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Diabetes increases the risk of poststroke cognitive impairment (PSCI). Greater hemorrhagic transformation (HT) after stroke is associated with vasoregression and cognitive decline in male diabetic rats. Iron chelator deferoxamine (DFX) prevents vasoregression and improves outcomes. Although diabetic female rats develop greater HT, its impact on poststroke cerebrovascularization and cognitive outcomes remained unknown. We hypothesized that diabetes mediates pathological neovascularization, and DFX attenuates poststroke cerebrovascular remodeling and improves neurological outcomes in female diabetic rats. Female control and diabetic animals were treated with DFX or vehicle for 7 days after stroke. Vascular indices, microglial activation, and blood-brain barrier (BBB) integrity were evaluated on day 14 . Results from diabetic female rats were partially compared with our previously published findings in male counterparts. Hemin-induced programmed cell death was studied in male and female brain microvascular endothelial cell lines (BMVEC). There was no vasoregression after stroke in either control or diabetic female animals. DFX prevented diabetes-mediated gliovascular remodeling and compromised BBB integrity while improving memory function in diabetes. Comparisons of female and male rats indicated sex differences in cognitive and vascular outcomes. Hemin mediated ferroptosis in both male and female BMVECs. DFX improved survival but had differential effects on ferroptosis signaling in female and male cells. These results suggest that stroke and associated HT do not affect cerebrovascularization in diabetic female rats, but iron chelation may provide a novel therapeutic strategy in the prevention of poststroke memory impairment in females with diabetes via the preservation of gliovascular integrity and improvement of endothelial cell survival. NEW & NOTEWORTHY The current study shows for the first time that diabetes does not promote aberrant cerebrovascularization in female rats. This contrasts with what we reported in male animals in various diabetes models. Deferoxamine preserved recognition memory function in diabetic female animals after stroke. The effect(s) of stroke and deferoxamine on cerebrovascular density and microglial activation also appear(s) to be different in female diabetic rats. Lastly, deferoxamine exerts detrimental effects on animals and BMVECs under control conditions.

We and others have previously shown that angiotensin II receptor type 2 receptor (AT2R) is upregulated in the contralesional hemisphere after stroke in normoglycemic Wistar rats. In this study, we examined the expression of AT2R in type 2 diabetic Goto-Kakizaki (GK) rats and control Wistars after stroke. We also tested the contribution of the contralesional AT2R in recovery after stroke through a specific knockdown of the AT2R in this hemisphere only. Two experiments were conducted. In the first experiment, GK rats were subjected to middle cerebral artery occlusion (MCAO) and treated with the angiotensin II receptor type 1 receptor (AT1R) blocker candesartan or saline at reperfusion. Stroke outcomes, as well as AT2R expression, were examined and compared to control Wistars at 24 h. In the second experiment, localized AT2R knockdown was achieved through intrastriatal injection of short hairpin RNA (shRNA) lentiviral particles or non-targeting control into the left-brain hemisphere of Wistar rats. After 14 days, rats were subjected to right MCAO and treated with the AT2R agonist, Compound 21 (C21), or saline for 7 days. Behavioral outcomes were assessed for up to 10 days. In the first experiment, stroke reduced the expression of AT2R in GK rats. Candesartan treatment failed to improve the neurobehavioral outcomes, preserve vascular integrity or reduce oxidative/nitrative stress or apoptotic markers at 24 h post stroke in these animals. In the second experiment, contralesional AT2R knockdown reduced the C21-mediated functional recovery after stroke. In conclusion, contralesional AT2R upregulation after stroke is blunted in diabetic rats which show reduced sensitivity to post-stroke candesartan treatment. Contralesional AT2R could be involved in C21-mediated functional recovery after stroke., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Angiotensin signaling is known to be sexually dimorphic. Although it is a well-studied target for intervention in stroke and cognitive impairment, female studies are rare. With females suffering a disproportionately greater negative impact of stroke and dementia vs. males, effective interventions are of utmost urgency. The aim of the current study was to determine the impact of activation of the angiotensin II type 2 receptor (AT2R) with the agonist compound 21 (C21) on the development of post-stroke cognitive impairment, after experimental ischemic stroke. Ovariectomized (OVX) spontaneously hypertensive rats (SHRs) were subjected to 1 h of middle cerebral artery occlusion (MCAO). At 24 h, rats with a significant neurologic deficit were randomized to receive either saline or C21 (0.03 mg/kg/day) intraperitoneally (IP) for 5 days, then orally (0.12 mg/kg/day) for a total of 6 weeks. Cognitive function, brain structure by MRI and vascular architecture by microCT angiography were measured. C21 preserved cognitive function, specifically spatial memory, and improved vascular density in the ischemic hemisphere at 6 weeks, reflecting both arteriogenesis and angiogenesis. In conclusion, C21 prevented cognitive impairment after stroke, likely through a mechanism involving vascular protection and restoration., (Copyright © 2021 Elsevier Inc. All rights reserved.)

