This Article Abstract Full Text (PDF) All Versions of this Article: 35/9/2220    most recent 01.STR.0000138023.60272.9ev1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fagan, S. C. Articles by Ergul, A. Search for Related Content PubMed PubMed Citation Articles by Fagan, S. C. Articles by Ergul, A. Related Collections Acute Cerebral Infarction Other Stroke Treatment - Medical Endothelium/vascular type/nitric oxide

(Stroke. 2004;35:2220.)
© 2004 American Heart Association, Inc.

Comments, Opinions, and Reviews

Targets for Vascular Protection After Acute Ischemic Stroke

Susan C. Fagan, PharmD; David C. Hess, MD; Elizabeth J. Hohnadel, MS; David M. Pollock, PhD Adviye Ergul, MD, PhD

From the Program in Clinical and Experimental Therapeutics (S.C.F., E.J.H., A.E.), College of Pharmacy, University of Georgia, Athens, Ga; the Department of Neurology (S.C.F., D.C.H.) and the Vascular Biology Center (D.M.P., A.E.), Medical College of Georgia, Augusta, Ga; and the Specialty Care Service Line, the Veterans Administration Medical Center (S.C.F., D.C.H.), Augusta, Ga.

Correspondence to Dr Susan C. Fagan, UGA Clinical Pharmacy, CJ-1020 Medical College of Georgia, 1120 15th St, Augusta, GA 30912-2450. E-mail sfagan{at}mail.mcg.edu

	Abstract

Top Abstract Introduction Vascular Protection Targets A Case for Intervention Conclusions References

 
Background— Vascular damage caused by cerebral ischemia leads to edema, hemorrhage formation, and worsened outcomes in ischemic stroke patients. Therapeutic interventions need to be developed to provide vascular protection. The purpose of this review is to identify the pathophysiologic processes involved in vascular damage after ischemia, which may lead to strategies to provide vascular protection in ischemic stroke patients.

Summary of Comment— The pathologic processes caused by vascular injury after an occlusion of a cerebral artery can be separated into acute (hours), subacute (hours to days), and chronic (days to months). Targets for intervention can be identified for all 3 stages. Acutely, superoxide is the predominant mediator, followed by inflammatory mediators and proteases subacutely. In the chronic phase, proapoptotic gene products have been implicated.

Conclusions— Pharmacological agents designed to target specific pathologic and protective processes affecting the vasculature should be used in clinical trials of vascular protection after acute ischemic stroke.

Key Words: cerebral ischemia, focal • clinical trials • free radicals • ischemia • pharmacology

	Introduction

Top Abstract Introduction Vascular Protection Targets A Case for Intervention Conclusions References

 
During focal cerebral ischemia, cerebral blood vessel damage occurs early and in a progressive fashion.¹ If prolonged, cerebral edema and hemorrhagic transformation will ensue. Reperfusion through damaged cerebral blood vessels is likely to further increase the ultimate tissue damage caused by ischemic stroke. There has been a recent call to develop means to protect the vasculature to improve stroke outcome.² Neuroprotection is a well-studied therapeutic intervention for acute stroke, with many targets identified.³ The purpose of this review is to identify targets on which to focus for development of vascular protection after acute ischemic stroke.

Chronic vascular protection has been approached traditionally through enhancement of endothelial function, prolongation of endothelial cell survival, and suppression of thrombosis and antiinflammatory effects within the vasculature.⁴ In practical terms, these mechanisms translate into a reduction in vascular events including myocardial infarction, stroke, and claudication.⁵ Of course, any strategy proven to reduce the incidence of fatal and nonfatal vascular events could be said to be "vascular protective," including antithrombotic and antihypertensive therapies, but historically, this moniker has been reserved for agents with direct beneficial effects on vascular endothelium, often beyond their primary pharmacological action.^5–10 The most prominent agents in this realm include the statins, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers. Whether vascular protection strategies will prove useful in the initial hours after stroke remains to be demonstrated.

	Vascular Protection Targets

Top Abstract Introduction Vascular Protection Targets A Case for Intervention Conclusions References

 
Vascular protection is defined as an augmentation of endothelial function to prevent vascular smooth muscle cell proliferation, inflammation, thrombosis, and endothelial apoptosis. Although vascular protection is a distinct entity from neuroprotection, endothelial dysfunction may impact the ultimate degree of tissue damage in acute ischemic stroke. Moreover, recent observations suggest that endothelium and blood vessels not only provide metabolic sustenance for tissues but inductive signals for organogenesis.^11,12 Therefore, mechanisms serving as targets for vascular protection should be evaluated in the context of ischemic stroke pathophysiology and can be separated into acute (hours), subacute (hours to days), and chronic (days to months) events, as depicted in Figure 1.

View larger version (47K): [in this window] [in a new window]   Time course of vascular damage after cerebral ischemia and reperfusion. In the acute phase, neutrophils adhere to the endothelium and, within hours, the BBB begins to leak. Mediators of vascular damage acutely include superoxide (O2–) and ET-1. Endogenously produced protectors of the vasculature acutely include NO, angiopoietin 1, and potentially VEGF. In the subacute phase (hours), frank edema occurs, and if the injury is of sufficient magnitude, hemorrhagic transformation (HT) can occur. Mediators of this damage include MMP-9, IL-1, and potentially MMP-2. Protectors in the subacute phase include VEGF, angiopoietin 2, and bFGF. Chronically, the proapoptotic gene products caspases, Bax, and Trp53 predominate, and the antiapoptotic proteins Bcl2 and lap are protective. In addition, VEGF may promote angiogenesis, and superoxide dismutases (SODs) may protect against further oxidative damage. Eventually, the injured blood vessel may either promote recovery by angiogenesis or underapoptosis or atherosclerosis, depending on its size and function. PMN indicates polymorphonuclear leukocyte; RBC, red blood cell.

