Inhibition of experimental vasospasm in rats with the periadventitial administration of ibuprofen using controlled-release polymers

Systemic Inflammation after Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is one of the most severe neurological disorders, with a high mortality rate and severe disabling functional sequelae. Systemic inflammation following hemorrhagic stroke may play an important role in mediating intracranial and extracranial tissue damage. Previous studies showed that various systemic inflammatory biomarkers might be useful in predicting clinical outcomes. Anti-inflammatory treatment might be a promising therapeutic approach for improving the prognosis of patients with aSAH. This review summarizes the complicated interactions between the nervous system and the immune system.

Impact of analgesic regimen on patient outcome following subarachnoid hemorrhage: positive adjuvant effects of metamizole

INTRODUCTION

Various analgesics are used to control intense headaches in patients following subarachnoid hemorrhage. In addition to pain control, it has been shown that some analgesics can affect various pathophysiological cascades. Therefore, we devised a study to assess whether the use of metamizole has a significant impact on the development of ischemic complications, hydrocephalus, and the overall outcome in patients following aneurysmal subarachnoid hemorrhage in the context of the other non-opioids and opioids effects.

METHODS

In our retrospective, single-center cohort study, we enrolled 192 patients diagnosed with subarachnoid hemorrhage. We recorded their initial clinical status, comorbidities, and the daily dosage of analgesics over 14 days of hospitalization after the onset of subarachnoid hemorrhage. Using univariate and subsequent multivariate logistic regression analysis, we assessed the influence of various factors, including analgesics, on the development of delayed cerebral ischemia and hydrocephalus, as well as on 2-week and 6-month outcomes.

RESULTS

Although the administration of non-opioids, in general, had no effect on the development of delayed cerebral ischemia or hydrocephalus, the use of metamizole as the main analgesic was associated with a significantly lower chance of poor outcome at both 2-weeks and 6-months, as well as the development of delayed cerebral ischemia. As opioids were indicated primarily for analgosedation in mechanically ventilated patients with poor clinical status, their usage was associated with a significantly higher chance of poor outcome, delayed cerebral ischemia, and hydrocephalus.

CONCLUSION

Our results suggest that the prescription of metamizole may be associated with better outcomes and a lower chance of delayed cerebral ischemia development in patients after subarachnoid hemorrhage. Considering the retrospective nature of our study and the limited worldwide availability of metamizole due to its prohibition in some countries, our results do not demonstrate a clear benefit but rather justify the need for subsequent prospective studies.

Monocyte-based inflammatory indices predict outcomes following aneurysmal subarachnoid hemorrhage

The contribution of specific immune cell populations to the post-hemorrhagic inflammatory response in aneurysmal subarachnoid hemorrhage (aSAH) and correlations with clinical outcomes, such as vasospasm and functional status, remains unclear. We aimed to compare the predictive value of leukocyte ratios that include monocytes as compared to the neutrophil-to-lymphocyte ratio (NLR) in aSAH. A prospectively accrued database of consecutive patients presenting to our institution with aSAH between January 2013 and December 2018 was used. Patients with signs and symptoms of infection (day 1-3) were excluded. Admission values of the NLR, monocyte-neutrophil-to-lymphocyte ratio (M-NLR), and lymphocyte-to-monocyte ratio (LMR) were calculated. Associations with functional status, the primary outcome, and vasospasm were evaluated using univariable and multivariable logistic regression analyses. In the cohort of 234 patients with aSAH, the M-NLR and LMR, but not the NLR, were significantly associated with poor functional status (modified Rankin scale > 2) at 12-18 months following discharge (p = 0.001, p = 0.023, p = 0.161, respectively). The area under the curve for predicting poor functional status was significantly lower for the NLR (0.543) compared with the M-NLR (0.603, p = 0.024) and LMR (0.608, p = 0.040). The M-NLR (OR = 1.01 [1.01-1.02]) and LMR (OR = 0.88 [0.78-0.99]) were independently associated with poor functional status while controlling for age, hypertension, Fisher grade, and baseline clinical status. The LMR was significantly associated with vasospasm (OR = 0.84 [0.70-0.99]) while adjusting for age, hypertension, Fisher grade, aneurysm size, and current smoking. Inflammatory indices that incorporate monocytes (e.g., M-NLR and LMR), but not those that include only neutrophils, predict outcomes after aSAH.

Controlled local release of PPARγ agonists from biomaterials to treat peripheral nerve injury

OBJECTIVE

Poor clinical outcomes following peripheral nerve injury (PNI) are partly attributable to the limited rate of neuronal regeneration. Despite numerous potential drug candidates demonstrating positive effects on nerve regeneration rate in preclinical models, no drugs are routinely used to improve restoration of function in clinical practice. A key challenge associated with clinical adoption of drug treatments in nerve injured patients is the requirement for sustained administration of doses associated with undesirable systemic sideeffects. Local controlled-release drug delivery systems could potentially address this challenge, particularly through the use of biomaterials that can be implanted at the repair site during the microsurgical repair procedure.

APPROACH

In order to test this concept, this study used various biomaterials to deliver ibuprofen sodium or sulindac sulfide locally in a controlled manner in a rat sciatic nerve injury model. Following characterisation of release parameters in vitro, ethylene vinyl acetate tubes or polylactic-co-glycolic acid wraps, loaded with ibuprofen sodium or sulindac sulfide, were placed around directly-repaired nerve transection or nerve crush injuries in rats.

MAIN RESULTS

Ibuprofen sodium, but not sulindac sulfide caused an increase in neurites in distal nerve segments and improvements in functional recovery in comparison to controls with no drug treatment.

SIGNIFICANCE

This study showed for the first time that local delivery of ibuprofen sodium using biomaterials improves neurite growth and functional recovery following PNI and provides the basis for future development of drug-loaded biomaterials suitable for clinical translation.

Blocking VEGF by Bevacizumab Attenuates VEGF-Induced Vasospasm After Experimental Subarachnoid Hemorrhage in Rabbits

OBJECTIVE

Vasospasm after subarachnoid hemorrhage (SAH) plays a vital role in the development of delayed cerebral ischemia. Anti- vascular endothelial growth factor (VEGF) antibodies, like bevacizumab (BEV), may attenuate VEGF-stimulated angiogenesis, reduced vascular cell proliferation, and improve vasospasm after SAH.

METHODS

Thirty-two adult male New Zealand white rabbits were randomly divided into 4 groups of 8 rabbits in each group: group 1 (control); group 2 (SAH); group 3 (SAH + vehicle); and group 4 (SAH + BEV). BEV (5 mg/kg, intraperitoneally) was administered 5 minutes after the intracisternal blood injection and continued for 72 hours once per day in the same dose for group 4. Animals were sacrificed 72 hours after SAH. Basilar artery cross-sectional areas, arterial wall thicknesses, and hippocampal degeneration scores were evaluated in all groups.

RESULTS

VEGF is associated with the narrowing of the basilar artery. Treatment with BEV statistically significantly increased the cross-sectional area of the basilar artery when compared with the SAH and the vehicle groups. Basilar artery wall thicknesses in the BEV group was statistically significant smaller than in the SAH and vehicle groups. The hippocampal degeneration scores for the BEV and control groups were similar and significantly lower than those for the SAH and vehicle groups.

CONCLUSIONS

Cellular proliferation and subsequent vessel wall thickening is a reason to delay cerebral ischemia and deterioration of the neurocognitive function. Intraperitoneal administration of BEV was found to attenuate cerebral vasospasm and prevent delayed cerebral ischemia and improve neurocognitive function after SAH in rabbits.

Peripheral Monocytosis at Admission to Predict Cerebral Infarct and Poor Functional Outcomes in Subarachnoid Hemorrhage Patients

OBJECTIVE

Increasing evidence points monocytes' role to be larger than thought in developing cerebral infarction (CI) after subarachnoid hemorrhage (SAH). However, there is no clinical evidence of the relationship between peripheral monocytes and CI and clinical outcomes. Therefore we determine whether an increase in monocytes in the acute phase is useful to predict CI and functional outcomes in SAH patients.

METHODS

We included 204 patients with an SAH diagnosis. We collected patient-related factors, comorbidities, Hunt-Hess grade, modified Fisher grade, treatment, delayed cerebral ischemia, CI, aneurysm characteristics, and peripheral monocytes from vein blood at admission. Poor outcomes were defined as modified Rankin Scale score ≥3.

RESULTS

Fifty (24.5%) patients had CI before discharge. In a multivariate model, increased monocytes at admission were significantly associated with CI after adjusting for IV-V Hunt-Hess grade and delayed cerebral ischemia (odds ratio: 3.193, 95% confidence interval: 1.069-9.532, P = 0.037). In receiver operating characteristic curve analysis, a monocyte count of 0.60 was identified as the best cutoff value to discriminate the development of CI (area under the curve = 0.622, P = 0.010; CI for monocytes <0.60 17.4% vs. CI for monocytes ≥0.60 29.1% P = 0.046). Admission monocytes ≥0.60 predicted poor functional outcomes at discharge (monocytes <0.60 52% vs. monocytes ≥0.60 64.7%) and at 12 months (monocytes <0.60 29.4% vs. monocytes ≥0.60 70.6%).