It is a clinically well-established fact that patients with diabetes have very poor stroke outcomes. Yet, the underlying mechanisms remain largely unknown. Our previous studies showed that male diabetic animals show greater hemorrhagic transformation (HT), profound loss of cerebral vasculature in the recovery period, and poor sensorimotor and cognitive outcomes after ischemic stroke. This study aimed to determine the impact of iron chelation with deferoxamine (DFX) on (1) cerebral vascularization patterns and (2) functional outcomes after stroke in control and diabetic rats. After 8 weeks of type 2 diabetes induced by a combination of high-fat diet and low-dose streptozotocin, male control and diabetic animals were subjected to thromboembolic middle cerebral artery occlusion (MCAO) and randomized to vehicle, DFX, or tPA/DFX and followed for 14 days with behavioral tests. Vascular indices (vascular volume and surface area), neurovascular remodeling (AQP4 polarity), and microglia activation were measured. Brain microvascular endothelial cells (BMVEC) from control and diabetic animals were evaluated for the impact of DFX on ferroptotic cell death. DFX treatment prevented vasoregression and microglia activation while improving AQP4 polarity as well as blood-brain barrier permeability by day 14 in diabetic rats. These pathological changes were associated with improvement of functional outcomes. In control rats, DFX did not have an effect. Iron increased markers of ferroptosis and lipid reactive oxygen species (ROS) to a greater extent in BMVECs from diabetic animals, and this was prevented by DFX. These results strongly suggest that (1) HT impacts post-stroke vascularization patterns and recovery responses in diabetes, (2) treatment of bleeding with iron chelation has differential effects on outcomes in comorbid disease conditions, and (3) iron chelation and possibly inhibition of ferroptosis may provide a novel disease-modifying therapeutic strategy in the prevention of post-stroke cognitive impairment in diabetes.

About 70% of stroke victims present with comorbid diseases such as diabetes and hypertension. The integration of comorbidities in pre-clinical experimental design is important in understanding the mechanisms involved in the development of stroke injury and recovery. We recently showed that administration of compound C21, an angiotensin II type 2 receptor agonist, at day 3 post-stroke improved sensorimotor outcomes by lowering neuroinflammation in diabetic male animals. In the current study, we hypothesized that a delayed administration of C21 would also lower chronic inflammation post-stroke in diabetic female animals. Young female diabetic rats were subjected to 1 h of middle cerebral artery occlusion (MCAO). Three days post-stroke, rats were administered C21 or vehicle in drinking water at a dose of 0.12 mg/kg/day for 4 weeks. The impact of C21 on microglial polarization was analyzed by flow cytometry in vivo and in vitro. Compound 21 treatment improved fine motor skills after MCAO through modulation of the microglia/macrophage inflammatory properties. In addition, C21 increased M2 polarization and reduced the M1:M2 ratio in vitro. In conclusion, delayed administration of C21 downregulates post-stroke inflammation in female diabetic animals. C21 may be a useful therapeutic option to lower neuro-inflammation and improve the post-stroke recovery in diabetes.

A disabling consequence of stroke is cognitive impairment, occurring in 12%-48% of patients, for which there is no therapy. A critical barrier is the lack of understanding of how post-stroke cognitive impairment (PSCI) develops. While 70% of stroke victims present with comorbid diseases such as diabetes and hypertension, the limited use of comorbid disease models in preclinical research further contributes to this lack of progress. To this end, we used a translational model of diabetes to study the development of PSCI. In addition, we evaluated the application of compound 21 (C21), an angiotensin II Type 2 receptor agonist, for the treatment of PSCI by blinding the treatment assignment, setting strict inclusion criteria, and implementing a delayed administration time point. Diabetes was induced by a high-fat diet (HFD) and low-dose streptozotocin (STZ) combination. Control and diabetic rats were subjected to 1 h middle cerebral artery occlusion (MCAO) or sham surgery. Adhesive removal task (ART) and two-trial Y-maze were utilized to test sensorimotor and cognitive function. Three days post-stroke, rats that met the inclusion criteria were administered C21 or vehicle in drinking water at a dose of 0.12 mg/kg/day for 8 weeks. Samples from freshly harvested brains were analyzed by flow cytometry and immunohistochemistry (IHC). Diabetes exacerbated the development of PSCI and increased inflammation and demyelination. Delayed administration of C21 3 days post-stroke reduced mortality and improved sensorimotor and cognitive deficits. It also reduced inflammation and demyelination through modulation of the M1:M2 ratio in the diabetic animals.

