the potential of DFO-bearing PEG-like nanoprobes (DFO-PNs) as therapeutics, we determined their pharmacokinetics (PK) in normal mice, and imaged their accumulation in a tumor model and in models of transient brain ischemia and inflammation. DFO-PNs consist of a DFO, a Cy5.5, and PEG (5 kDa or 30 kDa) attached to Lys-Cys scaffold. Tumor uptake of a [(89)Zr]:DFO-PN(10) (30 kDa PEG, diameter 10 nm) was imaged by PET, surface fluorescence, and fluorescence microscopy. DFO-PN(10) was internalized by tumor cells (fluorescence microscopy) and by cultured cells (by FACS). [(89)Zr]:DFO-PN(4.3) (5 kDa PEG, diameter 4.3 nm) concentrated at incision generated inflammations but not at sites of transient brain ischemia. DFO-PNs are fluorescent, PK tunable forms of DFO that might be investigated as antitumor or anti-inflammatory agents.

Protective effects of deferoxamine mesylate preconditioning on pancreatic tissue in orthotopic liver autotransplantation in rats

BACKGROUND

Deferoxamine mesylate is known to ameliorate tissue ischemia-reperfusion injury. This study was designed to explore the impact of deferoxamine mesylate preconditioning (DMP) on pancreatic tissue and its possible effects during orthotopic liver autotransplantation.

METHODS

A modified orthotopic liver autotransplantation model was used to simulate pancreatic ischemia-reperfusion injury. Sprague-Dawley rats (0.25-0.30 kg) were randomly divided into normal control, autotransplantation (AT), systemic deferoxamine mesylate preconditioning (SDMP), and partial deferoxamine mesylate conditioning (PDMC) groups. The SDMP group was injected with deferoxamine mesylate (75-90 mg; 300 mg/kg), via the celiac artery at 24 and 48 hours before surgery. During surgery, the PDMC group underwent liver perfusion by means of deferoxamine mesylate solution (20 ml; 0.6 mmol/L) rather than Ringer's lactate solution, with no prior preconditioning. At 6, 24, and 48 hours after surgery, the rats were sacrificed to sample their pancreatic tissues for the expression of hypoxia-inducible factor-1α (HIF-1α) and malondialdehyde (MDA) content. The samples were subjected to blood chemistry analyses, light and transmission electron microscopic morphological studies, and quantitative measurement of HIF-1α expression.

RESULTS

The serum levels of amylase, lipase, and MDA in SDMP and PDMC groups were significantly lower than those in the AT group at 6, 24, and 48 hours after orthotopic liver autotransplantation (P < .05). Light and electron microscopic analyses showed much more severe pancreatic injury in the autotransplantation than in the SDMP and PDMC groups. The HIF-1α expression was increased in the SDMP and PDMC groups more than in the autotransplantation group (P < .05).

CONCLUSIONS

Deferoxamine mesylate preconditioning protected pancreatic tissue in orthotopic liver autotransplantation in rats. Inhibition of oxidative toxic reactions and up-regulated expression of HIF-1α protein are possible mechanisms.

Mitochondrial approaches to protect against cardiac ischemia and reperfusion injury

The mitochondrion is a vital component in cellular energy metabolism and intracellular signaling processes. Mitochondria are involved in a myriad of complex signaling cascades regulating cell death vs. survival. Importantly, mitochondrial dysfunction and the resulting oxidative and nitrosative stress are central in the pathogenesis of numerous human maladies including cardiovascular diseases, neurodegenerative diseases, diabetes, and retinal diseases, many of which are related. This review will examine the emerging understanding of the role of mitochondria in the etiology and progression of cardiovascular diseases and will explore potential therapeutic benefits of targeting the organelle in attenuating the disease process. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate or manipulate mitochondrial function, to the use of light therapy directed to the mitochondrial function, and to modification of the mitochondrial genome for potential therapeutic benefit. The approach to rationally treat mitochondrial dysfunction could lead to more effective interventions in cardiovascular diseases that to date have remained elusive. The central premise of this review is that if mitochondrial abnormalities contribute to the etiology of cardiovascular diseases (e.g., ischemic heart disease), alleviating the mitochondrial dysfunction will contribute to mitigating the severity or progression of the disease. To this end, this review will provide an overview of our current understanding of mitochondria function in cardiovascular diseases as well as the potential role for targeting mitochondria with potential drugs or other interventions that lead to protection against cell injury.

