Initial Ischemic Injury Research Articles

Case Report: Human Tracheal Transplantation Undergoes Progressive Reepithelialization Over Time.

Tracheal transplantation is an ideal option for the reconstruction of long-segment circumferential tracheal defects. Our group performed the first successful vascularized single-staged tracheal transplantation in January 2021. Although a rigid biocompatible structure is necessary for a functioning tracheal replacement, the importance of ciliated epithelium, which allows for critical mucociliary clearance, is now being appreciated. Here, we examined the histological changes of the first single-staged human tracheal transplant from serial endoscopic biopsies. Biopsies of the tracheal mucosa were serially obtained since the time of the tracheal transplantation. Samples were examined via hematoxylin and eosin, electron microscopy, and immunohistochemistry. One week after transplantation, there is loss of ciliated epithelium and seromucinous cells, with only a basal layer of epithelium remaining. By 2 weeks, however, the epithelium begins to recover, albeit differently depending on the location of the biopsy. Near the site of tracheal anastomosis, there is epithelial proliferation, with the appearance of early ciliated cells. However, in the midgraft, there appears to be evidence of squamous metaplasia. Over time, however, normal ciliated epithelium and mucous cells appear without signs of chronic inflammation. Critically, the tracheal allograft regained normal appearing respiratory epithelium after initial ischemic injury. The histologic differences at the midgraft versus anastomosis may suggest unique mechanisms of reepithelialization. At the recipient-donor interface, there may be a faster direct migration of recipient-derived epithelial cells, in line with preclinical studies. The midgraft, in contrast, responds with epithelial proliferation from the donor basal cells or dedifferentiated mucous cells. N/A Laryngoscope, 134:2664-2671, 2024.

How to Best Protect Kidneys for Transplantation—Mechanistic Target

The increasing number of patients on the kidney transplant waiting list underlines the need to expand the donor pool and improve kidney graft utilization. By protecting kidney grafts adequately from the initial ischemic and subsequent reperfusion injury occurring during transplantation, both the number and quality of kidney grafts could be improved. The last few years have seen the emergence of many new technologies to abrogate ischemia-reperfusion (I/R) injury, including dynamic organ preservation through machine perfusion and organ reconditioning therapies. Although machine perfusion is gradually making the transition to clinical practice, reconditioning therapies have not yet progressed from the experimental setting, pointing towards a translational gap. In this review, we discuss the current knowledge on the biological processes implicated in I/R injury and explore the strategies and interventions that are being proposed to either prevent I/R injury, treat its deleterious consequences, or support the reparative response of the kidney. Prospects to improve the clinical translation of these therapies are discussed with a particular focus on the need to address multiple aspects of I/R injury to achieve robust and long-lasting protective effects on the kidney graft.

Cardioprotective effect of empagliflozin in acute myocardial infarction: the role of ketone bodies availability

Abstract Background The cardio-renal benefits of SGLT2i have been clearly established by clinical trials. Of interest, despite not having any effect on the incidence of classic atherothrombotic events (MI and strokes), patients receiving SGLT2i treatment had a higher chance of surviving myocardial infarction (MI). Purpose We aim to evaluate the cardioprotective potential of empagliflozin on acute myocardial infarction. We postulate that the benefits of SGLT2-I are mediated via an increase in circulating ketone bodies (KBs) induced by SGLT2i, and its preferential myocardial utilization energetically benefits the heart to better withstand an ischemic event. Methods The study was undertaken in our non-diabetic porcine model of ischemia/reperfusion. Animals were allocated to either one-week pre-treatment with empagliflozin or placebo before MI-induction. A third group received IV infusion of KBs at the time of the MI- induction to serve as positive-control. The acute effects of the treatments were studied 24 hours after MI-induction by Cardiac Magnetic Resonance (CMR). Immediately post-CMR, animals were sacrificed and heart samples collected for molecular analysis. Results (see Table and Figure): Despite similar initial ischemic injury (area at risk) in all groups, empagliflozin was associated with a significantly higher myocardial salvage (MSI 23.7±9.7 vs 4.5±3.6%, p<0.001) and better preserved cardiac function (LVEF 41.3±3.1 vs 33±5.5%, p<0.009) compared with placebo. The infusion of KBs replicated in part the beneficial profile of the empagliflozin group (MSI 16.7±8.8 and LVEF 39.1±3.6%). Histological analysis showed less cardiomyocyte apoptosis and less oxidative stress Conclusions To the best of our knowledge, this is the first study evaluating in vivo the cardioprotective potential of a SGLT2 inhibitor in a well-stablished porcine translational model. Furthermore, effects are evaluated using the gold standard for visualization and quantification of MI, Cardiac Magnetic Resonance (CMR). Three are the main conclusions: 1. One-week treatment with empagliflozin raises circulating KBs levels and confers significant cardio-protection during a myocardial infarction. Acute post-MI benefits (greater myocardial salvage and better preserved cardiac function) are already seen within 24 hours as compared with placebo. 2. Periprocedural IV infusion of KBs induces similar benefits than the SGLT2-I group. 3. These observations strongly support our hypothesis that SGLT2 inhibition is associated with increased circulating KBs and its selective use as preferential myocardial source of energy as a potential mechanism of action involved in the cardio-renal benefits observed with SGLT2i. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Spanish Society of Cardiology. Research Fellowship Grant.