Introduction: Unfortunately, over 40% of stroke victims have pre-existing diabetes which not only increases their risk of stroke up to 2-6 fold, but also worsens both functional recovery and the severity of cognitive impairment. Our lab has recently linked the chronic inflammation in diabetes to poor functional outcomes and exacerbated cognitive impairment, also known as post-stroke cognitive impairment (PSCI). Although we have shown that the development of PSCI in diabetes is associated with the upregulation and the activation of pro-inflammatory microglia, we have not established direct causation between the two. To this end, we evaluated the role of microglia in the development of PSCI., Methods: At 13 weeks of age, diabetic animals received bilateral intracerebroventricular (ICV) injections of short hairpin RNA (shRNA) lentiviral particles targeting the colony stimulating factor 1 receptor (CSF1R). After 14 days, animals were subjected to 60 min middle cerebral artery occlusion (MCAO) or sham surgery. Adhesive removal task (ART), novel object recognition (NOR), and 2-trial Y-maze were utilized to evaluate sensorimotor and cognitive function. Tissue from freshly harvested brains was analyzed by flow cytometry and immunohistochemistry., Results: CSF1R silencing resulted in a 94% knockdown of residential microglia to relieve inflammation and improve myelination of white matter in the brain. This prevented cognitive decline in diabetic animals., Conclusion: Microglial activation after stroke in diabetes may be causally related to the development of delayed neurodegeneration and PSCI.

Background: Understanding the metabolic response to exercise may aid in optimizing stroke management. Therefore, the purpose of this pilot study was to evaluate plasma metabolomic profiles in chronic stroke survivors following aerobic exercise training., Methods: Participants (age: 62 ± 1 years, body mass index: 31 ± 1 kg/m 2 , mean ± standard error of the mean) were randomized to 6 months of treadmill exercise (N = 17) or whole-body stretching (N = 8) with preintervention and postintervention measurement of aerobic capacity (VO 2 peak). Linear models for microarray data expression analysis was performed to determine metabolic changes over time, and Mummichog was used for pathway enrichment analysis following analysis of plasma samples by high-performance liquid chromatography coupled to ultrahigh resolution mass spectrometry., Results: VO 2 peak change was greater following exercise than stretching (18.9% versus -.2%; P < .01). Pathway enrichment analysis of differentially expressed metabolites results showed significant enrichment in 4 pathways following treadmill exercise, 3 of which (heparan-, chondroitin-, keratan-sulfate degradation) involved connective tissue metabolism and the fourth involve lipid signaling (linoleate metabolism). More pathways were altered in pre and post comparisons of stretching, including branched-chain amino acid, tryptophan, tyrosine, and urea cycle, which could indicate loss of lean body mass., Conclusions: These preliminary data show different metabolic changes due to treadmill training and stretching in chronic stroke survivors and suggest that in addition to improved aerobic capacity, weight-bearing activity, like walking, could protect against loss of lean body mass. Future studies are needed to examine the relationship between changes in metabolomic profiles to reductions in cardiometabolic risk after treadmill rehabilitation., (Published by Elsevier Inc.)

Neuroinflammation underlies the etiology of multiple neurodegenerative diseases and stroke. Our understanding of neuroinflammation has evolved in the last few years and major players have been identified. Microglia, the brain resident macrophages, are considered sentinels at the forefront of the neuroinflammatory response to different brain insults. Interestingly, microglia perform other physiological functions in addition to their role in neuroinflammation. Therefore, an updated approach in which modulation, rather than complete elimination of microglia is necessary. In this review, the emerging roles of microglia and their interaction with different components of the neurovascular unit are discussed. In addition, recent data on sex differences in microglial physiology and in the context of stroke will be presented. Finally, the multiplicity of roles assumed by microglia in the pathophysiology of ischemic stroke, and in the presence of co-morbidities such as hypertension and diabetes are summarized., (Published by Elsevier Ltd.)

Background: Optimal blood pressure (BP) levels during acute ischemic stroke have not been established. We studied associations between systolic BP trajectories during acute phase and subsequent clinical outcomes among patients with ischemic stroke., Methods: A total of 4,036 patients with acute ischemic stroke and elevated BP from the China Antihypertensive Trial in Acute Ischemic Stroke trial were included in this analysis. Three BPs were measured every 2 hours in day 1, every 4 hours during days 2 and 3, and every 8 hours thereafter until hospital discharge or death. Clinical outcomes were assessed at 3, 12, and 24 months. Latent variable mixture modeling was used to identify subgroups that share a similar underlying trajectory of systolic BP during the first 7 days after stroke onset. Logistic regression and Cox proportional hazards models were used to examine the associations between systolic BP trajectories and clinical outcomes during follow-up., Results: We identified 5 systolic BP trajectories of high, high-to-moderate-low, moderate-high, moderate-low, and low. Compared to participants in high trajectory, multiple-adjusted odds ratios (95% confidence interval) of all-cause mortality at 3 months for individuals in high-to-moderate-low, moderate-high, moderate-low, and low were 0.34 (0.15-0.77), 0.58 (0.32-1.04), 0.29 (0.15-0.56), and 0.56 (0.26-1.19), respectively. Likewise, the corresponding hazard ratios for all-cause mortality in 24 months were 0.66 (0.44-1.00), 0.74 (0.53-1.05), 0.45 (0.32-0.66), and 0.61 (0.40-0.93), respectively. Similar associations were observed for recurrent stroke and cardiovascular disease, and in both the intervention and control groups., Conclusions: Patients with moderate-low systolic BP during acute ischemic stroke had a lower risk of adverse clinical outcomes.