CONCLUSIONS

Increased peripheral monocytes at admission is a risk factor for developing CI after SAH. Moreover, short- and long-term poor clinical outcomes were associated with higher monocyte count. Therefore monocytes could be a convenient biomarker for prognosis unfavorable outcomes and a possible target for new therapeutic strategies.

Perivascular medical devices and drug delivery systems: Making the right choices

Perivascular medical devices and perivascular drug delivery systems are conceived for local application around a blood vessel during open vascular surgery. These systems provide mechanical support and/or pharmacological activity for the prevention of intimal hyperplasia following vessel injury. Despite abundant reports in the literature and numerous clinical trials, no efficient perivascular treatment is available. In this review, the existing perivascular medical devices and perivascular drug delivery systems, such as polymeric gels, meshes, sheaths, wraps, matrices, and metal meshes, are jointly evaluated. The key criteria for the design of an ideal perivascular system are identified. Perivascular treatments should have mechanical specifications that ensure system localization, prolonged retention and adequate vascular constriction. From the data gathered, it appears that a drug is necessary to increase the efficacy of these systems. As such, the release kinetics of pharmacological agents should match the development of the pathology. A successful perivascular system must combine these optimized pharmacological and mechanical properties to be efficient.

Novel Treatments in Neuroprotection for Aneurysmal Subarachnoid Hemorrhage

OPINION STATEMENT

New neuroprotective treatments aimed at preventing or minimizing "delayed brain injury" are attractive areas of investigation and hold the potential to have substantial beneficial effects on aneurysmal subarachnoid hemorrhage (aSAH) survivors. The underlying mechanisms for this "delayed brain injury" are multi-factorial and not fully understood. The most ideal treatment strategies would have the potential for a pleotropic effect positively modulating multiple implicated pathophysiological mechanisms at once. My personal management (RFJ) of patients with aneurysmal subarachnoid hemorrhage closely follows those treatment recommendations contained in modern published guidelines. However, over the last 5 years, I have also utilized a novel treatment strategy, originally developed at the University of Maryland, which consists of a 14-day continuous low-dose intravenous heparin infusion (LDIVH) beginning 12 h after securing the ruptured aneurysm. In addition to its well-known anti-coagulant properties, unfractionated heparin has potent anti-inflammatory effects and through multiple mechanisms may favorably modulate the neurotoxic and neuroinflammatory processes prominent in aneurysmal subarachnoid hemorrhage. In my personal series of patients treated with LDIVH, I have found significant preservation of neurocognitive function as measured by the Montreal Cognitive Assessment (MoCA) compared to a control cohort of my patients treated without LDIVH (RFJ unpublished data presented at the 2015 AHA/ASA International Stroke Conference symposium on neuroinflammation in aSAH and in abstract format at the 2015 AANS/CNS Joint Cerebrovascular Section Annual Meeting). It is important for academic physicians involved in the management of these complex patients to continue to explore new treatment options that may be protective against the potentially devastating "delayed brain injury" following cerebral aneurysm rupture. Several of the treatment options included in this review show promise and could be carefully adopted as the level of evidence for each improves. Other proposed neuroprotective treatments like statins and magnesium sulfate were previously thought to be very promising and to varying degrees were adopted at numerous institutions based on somewhat limited human evidence. Recent clinical trials and meta-analysis have shown no benefit for these treatments, and I currently no longer utilize either treatment as prophylaxis in my practice.

The impact of nonsteroidal anti-inflammatory drugs on inflammatory response after aneurysmal subarachnoid hemorrhage

BACKGROUND

The degree of inflammatory response with cytokine release is associated with poor outcomes after aneurysmal subarachnoid hemorrhage (SAH). Previously, we reported on an association between systemic IL-6 levels and clinical outcome in patients with aneurysmal SAH. The intention was to assess the impact of nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen on the inflammatory response after SAH.

METHODS

Our method involved exploratory analysis of data and samples collected within a previous study. In 138 patients with SAH, systemic interleukin (IL-6) and c-reactive protein (CRP) were measured daily up to day 14 after SAH. The correlations among the cumulatively applied amount of NSAIDs, inflammatory parameters, and clinical outcome were calculated.

RESULTS

An inverse correlation between cumulatively applied NSAIDs and both IL-6 and CRP levels was found (r = -0.437, p < 0.001 and r = -0.369, p < 0.001 respectively). Multivariable linear regression analysis showed a cumulative amount of NSAIDs to be independently predictive for systemic IL-6 and CRP levels. The cumulative amount of NSAIDs reduced the odds for unfavorable outcome, defined as Glasgow outcome scale 1-3.

CONCLUSIONS

The results indicate a potential beneficial effect of NSAIDs in patients with SAH in terms of ameliorating inflammatory response, which might have an impact on outcome.

Inflammation, vasospasm, and brain injury after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) can lead to devastating neurological outcomes, and there are few pharmacologic treatments available for treating this condition. Both animal and human studies provide evidence of inflammation being a driving force behind the pathology of SAH, leading to both direct brain injury and vasospasm, which in turn leads to ischemic brain injury. Several inflammatory mediators that are elevated after SAH have been studied in detail. While there is promising data indicating that blocking these factors might benefit patients after SAH, there has been little success in clinical trials. One of the key factors that complicates clinical trials of SAH is the variability of the initial injury and subsequent inflammatory response. It is likely that both genetic and environmental factors contribute to the variability of patients' post-SAH inflammatory response and that this confounds trials of anti-inflammatory therapies. Additionally, systemic inflammation from other conditions that affect patients with SAH could contribute to brain injury and vasospasm after SAH. Continuing work on biomarkers of inflammation after SAH may lead to development of patient-specific anti-inflammatory therapies to improve outcome after SAH.

A glutamate receptor antagonist, S-4-carboxyphenylglycine (S-4-CPG), inhibits vasospasm after subarachnoid hemorrhage in haptoglobin 2-2 mice [corrected]

BACKGROUND

Vasospasm contributes to delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (SAH). Glutamate concentrations increase after SAH and correlate with vasospasm in experimental SAH. The haptoglobin (Hp) 2-2 genotype is associated with higher risk of vasospasm after SAH. We tested the efficacy of (S)-4-carboxyphenylglycine (S-4-CPG), a metabotropic glutamate receptor inhibitor, for the treatment of vasospasm after SAH in Hp 2-2 and Hp 1-1 mice.

OBJECTIVE

To evaluate the effect on vasospasm and neurobehavioral scores after SAH of systemic S-4-CPG, as well as its toxicity, and phosphorylation of vasodilator-stimulated phosphoprotein (VASP) in Hp 2-2 mice.

METHODS

Western blot was used to assess changes in VASP phosphorylation in response to glutamate with and without S-4-CPG. A pharmacokinetics study was done to evaluate S-4-CPG penetration through the blood-brain barrier in vivo. Toxicity was assessed by administering increasing S-4-CPG doses. Efficacy of S-4-CPG assessed the effect of S-4-CPG on lumen patency of the basilar artery and animal behavior after SAH in Hp 1-1 and Hp 2-2 mice. Immunohistochemistry was used to evaluate the presence of neutrophils surrounding the basilar artery after SAH.

RESULTS

Exposure of human brain microvascular endothelial cells to glutamate decreased phosphorylation of VASP, but glutamate treatment in the presence of S-4-CPG maintains phosphorylation of VASP. S-4-CPG crosses the blood-brain barrier and was not toxic to mice. S-4-CPG treatment significantly prevents vasospasm after SAH. S-4-CPG administered after SAH resulted in a trend toward improvement of animal behavior.

CONCLUSION

S-4-CPG prevents vasospasm after experimental SAH in Hp2-2 mice. S-4-CPG was not toxic and is a potential therapeutic agent for vasospasm after SAH.

Current management of delayed cerebral ischemia: update from results of recent clinical trials

Subarachnoid hemorrhage (SAH) accounts for 5-7% of all strokes worldwide and is associated with high mortality and morbidity. Even after surgical intervention, approximately 30% of patients develop long-term cognitive and neurological deficits that significantly affect their capacity to return to work or daily life unassisted. Much of this stems from a secondary ischemic phenomenon referred to as delayed cerebral ischemia (DCI). While DCI has been historically attributed to the narrowing of the large basal cerebral arteries, it is now recognized that numerous pathways contribute to its pathogenesis, including microcirculatory dysfunction, microthrombosis, cortical spreading depression, and early brain injury. This paper seeks to summarize some of the key pathophysiological events that are associated with poor outcome after SAH, provide a general overview of current methods of treating SAH patients, and review the results of recent clinical trials directed at improving outcome after SAH. The scientific basis of these studies will be discussed, in addition to the available results and recommendations for effective patient management. Therapeutic methods under current clinical investigation will also be addressed. In particular, the mechanisms by which they are expected to elicit improved outcome will be investigated, as well as the specific study designs and anticipated time lines for completion.

