Restoration Of Cerebral Blood Flow Research Articles

Novel experimental model for repeated forebrain ischemia-reperfusion

Background and Purpose: The lack of reliable rodent model for repeated ischemia-reperfusion (I-R) hampers experimental research on stroke. Therefore, the objective of the present study was to develop a mouse model for repeated I-R cycles in a single animal on different days. Methods and Results: The right common carotid artery (CCA) was ligated and both vertebral arteries were coagulated. A customized vascular occluder, with its actuating tubing glued to a microport, was cuffed around the isolated left CCA and secured. Inflating of the occluder diaphragm via the microport restricted the blood flow via the left CCA and reduced the cerebral blood flow (CBF) by 75% in both hemispheres, while deflating allowed for the CBF restoration. Two minutes of forebrain ischemia followed by a 24 h reperfusion period was tolerated by animals for 5 cycles. Importantly, repeated 2 min I-R cycles attenuated the infarct volume induced by occlusion of the middle cerebral artery. Conclusions: The described model is a reliable method to induce transient I-R events in the forebrain. The model mimics transient ischemic attacks and allows for controlling the ischemic durations, intervals, and numbers of I-R cycles.

α-linolenic omega-3 fatty acid for stroke protection: from brain preconditioning paradigm to nutrition

Stroke is the third leading cause of death, due to its high incidence, the severity of the insult, and lack of treatment options. The only therapeutic is restoration of cerebral blood flow achieved by recombinant tissue plasminogen activator treatment, but only approximately 5% of patients receive it. In addition, therapeutics aimed at achieving neuroprotection by blocking the ischemic cascade, as identified in numerous preclinical studies, failed in clinical trials. This failure in translation from experimental models to clinical trials led to a re-evaluation of properties which would constitute the ‘‘best-in class’’ therapeutics to be used against stroke. Given that neuroprotection appears ineffective per se, an emerging direction is to identify therapies, probably combinatorial in nature, which protect the whole neurovascular unit and target timedependent neurotoxic mechanisms. Molecules that activate complex cellular signaling cascades that render the brain resistant to subsequent ischemia, known as preconditioners, offer a novel perspective in stroke protection. Preconditioning elicits complex endogenous neuroprotective responses that act by pleiotropic mechanisms to block death pathways, promote survival pathways and increase resistance. In addition to chemical preconditioners, natural/endogenous compounds such as adenosine, glutamate, lysophospholipids, and omega-3 polyunsaturated fatty acids have been demonstrated to be excellent preconditioners. Consequently, a major new concept in preconditioning to combat stroke is introduced, which is preconditioning achieved through supplementation of an essential item in diet or as a nutraceutical. Several epidemiologic studies suggested a beneficial effect of a seafood/omega-3-enriched diet in cerebral diseases, but the omega-3-induced protective mechanisms are still poorly identified. This review highlights how α-linolenic acid (ALA), the omega-3 polyunsaturated fatty acid precursor, protects the brain from in vivo and in vitro models of stroke, thus potentially fulfilling the goal of identifying the ‘‘best-in class’’ therapeutics against stroke. Also described is the surprising pleiotric nature of ALA in protecting neurons, vasodilating brain arteries and stimulating neuroplasticity. Importantly, feasibility of delivery has been demonstrated, since ALA supplementation can be achieved through modification of the daily diet, for which prevention of stroke-induced mortality and cerebral damage has been confirmed. Therefore evaluating ALA as an interesting preconditioner against stroke represents a novel and extremely relevant concept in the context of nutraceutical and functional food development.