Post stroke cognitive impairment (PSCI) is an understudied, long-term complication of stroke, impacting nearly 30-40% of all stroke survivors. No cure is available once the cognitive deterioration manifests. To our knowledge, this is the first study to investigate the long-term effects of C21 treatment on the development of PSCI in aged animals. Treatments with C21 or vehicle were administered orally, 24 h post-stroke, and continued for 30 days. Outcome measures for sensorimotor and cognitive function were performed using a sequence of tests, all blindly conducted and assessed at baseline as well as at different time points post-stroke. Our findings demonstrate that the angiotensin receptor (AT2R) agonist C21 effectively prevents the development of PSCI in aged animals., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Angiotensin type 1 receptor blockers (ARBs) have been shown to be neuroprotective and neurorestorative in experimental stroke. The mechanisms proposed include anti-inflammatory, antiapoptotic effects, as well as stimulation of endogenous trophic factors leading to angiogenesis and neuroplasticity. We aimed to investigate the involvement of the neurotrophin, brain-derived neurotrophic factor (BDNF), in ARB-mediated functional recovery after stroke. To achieve this aim, Wistar rats received bilateral intracerebroventricular (ICV) injections of short hairpin RNA (shRNA) lentiviral particles or nontargeting control (NTC) vector, to knock down BDNF in both hemispheres. After 14 days, rats were subjected to 90-min middle cerebral artery occlusion (MCAO) and received the ARB, candesartan, 1 mg/kg, or saline IV at reperfusion (one dose), then followed for another 14 days using a battery of behavioral tests. BDNF protein expression was successfully reduced by about 70 % in both hemispheres at 14 days after bilateral shRNA lentiviral particle injection. The NTC group that received candesartan showed better functional outcome as well as increased vascular density and synaptogenesis as compared to saline treatment. BDNF knockdown abrogated the beneficial effects of candesartan on neurobehavioral outcome, vascular density, and synaptogenesis. In conclusion, BDNF is directly involved in candesartan-mediated functional recovery, angiogenesis, and synaptogenesis.

Background and Purpose: Acute hyperglycemia worsens the clinical outcomes and exacerbates cerebral hemorrhage after stroke. The mediators of hemorrhagic transformation (HT) in hyperglycemic stroke are not fully understood. Matrix metalloproteinase 3 (MMP3) plays a critical role in the tissue-type plasminogen activator-induced HT. However, the role of MMP3 in exacerbating the HT and worsening the functional outcomes in hyperglycemic stroke remains unknown., Methods: Control/normoglycemic and hyperglycemic (blood glucose, 140-200 mg/dL) male Wistar rats were subjected to middle cerebral artery occlusion for 90 minutes and either 24 hours or 7 days reperfusion. MMP3 was inhibited pharmacologically (UK 356618, 15 mg/kg IV at reperfusion) or knocked down in the brain by shRNA lentiviral particles (injected intracerebroventricular). Neurovascular injury was assessed at 24 hours, and functional outcomes were assessed at 24 hours, day 3, and day 7. MMP3 activity was measured in brain homogenate and cerebral macrovessels. Localization of MMP3 within the neurovascular unit after hyperglycemic stroke was demonstrated by immunohistochemistry., Results: Hyperglycemia significantly increased MMP3 activity in the brain after stroke, and this was associated with exacerbated HT and worsened functional outcomes. MMP3 inhibition significantly reduced HT and improved functional outcomes., Conclusions: MMP3 plays a critical role in mediating cerebrovascular injury in hyperglycemic stroke. Our findings point out MMP3 as a potential therapeutic target in hyperglycemic stroke., (© 2016 American Heart Association, Inc.)