Delayed neurological deterioration after subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) causes early brain injury (EBI) that is mediated by effects of transient cerebral ischaemia during bleeding plus effects of the subarachnoid blood. Secondary effects of SAH include increased intracranial pressure, destruction of brain tissue by intracerebral haemorrhage, brain shift, and herniation, all of which contribute to pathology. Many patients survive these phenomena, but deteriorate days later from delayed cerebral ischaemia (DCI), which causes poor outcome or death in up to 30% of patients with SAH. DCI is thought to be caused by the combined effects of angiographic vasospasm, arteriolar constriction and thrombosis, cortical spreading ischaemia, and processes triggered by EBI. Treatment for DCI includes prophylactic administration of nimodipine, and current neurointensive care. Prompt recognition of DCI and immediate treatment by means of induced hypertension and balloon or pharmacological angioplasty are considered important by many physicians, although the evidence to support such approaches is limited. This Review summarizes the pathophysiology of DCI after SAH and discusses established treatments for this condition. Novel strategies--including drugs such as statins, sodium nitrite, albumin, dantrolene, cilostazol, and intracranial delivery of nimodipine or magnesium--are also discussed.

Brain ischemia in patients with intracranial hemorrhage: pathophysiological reasoning for aggressive diagnostic management

Patients with intracranial hemorrhage have to be managed aggressively to avoid or minimize secondary brain damage due to ischemia, which contributes to high morbidity and mortality. The risk of brain ischemia, however, is not the same in every patient. The risk of complications associated with an aggressive prophylactic therapy in patients with a low risk of brain ischemia can outweigh the benefits of therapy. Accurate and timely identification of patients at highest risk is a diagnostic challenge. Despite the availability of many diagnostic tools, stroke is common in this population, mostly because the pathogenesis of stroke is frequently multifactorial whereas diagnosticians tend to focus on one or two risk factors. The pathophysiological mechanisms of brain ischemia in patients with intracranial hemorrhage are not yet fully elucidated and there are several important areas of ongoing research. Therefore, this review describes physiological and pathophysiological aspects associated with the development of brain ischemia such as the mechanism of oxygen and carbon dioxide effects on the cerebrovascular system, neurovascular coupling and respiratory and cardiovascular factors influencing cerebral hemodynamics. Consequently, we review investigations of cerebral blood flow disturbances relevant to various hemodynamic states associated with high intracranial pressure, cerebral embolism, and cerebral vasospasm along with current treatment options.

Inflammation, cerebral vasospasm, and evolving theories of delayed cerebral ischemia

Cerebral vasospasm (CVS) is a potentially lethal complication of aneurysmal subarachnoid hemorrhage (aSAH). Recently, the symptomatic presentation of CVS has been termed delayed cerebral ischemia (DCI), occurring as early as 3-4 days after the sentinel bleed. For the past 5-6 decades, scientific research has promulgated the theory that cerebral vasospasm plays a primary role in the pathology of DCI and subsequently delayed ischemic neurological decline (DIND). Approximately 70% of patients develop CVS after aSAH with 50% long-term morbidity rates. The exact etiology of CVS is unknown; however, a well-described theory involves an antecedent inflammatory cascade with alterations of intracellular calcium dynamics and nitric oxide fluxes, though the intricacies of this inflammatory theory are currently unknown. Consequently, there have been few advances in the clinical treatment of this patient cohort, and morbidity remains high. Identification of intermediaries in the inflammatory cascade can provide insight into newer clinical interventions in the prevention and management of cerebral vasospasm and will hopefully prevent neurological decline. In this review, we discuss current theories implicating the inflammatory cascade in the development of CVS and potential treatment targets.

Influence of Fever and hospital-acquired infection on the incidence of delayed neurological deficit and poor outcome after aneurysmal subarachnoid hemorrhage

Although fever and infection have been implicated in the causation of delayed neurological deficits (DND) and poor outcome after aneurysmal subarachnoid hemorrhage (SAH), the relationship between these two often related events has not been extensively studied. We reviewed these events through of our retrospective database of patients with SAH. Multivariate logistic regression was used to determine independent predictors of DND and poor outcome. A total of 186 patients were analyzed. DND was noted in 76 patients (45%). Fever was recorded in 102 patients (55%); infection was noted in 87 patients (47%). A patient with one infection was more likely to experience DND compared to a patient with no infections (adjusted OR 3.73, 95% CI 1.62, 8.59). For those with more than two infections the likelihood of DND was even greater (adjusted OR 4.24, 95% CI 1.55, 11.56). Patients with 1-2 days of fever were less likely to have a favorable outcome when compared to their counterparts with no fever (adjusted OR 0.19, 95% CI 0.06, 0.62). This trend worsened as the number of days febrile increased. These data suggest that the presence of infection is associated with DND, but that fever may have a stronger independent association with overall outcome.

Trehalose treatment suppresses inflammation, oxidative stress, and vasospasm induced by experimental subarachnoid hemorrhage

Background

Subarachnoid hemorrhage (SAH) frequently results in several complications, including cerebral vasospasm, associated with high mortality. Although cerebral vasospasm is a major cause of brain damages after SAH, other factors such as inflammatory responses and oxidative stress also contribute to high mortality after SAH. Trehalose is a non-reducing disaccharide in which two glucose units are linked by α,α-1,1-glycosidic bond, and has been shown to induce tolerance to a variety of stressors in numerous organisms. In the present study, we investigated the effect of trehalose on cerebral vasospasm, inflammatory responses, and oxidative stress induced by blood in vitro and in vivo.

Methods

Enzyme immunoassay for eicosanoids, pro-inflammatory cytokines, and endothelin-1, and western blotting analysis for cyclooxygenase-2, inducible nitric oxide synthase, and inhibitor of NF-κB were examined in macrophage-like cells treated with hemolysate. After treatment with hemolysate and hydrogen peroxide, the levels of lipid peroxide and amounts of arachidonic acid release were also analyzed. Three hours after the onset of experimental SAH, 18 Japanese White rabbits received an injection of saline, trehalose, or maltose into the cisterna magna. Angiographic and histological analyses of the basilar arteries were performed. In a separate study, the femoral arteries from 60 rats were exposed to fresh autologous blood. At 1, 3, 5, 7, 10, and 20 days after treatment, cryosections prepared from the femoral arteries were histologically analyzed.

Results

When cells were treated with hemolysate, trehalose inhibited the production of several inflammatory mediators and degradation of the inhibitor of NF-κB and also suppressed the lipid peroxidation, the reactive oxygen species-induced arachidonic acid release in vitro. In the rabbit model, trehalose produced an inhibitory effect on vasospasm after the onset of experimental SAH, while maltose had only a moderate effect. When the rat femoral arteries exposed to blood were investigated for 20 days, histological analysis revealed that trehalose suppressed vasospasm, inflammatory response, and lipid peroxidation.

Conclusions

These data suggest that trehalose has suppressive effects on several pathological events after SAH, including vasospasm, inflammatory responses, and lipid peroxidation. Trehalose may be a new therapeutic approach for treatment of complications after SAH.

Expression of CD137 in the cerebral artery after experimental subarachnoid hemorrhage in rats: a pilot study

Inflammation and immunity play a crucial role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). CD137 is recognized as an independent costimulatory molecule of T cells and activator of monocytes. A growing body of evidence indicates that CD137 is vital for inflammation and immunity. Therefore, this study aimed to investigate the expression of CD137 in the basilar artery in a rat SAH model and to clarify the potential role of CD137 in cerebral vasospasm. A total of 107 rats were randomly divided into four groups: control group; day 3, day 5, and day 7 groups. Day 3, day 5, and day 7 groups were all SAH groups. The animals in SAH groups were subjected to injection of autologous blood into cisterna magna twice on day 0 and day 2 and were sacrificed on days 3, 5, and 7, respectively. Cross-sectional area of basilar artery was measured and the CD137 expression was assessed by quantitative real-time PCR, Western blot and immunohistochemistry. The cross-sectional area of basilar artery was found to be 57,944±5581μm(2) in control group, 26,100±2639μm(2) in day 3, 19,723±2412μm(2) in day 5, and 28,800±2980μm(2) in day 7 group, respectively. The basilar artery exhibited vasospasm after SAH and became more severe on day 5. The elevated mRNA and protein of CD137 were detected after SAH and peaked on day 5. CD137 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in a rat experimental model of SAH. These findings indicate the possible role of CD137 in the pathogenesis of cerebral vasospasm after SAH.