The thrombomodulin analog Solulin promotes reperfusion and reduces infarct volume in a thrombotic stroke model

See also Andreou AP, Crawley JTB. Thrombomodulin analogues for the treatment of ischemic stroke. This issue, pp 1171–3.SummaryBackground: Currently there is no approved anticoagulant for treating acute stroke. This is largely because of concern for hemorrhagic complications, and suggests a critical need for safer anticoagulants. Solulin is a soluble analog of the endothelial cell receptor thrombomodulin, able to bind free thrombin and convert it to an activator of the anticoagulant, protein C. Objective: Solulin was tested for its ability to inhibit middle cerebral artery occlusion (MCAO) induced by photothrombosis, and to restore MCA patency after establishment of stable occlusion. Methods: Cerebral blood flow (CBF) was monitored by laser Doppler for 1.5 h after occlusion and again 72 h later. Results: Solulin treatment 30 min before thrombosis resulted in an approximately 50% increase in time to form a stable occlusion. When administered 30 or 60 min after MCAO, Solulin significantly improved CBF within 90 min of treatment. In contrast, none of the vehicle-treated mice showed restoration of CBF in the first 90 min and only 17% did so by 72 h. Solulin treatment was associated with a significant reduction in infarct volume, and was well tolerated with no overt hemorrhage observed in any treatment group. Mechanistic studies in mice homozygous for the factor (F)V Leiden mutation, suggest that Solulin’s efficacy derives primarily from the anticoagulant activity of the thrombin–Solulin complex and not from direct anti-inflammatory or neuroprotective effects of Solulin or activated protein C. Conclusions: Our data indicate that Solulin is a safe and effective anticoagulant that is able to antagonize active thrombosis in acute ischemic stroke, and to reduce infarct volume.

Stroke Penumbra Defined by an MRI-Based Oxygen Challenge Technique: 2. Validation based on the Consequences of Reperfusion

Magnetic resonance imaging (MRI) with oxygen challenge (T(2)(*) OC) uses oxygen as a metabolic biotracer to define penumbral tissue based on CMRO(2) and oxygen extraction fraction. Penumbra displays a greater T(2)(*) signal change during OC than surrounding tissue. Since timely restoration of cerebral blood flow (CBF) should salvage penumbra, T(2)(*) OC was tested by examining the consequences of reperfusion on T(2)(*) OC-defined penumbra. Transient ischemia (109 ± 20 minutes) was induced in male Sprague-Dawley rats (n=8). Penumbra was identified on T(2)(*)-weighted MRI during OC. Ischemia and ischemic injury were identified on CBF and apparent diffusion coefficient maps, respectively. Reperfusion was induced and scans repeated. T(2) for final infarct and T(2)(*) OC were run on day 7. T(2)(*) signal increase to OC was 3.4% in contralateral cortex and caudate nucleus and was unaffected by reperfusion. In OC-defined penumbra, T(2)(*) signal increased by 8.4% ± 4.1% during ischemia and returned to 3.25% ± 0.8% following reperfusion. Ischemic core T(2)(*) signal increase was 0.39% ± 0.47% during ischemia and 0.84% ± 1.8% on reperfusion. Penumbral CBF increased from 41.94 ± 13 to 116.5 ± 25 mL per 100 g per minute on reperfusion. On day 7, OC-defined penumbra gave a normal OC response and was located outside the infarct. T(2)(*) OC-defined penumbra recovered when CBF was restored, providing further validation of the utility of T(2)(*) OC for acute stroke management.

Capillary Remodeling and Collateral Growth Without Angiogenesis After Unilateral Common Carotid Artery Occlusion in Mice

To clarify the mechanisms of blood flow restoration after major artery occlusion, we presented first dynamic changes in cortical vessel morphology observed through a cranial window in mice after unilateral common carotid artery (CCA) occlusion. The density and diameter of capillaries, as well as diameters of pial arteries, were measured by confocal laser-scanning microscopy and fluorescent microscopy, respectively. Possible angiogenesis was evaluated by detecting any outgrowth of endothelial cells from pre-existing vessels or intussusception in Tie2-GFP mice. Immediately after unilateral CCA occlusion, cerebral blood flow (CBF) index, the reciprocal of mean transit time, reduced significantly and returned to the previous level after 14 days. Repeated observation of the cortical vessels did not reveal any angiogenesis, whereas the cortical capillary diameter increased by 74% after 14 days. The anterior cerebral artery (ACA) and collateral vessels connecting ACA and middle cerebral artery also dilated significantly. The capillary dilatation to the size of arteriole in the settings of collateral growth and CBF restoration suggested capillary remodeling. Our results indicate that capillary remodeling, pial artery dilatation and collateral growth without angiogenesis are sufficient mechanisms to restore normal cerebral blood flow after unilateral CCA occlusion.