Acute
Vascular pathophysiology in the acute phase involves hemodynamic and metabolic changes, resulting in disruption of the blood–brain barrier (BBB) and dysregulation of vascular tonus.¹³ The basal cerebrovascular tonus, also referred to as myogenic tone, favors partial vasoconstriction and plays an important role in regulation of cerebrovascular blood flow in response to changes in perfusion pressure as well as to alterations in metabolic and endothelial factors by adjusting vessel caliber.^14–16 Vascular smooth muscle and endothelium interactions contribute to the ability of the cerebrovasculature to respond to changes in perfusion pressure. Especially after ischemia, the function and integrity of cerebral arteries are critical to maintain cerebrovascular flow and tonus to minimize brain injury during reperfusion. Myogenic tone is diminished after 30 minutes of ischemia, and this impairment of the cerebrovasculature to maintain vascular tonus is associated with alterations in the actin cytoskeleton.^1,17–19 Interestingly, the thrombolytic agent tissue plasminogen activator, the only recommended treatment option to open an occluded artery, reduces reactivity of middle cerebral artery subjected to 2 hours of ischemia. Alterations in cerebrovascular resistance caused by impairment of vascular response may contribute to reperfusion injury and provide another explanation why use of thrombolytics more than 3 hours after the onset of stroke may increase the risk of bleeding.¹⁹

Several factors including oxygen radicals as well as vasoactive factors such as NO, endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), and angiopoietin I play important roles in regulation of vascular tone and structure in this acute phase of stroke.^13,20 Reperfusion after partial or complete cerebral ischemia results in excessive production of oxygen radicals, which involves formation of hydrogen peroxide, hydroxy radicals, and predominantly superoxide.^21,22 Superoxide generation peaks immediately after reperfusion and subsides during the next 2 hours.²³ Vascular effects of superoxide are alterations in vascular response to CO₂ and endothelium-dependent vasodilators such as acetylcholine, increased platelet aggregability, increased endothelial and BBB permeability, and disruption of endothelial cell membranes.²² Nelson et al demonstrated that vasodilatation occurs during the early phases of reperfusion and parallels the time course of superoxide production in their experimental model.²³ During this period, disruption of BBB permeability causes extravasation of albumin and other high-molecular weight compounds, which results in edema and increased intracranial pressure. In addition to its effects on BBB integrity and vascular tonus, superoxide anion reacts with NO to form peroxynitrite, which causes further tissue damage and is an important signaling mechanism that triggers inflammation and apoptosis in the subacute and chronic phases of ischemic stroke. A number of studies have reported that neutralizing free oxygen radicals by spin traps or scavenger enzymes such as superoxide dismutase or catalase prevents abnormal vasoreactivity as well as increased permeability of the BBB,^23–26 and have provided evidence that limiting oxidant stress in the acute phase of ischemic stroke is critical for improving outcome. Administration of antioxidants such as -lipoic acid and ginkgo biloba extract before induction of ischemia also provided neuroprotection and reduced infarct volume.²⁷ A recent study reported that in addition to its antithrombotic actions, aspirin provides neuroprotection via its antioxidant effects in brain tissue subjected to hypoxia.²⁸ However, the effect of antioxidants on cerebrovascular function and integrity and the potential therapeutic window in the setting of acute ischemia still remain unclear. Recent studies by Kontos et al demonstrated that glutamate, which accumulates in the extracellular space, stimulates superoxide production via activation of -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors.²² Thus, further studies evaluating blockade of AMPA receptors in prevention of excess superoxide production in the acute phase are needed.

There are a number of other vasoactive factors that affect endothelial function in the acute phase. For example, plasma and brain tissue levels of ET-1, a potent vasoconstrictor with mitogenic properties, are increased in patients with ischemic stroke as well as in animal models. In addition to its effects on vascular tonus, ET-1 increases BBB permeability.^29–31 Local application of ET-1 has been shown to induce neuronal damage.³⁰ A recent study by Matsuo et al demonstrated that administration of an endothelin type A receptor antagonist during reperfusion after transient middle cerebral artery occlusion significantly attenuated edema formation and mortality of animals after cerebral ischemia, providing evidence for the involvement of ET-1 in the pathophysiology of acute ischemic stroke.²⁹

Another important factor is VEGF, which is critical for angiogenesis and promotes endothelial integrity by stimulating NO production. However, VEGF increases BBB permeability in the acute phase after ischemic stroke.^32,33 Therefore, VEGF administration in this phase may worsen BBB leakage. Although VEGF-induced NO production may be considered a means of improving endothelial integrity after ischemia, as discussed above, NO reacts strongly with superoxide to generate peroxynitrite that causes tissue damage. A recent study demonstrated that NO generated by neuronal NO synthase (NOS) during ischemia may be detrimental in addition to endothelial NO produced at reperfusion, causing damage via peroxynitrite formation.³⁴

Angiopoietin-1 is another growth factor involved in angiogenesis and regulation of BBB stability.^35,36 Angiopoietin-1 levels decrease immediately after ischemia, and this coincides with increased BBB permeability. Therefore, it has been proposed to have a protective effect on BBB integrity.

The balance between mediators of vascular damage and substances that protect the endothelium will determine whether the vasculature progresses onto a state of angiogenesis. At least in temporary ischemia limited to the striatum (30 minutes in the mouse), vascular protective factors give way to angiogenic factors within hours of reperfusion onset.³⁷ In summary, vascular protection strategies in the acute phase should be based on approaches that prevent increased permeability of the BBB, including blocking superoxide formation as well as scavenging radicals that are produced during ischemia.