Empagliflozin Ameliorates Diastolic Dysfunction and Left Ventricular Fibrosis/Stiffness in Nondiabetic Heart Failure: A Multimodality Study

ObjectivesThe purpose of this study was to investigate the effect of empagliflozin on diastolic function in a nondiabetic heart failure with reduced ejection fraction (HFrEF) scenario and on the pathways causing diastolic dysfunction. BackgroundThis group demonstrated that empagliflozin ameliorates adverse cardiac remodeling, enhances myocardial energetics, and improves left ventricular systolic function in a nondiabetic porcine model of HF. Whether empagliflozin also improves diastolic function remains unknown. Hypothetically, empagliflozin would improve diastolic function in HF mediated both by a reduction in interstitial myocardial fibrosis and an improvement in cardiomyocyte stiffness (titin phosphorylation). MethodsHF was induced in nondiabetic pigs by 2-h balloon occlusion of proximal left anterior descending artery. Animals were randomized to empagliflozin or placebo for 2 months. Cardiac function was evaluated with cardiac magnetic resonance (CMR), 3-dimensional echocardiography, and invasive hemodynamics. In vitro relaxation of cardiomyocytes was studied in primary culture. Myocardial samples were obtained for histological and molecular evaluation. Myocardial metabolite consumption was analyzed by simultaneous blood sampling from coronary artery and coronary sinus. ResultsDespite similar initial ischemic myocardial injury, the empagliflozin group showed significantly improved diastolic function at 2 months, assessed by conventional echocardiography (higher e′ and color M-mode propagation velocity, lower E/e′ ratio, myocardial performance Tei index, isovolumic relaxation time, and left atrial size), echocardiography-derived strain imaging (strain imaging diastolic index, strain rate at isovolumic relaxation time and during early diastole, and untwisting), and CMR (higher peak filling rate, larger first filling volume). Invasive hemodynamics confirmed improved diastolic function with empagliflozin (better peak LV pressure rate of decay (–dP/dt), shorter Tau, lower end-diastolic pressure-volume relationship (EDPVR), and reduced filling pressures). Empagliflozin reduced interstitial myocardial fibrosis at the imaging, histological and molecular level. Empagliflozin improved nitric oxide signaling (endothelial nitric oxide synthetase [eNOS] activity, nitric oxide [NO] availability, cyclic guanosine monophosphate (cGMP) content, protein kinase G [PKG] signaling) and enhanced titin phosphorylation (which is responsible for cardiomyocyte stiffness). Indeed, isolated cardiomyocytes exhibited better relaxation in empagliflozin-treated animals. Myocardial consumption of glucose and ketone bodies negatively and positively correlated with diastolic function, respectively. ConclusionsEmpagliflozin ameliorates diastolic function in a nondiabetic HF porcine model, mitigates histological and molecular remodeling, and reduces both left ventricle and cardiomyocyte stiffness.

Sex differences in T cell immune responses, gut permeability and outcome after ischemic stroke in aged mice