As our knowledge expands, it is now clear that the renin-angiotensin (Ang) system (RAS) mediates functions other than regulating blood pressure (BP). The RAS plays a central role in the pathophysiology of different neurovascular unit disorders including stroke and retinopathy. Moreover, the beneficial actions of RAS modulation in brain and retina have been documented in experimental research, but not yet exploited clinically. The RAS is a complex system with distinct yet interconnected components. Understanding the different RAS components and their functions under brain and retinal pathological conditions is crucial to reap their benefits. The aim of the present review is to provide an experimental and clinical update on the role of RAS in the pathophysiology and treatment of stroke and retinopathy. Combining the evidence from both these disorders allows a unique opportunity to move both fields forward., (© 2016 Authors; published by Portland Press Limited.)

Diabetes impedes vascular repair and causes vasoregression in the brain after stroke, but mechanisms underlying this response are still unclear. We hypothesized that excess peroxynitrite formation in diabetic ischemia/reperfusion (I/R) injury inactivates the p85 subunit of phosphoinositide 3-kinase (PI3K) by nitration and diverts the PI3K-Akt survival signal to the p38-mitogen-activated protein kinase apoptosis pathway. Nitrotyrosine (NY), Akt and p38 activity, p85 nitration, and caspase-3 cleavage were measured in brains from control, diabetic (GK), or metformin-treated GK rats subjected to sham or stroke surgery and in brain microvascular endothelial cells (BMVECs) from Wistar and GK rats subjected to hypoxia/reoxygenation injury. GK rat brains showed increased NY, caspase-3 cleavage, and p38 activation and decreased Akt activation. Metformin attenuated stroke-induced nitrative signaling in GK rats. GK rat BMVECs showed increased basal nitrative stress compared with controls. A second hit by hypoxia/reoxygenation injury dramatically increased the nitration of p85 and activation of p38 but decreased Akt. These effects were associated with impairment of angiogenic response and were restored by treatment with the peroxynitrite scavenger 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron III chloride or the nitration inhibitor epicatechin. Our results provide evidence that I/R-induced peroxynitrite inhibits survival, induces apoptosis, and promotes peroxynitrite as a novel therapeutic target for the improvement of reparative angiogenesis after stroke in diabetes., (© 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

Admission hyperglycemia (HG) amplifies vascular injury and neurological deficits in acute ischemic stroke, but the mechanisms remain controversial. We recently reported that ischemia-reperfusion (I/R) injury impairs the myogenic response in both hemispheres via increased nitration. However, whether HG amplifies contralateral myogenic dysfunction and whether loss of tone in the contralateral hemisphere contributes to stroke outcomes remain to be determined. Our hypothesis was that contralateral myogenic dysfunction worsens stroke outcomes after acute hyperglycemic stroke in an oxidative stress-dependent manner. Male wild-type or SOD1 transgenic rats were injected with saline or 40% glucose solution 10 min before surgery and then subjected to 30 min of ischemia/45 min or 24 h of reperfusion. In another set of animals (n = 5), SOD1 was overexpressed only in the contralateral hemisphere by stereotaxic adenovirus injection 2-3 wk before I/R. Myogenic tone and neurovascular outcomes were determined. HG exacerbated myogenic dysfunction in contralateral side only, which was associated with infarct size expansion, increased edema, and more pronounced neurological deficit. Global and selective SOD1 overexpression restored myogenic reactivity in ipsilateral and contralateral sides, respectively, and enhanced neurovascular outcomes. In conclusion, our results show that SOD1 overexpression nullified the detrimental effects of HG on myogenic tone and stroke outcomes and that the contralateral hemisphere may be a novel target for the management of acute hyperglycemic stroke.

Introduction: Angiotensin II type 2 receptor (AT2R) stimulation is neuroprotective after experimental stroke. However, the therapeutic utility of AT2R stimulation has been hampered by the lack of a specific agonist with favourable bioavailability. Compound 21 (C21) - the first non-peptide AT2R agonist - offers a potential option to enhance stroke recovery. This study aimed to investigate the effect of C21 administration on early and late stroke outcomes, and the molecular mediators involved., Methods: Rats were subjected to 3 h or 90 min of middle cerebral artery occlusion (MCAO) and randomized to intraperitoneal C21 (0.03 mg/kg) or saline at reperfusion. Animals were sacrificed at 24 h or 7 days and brains were collected for molecular analysis and immunostaining, respectively. Functional outcome at days 1, 4 and 7 was assessed blindly. C21 angiogenic potential was assessed in vitro., Results: After 3 h of MCAO, C21 treatment reduced infarct size and improved behavioural outcome at 24 h without affecting blood pressure. Co-administration of the AT2R antagonist (PD123319) blocked these effects. On the molecular level, C21 decreased brain haemoglobin content, down-regulated apoptotic and oxidative markers, and increased pro-survival molecules in the brain. After 90 min of MCAO, C21 treatment resulted in sustained functional improvement at 7 days, together with increased vascular density in the ischemic penumbra. In vitro, C21 showed a pro-angiogenic effect that was blocked with brain-derived neurotrophic factor neutralization., Conclusion: These findings demonstrate that a single dose of C21 is neurovascular-protective and improves stroke outcome possibly through increasing neurotrophin activity, mitigating brain inflammation, and promoting antioxidant and pro-angiogenic effects.