Subacute
Starting with the subacute phase and continuing in the chronic phase of ischemic stroke, gene activation plays an important role in the pathophysiology of vascular dysfunction. In the subacute phase, a number of proinflammatory genes, including interleukin-1ß (IL-1ß), tumor necrosis factor (TNF-), and transcription factors such as hypoxia-inducible factor 1, nuclear factor B, and interferon regulatory factor-1, are activated in response to the hypoxia, superoxide radical formation, and intracellular Ca²⁺ influx that occur during the acute phase.^38–41 These proinflammatory products influence expression of adhesion proteins that are critical for integrity of vascular endothelium. For example, intercellular adhesion molecule 1, P-selectins, and E-selectins are upregulated.^42–45 Blocking antibodies against these molecules have been shown to suppress complement activation, also implicated in furthering neurovascular injury after stroke.^46–50 Adhesion proteins interact with neutrophils, allowing them to penetrate into the vasculature and brain tissue. Recent studies demonstrated that within 2 to 24 hours of ischemia, matrix metalloproteinase (MMP)-2 and MMP-9, which cause pathological remodeling by degrading the basal lamina and disrupting the integrity of endothelium, are also upregulated.^51–56 Whether these proteins are stimulated by neutrophils or other proinflammatory gene products and to what extent they contribute to development of hemorrhagic complications of ischemia is still under investigation.

Inflammation could contribute to vascular injury by several mechanisms. First, increased leukocyte adhesion can cause microvascular obstruction, worsening ischemia.⁵⁷ Second, in addition to increased expression of proinflammatory genes as discussed above, inducible NOS is upregulated in infiltrating neutrophils, causing production of toxic amounts of NO.^58–60 Because inflammation is an important mechanism of vascular injury in the subacute phase with consequences such as endothelial cell death in the chronic phase, vascular protection strategies could be targeted to inhibition of neutrophil infiltration and toxic mediator production.

Gene activation involves not only expression of proteins that cause vascular injury but also induction of proteins that typically serve a protective function. Studies on regulation of VEGF, angiopoietin, and basic fibroblast growth factor (bFGF) systems demonstrated that these proteins and respective receptors are also activated within 2 to 4 hours of ischemia.^61–66 The roles of these proteins in vascular protection in acute ischemic stroke are not understood completely, but it is reasonable to speculate that these genes are activated as a feedback defense mechanism to restore endothelial function. The angiogenic properties of VEGF, angiopoietin 2, and FGF triggered studies evaluating potential use of these agents in therapeutic angiogenesis. A large number of studies provided evidence that VEGF induces re-endothelialization of blood vessels independent of its angiogenic effects, as discussed in detail in a recent review.⁴ In a model of neointimal hyperplasia where endothelium is intact, VEGF prevented intimal hyperplasia via an endothelial NOS–dependent mechanism.⁶⁷ Several studies demonstrated that VEGF-stimulated production of NO and prostaglandin I₂ by endothelial cells could exert antimitogenic effects as well as inhibit platelet aggregation and leukocyte adhesion to the endothelium via stimulation of cGMP and cAMP, respectively.^68–70 Although these past studies provided evidence that VEGF could play an important role in vascular protection, pleiotropic and potentially protective effects of VEGF on the vasculature in the ischemic stroke setting should be evaluated in further detail and may offer an important protective strategy in the subacute and chronic phase of ischemic stroke.

Chronic
The mechanism of vascular changes in the chronic phase of ischemic stroke involves induction of genes that participate in the regulation of apoptosis as well as stimulation of angiogenic factors in endothelial cells. Programmed cell death is triggered by activation of cell surface receptors via several factors, including TNF-, superoxide, and IL-1ß, all of which are stimulated in the acute phase of ischemic stroke. In response to these stimuli, a cascade of proteolytic enzymes known as caspases and other proteins such as B-cell lymphoma-leukemia 2 (Bcl2)-associated X protein (Bax) and transformation related protein 53 (Trp53) as well as antiapoptotic proteins including Bcl2 and inhibitor of apoptosis protein (Iap), are activated.^71–74 Therefore, inhibition of apoptotic gene expression and stimulation of antiapoptotic proteins may offer a vascular protection strategy. In addition to its angiogenic and antiproliferative effects as described above, VEGF also stimulates endothelial cell survival.^75–77 It has been demonstrated that VEGF induces the antiapoptotic pathway through phosphatidylinositol 3-kinase, resulting in inhibition of endothelial apoptosis. These findings suggest that VEGF may offer additional protection in the chronic phase of ischemic stroke.

	A Case for Intervention

Top Abstract Introduction Vascular Protection Targets A Case for Intervention Conclusions References

 
It is unclear whether protection of the vasculature during acute cerebral ischemia will result in improved outcomes in human stroke patients. Currently, the only effective strategy for improving clinical outcomes after ischemic stroke is reperfusion therapy with thrombolysis.^78–80 When an occluded artery is reopened, not only is the ischemic neuronal tissue spared, the vessel itself receives benefits associated with reperfusion. Neuroprotective strategies, although successful in experimental stroke models, have failed repeatedly to improve outcome in human stroke patients.³ Investigators have outlined a variety of reasons why all the clinical trials failed, but none include a role for vascular injury per se.^81,82 It is possible that neuroprotective therapies have failed in humans because the damaged vasculature is unable to supply the necessary nutrients to the jeopardized tissue, nor is it able to deliver the requisite concentration of neuroprotectant to the tissue at risk. This is particularly important because the 2 main consequences of ischemic vascular damage in the brain are hemorrhagic transformation and ischemic cerebral edema.

On the other hand, vascular protection may not be the optimal therapeutic target in the acute phases of ischemic stroke. Some investigators have argued that vessel breakdown is necessary for initiation of angiogenesis and the recovery process after ischemic damage.^37,83 Infiltration of circulating stem cells, which may release trophic factors necessary for neurogenesis, may depend on metalloproteinase activity to facilitate passage through the microvasculature.