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123I-iomazenil (IMZ)-SPECT is used as a tool to detect the viability of neuronal cells. We investigated the distribution of IMZ in the brain of patients suffering from moyamoya disease, comparing it with the images of MRI and the distribution of 123I-N-isopropyl-4-iodoamphetamin hydrochloride (IMP)-SPECT. In the present study, we investigated 5 patients (4 females and 1 male, aged 30 to 61) who received our modified surgery according to our strategy (EC-IC bypass surgery and/or EMS, EDAS) in our institution from July 2008 to November 2009. The initial symptoms were ischemic events in 4 patients, and bleeding in 1 patient. 123I-IMZ-SPECT was started 170 minutes after an injection of 123I-IMZ. The distribution of IMZ or IMP was analyzed by iSSP5 and NEUROFLEXER to obtain Z scores. The revascularization procedures were performed at the sites where cerebral blood flow (CBF) was significantly reduced and poor response to Diamox treatment was seen preoperatively. The uptake of 123I-IMZ-SPECT was lower on the symptomatic side than on the asymptomatic side. Only in the region where 123I-IMZ uptake had been preserved preoperatively, the surgery induced a successful restoration of CBF postoperatively. These results strongly suggest that 123I-IMZ-SPECT is useful for evaluation of preoperative neuronal viability of the patients with moyamoya disease as well as preoperative prediction of surgical efficacy.

Cerebral Malaria: A Vasculopathy

Cerebral Malaria: A Vasculopathy

Recovery of severe neurological dysfunction after restoration of cerebral blood flow in acute aortic dissection

Emergency repair has been successfully performed in acute type A aortic dissection complicated by cerebral malperfusion. Despite the lack of criteria to define irreversible brain damage, immediate surgery is often denied in case of stroke or coma. We report two patients presenting with coma and altered brainstem reflexes shortly after onset of aortic dissection, in whom aortic repair was successfully undertaken.

Protective effect of quercetin against intracerebral streptozotocin induced reduction in cerebral blood flow and impairment of memory in mice

The aim of the present study is to investigate the effect of quercetin, a naturally occurring flavonoid, on cerebral blood flow (CBF), brain energy metabolism, memory impairment, oxidative stress and cholinergic dysfunction in brain following intracerebral (i.c.) streptozotocin (STZ) administration in mice. STZ (0.5 mg/kg, i.c.) was administered twice at an interval of 48 h. We found a significant reduction in CBF as measured by Laser Doppler Flowmetry (LDF). The brain energy metabolism was also altered as evidenced by significant reduction in brain ATP content. Daily treatment with quercetin (2.5, 5 and 10 mg/kg, p.o.) starting from the first dose of STZ showed a dose-dependent restoration of CBF and ATP content. Further, quercetin prevented STZ induced memory impairment as assessed by Morris water maze and passive avoidance tests. Biochemical analysis revealed that STZ significantly increased malondialdehyde (MDA), nitrite and depleted glutathione (GSH) levels in the mice brain. Quercetin decreased oxidative and nitrosative stress as evidenced by a significant decrease in MDA, nitrite and increase in GSH levels. Quercetin also attenuated elevated acetylcholinesterase activity in the STZ-treated mice. Neither STZ (i.c.) nor quercetin showed any change in locomotor activity and blood glucose level. The present study demonstrates the beneficial effects of quercetin in improving CBF along with preventing memory impairment, oxidative stress, altered brain energy metabolism and cholinergic dysfunction caused by STZ in mice. Therefore, consumption of dietary stuff rich in quercetin should be encouraged to ward off dementia associated with vascular and neurodegenerative disorders.