IntroductionStroke is a disease that presents with well-known sex differences. While women account for more stroke deaths, recent data show that after adjusting for age and pre-stroke functional status, mortality is higher in men. Immune responses are key determinants of stroke outcome and may differ by sex. This study examined sex differences in central and peripheral T cell immune responses, systemic effects on gut permeability and microbiota diversity and behavioral outcomes after stroke in aged mice. We hypothesized that there are sex differences in the immune response to stroke in aged animals. MethodsC57BL/6CR mice (20–22 months) were subjected to 60 min middle cerebral artery occlusion, or sham surgery. T cells were quantified in brain and blood at 3, 7 and 15 days (d) post-stroke by flow cytometry. Peripheral effects on gut permeability and microbiota diversity, as well as neurological function were assessed up to 14 d, and at 21 d (cognitive function) post-stroke. Brain glial fibrillary acidic protein (GFAP) expression was evaluated at 42 d post-stroke. Results and discussionMortality (50% vs 14%, p < 0.05) and hemorrhagic transformation (44% vs 0%) were significantly higher in males than in females. No difference in infarct size at 3d were observed. Peripherally, stroke induced greater gut permeability of FITC-dextran in males at d3 (p < 0.05), and non-reversible alterations in microbiota diversity in males. Following the sub-acute phase, both sexes demonstrated a time-dependent increase of CD4+ and CD8+ T cells in the brain, with significantly higher levels of CD8+ T cells and Regulatory T cells in males at d15 (p < 0.01). Aged males demonstrated greater neurological deficits up to d5 and impaired sensorimotor function up to d15 when assessed by the corner asymmetry test (p < 0.001 and p < 0.01, respectively). A trend in greater cognitive decline was observed at d21 in males. Increased GFAP expression in the ischemic hemisphere, indicating astroglial activation and gliosis, was demonstrated in both males and females 42d post-stroke. Our findings indicate that despite a similar initial ischemic brain injury, aged male mice experience greater peripheral effects on the gut and ongoing central neuroinflammation past the sub-acute phase after stroke.

Abstract 9: Autologous Bone Marrow Cells Might Repair Corticospinal Tracts in Stroke Patients

Introduction: Many cell-based therapies attenuate secondary degeneration after initial ischemic injury and enhance repair. We serially compared over time the integrity of the corticospinal tract (CST) in ischemic stroke (IS) patients treated with autologous bone marrow cells versus a prospectively collected, comparable stroke patient population not treated with cells (controls). Methods: We imaged 37 IS patients (17=treated, 20=control) at 1, 3, and 12 mo after stroke on a 3T MRI. A maximum of 10 million cells/kg were administered IV within 72 hrs of stroke. 3D anatomical and DTI images were obtained. CST integrity was assessed by relative (ipsilesional/contralesional) rFA in the rostral pons (RP). A mixed model was used for statistical analysis. Results: Infarct size of controls was 26.4 ±27 mL and the treated group was 64.7 ± 40.3 mL. The rFA in the rostral pons (RP) of controls decreased from 0.91 ± 0.1 to 0.86 ± 0.1 over 12 months. In the cell treated group, rFA in the RP decreased initially from 0.73 ±0.1 to 0.69 ±0.1 between 1 and 3 months but then increased to 0.76 ± 0.1 at 12 months. Qualitative and quantitative results are summarized (fig). The rFA in the RP was significantly correlated (p &lt;0.05) to the mRS in the treated group. Conclusion: Despite smaller infarct size in controls, CST integrity continued to degenerate and showed no improvement by 12 months after stroke. In contrast, the cell treated patients with initial larger infarcts showed initial degeneration of the CST but then had improved CST integrity by 12 months after stroke. The temporal decrease in rFA in controls and increase in rFA in treated patients suggest a potential treatment effect from the cells. Although the results are generated from a non-randomized trial, the significant correlation between mRS and rFA suggests rFA could be used as a surrogate marker of treatment effect.

Empagliflozin Ameliorates Adverse Left Ventricular Remodeling in Nondiabetic Heart Failure by Enhancing Myocardial Energetics

BackgroundEmpagliflozin cardiac benefits in the EMPA-REG OUTCOME (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients) trial cannot be explained exclusively by its antihyperglycemic activity. ObjectivesThe hypothesis was that empagliflozin’s cardiac benefits are mediated by switching myocardial fuel metabolism away from glucose toward ketone bodies (KB), which improves myocardial energy production. MethodsHeart failure was induced in nondiabetic pigs (n = 14) by 2-h balloon occlusion of the proximal left anterior descending artery. Animals were randomized to empagliflozin or placebo for 2 months. Animals were evaluated with cardiac magnetic resonance imaging and 3-dimensional echocardiography. Myocardial metabolite consumption was analyzed by simultaneous blood sampling from coronary artery and coronary sinus. Myocardial samples were obtained for molecular evaluation. Nonmyocardial infarction animals served as comparison. ResultsDespite similar initial ischemic myocardial injury in both groups, the empagliflozin group showed amelioration of adverse remodeling at 2 months (lower left ventricular [LV] mass, reduced LV dilatation, less LV sphericity) versus the control group. LV systolic function (LV ejection fraction and echocardiography-derived strains) was improved, as was neurohormonal activation. Compared with nonmyocardial infarction, control animals increased myocardial glucose consumption mainly through anaerobic glycolysis while reducing utilization of free fatty acid (FFA) and branched-chain amino acid (BCAA). Empagliflozin-treated pigs did not consume glucose (reduction in myocardial glucose uptake, and glucose-related enzymes) but instead switched toward utilization of KB, FFA, and BCAA (increased myocardial uptake of these 3 metabolites, and enhanced expression/activity of the enzymes implicated in the metabolism of KB/FFA/BCAA). Empagliflozin increased myocardial ATP content and enhanced myocardial work efficiency. ConclusionsEmpagliflozin ameliorates adverse cardiac remodeling and heart failure in a nondiabetic porcine model. Empagliflozin switches myocardial fuel utilization away from glucose toward KB, FFA, and BCAA, thereby improving myocardial energetics, enhancing LV systolic function, and ameliorating adverse LV remodeling.