	Conclusions

Top Abstract Introduction Vascular Protection Targets A Case for Intervention Conclusions References

 
Protection of the cerebral vasculature after ischemic stroke is a strategy that appears to be a logical approach to prevent edema and hemorrhage and enhance recovery. Enhancement of NO production and inhibition of VEGF, angiopoietin, angiotensin II, ET-1, the MMPs, and inflammatory mediators are all potential pharmacological targets for vascular protection. Although experimental evidence of the beneficial effects of vascular protection exists for both acute and chronic time points, only chronic vascular protection in human stroke patients has been proven as a therapeutic intervention. The optimal end points of clinical trials of vascular protection may include development of cerebral edema or hemorrhagic transformation along with overall neurologic function. Acute vascular protection needs to be explored in humans as a strategy to improve neurologic outcomes after an acute ischemic stroke.

	Acknowledgments

 
This work was supported by grants from the National Institute of Neurological Disorders and Stroke (1U01NS43127-01 and RO1NS044216-01) and the American Heart Association Southeast Affiliate (S.C.F.); the American Heart Association scientist development grant and American Diabetes Association (A.E.); and the Veterans Affairs Merit Review (D.C.H.). S.C.F. and D.C.H. received a research grant in the past from Johnson and Johnson, Inc.

Received March 29, 2004; revision received June 10, 2004; accepted June 15, 2004.

	References

Top Abstract Introduction Vascular Protection Targets A Case for Intervention Conclusions References

 
1. Cipolla MJ, McCall AL, Lessov N, Porter JM, Kontos H. Reperfusion decreases myogenic reactivity and alters middle cerebral artery function after focal cerebral ischemia in rats. Stroke. 1997; 28: 176–180.[Abstract/Free Full Text]

2. Faraci FM. Vascular protection. Stroke. 2003; 34: 327–329.[Free Full Text]

3. Kidwell CS, Liebeskind DS, Starkman S, Saver JL. Trends in acute ischemic stroke trials through the 20th century. Stroke. 2001; 32: 1349–1359.[Abstract/Free Full Text]

4. Zachary I, Mathur A, Yla-Herttuala S, Martin J. Vascular protection: a novel nonangiogenic cardiovascular role for vascular endothelial growth factor. Arterioscler Thromb Vasc Biol. 2000; 20: 1512–1520.[Abstract/Free Full Text]

5. Faggiotto A, Paoletti R. State-of-the-art lecture. Statins and blockers of the renin-angiotensin system: vascular protection beyond their primary mode of action. Hypertension. 1999; 34: 987–996.[Abstract/Free Full Text]

6. Shah PK, Kaul S, Nilsson J, Cercek B. Exploiting the vascular protective effects of high-density lipoprotein and its apolipoproteins: an idea whose time for testing is coming, part II. Circulation. 2001; 104: 2498–2502.[Free Full Text]

7. Schiffrin EL. Effects of antihypertensive drugs on vascular remodeling: do they predict outcome in response to antihypertensive therapy? Curr Opin Nephrol Hypertens. 2001; 10: 617–624.[CrossRef][Medline] [Order article via Infotrieve]

8. Tzemos N, Lim PO, MacDonald TM. Nebivolol reverses endothelial dysfunction in essential hypertension: a randomized, double-blind, crossover study. Circulation. 2001; 104: 511–514.[Abstract/Free Full Text]

9. Ferro A. Statins and vascular protection: a "radical" view. J Hypertens. 2002; 20: 359–361.[CrossRef][Medline] [Order article via Infotrieve]

10. Vaughan DE. AT(1) receptor blockade and atherosclerosis: hopeful insights into vascular protection. Circulation. 2000; 101: 1496–1497.[Free Full Text]

11. Lammert E, Cleaver O, Melton D. Induction of pancreatic differentiation by signals from blood vessels. Science. 2001; 294: 564–567.[Abstract/Free Full Text]

12. Matsumoto K, Yoshitomi H, Rossant J, Zaret KS. Liver organogenesis promoted by endothelial cells prior to vascular function. Science. 2001; 294: 559–563.[Abstract/Free Full Text]

13. Dirnagl U, Iadecola C, Moskowitz MA. Pathobiology of ischemic stroke: an integrated view. Trends Neurosci. 1999; 22: 391–397.[CrossRef][Medline] [Order article via Infotrieve]

14. Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990; 2: 161–192.[Medline] [Order article via Infotrieve]

15. Strandgaard S, Paulson OB. Pathophysiology of stroke. J Cardiovasc Pharmacol. 1990; 15 (suppl 1): S38–S42.[Medline] [Order article via Infotrieve]

16. Cipolla MJ, Curry AB. Middle cerebral artery function after stroke: the threshold duration of reperfusion for myogenic activity. Stroke. 2002; 33: 2094–2099.[Abstract/Free Full Text]

17. Cipolla MJ, Osol G, Kontos HA. Vascular smooth muscle actin cytoskeleton in cerebral artery forced dilatation. Stroke. 1998; 29: 1223–1228.[Abstract/Free Full Text]

18. Cipolla MJ, Lessov N, Hammer ES, Curry AB. Threshold duration of ischemia for myogenic tone in middle cerebral arteries: effect on vascular smooth muscle actin. Stroke. 2001; 32: 1658–1664.[Abstract/Free Full Text]

19. Cipolla MJ, Lessov N, Clark WM, Haley EC Jr. Postischemic attenuation of cerebral artery reactivity is increased in the presence of tissue plasminogen activator. Stroke. 2000; 31: 940–945.[Abstract/Free Full Text]

20. Lipton P. Ischemic cell death in brain neurons. Physiol Rev. 1999; 79: 1431–1568.[Abstract/Free Full Text]

21. Kontos CD, Wei EP, Williams JI, Kontos HA, Povlishock JT. Cytochemical detection of superoxide in cerebral inflammation and ischemia in vivo. Am J Physiol. 1992; 263: H1234–H1242.[Medline] [Order article via Infotrieve]