Background and Purpose: Despite the availability of results from multiple newer clinical trials and changing healthcare costs, the cost-effectiveness of recombinant tissue-type plasminogen activator (r-tPA) for treatment of acute ischemic stroke within 0 to 3 hours of symptom onset was last evaluated in 1998 for the United States Using current evidence, we evaluate the long-term cost-effectiveness of r-tPA administered 0 to 3 hours after acute ischemic stroke onset versus no r-tPA., Methods: A disease-based decision model to project lifetime outcomes of patients after acute ischemic stroke by r-tPA treatment status from the US payer perspective was developed. Model inputs were derived from a recent meta-analysis of r-tPA trials, cohort studies, and health state preference studies. Cost data, inflated to 2013 dollars, were based on drug wholesale acquisition cost and the literature. To compare r-tPA to no r-tPA, we calculated incremental total direct costs, incremental quality-adjusted life years, and incremental cost-effectiveness ratios. We performed 1-way and probabilistic sensitivity analyses to evaluate uncertainty in the results., Results: r-tPA resulted in a gain of 0.39 quality-adjusted life years (95% confidence range, 0.16-0.66) on average per patient and a lifetime cost-saving of $25,000 (95% confidence range, -$42,500 to -$11,000) compared with no r-tPA. In probabilistic sensitivity analyses, r-tPA was dominant compared with no r-tPA in ≈100% of simulations. The model was sensitive to inputs for r-tPA efficacy, healthcare costs for disabled patients, mortality rates for disabled and nondisabled patients, and quality of life estimates., Conclusions: Our analysis supports earlier economic evaluations that r-tPA is a cost-effective method to treat stroke. Appropriate use of r-tPA should be prioritized nationally., (© 2014 American Heart Association, Inc.)

Neovascularization is an innate physiologic response by which tissues respond to various stimuli through collateral remodeling (arteriogenesis) and new vessel formation from existing vessels (angiogenesis) or from endothelial progenitor cells (vasculogenesis). Diabetes has a major impact on the neovascularization process but the response varies between different organ systems. While excessive angiogenesis complicates diabetic retinopathy, impaired neovascularization contributes to coronary and peripheral complications of diabetes. How diabetes influences cerebral neovascularization remained unresolved until recently. Diabetes is also a major risk factor for stroke and poor recovery after stroke. In this review, we discuss the impact of diabetes, stroke, and diabetic stroke on cerebral neovascularization, explore potential mechanisms involved in diabetes-mediated neovascularization as well as the effects of the diabetic milieu on poststroke neovascularization and recovery, and finally discuss the clinical implications of these effects.

Background and Purpose: Pre-existing diabetes mellitus worsens brain functionality in ischemic stroke. We have previously shown that type 2 diabetic rats exhibit enhanced dysfunctional cerebral neovascularization and when these rats are subjected to cerebral ischemic reperfusion injury develop hemorrhagic transformation and greater neurological deficits. However, our knowledge of vascular and functional plasticity during the recovery phase of diabetic stroke is limited. This study tested the hypothesis that vascular repair is impaired in the poststroke period in diabetes mellitus, and this is associated with poor sensorimotor and cognitive function. We further hypothesized that glycemic control prevents impaired vascularization and improves functional outcome in diabetes mellitus., Methods: Vascularization was assessed in the ipsilateral and contralateral hemispheres in control, diabetes mellitus and diabetes mellitus plus metformin groups 14 days after ischemic reperfusion injury, as well as in respective sham controls. Three-dimensional reconstruction of the fluorescein isothiocyanate (FITC)-stained vasculature was achieved by confocal microscopy, and stereological parameters, including vascular volume and surface area, were measured. Astrogliosis was determined by glial fibrillary acidic protein staining. The relative rates of sensorimotor recovery, cognitive decline, and spontaneous activity were assessed., Results: Vascular density in the peri-infarct area was significantly reduced in diabetes mellitus, whereas there was reparative neovascularization in control rats. Astroglial swelling and reactivity were more pronounced in diabetic stroke compared with control stroke. Diabetes mellitus blunted sensorimotor recovery and also exacerbated anxiety-like symptoms and cognitive deficits. Glycemic control started after stroke partially prevented these changes., Conclusions: Diabetes mellitus impairs poststroke reparative neovascularization and impedes the recovery. Glycemic control after stroke can improve neurovascular repair and improve functional outcome.