Sex Differences in Expression of Methionine Sulfoxide Reductase A in Hypothalamic Paraventricular Nucleus in Rats with Heart Failure after Myocardial Infarction

Myocardial‐infarction (MI)‐induced heart failure (HF) leads to elevated oxidative stress and proinflammatory cytokine (PIC) expression in the brain and arginine vasopressin (AVP) secretion, contributing to sympathetic excitation and the progression of HF. We recently reported that female rats with HF following MI have less PIC and AVP expression in the hypothalamic paraventricular nucleus (PVN), a key cardiovascular‐related center of the brain that regulates sympathetic nerve activity and extracellular fluid volume. Female animals also exhibited less peripheral sympathetic and vasopressinergic activity and less hemodynamic compromise than male HF rats with the same degree of initial ischemic cardiac injury. The mechanisms responsible for these sex differences remain unclear. Emerging evidence reveals that methionine sulfoxide reductase A (MsrA), an intracellular enzyme that reverses protein methionine oxidation, is protective against brain oxidative stress, neuroinflammation and sympathetic excitation. Here we examined whether MsrA is expressed in the cardiovascular‐related centers of the brain and whether MsrA is altered in HF after MI in male and female rats. Male and female SD rats at ~13 weeks of age underwent MI to induce HF and were euthanized for molecular and immunofluorescent studies 4 weeks later. Age‐matched male and female rats served as controls. There were no differences between male and female rats in ischemic zone or left ventricular ejection fraction at 24 hours and at 4 weeks after MI as assessed by echocardiography. mRNA expression of MsrA in the PVN was significantly higher in female than male control rats (2.06 ± 0.25 vs 1.09 ± 0.16, p &lt; 0.05). mRNA expression of MsrA in the PVN was not affected by HF in female rats (2.12 ± 0.46) but was significantly lower (0.43 ± 0.02, p &lt; 0.01) in male HF rats compared with their age‐matched controls. There was no difference in mRNA expression of MsrA in brain cortex among four experimental groups. Confocal imaging revealed MsrA positive immunofluorescence in the neurons of the PVN, mainly in the magnocellular subdivision, in both male control and female control rats. MsrA positive immunofluorescence was also observed in the subfornical organ, another cardiovascular‐related nucleus, and in the cortex in both male control and female control rats. These results indicate that MsrA is expressed in key cardiovascular‐related centers of the brain, and that there are sex differences in the expression of MsrA in the PVN under physiological conditions and in MI‐induced HF. Whether differences in the expression of MsrA in the PVN play a role in the sex differences in the central and peripheral manifestations of MI‐induced HF deserves further investigation.Support or Funding InformationSupported by NIH grants R01HL073986 and R01HL139521This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ischaemic stroke in mice induces lung inflammation but not acute lung injury

Stroke is a major cause of death worldwide and ischemic stroke is the most common subtype accounting for approximately 80% of all cases. Pulmonary complications occur in the first few days to weeks following ischemic stroke and are a major contributor to morbidity and mortality. Acute lung injury (ALI) occurs in up to 30% of patients with subarachnoid haemorrhage but the incidence of ALI after ischemic stroke is unclear. As ischemic stroke is the most common subtype of stroke, it is important to understand the development of ALI following the initial ischemic injury to the brain. Therefore, this study investigated whether focal ischemic stroke causes lung inflammation and ALI in mice. Ischemic stroke caused a significant increase in bronchoalveolar lavage fluid (BALF) macrophages and neutrophils and whole lung tissue proinflammatory IL-1β mRNA expression but this did not translate into histologically evident ALI. Thus, it appears that lung inflammation, but not ALI, occurs after experimental ischemic stroke in mice. This has significant implications for organ donors as the lungs from patient’s dying of ischemic stroke are not severely damaged and could thus be used for transplantation in people awaiting this life-saving therapy.

Sex differences in the central and peripheral manifestations of ischemia-induced heart failure in rats.