22. Kontos HA. Oxygen radicals in cerebral ischemia: the 2001 Willis Lecture. Stroke. 2001; 32: 2712–2716.[Abstract/Free Full Text]

23. Nelson CW, Wei EP, Povlishock JT, Kontos HA, Moskowitz MA. Oxygen radicals in cerebral ischemia. Am J Physiol. 1992; 263: H1356–H1362.[Medline] [Order article via Infotrieve]

24. Weisbrot-Lefkowitz M, Reuhl K, Perry B, Chan PH, Inouye M, Mirochnitchenko O. Overexpression of human glutathione peroxidase protects transgenic mice against focal cerebral ischemia/reperfusion damage. Brain Res Mol Brain Res. 1998; 53: 333–338.[Medline] [Order article via Infotrieve]

25. Zhao Q, Pahlmark K, Smith ML, Siesjo BK. Delayed treatment with the spin trap alpha-phenyl-N-tert-butyl nitrone (PBN) reduces infarct size following transient middle cerebral artery occlusion in rats. Acta Physiol Scand. 1994; 152: 349–350.[Medline] [Order article via Infotrieve]

26. Murakami K, Kondo T, Kawase M, Li Y, Sato S, Chen SF, Chan PH. Mitochondrial susceptibility to oxidative stress exacerbates cerebral infarction that follows permanent focal cerebral ischemia in mutant mice with manganese superoxide dismutase deficiency. J Neurosci. 1998; 18: 205–213.[Abstract/Free Full Text]

27. Clark WM, Rinker LG, Lessov NS, Lowery SL, Cipolla MJ. Efficacy of antioxidant therapies in transient focal ischemia in mice. Stroke. 2001; 32: 1000–1004.[Abstract/Free Full Text]

28. De La Cruz JP, Guerrero A, Gonzalez-Correa JA, Arrebola MM, de la Cuesta SF. Antioxidant effect of acetylsalicylic and salicylic acid in rat brain slices subjected to hypoxia. J Neurosci Res. 2004; 75: 280–290.[CrossRef][Medline] [Order article via Infotrieve]

29. Matsuo Y, Mihara S, Ninomiya M, Fujimoto M. Protective effect of endothelin type A receptor antagonist on brain edema and injury after transient middle cerebral artery occlusion in rats. Stroke. 2001; 32: 2143–2148.[Abstract/Free Full Text]

30. Macrae IM, Robinson MJ, Graham DI, Reid JL, McCulloch J. Endothelin-1-induced reductions in cerebral blood flow: dose dependency, time course, and neuropathological consequences. J Cereb Blood Flow Metab. 1993; 13: 276–284.[Medline] [Order article via Infotrieve]

31. Stanimirovic DB, Bertrand N, McCarron R, Uematsu S, Spatz M. Arachidonic acid release and permeability changes induced by endothelins in human cerebromicrovascular endothelium. Acta Neurochir Suppl (Wien). 1994; 60: 71–75.[Medline] [Order article via Infotrieve]

32. Zhang Z, Chopp M. Vascular endothelial growth factor and angiopoietins in focal cerebral ischemia. Trends Cardiovasc Med. 2002; 12: 62–66.[CrossRef][Medline] [Order article via Infotrieve]

33. Yancopoulos GD, Davis S, Gale NW, Rudge JS, Wiegand SJ, Holash J. Vascular-specific growth factors and blood vessel formation. Nature. 2000; 407: 242–248.[CrossRef][Medline] [Order article via Infotrieve]

34. Gursoy-Ozdemir Y, Bolay H, Saribas O, Dalkara T. Role of endothelial nitric oxide generation and peroxynitrite formation in reperfusion injury after focal cerebral ischemia. Stroke. 2000; 31: 1974–1980.[Abstract/Free Full Text]

35. Zhang ZG, Zhang L, Croll SD, Chopp M. Angiopoietin-1 reduces cerebral blood vessel leakage and ischemic lesion volume after focal cerebral embolic ischemia in mice. Neuroscience. 2002; 113: 683–687.[CrossRef][Medline] [Order article via Infotrieve]

36. Thurston G, Rudge JS, Ioffe E, Zhou H, Ross L, Croll SD, Glazer N, Holash J, McDonald DM, Yancopoulos GD. Angiopoietin-1 protects the adult vasculature against plasma leakage. Nat Med. 2000; 6: 460–463.[CrossRef][Medline] [Order article via Infotrieve]

37. Hayashi T, Noshita N, Sugawara T, Chan PH. Temporal profile of angiogenesis and expression of related genes in the brain after ischemia. J Cereb Blood Flow Metab. 2003; 23: 166–180.[CrossRef][Medline] [Order article via Infotrieve]

38. Rothwell NJ, Hopkins SJ. Cytokines and the nervous system II: actions and mechanisms of action. Trends Neurosci. 1995; 18: 130–136.[CrossRef][Medline] [Order article via Infotrieve]

39. Nawashiro H, Tasaki K, Ruetzler CA, Hallenbeck JM. TNF-alpha pretreatment induces protective effects against focal cerebral ischemia in mice. J Cereb Blood Flow Metab. 1997; 17: 483–490.[CrossRef][Medline] [Order article via Infotrieve]

40. Sairanen T, Carpen O, Karjalainen-Lindsberg ML, Paetau A, Turpeinen U, Kaste M, Lindsberg PJ. Evolution of cerebral tumor necrosis factor-alpha production during human ischemic stroke. Stroke. 2001; 32: 1750–1758.[Abstract/Free Full Text]