Hemorrhagic transformation (HT) is an important complication of ischemic stroke and is responsible for most of the mortality associated with acute reperfusion therapy. Although many important publications address the preclinical models of ischemic stroke, there are no current recommendations on the conduct of research aimed at understanding the mechanisms and consequences of HT. The purpose of this review is to present the various models used in HT research, the clinical correlates, and the experimental variables known to influence the quantitation of HT in preclinical investigation. Lastly, recommendations for the conduct of preclinical research in HT are provided.

Cerebrovascular complications make diabetic patients 2-6 times more susceptible to a stroke event and this risk is magnified in younger individuals and in patients with hypertension and complications in other vascular beds. In addition, when patients with diabetes and hyperglycemia experience an acute ischemic stroke they are more likely to die or be severely disabled and less likely to benefit from the one FDA-approved therapy, intravenous tissue plasminogen activator. Experimental stroke models have revealed that chronic hyperglycemia leads to deficits in cerebrovascular structure and function that may explain some of the clinical observations. Increased edema, neovascularization and protease expression as well as altered vascular reactivity and tone may be involved and point to potential therapeutic targets. Further study is needed to fully understand this complex disease state and the breadth of its manifestation in the cerebrovasculature.

Thrombolytic therapy with tissue plasminogen activator (tPA) remains the most effective treatment for acute ischemic stroke, but can cause vascular damage leading to edema formation and hemorrhagic transformation (HT). In this review, we discuss how tPA contributes to the pathogenesis of vascular damage and highlight evidence to support combination therapy of tPA with pharmacological agents that are vascular protective. There is an unmet need to develop therapeutic interventions which target the underlying mechanisms of vascular damage after acute ischemic stroke in order to prevent HT and improve the safety and impact of tPA.

Approximately 50% of patients hospitalized for stroke develop fever. In fact, experimental evidence suggests that high body temperature is significantly correlated to initial stroke severity, lesion size, mortality, and neurologic outcome. Fever occurring after stroke is associated with poor outcomes. We investigated the etiology of fever after stroke and present evidence evaluating the efficacy and safety of interventions used to treat stroke-associated fever. Oral antipyretics are only marginally effective in lowering elevated body temperature in this population and may have unintended adverse consequences. Nonpharmacologic approaches to cooling have been more effective in achieving normothermia, but whether stroke outcomes can be improved remains unclear. We recommend using body temperature as a biomarker and a catalyst for aggressive investigation for an infectious etiology. Care must be taken not to exceed the new standard of a maximum acetaminophen dose of 3 g/day to avoid patient harm.

We identified that the angiotensin receptor antagonist, candesartan, has profound neurovascular protective properties when administered after ischemic stroke and was associated with a proangiogenic state at least partly explained by vascular endothelial growth factor A (VEGFA). However, the spatial distribution of vascular endothelial growth factor (VEGF) isoforms and their receptors remained unknown. Protein analysis identified a significant increase in vascular endothelial grow factor B (VEGFB) in the cerebrospinal fluid (CSF) and the ischemic hemispheres (with increased VEGF receptor 1 activation) of treated animals (p<0.05) which was co-occurring with an increase in protein kinase B (Akt) phosphorylation (p<0.05). An increase in VEGFA protein in the contralesional hemisphere corresponded to a significant increase in vascular density at seven days (p<0.01) after stroke onset. Vascular restoration by candesartan after stroke maybe related to differential regional upregulation of VEGFB and VEGFA, promoting a "prosurvival state" in the ischemic hemisphere and angiogenesis in the contralesional side, respectively. These vascular changes in both hemispheres after effective treatment are likely to contribute to enhanced recovery after stroke.

The attempts to develop new treatments for acute ischemic stroke have been fraught with costly and spectacularly disappointing failures. Repurposing of safe, older drugs provides a lower risk alternative. Vascular protection is a novel strategy for improving stroke outcome. Promising targets for vascular protection after stroke have been identified, and several of these targets can be approached with "repurposed" old drugs, including statins, angiotensin receptor blockers (ARBs), and minocycline. We tested the vascular protection (ability to reduce hemorrhagic transformation) of three marketed drugs (candesartan, minocycline, and atorvastatin) in the experimental stroke model using three different rat strains [Wistar, spontaneously hypertensive rats (SHR) and type 2 diabetic Goto-Kakizaki (GK) rats]. All agents decreased the infarct size, improved the neurological outcome and decreased bleeding. Mechanisms identified include inhibition of MMP-9, activation of Akt, and increased expression of proangiogenic growth factors. Premorbid vascular damage (presence of either diabetes or hypertension) increased the likelihood of vascular injury after ischemia and reperfusion and improved the response to vascular protection.

The development of new treatments for acute stroke has been fraught with costly and spectacularly disappointing failures. Repurposing of safe, older drugs provides a lower risk alternative. Vascular protection with candesartan is one such approach.