Sex differences in the presentation, outcome, and responses to treatment of systolic heart failure (HF) have been reported. In the present study, we examined the effect of sex on central neural mechanisms contributing to neurohumoral excitation and its peripheral manifestations in rats with HF. Male and female Sprague-Dawley rats underwent coronary artery ligation (CL) to induce HF. Age-matched rats served as controls. Ischemic zone and left ventricular function were similar 24 h and 4 wk after CL. Female rats with HF had a lower mortality rate and less hemodynamic compromise, pulmonary congestion, and right ventricular remodeling 4 wk after CL. Plasma angiotensin II (ANG II), arginine vasopressin (AVP), and norepinephrine levels were increased in HF rats in both sexes, but AVP and norepinephrine levels increased less in female rats. In the hypothalamic paraventricular nucleus, a key cardiovascular-related nucleus contributing to neurohumoral excitation in HF, mRNA levels for the proinflammatory cytokines tumor necrosis factor-α and interleukin-1β as well as cyclooxygenase-2 and the ANG II type 1a receptor were increased in HF rats of both sexes, but less so in female rats. Angiotensin-converting enzyme 2 protein levels increased in female HF rats but decreased in male HF rats. mRNA levels of AVP were lower in female rats in both control and HF groups compared with the respective male groups. Activation of extracellular signal-regulated protein kinases 1 and 2 increased similarly in both sexes in HF. The results suggest that female HF rats have less central neural excitation and less associated hemodynamic compromise than male HF rats with the same degree of initial ischemic cardiac injury. NEW & NOTEWORTHY Sex differences in the presentation and responses to treatment of heart failure (HF) are widely recognized, but the underlying mechanisms are poorly understood. The present study describes sex differences in the central nervous system mechanisms that drive neurohumoral excitation in ischemia-induced HF. Female rats had a less intense central neurochemical response to HF and experienced less hemodynamic compromise. Sex hormones may contribute to these differences in the central and peripheral adaptations to HF.

Sex Differences in the Central and Peripheral Manifestations of Heart Failure in Rats

Heart failure (HF) is a leading cause of morbidity and mortality for both men and women. Increased sympathetic nerve activity (SNA) is a hallmark of HF and correlates with poor prognosis. We and others have demonstrated that neuroinflammation and renin‐angiotensin system activity are elevated in the cardiovascular‐related regions of the brain in HF, contributing to SNA and the progression of HF. However, most studies that have examined these sympathoexcitatory mediators in the brain in HF have been performed in male animals. The goal of this study was to determine whether sex differences exist in neuroinflammation and renin‐angiotensin system activity in the hypothalamic paraventricular nucleus (PVN), a key cardiovascular‐related center of the brain that regulates SNA and extracellular fluid volume, in rats with HF. Male and female SD rats at ~13 weeks of age underwent coronary artery ligation (CL) to induce HF and were euthanized for anatomical and molecular studies 4 weeks later. Age‐matched male and female rats served as controls. There were no differences between male and female rats in echocardiography‐defined ischemic zone or left ventricular ejection fraction at 24 hours and at 4 weeks after CL. Female rats had lower body weight than male rats, but there was no difference in body weight between HF and control rats in either sex. At 4 weeks, lung weight was similar but right ventricular (RV) and left ventricular (LV) weights were smaller in female control than male control rats. Compared with their respective controls, male HF but not female HF rats had increases in lung weight/tibial length and RV weight/tibial length. There was no difference in LV dP/dtmax and LV end‐diastolic pressure between male and female controls. LV dP/dtmax was decreased in both male HF rats and female HF rats, but male HF rats had a lower dP/dtmax. Compared with their respective control rats, male but not female HF rats had increased LV end‐diastolic pressure. In the PVN, mRNA for tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), angiotensin receptor subtype 1a receptor (AT1aR) and estrogen receptors α and β (ER‐α, ER‐β) was similar in male and female controls. mRNA for G protein‐coupled estrogen receptor (GPER) was higher and mRNA for arginine vasopressin (AVP) was lower in female control than male control rats. Both male HF and female HF rats had increases in TNF‐α, IL‐1β, AT1aR and AVP mRNA in the PVN, compared with their respective controls, but the levels were higher in the male HF rats. ER‐α and ER‐β mRNA was decreased and GPER mRNA was unchanged in male HF and female HF rats, compared with respective controls. There was no difference in ERK1/2 activity in the PVN between male and female control rats, and ERK1/2 activity in the PVN was equally increased in both male and female HF rats. Plasma angiotensin II, AVP and norepinephrine levels were similar in male and female control rats. The plasma levels of these humoral factors were higher in HF rats in either sex, but the AVP and norepinephrine levels were greater in male HF rats. These preliminary results suggest that female rats with HF following CL have less central neural inflammation and renin‐angiotensin system activity, less peripheral sympathetic and vasopressinergic activity and less hemodynamic compromise than male HF rats with the same degree of initial ischemic cardiac injury. The mechanisms responsible for these sex differences remain to be determined.Support or Funding InformationSupported by NIH HLR01HL136149 and R01HL073986.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Enhancing Spinal Plasticity Amplifies the Benefits of Rehabilitative Training and Improves Recovery from Stroke.