41. Vila N, Castillo J, Davalos A, Chamorro A. Proinflammatory cytokines and early neurological worsening in ischemic stroke. Stroke. 2000; 31: 2325–2329.[Abstract/Free Full Text]

42. Lindsberg PJ, Hallenbeck JM, Feuerstein G. Platelet-activating factor in stroke and brain injury. Ann Neurol. 1991; 30: 117–129.[CrossRef][Medline] [Order article via Infotrieve]

43. Gong C, Qin Z, Betz AL, Liu XH, Yang GY. Cellular localization of tumor necrosis factor alpha following focal cerebral ischemia in mice. Brain Res. 1998; 801: 1–8.[CrossRef][Medline] [Order article via Infotrieve]

44. Tilton RG, Berens KL. Functional role for selectins in the pathogenesis of cerebral ischemia. Drug News Perspect. 2002; 15: 351–357.[CrossRef][Medline] [Order article via Infotrieve]

45. Hess DC, Howard E, Cheng C, Carroll J, Hill WD, Hsu CY. Hypertonic mannitol loading of NF-B transcription factor decoys in human brain microvascular endothelial cells blocks upregulation of ICAM-1 editorial comment. Stroke. 2000; 31: 1179–1186.[Abstract/Free Full Text]

46. Mocco J, Choudhri T, Huang J, Harfeldt E, Efros L, Klingbeil C, Vexler V, Hall W, Zhang Y, Mack W, Popilskis S, Pinsky DJ, Connolly ES Jr. HuEP5C7 as a humanized monoclonal anti-E/P-selectin neurovascular protective strategy in a blinded placebo-controlled trial of nonhuman primate stroke. Circ Res. 2002; 91: 907–914.[Abstract/Free Full Text]

47. D’Ambrosio AL, Pinsky DJ, Connolly ES. The role of the complement cascade in ischemia/reperfusion injury: implications for neuroprotection. Mol Med. 2001; 7: 367–382.[Medline] [Order article via Infotrieve]

48. Di Napoli M. Systemic complement activation in ischemic stroke. Stroke. 2001; 32: 1443–1448.[Free Full Text]

49. Huang J, Kim LJ, Mealey R, Marsh HC Jr, Zhang Y, Tenner AJ, Connolly ES Jr, Pinsky DJ. Neuronal protection in stroke by an sLex-glycosylated complement inhibitory protein. Science. 1999; 285: 595–599.[Abstract/Free Full Text]

50. del Zoppo GJ. In stroke, complement will get you nowhere. Nat Med. 1999; 5: 995–996.[CrossRef][Medline] [Order article via Infotrieve]

51. Rosenberg GA, Kornfeld M, Estrada E, Kelley RO, Liotta LA, Stetler-Stevenson WG. TIMP-2 reduces proteolytic opening of blood-brain barrier by type IV collagenase. Brain Res. 1992; 576: 203–207.[CrossRef][Medline] [Order article via Infotrieve]

52. Rosenberg GA, Estrada EY, Dencoff JE. Matrix metalloproteinases and TIMPs are associated with blood-brain barrier opening after reperfusion in rat brain. Stroke. 1998; 29: 2189–2195.[Abstract/Free Full Text]

53. Rosenberg GA, Cunningham LA, Wallace J, Alexander S, Estrada EY, Grossetete M, Razhagi A, Miller K, Gearing A. Immunohistochemistry of matrix metalloproteinases in reperfusion injury to rat brain: activation of MMP-9 linked to stromelysin-1 and microglia in cell cultures. Brain Res. 2001; 893: 104–112.[CrossRef][Medline] [Order article via Infotrieve]

54. Heo JH, Lucero J, Abumiya T, Koziol JA, Copeland BR, del Zoppo GJ. Matrix metalloproteinases increase very early during experimental focal cerebral ischemia. J Cereb Blood Flow Metab. 1999; 19: 624–633.[CrossRef][Medline] [Order article via Infotrieve]

55. Asahi M, Asahi K, Jung JC, del Zoppo GJ, Fini ME, Lo EH. Role for matrix metalloproteinase 9 after focal cerebral ischemia: effects of gene knockout and enzyme inhibition with BB-94. J Cereb Blood Flow Metab. 2000; 20: 1681–1689.[CrossRef][Medline] [Order article via Infotrieve]

56. Chang DI, Hosomi N, Lucero J, Heo JH, Abumiya T, Mazar AP, del Zoppo GJ. Activation systems for latent matrix metalloproteinase-2 are upregulated immediately after focal cerebral ischemia. J Cereb Blood Flow Metab. 2003; 23: 1408–1419.[CrossRef][Medline] [Order article via Infotrieve]

57. del Zoppo GJ, Schmid-Schonbein GW, Mori E, Copeland BR, Chang CM. Polymorphonuclear leukocytes occlude capillaries following middle cerebral artery occlusion and reperfusion in baboons. Stroke. 1991; 22: 1276–1283.[Abstract/Free Full Text]

58. Iadecola C. Bright and dark sides of nitric oxide in ischemic brain injury. Trends Neurosci. 1997; 20: 132–139.[CrossRef][Medline] [Order article via Infotrieve]

59. Lerouet D, Beray-Berthat V, Palmier B, Plotkine M, Margaill I. Changes in oxidative stress, iNOS activity and neutrophil infiltration in severe transient focal cerebral ischemia in rats. Brain Res. 2002; 958: 166–175.[CrossRef][Medline] [Order article via Infotrieve]

60. Zhu DY, Deng Q, Yao HH, Wang DC, Deng Y, Liu GQ. Inducible nitric oxide synthase expression in the ischemic core and penumbra after transient focal cerebral ischemia in mice. Life Sci. 2002; 71: 1985–1996.[CrossRef][Medline] [Order article via Infotrieve]