Treatment of subarachnoid hemorrhage with human albumin: ALISAH study. Rationale and design

The primary objective of this prospective dose-finding pilot study is to demonstrate the tolerability and safety of four dosages of 25% human albumin in patients with subarachnoid hemorrhage (SAH). For each dosage group, the study will enroll 20 patients who meet the eligibility criteria. The enrolled patients will undergo follow-up for 90 days post-treatment. The primary tolerability hypothesis is that intravenous 25% human albumin can be given without precipitating treatment related serious adverse events beyond expectations. The study will determine the maximum tolerated dosage of 25% human albumin therapy based on the rate of treatment related serious adverse events during treatment: severe or life-threatening heart failure. The secondary objectives are to obtain preliminary estimates of the albumin treatment effect using the incidence of neurological deterioration within 15 days after symptom onset. In addition, the incidence of rebleeding, hydrocephalus, seizures, delayed cerebral ischemia and the incidence of vasospasm (both symptomatic and by transcranial Doppler ultrasound criteria) within 15 days after symptom onset will be evaluated. Furthermore, the serum osmolality and serum albumin concentrations, serum magnesium concentration, blood pressure and heart rate within 15 days of symptom onset will also be observed. The Glasgow Outcome Scale, Barthel Index, modified Rankin Scale, NIH Stroke Scale, and Stroke Impact Scale will be performed 3 months after the onset of symptoms to assess residual neurological deficits.

Inflammation and cerebral vasospasm after subarachnoid hemorrhage

Morbidity and mortality of patients with aneurysmal subarachnoid hemorrhage (aSAH) is significantly related to the development of chronic cerebral vasospasm. Despite extensive clinical and experimental research, the pathophysiology of the events that result in delayed arterial spasm is not fully understood. A review of the published literature on cerebral vasospasm that included but was not limited to all PubMed citations from 1951 to the present was performed. The findings suggest that leukocyte-endothelial cell interactions play a significant role in the pathophysiology of cerebral vasospasm and explain the clinical variability and time course of the disease. Experimental therapeutic targeting of the inflammatory response when timed correctly can prevent vasospasm, and supplementation of endothelial relaxation by nitric oxide-related therapies and other approaches could result in reversal of the arterial narrowing and improved outcomes in patients with aSAH.

6-Mercaptopurine attenuates adhesive molecules in experimental vasospasm

OBJECTIVE

Adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin, are important inflammatory mediators which are elevated in the serum of patients following aneurysmal subarachnoid hemorrhage (SAH). The authors previously found that 6-mercaptopurine (6-mp) was effective in preventing and reversing arterial narrowing in a rodent SAH model. The present study was to examine whether levels of adhesion molecules were altered after treatment with 6-mp in this animal model.

MATERIALS AND METHODS

Animals were each injected with autologous blood into the cisterna magna, and intraperitoneal treatment with 6-mp (2 mg/kg) was initiated 1 h before (prevention) or later (treatment). The compound was subsequently administered at 24 and 48 h post-SAH. Blood samples were collected at 72 h post-SAH to measure ICAM-1, VCAM-1, and E-selectin levels. The basilar arteries were harvested and sliced, and their cross-sectional areas were measured. Morphologically, convolution of the internal elastic lamina, distorted endothelial wall, and myonecrosis of the smooth muscle were prominently observed in the SAH only and vehicle-treated SAH groups, but not in the 6-mp-treated SAH group or in healthy controls. No significant differences were found in the levels of VCAM-1 among all groups. However, the levels of E-selectin were increased in all animals subjected to SAH (SAH only and SAH plus vehicle groups) compared with healthy controls (no SAH), but not in the 6-mp group (SAH plus 6-mp treatment and preventive treatment with 6-mp).Likewise, the levels of ICAM-1 in the SAH only and SAH plus vehicle groups were significantly elevated (p < 0.001), and pretreatment and treatment with 6-mp reduced ICAM-1 to control levels.

CONCLUSION

These results show that ICAM-1 and E-selectin may play a role in mediating SAH-induced vasospasm and that a reduction of both adhesive molecules after SAH may partly contribute to the antispastic effect of 6-mp.

Role of inflammation (leukocyte-endothelial cell interactions) in vasospasm after subarachnoid hemorrhage

BACKGROUND

Delayed vasospasm is the leading cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). This phenomenon was first described more than 50 years ago, but only recently has the role of inflammation in this condition become better understood.

METHODS

The literature was reviewed for studies on delayed vasospasm and inflammation.

RESULTS

There is increasing evidence that inflammation and, more specifically, leukocyte-endothelial cell interactions play a critical role in the pathogenesis of vasospasm after aSAH, as well as in other conditions including meningitis and traumatic brain injury. Although earlier clinical observations and indirect experimental evidence suggested an association between inflammation and chronic vasospasm, recently direct molecular evidence demonstrates the central role of leukocyte-endothelial cell interactions in the development of chronic vasospasm. This evidence shows in both clinical and experimental studies that cell adhesion molecules (CAMs) are up-regulated in the perivasospasm period. Moreover, the use of monoclonal antibodies against these CAMs, as well as drugs that decrease the expression of CAMs, decreases vasospasm in experimental studies. It also appears that certain individuals are genetically predisposed to a severe inflammatory response after aSAH based on their haptoglobin genotype, which in turn predisposes them to develop clinically symptomatic vasospasm.

CONCLUSION

Based on this evidence, leukocyte-endothelial cell interactions appear to be the root cause of chronic vasospasm. This hypothesis predicts many surprising features of vasospasm and explains apparently unrelated phenomena observed in aSAH patients. Therapies aimed at preventing inflammation may prevent and/or reverse arterial narrowing in patients with aSAH and result in improved outcomes.

Simvastatin for the prevention of symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage: a single-institution prospective cohort study

OBJECT

Vasospasm is the major cause of disability and death after aneurysmal subarachnoid hemorrhage (aSAH). Although the results of 2 randomized clinical trials demonstrated that statin decreases the incidence of symptomatic cerebral vasospasm after aSAH, retrospective studies have failed to confirm this. The authors conducted a prospective observational study to determine whether a standardized regimen of simvastatin would reduce the incidence of cerebral vasospasm and improve neurological outcomes in patients with aSAH.

METHODS

Since 1991, all patients with aSAH admitted to the authors' institution have been prospectively followed up with standardized outcomes recording. Starting in September 2005, all patients admitted with aSAH were given enteral simvastatin (80 mg/day for 14 days) in addition to the standard care. The incidence of symptomatic cerebral vasospasm, length of hospitalization, in-hospital mortality rate, and discharge Glasgow Outcome Scale scores in these 170 patients were compared to data obtained in 170 consecutive patients who underwent treatment in our unit prior to the introduction of statin therapy.

RESULTS

The 5-year study period included 340 consecutively treated patients (170 who received statins and 170 who did not). Patients who received simvastatin therapy were more frequently male (29 vs 20%) and had a smaller median aneurysm diameter (6 vs 7 mm). Baseline characteristics were otherwise similar between the cohorts. There were no differences in the incidence of symptomatic vasospasm (25.3 vs 30.5%; p = 0.277), in-hospital mortality rate (18 vs 15%; p = 0.468), length of hospitalization (21 +/- 15 vs 19 +/- 12 days; p = 0.281), or poor outcome at discharge (Glasgow Outcome Scale Scores 1-2: 21.7 vs 18.2%; p = 0.416) between the simvastatin and nonstatin cohorts. There were no statin-related complications.

CONCLUSIONS

The uniform introduction of simvastatin did not reduce the incidence of symptomatic cerebral vasospasm, death, or poor outcome in patients with aSAH. Simvastatin was well tolerated, but its benefit may be less than has been previously reported.

Treatment of cerebral vasospasm with biocompatible controlled-release systems for intracranial drug delivery

OBJECTIVE

The pharmacological treatment of cerebral vasospasm (CVS) now includes the experimental use of controlled-release biocompatible compounds that deliver a desired drug locally into the subarachnoid space. A controlled-release system consists of an active material that is incorporated into a carrier, usually in the form of a pellet or a gel. With such systems, the desired agent is delivered slowly and continuously, for long periods of time, directly to the desired site. This technology makes it possible to achieve high local concentrations of therapeutic agents while minimizing systemic toxicity and circumventing the need to cross the blood-brain barrier. This review describes controlled-release systems developed to date for local drug delivery in the treatment of CVS in both animal models and humans.

METHODS

A MEDLINE PubMed database search was performed for articles published from 1975 to 2007 with the following search topics: "controlled-release system/polymer," "controlled-release implants," "cerebral vasospasm," "subarachnoid hemorrhage," "subarachnoid space," and "intracranial drug delivery."