The limited recovery that occurs following stroke happens almost entirely in the first weeks postinjury. Moreover, the efficacy of rehabilitative training is limited beyond this narrow time frame. Sprouting of spared corticospinal tract axons in the contralesional spinal cord makes a significant contribution to sensorimotor recovery, but this structural plasticity is also limited to the first few weeks after stroke. Here, we tested the hypothesis that inducing plasticity in the spinal cord during chronic stroke could improve recovery from persistent sensorimotor impairment. We potentiated spinal plasticity during chronic stroke, weeks after the initial ischemic injury, in male Sprague-Dawley rats via intraspinal injections of chondroitinase ABC. Our data show that chondroitinase injections into the contralesional gray matter of the cervical spinal cord administered 28 d after stroke induced significant sprouting of corticospinal axons originating in the peri-infarct cortex. Chondroitinase ABC injection during chronic stroke without additional training resulted in moderate improvements of sensorimotor deficits. Importantly, this therapy dramatically potentiated the efficacy of rehabilitative training delivered during chronic stroke in a skilled forelimb reaching task. These novel data suggest that spinal therapy during chronic stroke can amplify the benefits of delayed rehabilitative training with the potential to reduce permanent disability in stroke survivors.SIGNIFICANCE STATEMENT The brain and spinal cord undergo adaptive rewiring ("plasticity") following stroke. This plasticity allows for partial functional recovery from stroke induced sensorimotor impairments. However, the plasticity that underlies recovery occurs predominantly in the first weeks following stroke, and most stroke survivors are left with permanent disability even after rehabilitation. Using animal models, our data show that removal of plasticity-inhibiting signals in the spinal cord (via intraspinal injections of the enzyme chondroitinase ABC) augments rewiring of circuits connecting the brain to the spinal cord, even weeks after stroke. Moreover, this plasticity can be harnessed by rehabilitative training to significantly promote sensorimotor recovery. Thus, intraspinal therapy may augment rehabilitative training and improve recovery even in individuals living with chronic disability due to stroke.

MR perfusion lesions after TIA or minor stroke are associated with new infarction at 7 days.

To investigate the relationship between acute perfusion-weighted imaging (PWI) lesions occurring within the first hours after a TIA or a minor brain infarction (BI) and the incidence of new BI detected on a systematic MRI at 1 week. Consecutive patients who experienced a TIA or BI with a neurologic deficit that lasted <24 hours, did not receive any revascularization therapy (thrombolysis/thrombectomy), and underwent DWI/PWI at baseline and fluid-attenuated inversion recovery (FLAIR)/DWI 1 week after symptom onset were enrolled. Investigators blinded to clinical information independently assessed the presence of acute ischemic lesions on baseline DWI/PWI and follow-up DWI and FLAIR. Baseline and follow-up MRIs were then compared to determine the occurrence and location of new infarctions. Sixty-four patients met the inclusion criteria. Median (IQR) ABCD2 score was 4 (3-5). Median delay from onset to baseline and follow-up MRI was 5 (2-10) hours and 6 (5-7) days, respectively. MRI revealed an acute ischemic lesion on DWI and/or PWI in 38 patients. Nine patients (14%) had a new infarction on follow-up MRI. Each had a PWI and 4 had a DWI lesion on baseline MRI. All new BIs except one were asymptomatic and in the same location as the acute PWI lesion. Our results showed that 30% of the acute focal PWI lesions detected after a TIA are associated with a new BI at 1 week. Those new BIs may result from the progression of the initial ischemic injury.

Collateral flow as causative of good outcomes in endovascular stroke therapy

BackgroundEndovascular reperfusion techniques are a promising intervention for acute ischemic stroke (AIS). Prior studies have identified markers of initial injury (arrival NIH stroke scale (NIHSS) or infarct volume) as predictive...