61. Croll SD, Wiegand SJ. Vascular growth factors in cerebral ischemia. Mol Neurobiol. 2001; 23: 121–135.[CrossRef][Medline] [Order article via Infotrieve]

62. Plate KH, Beck H, Danner S, Allegrini PR, Wiessner C. Cell type specific upregulation of vascular endothelial growth factor in an MCA-occlusion model of cerebral infarct. J Neuropathol Exp Neurol. 1999; 58: 654–666.[Medline] [Order article via Infotrieve]

63. Huang Z, Chen K, Huang PL, Finklestein SP, Moskowitz MA. bFGF ameliorates focal ischemic injury by blood flow-independent mechanisms in eNOS mutant mice. Am J Physiol. 1997; 272: H1401–H1405.[Medline] [Order article via Infotrieve]

64. Ay H, Ay I, Koroshetz WJ, Finklestein SP. Potential usefulness of basic fibroblast growth factor as a treatment for stroke. Cerebrovasc Dis. 1999; 9: 131–135.[CrossRef][Medline] [Order article via Infotrieve]

65. Beck H, Acker T, Wiessner C, Allegrini PR, Plate KH. Expression of angiopoietin-1, angiopoietin-2, and tie receptors after middle cerebral artery occlusion in the rat. Am J Pathol. 2000; 157: 1473–1483.[Abstract/Free Full Text]

66. Lin TN, Wang CK, Cheung WM, Hsu CY. Induction of angiopoietin and tie receptor mRNA expression after cerebral ischemia-reperfusion. J Cereb Blood Flow Metab. 2000; 20: 387–395.[CrossRef][Medline] [Order article via Infotrieve]

67. Laitinen M, Zachary I, Breier G, Pakkanen T, Hakkinen T, Luoma J, Abedi H, Risau W, Soma M, Laakso M, Martin JF, Yla-Herttuala S. VEGF gene transfer reduces intimal thickening via increased production of nitric oxide in carotid arteries. Hum Gene Ther. 1997; 8: 1737–1744.[Medline] [Order article via Infotrieve]

68. Servos S, Zachary I, Martin JF. VEGF modulates NO production: the basis of a cytoprotective effect? Cardiovasc Res. 1999; 41: 509–510.[Free Full Text]

69. Tsurumi Y, Murohara T, Krasinski K, Chen D, Witzenbichler B, Kearney M, Couffinhal T, Isner JM. Reciprocal relation between VEGF and NO in the regulation of endothelial integrity. Nat Med. 1997; 3: 879–886.[CrossRef][Medline] [Order article via Infotrieve]

70. Wheeler-Jones C, Abu-Ghazaleh R, Cospedal R, Houliston RA, Martin J, Zachary I. Vascular endothelial growth factor stimulates prostacyclin production and activation of cytosolic phospholipase A2 in endothelial cells via p42/p44 mitogen-activated protein kinase. FEBS Lett. 1997; 420: 28–32.[CrossRef][Medline] [Order article via Infotrieve]

71. Chen J, Zhu RL, Nakayama M, Kawaguchi K, Jin K, Stetler RA, Simon RP, Graham SH. Expression of the apoptosis-effector gene, Bax, is upregulated in vulnerable hippocampal CA1 neurons following global ischemia. J Neurochem. 1996; 67: 64–71.[Medline] [Order article via Infotrieve]

72. Hara A, Iwai T, Niwa M, Uematsu T, Yoshimi N, Tanaka T, Mori H. Immunohistochemical detection of Bax and Bcl-2 proteins in gerbil hippocampus following transient forebrain ischemia. Brain Res. 1996; 711: 249–253.[CrossRef][Medline] [Order article via Infotrieve]

73. Sairanen TR, Lindsberg PJ, Brenner M, Siren AL. Global forebrain ischemia results in differential cellular expression of interleukin-1beta (IL-1beta) and its receptor at mRNA and protein level. J Cereb Blood Flow Metab. 1997; 17: 1107–1120.[CrossRef][Medline] [Order article via Infotrieve]

74. Saito T, Nagao T, Okabe M, Saito K. Neurochemical and histochemical evidence for an abnormal catecholamine metabolism in the cerebral cortex of the Long-Evans cinnamon rat before excessive copper accumulation in the brain. Neurosci Lett. 1996; 216: 195–198.[Medline] [Order article via Infotrieve]

75. Abid MR, Guo S, Minami T, Spokes KC, Ueki K, Skurk C, Walsh K, Aird WC. Vascular endothelial growth factor activates PI3K/Akt/Forkhead signaling in endothelial cells. Arterioscler Thromb Vasc Biol. 2004; 24: 294–300.[Abstract/Free Full Text]

76. Zachary I. VEGF signaling: integration and multi-tasking in endothelial cell biology. Biochem Soc Trans. 2003; 31: 1171–1177.[Medline] [Order article via Infotrieve]

77. Cai J, Ahmad S, Jiang WG, Huang J, Kontos CD, Boulton M, Ahmed A. Activation of vascular endothelial growth factor receptor-1 sustains angiogenesis and Bcl-2 expression via the phosphatidylinositol 3-kinase pathway in endothelial cells. Diabetes. 2003; 52: 2959–2968.[Abstract/Free Full Text]

78. The National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med. 1995; 333: 1581–1587.[Abstract/Free Full Text]

79. del Zoppo GJ, Higashida RT, Furlan AJ, Pessin MS, Rowley HA, Gent M. PROACT: a phase II randomized trial of recombinant pro-urokinase by direct arterial delivery in acute middle cerebral artery stroke. Stroke. 1998; 29: 4–11.[Abstract/Free Full Text]

80. Sherman DG, Atkinson RP, Chippendale T, Levin KA, Ng K, Futrell N, Hsu CY, Levy DE. Intravenous ancrod for treatment of acute ischemic stroke: the STAT Study: a randomized controlled trial. Stroke Treatment with Ancrod Trial. JAMA. 2000; 283: 2395–2403.[Abstract/Free Full Text]