Potential therapeutic benefits of strategies directed to mitochondria

The mitochondrion is the most important organelle in determining continued cell survival and cell death. Mitochondrial dysfunction leads to many human maladies, including cardiovascular diseases, neurodegenerative disease, and cancer. These mitochondria-related pathologies range from early infancy to senescence. The central premise of this review is that if mitochondrial abnormalities contribute to the pathological state, alleviating the mitochondrial dysfunction would contribute to attenuating the severity or progression of the disease. Therefore, this review will examine the role of mitochondria in the etiology and progression of several diseases and explore potential therapeutic benefits of targeting mitochondria in mitigating the disease processes. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate and manipulate mitochondrial function and genomics for therapeutic benefit. These approaches to treat mitochondrial dysfunction rationally could lead to selective protection of cells in different tissues and various disease states. However, most of these approaches are in their infancy.

Therapeutic manipulation of the HIF hydroxylases

The hypoxia-inducible factor (HIF) family of transcription factors is responsible for coordinating the cellular response to low oxygen levels in animals. By regulating the expression of a large array of target genes during hypoxia, these proteins also direct adaptive changes in the hematopoietic, cardiovascular, and respiratory systems. They also play roles in pathological processes, including tumorogenesis. In recent years, several oxygenases have been identified as key molecular oxygen sensors within the HIF system. The HIF hydroxylases regulate the stability and transcriptional activity of the HIF-alpha subunit by catalyzing hydroxylation of specific proline and asparaginyl residues, respectively. They require oxygen and 2-oxoglutarate (2OG) as co-substrates, and depend upon non-heme ferrous iron (Fe(II)) as a cofactor. This article summarizes current understanding of the biochemistry of the HIF hydroxylases, identifies targets for their pharmacological manipulation, and discusses their potential in the therapeutic manipulation of the HIF system.

Effects of deferoxamine on brain injury after transient focal cerebral ischemia in rats with hyperglycemia

Hemorrhagic transformation (HT) is a major factor limiting the use of tissue plasminogen activator (tPA) for stroke patients. This study examined the role of deferoxamine (DFX) in brain injury and HT in a rat model of transient focal ischemia with hyperglycemia. Rats received an injection of 50% glucose (6 mL/kg, i.p.) 15 min before undergoing transient middle cerebral artery occlusion (tMCAO; 2 h occlusion) with reperfusion. Rats were treated with DFX (100 mg/ kg, i.m.) or vehicle immediately after tMCAO. Rats were killed at 4, 8 and 24 h later and used for brain edema, blood-brain barrier permeability, hemorrhage volume, hemoglobin content, and infarct volume measurements. Mortality rate was also evaluated. DFX treatment reduced mortality at 24 h (4% vs. 24% in the vehicle-treated group, p<0.05). DFX also reduced infarct volume (85.1+/-56.3 vs. 164.3+/-93.4 mm(3) in vehicle, p<0.05) and swelling in the basal ganglia (p<0.05) 24 h after tMCAO. The total hemorrhage volume in the ipsilateral hemisphere at 8 h post tMCAO was less in DFX-treated animals (p<0.05). However, blood-brain barrier permeability was same in DFX- and vehicle-treated groups. DFX attenuates death rate, hemorrhagic transformation, infarct volume, and brain swelling in a rat transient focal ischemia with hyperglycemia model, suggesting that DFX could be potential treatment to reduce the hemorrhagic transformation for stroke patients.

Faster recovery of cerebral perfusion in SOD1-overexpressed rats after cardiac arrest and resuscitation

BACKGROUND AND PURPOSE

Protracted hypoperfusion is one of the hallmarks of secondary cerebral derangement after cardiac arrest and resuscitation (CAR), and reactive oxygen species have been implicated in reperfusion abnormalities.