Abstract WP262: Therapeutically Targeting TNFa-S1P Signaling Restores Microvascular Reactivity after Experimental Subarachnoid Hemorrhage

Background: Subarachnoid hemorrhage (SAH) is characterized by an initial hemorrhagic and ischemic brain injury followed by delayed macro- and microvascular constriction. Large-artery vasospasm and enhanced microcirculatory myogenic tone may contribute to delayed cerebral ischemia. Although this implies that therapeutic interventions must specifically correct the SAH-induced myogenic tone enhancement, current therapeutic approaches non-selectively interfere with vasoconstriction and risk disrupting cerebral autoregulation. This may explain why most interventions do not improve clinical outcome. This study identifies the molecular basis for exacerbated cerebrovascular constriction and validates new targets for SAH treatment. Methods: Wild-type, tumor necrosis factor α (TNFα) knockout, sphingosine-1-kinase (Sphk1) knockout and inducible, smooth muscle cell-targeted TNFα knockout mice were used. SAH was created by injection of 80 μl of arterial blood into the prechiasmatic cistern. Myogenic tone in the olfactory artery was assessed with a myograph system. Standard procedures for fluorescent immunolocalization, Western blotting and assessment of apoptosis were used. Results: SAH increased myogenic tone and vascular wall TNFα expression, without enhancing overall vascular contractility in response to phenylephrine. Knockout of TNFα globally or smooth muscle cell-specifically prevented SAH-induced increased myogenic tone. Inhibition of TNFα-shedding (TAPI, 50 μmol/L) or receptor-binding (etanercept, 10 mg/ml) eliminated SAH-mediated myogenic tone augmentation. Cystic fibrosis transmembrane regulator (CFTR) protein expression was down-regulated in cerebral arteries after SAH, which was abolished by antagonism of TNFα. Genetic mouse models confirmed that S1P signaling mediates the myogenic tone augmentation in SAH. Finally, disrupting TNFα signaling attenuated neuronal apoptosis in SAH animals. Conclusion: We identify a novel smooth muscle cell autocrine/paracrine signaling network that augments myogenic tone in SAH. It links TNFα, CFTR and sphingosine-1-phosphate (S1P) signaling. Targeting TNFα and the S1P 2 receptor subtype are potential therapeutic options to improve clinical outcome in SAH.

Carbon Monoxide Releasing Molecules Inhibit Cell Death Resulting from Renal Transplantation Related Stress

Organ cold storage and subsequent transplantation are associated with significant ischemia-reperfusion injury, leading to cell death, graft inflammation and decreased graft function. CORM-3s reduce oxidative stress and prevent inflammation in kidneys stored at 4C and subsequently transplanted. Graft survival and function are markedly improved compared to kidneys preserved and stored in University of Wisconsin solution alone. We determined whether CORM-3 has direct antiapoptotic effects on in vitro preparations of human HUVECs exposed to anoxic conditions. We also determined whether direct administration of CORM-3 to renal grafts before and/or after cold storage would prevent renal damage during the transplantation process. CORM-3 supplementation led to a significantly increased frequency of live cells (mean ± SD 72.3% ± 1.9%, p <0.01), reduced apoptosis (14.9% ± 6.1%, p <0.01) and decreased mitochondrial transmembrane potential (40.2% ± 7.2%, p <0.05) in HUVECs exposed to 20 hours of cold storage compared to controls (11.6% ± 3.5%, 82.2% ± 2.3% and 78.2% ± 3.2%, respectively). In keeping with this antiapoptotic effect CORM-3 supplementation led to a mean 7.4 ± 2.1-fold up-regulation in Bcl-2 gene expression. CORM-3 supplementation in standard preservation solution was most beneficial at initial ischemic injury and before cold storage exposure. However, additional reflushing before vascular reperfusion showed an additive benefit to graft survival and function after transplantation. This was confirmed by decreased glomerular and tubular necrosis, and apoptosis in double flushed grafts. CORM-3 supplementation in standard University of Wisconsin solution has a significant impact on decreasing cellular and graft injury, and improving survival through its antiapoptotic effects, which are likely mediated through mitochondrial membrane stabilization.

Biomarkers assessing warm ischemic injury using an isolated porcine kidney hemoreperfusion model