81. Gladstone DJ, Black SE, Hakim AM. Toward wisdom from failure: lessons from neuroprotective stroke trials and new therapeutic directions. Stroke. 2002; 33: 2123–2136.[Abstract/Free Full Text]

82. Jonas S, Aiyagari V, Vieira D, Figueroa M. The failure of neuronal protective agents versus the success of thrombolysis in the treatment of ischemic stroke. The predictive value of animal models. Ann N Y Acad Sci. 2001; 939: 257–267.[Medline] [Order article via Infotrieve]

83. George SJ. Therapeutic potential of matrix metalloproteinase inhibitors in atherosclerosis. Expert Opin Investig Drugs. 2000; 9: 993–1007.[CrossRef][Medline] [Order article via Infotrieve]

This article has been cited by other articles:

				B. K. Wacker, T. S. Park, and J. M. Gidday Hypoxic Preconditioning-Induced Cerebral Ischemic Tolerance: Role of Microvascular Sphingosine Kinase 2 Stroke, October 1, 2009; 40(10): 3342 - 3348. [Abstract] [Full Text] [PDF]

				H. F. Elewa, A. Kozak, A. B. El-Remessy, R. F. Frye, M. H. Johnson, A. Ergul, and S. C. Fagan Early Atorvastatin Reduces Hemorrhage after Acute Cerebral Ischemia in Diabetic Rats J. Pharmacol. Exp. Ther., August 1, 2009; 330(2): 532 - 540. [Abstract] [Full Text] [PDF]

				G. Jin, K. Arai, Y. Murata, S. Wang, M. F. Stins, E. H. Lo, and K. van Leyen Protecting Against Cerebrovascular Injury: Contributions of 12/15-Lipoxygenase to Edema Formation After Transient Focal Ischemia Stroke, September 1, 2008; 39(9): 2538 - 2543. [Abstract] [Full Text] [PDF]

				H.-C. Diener, D. Schneider, Y. Lampl, N. M. Bornstein, A. Kozak, G. Rosenberg, and on Behalf of the Study Group DP-b99, a Membrane-Activated Metal Ion Chelator, as Neuroprotective Therapy in Ischemic Stroke Stroke, June 1, 2008; 39(6): 1774 - 1778. [Abstract] [Full Text] [PDF]

				X. Wang, W. H. Baldridge, and B. C. Chauhan Acute Endothelin-1 Application Induces Reversible Fast Axonal Transport Blockade in Adult Rat Optic Nerve Invest. Ophthalmol. Vis. Sci., March 1, 2008; 49(3): 961 - 967. [Abstract] [Full Text] [PDF]

				S. H. Jia, J. Parodo, A. Kapus, O. D. Rotstein, and J. C. Marshall Dynamic Regulation of Neutrophil Survival through Tyrosine Phosphorylation or Dephosphorylation of Caspase-8 J. Biol. Chem., February 29, 2008; 283(9): 5402 - 5413. [Abstract] [Full Text] [PDF]

				T. N. Nagaraja, K. Karki, J. R. Ewing, R. L. Croxen, and R. A. Knight Identification of Variations in Blood-Brain Barrier Opening After Cerebral Ischemia by Dual Contrast-Enhanced Magnetic Resonance Imaging and T1sat Measurements Stroke, February 1, 2008; 39(2): 427 - 432. [Abstract] [Full Text] [PDF]

				H. Taniguchi, I. Mohri, H. Okabe-Arahori, K. Aritake, K. Wada, T. Kanekiyo, S. Narumiya, M. Nakayama, K. Ozono, Y. Urade, et al. Prostaglandin D2 Protects Neonatal Mouse Brain from Hypoxic Ischemic Injury J. Neurosci., April 18, 2007; 27(16): 4303 - 4312. [Abstract] [Full Text] [PDF]

				D. C. Hess NXY-059: A Hopeful Sign in the Treatment of Stroke Stroke, October 1, 2006; 37(10): 2649 - 2650. [Full Text] [PDF]

				N. P.J. Brindle, P. Saharinen, and K. Alitalo Signaling and Functions of Angiopoietin-1 in Vascular Protection Circ. Res., April 28, 2006; 98(8): 1014 - 1023. [Abstract] [Full Text] [PDF]

				M. J. Maneen, R. Hannah, L. Vitullo, N. DeLance, and M. J. Cipolla Peroxynitrite Diminishes Myogenic Activity and Is Associated With Decreased Vascular Smooth Muscle F-Actin in Rat Posterior Cerebral Arteries Stroke, March 1, 2006; 37(3): 894 - 899. [Abstract] [Full Text] [PDF]

				B. Ovbiagele, C. S. Kidwell, S. Starkman, S. L. Selco, V. Rajajee, T. Razinia, and J. L. Saver Angiotensin 2 type 2 receptor activity and ischemic stroke severity Neurology, September 27, 2005; 65(6): 851 - 854. [Abstract] [Full Text] [PDF]

				L. Belayev, I. Saul, R. Busto, K. Danielyan, A. Vigdorchik, L. Khoutorova, and M. D. Ginsberg Albumin Treatment Reduces Neurological Deficit and Protects Blood-Brain Barrier Integrity After Acute Intracortical Hematoma in the Rat Stroke, February 1, 2005; 36(2): 326 - 331. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) All Versions of this Article: 35/9/2220    most recent 01.STR.0000138023.60272.9ev1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fagan, S. C. Articles by Ergul, A. Search for Related Content PubMed PubMed Citation Articles by Fagan, S. C. Articles by Ergul, A. Related Collections Acute Cerebral Infarction Other Stroke Treatment - Medical Endothelium/vascular type/nitric oxide