RESULTS

Over the past several decades, several controlled-release systems (lactic/ glycolic acid pellets, ethylene vinyl acetate copolymer, liposomes, silicone elastomers) have been developed to deliver various pharmacological agents (papaverine, nicardipine, ibuprofen, nitric oxide donor, calcitonin gene-related peptide, fasudil, recombinant tissue plasminogen activator) intracranially to treat subarachnoid hemorrhage in animal models (rats, rabbits, dogs, and primates). Animal studies have shown promising results, and the few human studies that have been published using controlled-release systems with papaverine or nicardipine report similarly encouraging outcomes.

CONCLUSION

Controlled-release systems have evolved over the past few years and have been shown experimentally to be an effective strategy for the local delivery of drugs to treat CVS.

Molecular mechanisms of cerebral vasospasm following aneurysmal SAH

Cerebral vasospasm following aneurysmal vasospasm has been the subject of intensive research. However the underlying pathophysiological mechanisms remain obscure. This article should summarize the present state concerning smooth muscle contraction, endothelial dysfunction, inflammatory changes, gene expression, in the genesis of vasospasm following aneurysmal subarachnoid hemorrhage.

Novel treatments for cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Cerebral vasospasm is a major cause of cerebral ischemia and poor outcomes in the setting of aneurysmal subarachnoid hemorrhage (SAH). Despite advances in diagnosis and treatment of SAH, the pathophysiology of vasospasm is still poorly understood and outcomes remain disappointing. Recent advances in understanding the role of hemoglobin in initiating an inflammatory cascade in the subarachnoid space open new avenues for therapy. Preliminary experimental and clinical evidence indicate that targets in the inflammatory and oxidative cascades hold promise in reducing the incidence and impact of cerebral vasospasm.

Anti-inflammatory effect of meloxicam on experimental vasospasm in the rat femoral artery

Cerebral vasospasm influences morbidity and mortality following subarachnoid haemorrhage (SAH). Inflammation is believed to play a role in post-haemorrhagic vasospasm. Meloxicam is a non-steroidal anti-inflammatory drug. We investigated the effect of meloxicam on a rat femoral artery vasospasm model using the radial wall thickness and cross-sectional lumen area as parameters under light, scanning and transmission electron microscopy examination. Rats were randomly separated into SAH, SAH+ meloxicam and control groups. Rats in the SAH+ meloxicam group were given meloxicam at 2 mg/kg daily for 7 days. Femoral arteries were examined by light microscopy and scanning and transmission electron microscopy, and for morphometric analysis. A statistically significant difference (p<0.001) was detected between the SAH and SAH+ meloxicam groups. Meloxicam treatment reduced ultrastructural and morphometric vasospastic changes. These findings support the hypothesis that inflammation may play a role in the pathophysiologyical pathways of post-haemorrhagic cerebral vasospasm.

The systemic implications of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is analogous to a pathophysiological watershed, disrupting brain integrity and function and precipitating an array of systemic derangements including cardiovascular, respiratory, endocrine, hematological, and immune dysfunction. Extracerebral organ dysfunction is closely linked to the magnitude of the primary neurological insult, suggesting neurogenic, neuroendocrine and neuroimmunomodulatory mechanisms. Systemic organ involvement is associated with increased mortality and neurological impairment, even after adjustment for other outcome predictors such as the severity of the initial neurological injury. This may be a reflection of secondary brain injury precipitated by hypoxemia, circulatory failure, fever, or hyperglycemia, all of which have been linked to adverse clinical outcomes. Interventions to avert or reverse these and other perturbations need to be tested in clinical trials as they represent opportunities to improve survival and neurological recovery in patients with SAH.

Expression of Toll-like receptor 4 in the basilar artery after experimental subarachnoid hemorrhage in rabbits: a preliminary study

Inflammation and immunity play a crucial role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). Recently, a growing body of evidence indicates that Toll-like receptor (TLR) 4 is vital for inflammation and immunity. Therefore, this study aimed to detect the expression of TLR4 in the basilar artery in a rabbit SAH model and to clarify the potential role of TLR4 in cerebral vasospasm. A total of 48 rabbits were randomly divided into four groups: control group; day 3, day 5, and day 7 groups. Day 3, day 5, and day 7 groups were all SAH groups. The animals in day 3, day 5 and day 7 groups were subjected to injection of autologous blood into cisterna magna twice on day 0 and day 2 and were killed on days 3, 5, and 7, respectively. Cross-sectional area of basilar artery was measured and the TLR4 expression was assessed by immunohistochemistry and Western blot analysis. The basilar arteries exhibited vasospasm after SAH and became more severe on day 3 and 5. The elevated expression of TLR4 was detected after SAH and peaked on day 3 and 5. TLR4 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in a rabbit experimental model of SAH.

THE ADENOSINE 2A RECEPTOR AGONIST ATL-146E ATTENUATES EXPERIMENTAL POSTHEMORRHAGIC VASOSPASM

OBJECTIVE

Selective adenosine 2A receptor agonists, such as ATL-146e, are known to be potent anti-inflammatory agents devoid of systemic side effects and have been used clinically in a number of disease states. However, adenosine 2A receptor agonists have not been studied in the treatment of cerebral vasospasm after subarachnoid hemorrhage. The present study investigated the efficacy of ATL-146e in the prevention of leukocyte infiltration and attenuation of posthemorrhagic vasospasm.

METHODS

The rodent femoral artery model of vasospasm was used. Forty male Sprague-Dawley rats were randomly assigned to four different groups (vehicle, 1 ng/kg/min, 10 ng/kg/min, or 100 ng/kg/min ATL-146e administered via subcutaneous osmotic minipump). Vasospasm was evaluated at posthemorrhage Day 8 (period of peak constriction) by calculating the lumen cross-sectional area (expressed as percent change in luminal area: ratio of blood-exposed vessel to normal saline-exposed vessel) and radial wall thickness. Immunostaining with anti-CD45 monoclonal antibody to detect leukocytes was used to evaluate localized inflammation.

RESULTS

Significant vasospasm was noted in the vehicle-treated (blood-exposed) control group (78.5%, P < 0.001; expressed as a ratio of luminal area of the saline [no blood] control), but not in the ATL-146e-treated groups (lumen ratio to control: 105.0, 83.4, and 91.3% for the 1, 10, and 100 ng/kg/min groups, respectively). Additionally, infiltration of inflammatory cells was reduced significantly and radial wall thickness was decreased in the ATL-146e-treated groups compared with the vehicle-treated control group.

CONCLUSION

Selective activation of the adenosine 2A receptor with ATL-146e prevented posthemorrhagic vasospasm and reduced leukocyte infiltration in this experimental model. This agent is worthy of further investigation and lends credence to the hypothesis supporting a role for inflammation in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage.

A novel inhibitor of inflammatory cytokine production (CNI-1493) reduces rodent post-hemorrhagic vasospasm

INTRODUCTION

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is a devastating complication, yet despite multiple lines of investigation an effective treatment remains lacking. Cytokine-mediated inflammation has been implicated as a causative factor in the development of posthemorrhagic vasospasm. In previous experiments using the rat femoral artery model of vasospasm, we demonstrated that elevated levels of the proinflammatory cytokine interleukin (IL)-6 are present after hemorrhage and that a polyclonal antibody against IL-6 is capable of attenuating experimental vasospasm.

METHODS

In the present study, we tested the ability of a novel selective proinflammatory cytokine inhibitor (CNI-1493) to protect against the occurrence of experimental vasospasm in the same rat femoral artery model. CNI-1493 was administered by injection directly into the blood-filled femoral pouches of animals at the time of their initial surgery (hemorrhage). Control animals received an equal volume of vehicle alone. Animals were killed at 8 days posthemorrhage and degree of vasospasm was assessed by image analysis of artery cross-sectional area. In a separate series of experiments, enzyme-linked immunosorbent assay (ELISA) was used to assess levels of the proinflammatory cytokine IL-6 and the prototypical antiinflammatory cytokine transforming growth factor (TGF)-beta1 after treatment with CNI-1493.

RESULTS

Pretreatment with CNI-1493 provided dose-dependent attenuation of posthemorrhagic vasospasm, with the highest dose (200 microg in 8 microL dH2O) causing complete reversal of vasospasm (vessel cross-sectional area ratio 1.06 +/- 0.04 versus 0.87 +/- 0.06, p < 0.05, one-way analysis of variance). Assessment of cytokine levels by ELISA confirmed the selectivity of CNI-1493 by demonstrating significant reductions in IL-6 levels, but no suppression of TGF-beta1 levels.

CONCLUSIONS

These findings support the conclusion that inflammatory cytokines, in particular IL-6, play an important role in development of vasospasm in the rat femoral artery model. Furthermore, these results suggest that the inhibition of inflammatory cytokines may be an appropriate strategy for the treatment of vasospasm after SAH.