Background and Purpose: New treatment strategies for acute ischemic stroke must be evaluated in the context of effective reperfusion. Minocycline is a neuroprotective agent that inhibits proteolytic enzymes and therefore could potentially both inactivate the clot lysis effect and decrease the damaging effects of tissue-type plasminogen activator (t-PA). This study aimed to determine the effect of minocycline on t-PA clot lysis and t-PA-induced hemorrhage formation after ischemia., Methods: Fibrinolytic and amidolytic activities of t-PA were investigated in vitro over a range of clinically relevant minocycline concentrations. A suture occlusion model of 3-hour temporary cerebral ischemia in rats treated with t-PA and 2 different minocycline regimens was used. Blood-brain barrier basal lamina components, matrix metalloproteinases (MMPs), hemorrhage formation, infarct size, edema, and behavior outcome were assessed., Results: Minocycline did not affect t-PA fibrinolysis. However, minocycline treatment at 3 mg/kg IV decreased total protein expression of both MMP-2 (P=0.0034) and MMP-9 (P=0.001 for 92 kDa and P=0.0084 for 87 kDa). It also decreased the incidence of hemorrhage (P=0.019), improved neurologic outcome (P=0.0001 for Bederson score and P=0.0391 for paw grasp test), and appeared to decrease mortality. MMP inhibition was associated with decreased degradation in collagen IV and laminin-alpha1 (P=0.0001)., Conclusions: Combination treatment with minocycline is beneficial in t-PA-treated animals and does not compromise clot lysis. These results also suggest that neurovascular protection by minocycline after stroke may involve direct protection of the blood-brain barrier during thrombolysis with t-PA.

Background and Purpose: We have shown that acute treatment with candesartan in an experimental model of stroke resulted in vascular protection and improved outcomes at 24 hours poststroke, but the mechanisms are unknown. We now examine effects of candesartan on proangiogenic factors and 7-day outcomes using the same treatment paradigm., Methods: Male Wistar rats underwent 3 hours of middle cerebral artery occlusion followed by reperfusion. A single dose of 1 mg/kg candesartan intravenously was given at reperfusion. Animals received neurobehavioral testing before middle cerebral artery occlusion, at 24 hours after middle cerebral artery occlusion, and at 7 days. Blood pressure was measured by telemetry. Animals euthanized at 24 hours had brain tissue and cerebrospinal fluid collected for matrix metalloproteinase activity, vascular endothelial growth factor expression, and tube formation assay. Neurobehavioral testing included elevated body swing test, Bederson, beam walk, and paw grasp. Cerebrovascular density was quantified using immunohistochemistry at 24 hours and 7 days., Results: Matrix metalloproteinase-2 activity and vascular endothelial growth factor expression were higher (P=0.035, P=0.042, respectively) and cerebrospinal fluid was significantly more proangiogenic (5x tube formation; P=0.002) in the candesartan group at 24 hours. Although no difference was seen in infarct size at 7 days, treatment improved Bederson scores (2.1 versus 2.9, P=0.0083), elevated body swing test (22.9 versus 39.4, P=0.021), and paw grasp (1.29 versus 2.88, P=0.0001) at 7 days. Candesartan treatment resulted in increased vascular density in the striatum at 7 days (P=0.037)., Conclusions: Candesartan after reperfusion augments ischemia-induced angiogenic state and provides long-term benefits. The beneficial effects may involve vascular protection and enhancement of early angiogenic remodeling.

Objective: To review symptom awareness, diagnostic techniques, and therapeutic interventions for the recognition and treatment of transient ischemic attack (TIA) and to discuss secondary stroke prevention after TIA., Data Sources: Published information related to recognition and treatment of TIA and the prevention of a secondary cerebrovascular event after TIA., Data Synthesis: Literature review reveals high risk for an early, secondary cerebrovascular event after TIA. Historically, TIA was not treated urgently; today, it is understood that TIA is a sign of a serious condition and may be an indication of impending disability and death. Prompt initiation of treatment may significantly reduce morbidity and mortality. However, many factors, such as low public awareness of symptoms, lack of urgency, or unavailability of brain imaging devices, are responsible for treatment delay. Delay between symptom onset and symptom diagnosis may preclude the use of tissue-plasminogen activator, which must be administered within a three-hour window from time of onset. Other therapeutic interventions for secondary stroke prevention after a TIA include the early use of antiplatelet agents (aspirin, clopidogrel, dipyridamole), and may involve procedures such as carotid endarterectomy and stenting. Risk reduction may also be achieved by treating hypertension and hypercholesterolemia., Conclusion: TIA and stroke must be recognized and treated urgently. Through public education, readily available information, access to diagnostic imaging devices, and aggressive preventive strategies and treatments, the frequency and severity of secondary cerebrovascular events, as well as the economic burden of secondary stroke, could be substantially reduced.