METHODS

Using transgenic (Tg) rats overexpressing copper zinc superoxide dismutase (SOD1), we investigated the role of this intrinsic antioxidant in the restoration of cerebral blood flow (CBF) after CAR. Nine Tg and 11 wild-type (WT) rats were subjected to a nominal 15-minute cardiac arrest, and CBF was measured using the noninvasive arterial spin labeling MRI method before and during cardiac arrest, and 0 to 2 hours and 1 to 5 days after resuscitation.

RESULTS

The SOD1-Tg rats showed rapid normalization of CBF 1 day after the insult, whereas CBF in WT animals remained abnormal for at least 5 days, showing a progressive increase in CBF from hypo- to hyperperfusion on postresuscitation days 1 to 5. The long-term outcome, as measured by survival time, change in body weight, and mapping of apparent diffusion coefficient (ADC) for ion/water homeostasis, was significantly better in the SOD1-Tg rats.

CONCLUSIONS

Our results support the notion that reactive oxygen species are at least partially responsible for microvascular reperfusion disorders.

Edaravone, a free radical scavenger, mitigates both gray and white matter damages after global cerebral ischemia in rats

Recent studies have shown that similar to cerebral gray matter (mainly composed of neuronal perikarya), white matter (composed of axons and glias) is vulnerable to ischemia. Edaravone, a free radical scavenger, has neuroprotective effects against focal cerebral ischemia even in humans. In this study, we investigated the time course and the severity of both gray and white matter damage following global cerebral ischemia by cardiac arrest, and examined whether edaravone protected the gray and the white matter. Male Sprague-Dawley rats were used. Global cerebral ischemia was induced by 5 min of cardiac arrest and resuscitation (CAR). Edaravone, 3 mg/kg, was administered intravenously either immediately or 60 min after CAR. The morphological damage was assessed by cresyl violet staining. The microtubule-associated protein 2 (a maker of neuronal perikarya and dendrites), the beta amyloid precursor protein (the accumulation of which is a maker of axonal damage), and the ionized calcium binding adaptor molecule 1 (a marker of microglia) were stained for immunohistochemical analysis. Significant neuronal perikaryal damage and marked microglial activation were observed in the hippocampal CA1 region with little axonal damage one week after CAR. Two weeks after CAR, the perikaryal damage and microglial activation were unchanged, but obvious axonal damage occurred. Administration of edaravone 60 min after CAR significantly mitigated the perikaryal damage, the axonal damage, and the microglial activation. Our results show that axonal damage develops slower than perikaryal damage and that edaravone can protect both gray and white matter after CAR in rats.

Brain edema after intracerebral hemorrhage in rats: the role of iron overload and aquaporin 4

OBJECT

Brain edema formation following intracerebral hemorrhage (ICH) appears to be partly related to erythrocyte lysis and hemoglobin release. An increase of brain water content was associated with an increase of brain iron, which is an erythrocyte degradation product. Expression of AQP4 is highly modified in several brain disorders, and it can play a key role in cerebral edema formation. However, the question whether AQP4 is regulated by drugs lacks reliable evidence, and the interacting roles of iron overload and AQP4 in brain edema after ICH are unknown. The goal of this study was to clarify the relationship between iron overload and AQP4 expression and to characterize the effects of the iron chelator deferoxamine (DFO) on delayed brain edema after experimental ICH.

METHODS

A total of 144 Sprague-Dawley rats weighing between 250 and 300 g were used in this work. The animals were randomly divided into 4 groups. The ICH models (Group C) were generated by injecting 100 microl autologous blood stereotactically into the right caudate nucleus; surgical control rats (Group B) were generated in a similar fashion, by injecting 100 microl saline into the right caudate nucleus. Intervention models (Group D) were established by intraperitoneal injection of DFO into rats in the ICH group. Healthy rats (Group A) were used for normal control models. Brain water content, iron deposition, and AQP4 in perihematomal brain tissue were evaluated over the time course of the study (1, 3, 7, and 14 days) in each group.

RESULTS

Iron deposition was found in the perihematomal zone as early as the 1st day after ICH, reaching a peak after 7 days and remaining at a high level thereafter for at least 14 days following ICH. Rat brain water content around the hematoma increased progressively over the time course, reached its peak at Day 3, and still was evident at Day 7 post-ICH. Immunohistochemical analysis showed that AQP4 was richly expressed over glial cell processes surrounding microvessels in the rat brain; there was upregulation of the AQP4 expression in perihematomal brain during the observation period, and it reached maximum at 3 to 7 days after ICH. The changes of brain water content were accompanied by an alteration of AQP4. The application of the iron chelator DFO significantly reduced iron overload, brain water content, and AQP4 level in the perihematomal area compared with the control group.