Attenuation of experimental subarachnoid hemorrhage-induced increases in circulating intercellular adhesion molecule-1 and cerebral vasospasm by the endothelin-converting enzyme inhibitor CGS 26303

OBJECT

Adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin, are important mediators of inflammation, and their levels are elevated in the serum of patients following aneurysmal subarachnoid hemorrhage (SAH). The investigators previously found that CGS 26303 is effective in preventing and reversing arterial narrowing in a rabbit model of SAH. The purpose of the present study was to examine whether levels of adhesion molecules are altered after treatment with CGS 26303 in this animal model.

METHODS

New Zealand White rabbits were each injected with 3 ml of autologous blood in the cisterna magna, and intravenous treatment with CGS 26303 (30 mg/kg) was initiated 1 hour later. The compound was subsequently administered at 12, 24, and 36 hours post-SAH. Blood samples were collected at 48 hours post-SAH to measure ICAM-1, VCAM-1, and E-selectin levels. After the rabbits had been killed by perfusion-fixation, the basilar arteries (BAs) were removed and sliced, and their cross-sectional areas were measured. Treatment with CGS 26303 attenuated arterial narrowing after SAH. Morphologically, corrugation of the internal elastic lamina of BAs was prominently observed in the SAH only and vehicle-treated SAH groups, but not in the CGS 26303-treated SAH group or in healthy controls. There were no significant differences in the levels of VCAM-1 among the four groups. The levels of E-selectin were increased in all animals subjected to SAH (those in the SAH only, SAH plus vehicle, and SAH plus CGS 26303 groups) compared with healthy controls (no SAH); however, the levels of ICAM-1 in the SAH only and SAH plus vehicle groups were significantly elevated (p < 0.001), and treatment with CGS 26303 reduced ICAM-1 to control levels following SAH.

CONCLUSIONS

These results show that ICAM-1 may play a role in mediating SAH-induced vasospasm and that a reduction of ICAM-1 levels after SAH may partly contribute to the antispastic effect of CGS 26303.

Contribution of the remodeling response to cerebral vasospasm

The authors review the remodeling response of blood vessels that occurs after various injuries to arteries. The role of this response in vasospasm after subarachnoid hemorrhage (SAH) is reviewed. There is some evidence that cerebral arteries remodel after SAH in that they are less compliant and contractile than normal. Evidence for other features, such as alteration of smooth muscle phenotype, proliferation of cells and synthesis of extracellular matrix, is conflicting and requires a further study. A remodeling response probably contributes to vasospasm but the magnitude of its importance, in relation to smooth muscle contraction, which also occurs, also needs to be further defined.

Leukocyte-endothelial cell interactions in chronic vasospasm after subarachnoid hemorrhage

Leukocyte-endothelial cell interactions appear to be the root cause of chronic vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). Early clinical observations and indirect experimental evidence suggested an association between inflammation and chronic vasospasm. Early clinical observations in patients with post-hemorrhagic vasospasm included pyrexia, leukocytosis and the presence of circulating immune complexes. Inflammatory infiltrates and increased levels of immunoglobulins and complement fractions within spastic cerebral arteries also provided early evidence for an inflammatory mechanism underlying chronic vasospasm. Early indirect experimental evidence included the ability to reproduce chronic vasospasm with the introduction of inflammatory agents into the subarachnoid space and the inhibition of vasospasm with anti-inflammatory agents. Currently, however, there is an increasing body of direct molecular evidence that demonstrates the pivotal role of leukocyte-endothelial cell interactions in the development of chronic vasospasm. Cell adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1) and endothelial (E)-selectin mediate interactions between circulating leukocytes and cerebral endothelium. Following aSAH, ICAM-1 is up-regulated in cerebral endothelial cells and along with other cell adhesion molecules, can be detected in the serum and cerebrospinal fluid (CSF) of patients with post-hemorrhagic vasospasm. Monoclonal antibody blocking experiments have demonstrated that the prevention of leukocyte extravasation into the subarachnoid space prevents chronic vasospasm. Similarly, drugs like ibuprofen, which prevent ICAM-1 up-regulation and transendothelial cell migration of leukocytes, prevent vasospasm. In this review, we highlight early observations that suggested an association between inflammation and post-hemorrhagic vasospasm, detail the role of leukocyte-endothelial cell interactions in the development of chronic vasospasm and discuss therapeutic implications of an inflammatory etiology of post-hemorrhagic cerebral vasospasm.

Controlled release of lipopolysaccharide in the subarachnoid space of rabbits induces chronic vasospasm in the absence of blood

OBJECTIVE

Leukocyte-endothelial cell interactions appear to play a role in the development of vasospasm after SAH. Using a purely inflammatory protein, LPS, we evaluated the effect of inflammation on the development of chronic vasospasm in the absence of blood and compared it to SAH-induced vasospasm in rabbits.

METHODS

Lipopolysaccharide was incorporated into EVAc polymers to produce 20% LPS/EVAc polymers (wt/wt). Rabbits (n = 23) were randomized to 4 experimental groups: (1) empty polymer (n = 6), (2) SAH (n = 5), (3) 0.7 mg/kg polymeric LPS dose (n = 6), and (4) 1.4 mg/kg polymeric LPS dose (n = 6). Blood and polymers were inserted into the cisterna magna. The rabbits were killed 3 days postoperatively, and the basilar arteries were harvested for morphometric analysis. Clinical response and lumen patencies were analyzed using ANOVA and a post hoc Newman-Keuls Multiple Comparisons test.

RESULTS

Significant narrowing of the basilar artery was observed by insertion of 20% LPS/EVAc polymers into the subarachnoid space at a polymeric dose of 1.4 mg/kg (actual dose, 66 microg kg(-1) d(-1)) (75.4% +/- 4.2%; P < .01) and by SAH (80.3% +/- 8.1%; P < .01) as compared with the empty polymer group. A trend toward narrowing was observed in the 0.7 mg/kg polymeric LPS dose group (actual dose, 33 microg kg(-1) d(-1)) (85.2% +/- 2.6%; P > .05). Symptoms associated with SAH were noted in 50% of the rabbits in the 0.7 mg/kg LPS group and in 100% of rabbits in the 1.4 mg/kg LPS group.

CONCLUSION

Controlled release of LPS into the subarachnoid space of rabbits produced chronic vasospasm in a dose-dependent manner. At a polymeric dose of 1.4 mg/kg, LPS-induced vasospasm was equivalent to that induced by SAH. This suggests that LPS and SAH may induce vasospasm through similar mechanisms and provides further evidence that inflammation plays a central role in the etiology of chronic vasospasm.

Thromboembolism and delayed cerebral ischemia after subarachnoid hemorrhage: an autopsy study

OBJECTIVE

Recent findings have cast doubt on vasospasm as the sole cause of delayed cerebral ischemia after subarachnoid hemorrhage.

METHODS

We reviewed the medical records of 29 patients who died after subarachnoid hemorrhage. Brain sections were taken from the insula, cingulate gyrus, and hippocampus. Adjacent sections were stained with hematoxylin-eosin and immunostained for thromboemboli. The density (burden) of the latter was calculated blindly and correlated with evidence for ischemia and with the amount of subarachnoid blood.

RESULTS

There is a strong correlation between microclot burden and delayed cerebral ischemia. Patients with clinical or radiological evidence of delayed ischemia had mean microclot burdens of 10.0/cm2 (standard deviation [SD], +/-6.6); those without had mean burdens of 2.8 (SD, +/-2.6), a highly significant difference (P = 0.002). There is also significant association (P = 0.001) between microclot burden and histological evidence of ischemia, with the mean burdens being 10.9 in sections exhibiting severe ischemia and 4.1 in those in which ischemia was absent. Microclot burden is high in patients who died within 2 days of hemorrhage, decreasing on Days 3 and 4. In delayed ischemia, the numbers rise again late in the first week and remain high until after the second week. In contrast, the average clot burden is low in patients dying without developing delayed ischemia. The amount of blood on an individual slide influenced the microclot burden on that slide to a highly significant extent (P < 0.001).

CONCLUSION

Thromboembolism after subarachnoid hemorrhage may contribute to delayed cerebral ischemia, which parallels that caused by vasospasm. The pathogenesis of thromboembolism is discussed.

Lysis of intracerebral hematoma with stereotactically implanted tissue plasminogen activator polymers in a rabbit model

OBJECT

Currently no adequate surgical treatment exists for spontaneous intracerebral hemorrhage (ICH). Implantable polymers can be used effectively to deliver therapeutic agents to the local site of the pathological process, thus reducing adverse systemic effects. The authors report the use of stereotactically implanted polymers loaded with tissue plasminogen activator (tPA) to induce lysis of ICH in a rabbit model.