Prolonged warm ischemia (WI) occurring in marginal kidney donors together with reperfusion injury determines allograft survival, in which apoptosis and inflammation play crucial roles. There is no single valid biomarker, so far, to assess the degree of kidney donor injury. To define new biomarkers for detecting initial donor ischemic injury, caspase-3, caspase-7, apoptosis, inflammation, HSP70 and renal histological changes were examined in porcine kidneys subjected to 7- 15- 25- or 40-min WI, two-hour cold storage and six-hour hemoreperfusion. Caspase-3 activity was gradually increased by prolonged reperfusion, with a decrease trend against WI time. This result was verified by raised 17 kDa active caspase-3 in postreperfusion kidneys, with elevated 12 kDa active caspase-3 and lowered precursor at seven-minute WI. Active caspase-7 was also doubled by reperfusion with decreased precursor at seven-minute WI, but declined against prolonged WI. Apoptotic cells in tubular and interstitial areas were greatly increased by reperfusion at seven-minute WI, but decreased against prolonged WI. In addition, myeloperoxidase (MPO)+ cells were dramatically increased by reperfusion and presented as a bell-shape against WI time, while HSP70 was significantly increased at 7-min WI, but decreased at 40-min WI after reperfusion. In postreperfusion kidneys, tubular dilation and cell shedding were observed at 7- and 15-min WI, while tubular vacuolation and cell debris were found in tubular lumens at longer WI times. At 40-min WI, early nuclear pyknosis, tubular epithelia detachment and peri-tubular capillary dilation were detected. Furthermore, caspase-3, caspase-7, apoptosis, but not MPO+ cells or HSP70, were correlated with renal function. In conclusion, caspase-3, caspase-7 and apoptosis appear to be better biomarkers than MPO+ cells or HSP70 for assessing warm ischemic injury in donor kidneys. Hemoreperfusion activates caspase-3 and caspase-7, promotes apoptosis of damaged cells in kidneys only with limited WI, which might be beneficial to renal structural re-modeling and functional recovery.

Compartment Syndrome in the Setting of Vascular Injury

Compartment syndrome after extremity vascular injury has gained attention with the current conflicts in Iraq and Afghanistan. Compartment syndrome after extremity vascular injury is due to the initial ischemic insult and reperfusion injury. Complications from compartment syndrome can be lessened by fasciotomy, which is reviewed in this article.

Recovered changes in the spleen by agmatine treatment after transient cerebral ischemia

Stroke or cerebrovascular injury is the leading cause of disability and the third leading cause of deaths worldwide. After the initial ischemic injury, sympathetic signals are transmitted to the spleen and a compromised blood-brain barrier, coupled with expression of adhesion molecules by the vascular endothelial cells permits an influx of peripheral immune cells. This influx of peripheral immune cells into the brain exacerbates the local brain inflammatory response, leading to enhanced neurodegeneration. Agmatine is a primary amine formed by decarboxylation of L-arginine synthesized in the mammalian brain. In this study, we determined the effect of agmatine on the immune response in the spleen after transient cerebral ischemia. Twenty-three hours after transient cerebral ischemia, the white pulp area was reduced and the number of CD11b+ macrophages and CD4+CD25+ regulatory T cells (T reg cells) were increased in the spleens in the experimental group as a result of alteration of the immune response in the spleen, as regulated by inflammatory cytokines. In the agmatine treatment group (100 mg/kg IP), the contraction of white pulp was diminished and the number of CD11b+ macrophages and CD4+CD25+T reg cells were decreased. Twenty-three hours after transient cerebral ischemia, the brain infarction area was significantly reduced (5.51±1.63% of the whole brain) in the agmatine treatment group compared to 15.02±4.28% of the whole brain in the experimental control group. These results suggest that agmatine treatment can reduce brain infarction through minimizing neuroinflammation and can lessen the danger of post-stroke infection from depression of the immune system after stroke.

Spatiotemporal Correlations between Blood-Brain Barrier Permeability and Apparent Diffusion Coefficient in a Rat Model of Ischemic Stroke

Variations in apparent diffusion coefficient of water (ADC) and blood-brain barrier (BBB) permeability after ischemia have been suggested, though the correlation between ADC alterations and BBB opening remains to be studied. We hypothesized that there are correlations between the alteration of ADC and BBB permeability. Rats were subjected to 2 h of transient middle cerebral artery occlusion and studied at 3 and 48 h of reperfusion, which are crucial times of BBB opening. BBB permeability and ADC values were measured by dynamic contrast-enhanced MRI and diffusion-weighted imaging, respectively. Temporal and spatial analyses of the evolution of BBB permeability and ADC alteration in cortical and subcortical regions were conducted along with the correlation between ADC and BBB permeability data. We found significant increases in BBB leakage and reduction in ADC values between 3 and 48 h of reperfusion. We identified three MR tissue signature models: high Ki and low ADC, high Ki and normal ADC, and normal Ki and low ADC. Over time, areas with normal Ki and low ADC transformed into areas with high Ki. We observed a pattern of lesion evolution where the extent of initial ischemic injury reflected by ADC abnormalities determines vascular integrity. Our results suggest that regions with vasogenic edema alone are not likely to develop low ADC by 48 h and may undergo recovery.