CONCLUSIONS

Iron overload and AQP4 may play a critical role in the formation of brain edema after ICH. In addition, AQP4 expression was affected by iron concentration. Importantly, treatment with DFO significantly reduced brain edema in rats and inhibited the AQP4 upregulation after ICH. Deferoxamine may be a potential therapeutic agent for treating ICH.

Activation of c-Jun-N-terminal kinase in a rat model of intracerebral hemorrhage: the role of iron

Iron accumulates in the brain and contributes to brain injury after intracerebral hemorrhage (ICH). The c-Jun-N-terminal kinase (JNK) signaling pathway mediates cell death after ischemic stroke, however, the involvement of JNK in ICH is not well known. This study investigated whether the JNK signaling pathway is activated by iron after ICH. Male Sprague-Dawley rats received an infusion of autologous whole blood (as a model of ICH) or ferrous iron into the right basal ganglia and control rats had an infusion of saline. Some ICH rats were treated with either deferoxamine (DFX), an iron chelator, or vehicle. Activation of JNK was measured by Western blot analysis and immunohistochemistry. Free iron in cerebrospinal fluid (CSF) and behavioral outcomes following ICH were also examined. We found that activated JNK in the brain were increased after ICH, and an intracerebral infusion of ferrous iron also upregulated brain activated JNK. Free iron accumulated in CSF and systemic administration of DFX after ICH reduces free iron contents in CSF, suppresses JNK activation and improves ICH-induced neurological deficits. Our results demonstrated that the JNK signaling pathway is activated after ICH and iron may contribute to this activation. DFX reduces free iron levels and attenuates activation of JNK suggesting iron chelation may be useful therapy for ICH patients.

Modulation of inflammatory responses after global ischemia by transplanted umbilical cord matrix stem cells

Rat umbilical cord matrix (RUCM) cells are stem-cell-like cells and have been shown to reduce neuronal loss in the selectively vulnerable brain regions after cardiac arrest (CA). Here, we investigate whether this protection is mediated by the RUCM cells' modulation of the postischemia inflammation responses, which have long been implicated as a secondary mechanism of injury following ischemia. Brain sections were examined immunohistochemically for glial fibrillary acidic protein (GFAP), vimentin, and nestin as markers for astroglia and reactive astrogliosis, Ricinus Communis Agglutinin-1 (RCA-1) as a marker for microglia, and Ki67 as a marker for cell proliferation. Rats were randomly assigned to six experimental groups: (1) 8-minute CA without treatment, (2) 8-minute CA pre-treated with culture medium injection, (3) 8-minute CA pre-treated with RUCM cells, (4) sham-operated CA, (5) medium injection without CA, and (6) RUCM cell transplantation without CA. Groups 1-3 have significantly higher Ki67(+) cell counts and higher GFAP(+) immunoreactivity in the hippocampal Cornu Ammonis layer 1 (CA1) region compared to groups 4-6, irrespective of treatment. Groups 1 and 2 have highly elevated GFAP(+), vimentin(+), and nestin(+) immunoreactivity, indicating reactive astrogliosis. Strikingly, RUCM cell treatment nearly completely inhibited the appearance of vimentin(+) and greatly reduced nestin(+) reactive astrocytes. RUCM cell treatment also greatly reduced RCA-1 staining, which is found to strongly correlate with the neuronal loss in the CA1 region. Our study indicates that treatment with stem-cell-like RUCM cells modulates the inflammatory response to global ischemia and renders neuronal protection by preventing permanent damage to the selectively vulnerable astrocytes in the CA1 region. Disclosure of potential conflicts of interest is found at the end of this article.