METHODS

Ethylene vinyl acetate (EVAc) polymers were loaded with bovine serum albumin (BSA) only or with BSA plus tPA. In vitro pharmacokinetic (three polymers) and thrombolysis (12 polymers) studies were performed. For the in vivo study, 12 rabbits were fixed in a stereotactic frame, and 0.2 ml of clotted autologous blood was injected into the right frontal lobe parenchyma. After 20 minutes, control BSA polymers were stereotactically implanted at the hemorrhage site in six rabbits, and experimental BSA plus tPA polymers were implanted in six rabbits. Animals were killed at 3 days, and blood clot volume was assessed. The pharmacokinetic study showed release of 146 ng of tPA over 3 days. The tPA activity correlated with in vitro thrombolysis. In the in vivo study, the six animals treated with tPA polymers had a mean (+/- standard error of the mean [SEM]) thrombus volume of 1.43 +/- 0.29 mm3 at 3 days, whereas the six animals treated with blank (BSA-only) polymers had a mean (+/- SEM) thrombus volume of 19.99 +/- 3.74 mm3 (p < 0.001).

CONCLUSIONS

Ethylene vinyl acetate polymers release tPA over the course of 3 days. Stereotactic implantation of tPA-loaded EVAc polymers significantly reduced ICH volume. Polymers loaded with tPA may be useful clinically for lysis of ICH without the side effects of systemic administration of tPA.

Vasospasm as the sole cause of cerebral ischemia: how strong is the evidence?

✓ The authors review literature that challenges the view that vasospasm involving large arteries is the exclusive cause of delayed ischemic neurological deficits (DINDs) following subarachnoid hemorrhage. They discuss alternative mechanisms and review the evidence supporting a potential role for thromboembolism. They conclude that vasospasm and thromboembolism play interrelated and additive roles in the development of DINDs, and that this interaction provides opportunities for novel therapeutic approaches.

Systemic administration of simvastatin after the onset of experimental subarachnoid hemorrhage attenuates cerebral vasospasm

OBJECTIVE

Experimental evidence suggests that intercellular adhesion molecule-1 mediated leukocyte extravasation contributes to the pathogenesis of cerebral vasospasm. Simvastatin, an HMG-CoA reductase inhibitor, decreases intercellular adhesion molecule-1 expression and competitively inhibits leukocyte intercellular adhesion molecule-1 binding. We hypothesized that administration of simvastatin after the onset of subarachnoid hemorrhage (SAH) would attenuate perivascular granulocyte migration and ameliorate cerebral vasospasm in a rabbit model of SAH.

METHODS

New Zealand white rabbits (n = 15) underwent injection of autologous blood into the cisterna magna or sham surgery followed by subcutaneous injection of simvastatin (40 mg/kg) or vehicle 30 minutes, 24 hours, and 48 hours after SAH or sham surgery. Seventy-two hours later, basilar artery lumen diameter was measured by in situ perfusion/fixation and image analysis. CD-18 monoclonal antibody stained perivascular granulocytes and macrophages were counted under light microscopy.

RESULTS

In vehicle treated rabbits, mean +/- standard deviation basilar artery diameter was reduced 3 days after SAH (n = 5) versus sham (n = 5) rabbits (0.49 +/- 0.08 mm versus 0.75 +/- 0.03 mm, P < 0.01). After SAH, mean +/- standard deviation basilar artery diameter was greater in simvastatin (n = 5) treated rabbits versus vehicle (n = 5) (0.63 +/- 0.04 mm versus 0.49 +/- 0.08 mm, P < 0.01). In vehicle treated rabbits, SAH resulted in an increase in the mean +/- standard deviation perivascular CD18 cell count (sham-vehicle, 2.8 +/- 2; SAH-vehicle 90 +/- 27; P < 0.01). Subcutaneous administration of simvastatin attenuated this increase in perivascular CD18-positive cells after SAH (SAH statin, 41.6 +/- 13; SAH vehicle, 90 +/- 27; P < 0.001).

CONCLUSION

Subcutaneous administration of simvastatin after the onset of SAH attenuates perivascular granulocyte migration and ameliorates basilar artery vasospasm after experimental SAH in rabbits. 5-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, such as simvastatin, may potentially serve as agents in the prevention of cerebral vasospasm after SAH.

Intracranial delivery of the nitric oxide donor diethylenetriamine/nitric oxide from a controlled-release polymer: toxicity in cynomolgus monkeys

OBJECTIVE

Diethylenetriamine/nitric oxide (DETA/NO) has been shown to be an effective treatment for delayed posthemorrhagic vasospasm when released abluminally from ethylene-vinyl acetate copolymer (EVAc). However, the observed mortality associated with this drug warrants further investigation. To establish a maximum tolerable dose, this study evaluated the toxicity of DETA/NO released from EVAc in a dose-escalation series in cynomolgus monkeys (Macaca fascicularis).

METHODS

DETA/NO was incorporated into EVAc at a 20:80 dry weight ratio (DETA/NO:EVAc). A total of 13 animals underwent a right frontotemporal craniotomy for placement of a single polymer delivering no drug (n = 3), 0.5 +/- 0.1 mg/kg (n = 3), 0.9 +/- 0.1 mg/kg (n = 3), 1.9 +/- 0.2 mg/kg (n = 3), or a 3.2 mg/kg dose (n = 1) into the subarachnoid space.

RESULTS

The animal receiving the highest dose of DETA/NO (3.2 mg/kg) died 46 hours after surgery. The remaining animals survived for the planned duration of the study. One animal in the group receiving the 1.9 mg/kg dose experienced a seizure 25 hours after surgery and remained lethargic for 2 days before making a complete recovery. The remaining animals exhibited no adverse behavioral effects. Histopathological examination of brain tissue revealed hemorrhagic and ischemic changes at doses above 0.9 mg/kg. No evidence of vascular wall pathology or infection was observed in any animal.

CONCLUSION

The greatest amount of DETA/NO safely delivered from EVAc copolymer to the subarachnoid space of the cynomolgus monkey is approximately 1.0 mg/kg. These findings show that continuous intracisternal delivery of DETA/NO is a safe and potentially effective strategy for prophylactic treatment of delayed cerebral vasospasm.

Safe and efficient drug delivery system with liposomes for intrathecal application of an antivasospastic drug, fasudil

Pharmacological treatment for cerebral ischemia and cerebral vasospasm following subarachnoid hemorrhage (SAH) cannot attain sufficiently high concentrations of the drugs in the cerebrospinal fluid (CSF) without precipitating systemic side effects. We recently developed a liposomal drug delivery system for intrathecal application that can maintain effective concentrations of cerebral vasodilator, fasudil, in the CSF. A single intrathecal injection of liposomal fasudil could maintain a therapeutic drug concentration in the CSF over a period time due to their sustained-release property, significantly decreasing infarct size in a rat model of acute ischemia and reducing vasoconstriction of the rat and dog basilar artery in a model of SAH. In this review, we are introducing our new less-invasive intrathecal drug delivery system that provides an alternative and safe method to deliver therapeutic agents.

ICAM-1 and VCAM-1 expression following aneurysmal subarachnoid hemorrhage and their possible role in the pathophysiology of subsequent ischemic deficits

BACKGROUND

The pathophysiology of ischemic cerebral lesions following aneurysmal subarachnoid hemorrhage (SAH) is poorly understood. There is growing evidence that inflammatory reactions could be involved in the pathogenesis of such delayed occurring ischemic lesions. The aim of this study was to evaluate adhesion molecules with regard to these lesions following SAH.

METHODS

Serum and cerebrospinal fluid (CSF) samples were taken daily from 15 patients up to day 9 after SAH and evaluated for intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1).

RESULTS

CSF and serum samples correlated well during nearly the whole time course (p < 0.0001). A secondary increase in ICAM-1 and VCAM-1 in the serum and CSF correlated with an increase in flow velocity in the transcranial Doppler (p > 0.0001 and p < 0.007) but not to a delayed lesion in the CT scan.

CONCLUSION

We believe that inflammatory processes are involved in the pathogenesis of cerebral vasospasm but they might only be a part of a multifactorial pathogenesis.

Controlled release of a nitric oxide donor for the prevention of delayed cerebral vasospasm following experimental subarachnoid hemorrhage in nonhuman primates

OBJECT

Results of prior studies in rats and rabbits show that the alteration of vasomotor tone in vasospasm following periadventitial blood exposure may be reversed, at least in part, by the administration of compounds releasing nitric oxide (NO). The authors have now generalized this finding to nonhuman primates.

METHODS

Ten cynomolgus monkeys underwent cerebral angiography before and 7 days following the induction of subarachnoid hemorrhage (SAH) by the placement of 2 to 3 ml clotted autologous blood around the supraclinoid carotid, proximal anterior cerebral, and proximal middle cerebral arteries. An ethylene vinyl acetate copolymer, either blank (five animals) or containing 20% w/w (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO, 4.3 mg/kg; five animals) was placed adjacent to the vessels at the time of surgery. Animals were killed on Day 7 post-SAH following repeated cerebral angiography. The mean percentage of control vascular areal fraction was calculated from angiograms. Cerebral vessels were sectioned and the mean percentage of lumen patency was calculated. One animal that had received the DETA/NO polymer died prior to repeated angiography. In the remaining animals, DETA/NO caused a significant decrease in vasospasm compared with controls, according to both angiographic (84.8 +/- 8.6 compared with 56.6 +/- 5.2%, respectively, p < 0.05) and histological studies (internal carotid artery 99.3 +/- 1.8 compared with 60.1 +/- 4.4%, respectively, p < 0.001; middle cerebral artery 98.4 +/- 3 compared with 56.1 +/- 3.7%, respectively, p < 0.001; and anterior cerebral artery 89.2 +/- 8.5 compared with 55.8 +/- 6.3%, respectively, p < 0.05).

CONCLUSIONS

The controlled release of DETA/NO is effective in preventing delayed cerebral vasospasm in an SAH model in nonhuman primates. The death of one animal in the treatment group indicates that the present dosage is at the threshold between therapeutic efficacy and toxicity.

Monoclonal antibody against E selectin attenuates subarachnoid hemorrhage–induced cerebral vasospasm

BACKGROUND

Increasing evidence indicates that inflammatory responses are implicated in the pathogenesis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). However, the role of adhesion molecules in SAH-induced vasospasm is less clear. This study was designed to examine the effect of a highly specific antibody, monoclonal anti-E-selectin antibody, on cerebral vasospasm in a new murine SAH model.

METHODS

Experimental SAH was induced in C57Black/6J mice by injecting autogenous blood into the cisterna magna, and anti-E-selectin antibody was administered intravenously immediately after SAH. All animals were killed by perfusion-fixation 24 hours after SAH. The diameters of anterior cerebral arteries (ACAs) were measured after arteries were cast with gelatin and india ink. Peripheral white blood cell count was also investigated.

RESULTS

The average diameters of ACA were reduced by 22% and 25% in the SAH only and SAH plus vehicle groups, respectively, when compared with the healthy control group. After treatment with 12.5, 4, and 1 microg of anti-E-selectin antibody in mice subject to SAH, the average diameter of ACA was decreased by 9%, 10%, and 22%, respectively, when compared with the healthy control group. The protective effects of anti-E-selectin antibody achieved statistical significance at doses of 12.5 and 4 microg. Animals in the SAH only and SAH plus vehicle groups exhibited leukopenia. Administration of 12.5, 4, and 1 microg of anti-E-selectin antibody reduced leukopenia, and the total white blood cell count obtained in animals treated with 12.5- and 4-microg doses were significantly higher as compared with SAH animals.

CONCLUSIONS

These findings provide the first evidence that anti-E-selectin antibody was effective in prevention of SAH-induced vasospasm and imply a possible role of E selectin in the pathogenesis of vasospasm after SAH.

Local Delivery of Ibuprofen via Controlled-release Polymers Prevents Angiographic Vasospasm in a Monkey Model of Subarachnoid Hemorrhage

OBJECTIVE:

Adhesion and migration of leukocytes into the periadventitial space play a role in the pathophysiology of vasospasm after subarachnoid hemorrhage (SAH). Intercellular adhesion molecule-1 is a determinant cell adhesion molecule involved in this process. Ibuprofen has been shown to inhibit intercellular adhesion molecule-1 upregulation and prevent vasospasm in animal models of SAH. In this study, we report the toxicity and efficacy of locally delivered ibuprofen incorporated into controlled-release polymers to prevent vasospasm in a monkey model of SAH.

METHODS:

Ibuprofen was incorporated into ethylene-vinyl acetate (EVAc) polymers at 45% loading (wt:wt). For the toxicity study, cynomolgus monkeys (n = 5) underwent surgical implantation of either blank/EVAc polymers (n = 3) or 45% ibuprofen/EVAc polymers (n = 2) in the subarachnoid space, were followed up for 13 weeks, and were killed for histopathological analysis. For the efficacy study, cynomolgus monkeys (n = 14) underwent cerebral angiography 7 days before and 7 days after surgery and SAH and were randomized to receive either a 45% ibuprofen/EVAc polymer (n = 7; mean dose of ibuprofen, 6 mg/kg) or blank EVAc polymers (n = 7) in the subarachnoid space. Angiographic vasospasm was determined by digital image analysis. Student's t test was used for analysis.

RESULTS:

Animals implanted with ibuprofen polymers showed no signs of local or systemic toxicity. Animals treated with ibuprofen polymers had 91 ± 9% lumen patency of the middle cerebral artery, compared with 53 ± 11% of animals treated with blank/EVAc polymers (P &lt; 0.001).

CONCLUSION:

Ibuprofen polymers are safe and prevent angiographic vasospasm after SAH in the monkey model. These findings support the role of cell adhesion molecules and inflammation in the pathophysiology of vasospasm.

Detection of soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in both cerebrospinal fluid and serum of patients after aneurysmal subarachnoid hemorrhage

OBJECT

The aim of this study was to explore whether levels of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are elevated in the cerebrospinal fluid (CSF) and serum of patients after aneurysmal subarachnoid hemorrhage (SAH).

METHODS

This prospective clinical study focused on 21 patients who had recently suffered an SAH due to aneurysmal rupture and 15 control patients with hydrocephalus who had no other central nervous system disease. Cerebrospinal fluid and serum samples obtained within the first 3 days and on the 5th and 7th days of SAH were assayed for ICAM-1 and VCAM-1 by using quantitative enzyme-linked immunosorbent assays. Levels of soluble forms of ICAM-1 (p = 0.00001) and VCAM-1 (p = 0.009) in the patients' CSF and those of ICAM-1 (p = 0.00001) and VCAM-1 (p = 0.00001) in their serum were found to be elevated after SAH compared with levels in the CSF and serum of control patients with hydrocephalus. In addition, when the authors compared the increased levels of adhesion molecules in the CSF and serum of patients after SAH, the only statistically insignificant difference that they found was between the levels of VCAM-1 in serum obtained on Days 5 and 7 after SAH (p = 0.27).

CONCLUSIONS

Adhesion molecules are a group of macromolecules that may participate in the inflammatory process, a common pathway leading to vasospasm after SAH. Leukocyte adherence to the vascular endothelium, which is induced by adhesion molecules, has been believed to be the initial signal of the development of vasospasm. The authors have demonstrated the synchronized elevation of two adhesion molecules in both CSF and serum following aneurysmal SAH. Blocking of ICAM-1 as well as VCAM-1 by monoclonal antibodies post-SAH may provide a beneficial effect on vasospasm.

Delayed Intracranial Delivery of a Nitric Oxide Donor from a Controlled-release Polymer Prevents Experimental Cerebral Vasospasm in Rabbits

OBJECTIVE

Decreased local availability of nitric oxide (NO) may mediate chronic vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Previous reports have shown that early treatment with NO prevents vasospasm in animals. We evaluated the efficacy of controlled-release polymers that contain the NO donor diethylenetriamine (DETA-NO) for the delayed treatment of vasospasm in a rabbit model of SAH.

METHODS

DETA-NO 20% (wt/wt) was incorporated into ethylene-vinyl acetate (EVAc) polymers. Animals (n = 52) were randomized to two experimental groups. In the first group (n = 32), animals received SAH and implantation of either 20% DETA-NO/EVAc polymer at a dose of 0.5 mg/kg of DETA-NO (n = 16) or empty EVAc polymer (n = 16). Polymers were implanted 24 (n = 16) or 48 hours (n = 16) after SAH. In the second group (n = 20), animals received SAH and implantation of either 20% DETA-NO/EVAc polymer at a dose of 1.3 mg/kg (n = 10) or empty EVAc (n = 10). Polymers were implanted 24 (n = 10) or 48 hours (n = 10) after SAH. An additional group (n = 16) underwent either sham operation (n = 6) or SAH only (n = 10). Animals were killed 3 days after hemorrhage, and the basilar arteries were processed for morphometric measurements. Results were analyzed using Student's t test.

RESULTS

Treatment with 20% DETA-NO/EVAc polymers at a dose of 1.3 mg/kg significantly increased basilar artery lumen patency when administered at 24 (97 +/- 6% versus 73 +/- 10%; P = 0.0396) or 48 hours (94 +/- 6% versus 71 +/- 9%; P = 0.03) after SAH. Treatment with 20% DETA-NO/EVAc polymers at a dose of 0.5 mg/kg administered 48 hours after SAH significantly increased lumen patency (82 +/- 8% versus 68 +/- 12%; P = 0.03); a dose of 0.5 mg/kg, 24 hours after SAH, did not reach statistical significance (74 +/- 7% versus 65 +/- 9%; P = 0.16). The SAH-only group had a lumen patency of 67 +/- 12%.

CONCLUSION

Delayed treatment of SAH with controlled-release DETA-NO polymers prevented experimental posthemorrhagic vasospasm in the rabbit. This inhibition was dose-dependent. This further confirms the role of NO in the pathogenesis of vasospasm.