Long-term functional and protective actions of preconditioning with hypoxia, cobalt chloride, and desferrioxamine against hypoxic-ischemic injury in neonatal rats

Preconditioning with hypoxia and hypoxia-mimetic compounds cobalt chloride (CoCl2) and desferrioxamine (DFX) protects against hypoxic-ischemic (HI) injury in neonatal rat brain. We examined long-term functional and protective actions of preconditioning induced by hypoxia, CoCl(2) and DFX in a neonatal rat model of HI. Postnatal day six rat pups were exposed to preconditioning with hypoxia (8% oxygen) or injections of CoCl(2), DFX or saline vehicle and 24 h later rats underwent HI or sham surgery. Behavioral tests were performed and at the conclusion of experiments, brains removed for morphologic analyses. HI resulted in a large unilateral lesion in the ipsilateral hemisphere compared with sham control rats. All preconditioning treatments significantly reduced the total lesion volume. Behavioral deficits were observed in HI rats compared with sham controls. The reduction in forelimb grasping strength in HI rats was attenuated by preconditioning with hypoxia, CoCl(2) and DFX. HI increased the number of foot faults in a grid-walking test and resulted in forelimb asymmetry in the cylinder test. Only preconditioning with hypoxia reversed all three functional deficits after HI. These findings indicate that preconditioning, especially when induced by hypoxia, has the potential to minimize the morphologic and functional effects of neonatal HI injury.

Dysregulation of hepatic iron with aging: implications for heat stress-induced oxidative liver injury

Environmental heat stress is associated with an age-related increase in hepatic oxidative damage and an exaggerated state of oxidative stress. The purpose of this investigation was to evaluate the regulation of hepatic iron after heat stress. A secondary aim was to determine a potential role for iron in heat stress-induced liver injury. Hyperthermia-induced alterations in hepatic iron were evaluated in young (6 mo) and old (24 mo) Fischer 344 rats by exposing them to a two-heat stress protocol. Livers were harvested at several time points after the second heating and assayed for labile and nonheme iron. In the control condition, there was no difference in labile iron between age groups. Both labile iron and storage iron were not altered by hyperthermia in young rats, but both were increased immediately after heating in old rats. To evaluate a role for iron in liver injury, hepatic iron content was manipulated in young and old rats, and then both groups were exposed to heat stress. Iron administration to young rats significantly increased hepatic iron content and ferritin but did not affect markers of lipid peroxidation under control conditions or after heat stress. In old rats, iron chelation with deferoxamine prevented the increase in nonheme iron, labile iron, ferritin, and lipid peroxidation after heat stress. These results suggest that iron may play a role in hepatic injury after hyperthermia. Thus, dysregulation of iron may contribute to the gradual decline in cellular and physiological function that occurs with aging.

Potential treatment of cerebral global ischemia with Oct-4+ umbilical cord matrix cells

Potential therapeutic effects of Oct-4-positive rat umbilical cord matrix (RUCM) cells in treating cerebral global ischemia were evaluated using a reproducible model of cardiac arrest (CA) and resuscitation in rats. Animals were randomly assigned to four groups: A, sham-operated; B, 8-minute CA without pretreatment; C, 8-minute CA pretreated with defined media; and D, 8-minute CA pretreated with Oct-4(+) RUCM cells. Pretreatment was done 3 days before CA by 2.5-microl microinjection of defined media or approximately 10(4) Oct-4(+) RUCM cells in left thalamic nucleus, hippocampus, corpus callosum, and cortex. Damage was assessed histologically 7 days after CA and was quantified by the percentage of injured neurons in hippocampal CA1 regions. Little damage (approximately 3%-4%) was found in the sham group, whereas 50%-68% CA1 pyramidal neurons were injured in groups B and C. Pretreatment with Oct-4(+) RUCM cells significantly (p < .001) reduced neuronal loss to 25%-32%. Although the transplanted cells were found to have survived in the brain with significant migration, few were found directly in CA1. Therefore, transdifferentiation and fusion with host cells cannot be the predominant mechanisms for the observed protection. The Oct-4(+) RUCM cells might repair nonfocal tissue damage by an extracellular signaling mechanism. Treating cerebral global ischemia with umbilical cord matrix cells seems promising and worthy of further investigation.

Deferoxamine reduces CSF free iron levels following intracerebral hemorrhage

Iron overload occurs in brain after intracerebral hemorrhage (ICH). Deferoxamine, an iron chelator, attenuates perihematomal edema and oxidative stress in brain after ICH. We investigated the effects of deferoxamine on cerebrospinal fluid (CSF) free iron and brain total iron following ICH. Rats received an infusion of 100-microL autologous whole blood into the right basal ganglia, then were treated with either deferoxamine (100 mg/kg, i.p., administered 2 hours after ICH and then at 12-hour intervals for up to 7 days) or vehicle. The rats were killed at different time points from 1 to 28 days for measurement of free and total iron. Behavioral tests were also performed. Free iron levels in normal rat CSF were very low (1.1 +/- 0.4 micromol). After ICH, CSF free iron levels were increased at all time points. Levels of brain total iron were also increased after ICH (p < 0.05). Deferoxamine given 2 hours after ICH reduced free iron in CSF at all time points. Deferoxamine also reduced ICH-induced neurological deficits (p < 0.05), but did not reduce total brain iron. In conclusion, CSF free iron levels increase after ICH and do not clear for at least 28 days. Deferoxamine reduces free iron levels and improves functional outcome in the rat, indicating that it may be a potential therapeutic agent for ICH patients.

Long-term effects of experimental intracerebral hemorrhage: the role of iron

OBJECT

Intracerebral hemorrhage (ICH) causes brain atrophy and neurological deficits. The mechanisms of brain atrophy after ICH are poorly understood, although recent evidence suggests that some ICH-induced brain injury results from the products of hemoglobin degradation, including iron. In this study the authors examine the role of iron in brain atrophy and neurological deficits following ICH.

METHODS

Male Sprague-Dawley rats received an infusion of either 100 microl autologous whole blood or saline into the right caudate. Hematoxylin and eosin staining was used for histological examination, and iron levels and ferritin immunoreactivities were also examined. Deferoxamine was used as an iron chelator. Over the duration of the experiment, the rats underwent behavioral testing (forelimb placing, forelimb use asymmetry, and corner turn tests). Brain atrophy in the caudate with prolonged neurological deficits occurred after ICH. Although partial functional recovery occurred with time, residual neurological deficits were still detectable at 3 months postprocedure. Iron accumulation and ferritin upregulation were present in the ipsilateral caudate. Deferoxamine reduced brain atrophy and improved behavioral outcomes, and it also reduced brain ferritin immunoreactivity.

CONCLUSIONS

An ICH results in an accumulation of iron in the brain that is not cleared within 3 months and that contributes to brain tissue loss and neurological deficits posthemorrhage. Iron chelation may be a useful therapy for patients with ICH.

Iron chelators do not reduce cold-induced cell injury in the isolated perfused rat kidney model

BACKGROUND

In vitro, cold-induced injury is an important contributor to renal tubular cell damage. It is mediated by iron-dependent formation of reactive oxygen species and can be prevented by iron chelation. We studied whether iron chelators can prevent cold-induced damage in the isolated perfused rat kidney (IPK) model both after cold perfusion (CP) and after cold storage (CS). We hypothesized that in the CP model iron-dependent cold-induced injury is more pronounced, since oxygen is constantly provided.

METHODS

The IPK was either flushed with University of Wisconsin (UW) solution and stored for 4, 18 or 24 h at 4 degrees C or perfused during 4 h at 4 degrees C with UW for machine perfusion. The iron chelators 2,2'-dipyridyl or desferal, or the negative control 4,4'-dipyridyl were added during the cold perfusion. Kidney function was measured during 2 h reperfusion at 37.5 degrees C and compared to a control group (without cold preservation).

RESULTS

Compared to control perfusion, kidney function was decreased in all experimental protocols. glomerular filtration rate and FR(H2O) were significantly decreased, while FE(gluc) and FE(Na) were higher after 4 h CS and CP. After 4 h CP, also renal vascular resistance was increased. Addition of 2,2'-dipyridyl did not improve kidney function after either CS or CP. Prolonged periods of CS worsened kidney function. The addition of 2,2'-dipyridyl or desferal did not improve kidney function after longer periods of CS.

CONCLUSIONS

Addition of an iron chelator to the preservation solution UW did not improve kidney function after both CS and CP. Iron chelation is not able to prevent cold-induced damage in the isolated perfused rat kidney.

Oxidants, antioxidants and the ischemic brain

Despite numerous defenses, the brain is vulnerable to oxidative stress resulting from ischemia/reperfusion. Excitotoxic stimulation of superoxide and nitric oxide production leads to formation of highly reactive products, including peroxynitrite and hydroxyl radical, which are capable of damaging lipids, proteins and DNA. Use of transgenic mutants and selective pharmacological antioxidants has greatly increased understanding of the complex interplay between substrate deprivation and ischemic outcome. Recent evidence that reactive oxygen/nitrogen species play a critical role in initiation of apoptosis, mitochondrial permeability transition and poly(ADP-ribose) polymerase activation provides additional mechanisms for oxidative damage and new targets for post-ischemic therapeutic intervention. Because oxidative stress involves multiple post-ischemic cascades leading to cell death, effective prevention/treatment of ischemic brain injury is likely to require intervention at multiple effect sites.

Perfusion imaging using arterial spin labeling

Arterial spin labeling is a magnetic resonance method for the measurement of cerebral blood flow. In its simplest form, the perfusion contrast in the images gathered by this technique comes from the subtraction of two successively acquired images: one with, and one without, proximal labeling of arterial water spins after a small delay time. Over the last decade, the method has moved from the experimental laboratory to the clinical environment. Furthermore, numerous improvements, ranging from new pulse sequence implementations to extensive theoretical studies, have broadened its reach and extended its potential applications. In this review, the multiple facets of this powerful yet difficult technique are discussed. Different implementations are compared, the theoretical background is summarized, and potential applications of various implementations in research as well as in the daily clinical routine are proposed. Finally, a summary of the new developments and emerging techniques in this field is provided.

Deferoxamine-induced attenuation of brain edema and neurological deficits in a rat model of intracerebral hemorrhage

OBJECT

Previous studies undertaken by the authors have indicated that iron accumulation and oxidative stress in the brain contribute to secondary brain damage after intracerebral hemorrhage (ICH). In the present study the authors investigate whether deferoxamine, an iron chelator, can reduce ICH-induced brain injury.

METHODS

Male Sprague-Dawley rats each received an infusion of 100 microl of autologous whole blood into the right basal ganglia and were killed 1, 3, or 7 days later. Iron distribution was examined histochemically (enhanced Perls reaction). The effects of deferoxamine on ICH-induced brain injury were examined by measuring brain edema and neurological deficits. Immunohistochemical analysis was performed to investigate 8-hydroxyl-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, and Western blot analysis was performed to measure the amount of apurinic/apyrimidinic endonuclease/redox effector factor-1 (APE/Ref-1), a repair mechanism for DNA oxidative damage. Iron accumulation was observed in the perihematomal zone from 1 day after ICH. Deferoxamine attenuated brain edema, neurological deficits, and ICH-induced changes in 8-OHdG and APE/Ref-1.

CONCLUSIONS

Deferoxamine and other iron chelators may be potential therapeutic agents for ICH. They may act by reducing the oxidative stress caused by the release of iron from the hematoma.

Deferoxamine-induced attenuation of brain edema and neurological deficits in a rat model of intracerebral hemorrhage

Object

In the authors' previous studies they found that brain iron accumulation and oxidative stress contribute to secondary brain damage after intracerebral hemorrhage (ICH). In the present study they investigated whether deferoxamine, an iron chelator, can reduce ICH-induced brain injury.

Methods

Male Sprague–Dawley rats received an infusion of 100 μl of autologous whole blood into the right basal ganglia and were killed 1, 3, or 7 days thereafter. Iron distribution was examined histochemically (enhanced Perl reaction). The effects of deferoxamine on ICH-induced brain injury were examined by measuring brain edema and neurological deficits. Apurinic/apyrimidinic endonuclease/redox effector factor–1 (APE/Ref-1), a repair mechanism for DNA oxidative damage, was quantitated by Western blot analysis.

Iron accumulation was observed in the perihematoma zone beginning 1 day after ICH. Deferoxamine attenuated brain edema, neurological deficits, and ICH-induced changes in APE/Ref-1.

Conclusions

Deferoxamine and other iron chelators may be potential therapeutic agents for treating ICH. They may act by reducing the oxidative stress caused by the release of iron from the hematoma.