Neuropathology and structural changes in hydrocephalus

In the context of spina bifida, hydrocephalus is usually caused by crowding of the posterior fossa with obstruction to cerebrospinal fluid flow from the forth ventricle, and less often by malformation of the cerebral aqueduct. Enlargement of the cerebral ventricles causes gradual destruction of periventricular white matter axons. Motor, sensory, visual, and memory systems may be disturbed through involvement of the long projection axons, periventricular structures including the corpus callosum, and the fimbria-fornix pathway. Secondary changes occur in neuronal cell bodies and synapses, but there is minimal death of neurons. The clinical syndrome of hydrocephalic brain dysfunction is thus due to subcortical disconnection. Some of the brain dysfunction is reversible by shunting, probably through restoration of cerebral blood flow and normalization of the extracellular environment. However, destroyed axons cannot be restored.

The state of systemic circulation, collapsed or preserved defines the need for hyperoxic or normoxic resuscitation in neonatal mice with hypoxia–ischemia

Background The return of spontaneous circulation (ROSC) is a primary goal of resuscitation. For neonatal resuscitation the International Liaison Committee on Resuscitation (ILCOR) recommends oxygen concentrations ranging from 21% to 100%. Aims and methods This study (a) compared the efficacy of resuscitation with room air (RA) or 100% O 2 in achieving ROSC in 46 neonatal mice with circulatory collapse induced by lethal hypoxia–ischemia (HI) and (b) determined whether re-oxygenation with RA or 100% O 2 alters the extent of HI cerebral injury in mice with preserved systemic circulation ( n = 31). We also compared changes in generation of reactive oxygen species (ROS) in cerebral mitochondria in response to re-oxygenation with RA or 100% O 2. Result In HI-mice with collapsed circulation re-oxygenation with 100% O 2 versus RA resulted in significantly greater rate of ROSC. In HI-mice with preserved systemic circulation and regional (unilateral) cerebral ischemia the restoration of cerebral blood flow was significantly faster upon re-oxygenation with 100% O 2, than RA. However, no difference in the extent of brain injury was detected. Regardless of the mode of re-oxygenation, reperfusion in these mice was associated with markedly accelerated ROS production in brain mitochondria. Conclusion In murine HI associated with circulatory collapse the resuscitation limited to re-oxygenation with 100% O 2 is superior to the use of RA in achievement of the ROSC. However, in HI-mice with preserved systemic circulation hyperoxic re-oxygenation has no benefit over the normoxic brain recovery.

Faster Recovery of Cerebral Perfusion in SOD1-Overexpressed Rats After Cardiac Arrest and Resuscitation

Protracted hypoperfusion is one of the hallmarks of secondary cerebral derangement after cardiac arrest and resuscitation (CAR), and reactive oxygen species have been implicated in reperfusion abnormalities. Using transgenic (Tg) rats overexpressing copper zinc superoxide dismutase (SOD1), we investigated the role of this intrinsic antioxidant in the restoration of cerebral blood flow (CBF) after CAR. Nine Tg and 11 wild-type (WT) rats were subjected to a nominal 15-minute cardiac arrest, and CBF was measured using the noninvasive arterial spin labeling MRI method before and during cardiac arrest, and 0 to 2 hours and 1 to 5 days after resuscitation. The SOD1-Tg rats showed rapid normalization of CBF 1 day after the insult, whereas CBF in WT animals remained abnormal for at least 5 days, showing a progressive increase in CBF from hypo- to hyperperfusion on postresuscitation days 1 to 5. The long-term outcome, as measured by survival time, change in body weight, and mapping of apparent diffusion coefficient (ADC) for ion/water homeostasis, was significantly better in the SOD1-Tg rats. Our results support the notion that reactive oxygen species are at least partially responsible for microvascular reperfusion disorders.

Amelioration of hypoperfusion after traumatic brain injury by in vivo endothelin-1 knockout

Endothelin 1 (ET-1) is one of the most powerful vasoconstrictors in the brain. Its expression is upregulated after traumatic brain injury (TBI) and is a major factor in the ensuing hypoperfusion. Attenuation of ET-1 effects has been mainly achieved by blockade of its receptors. The result of a direct blockade of ET-1 mRNA synthesis is not known. We used the Marmarou's model to inflict injury to male Sprague-Dawley rats injected with antisense ET-1 oligodeoxynucleotides (ODNs) before injury. Laser Doppler flowmetry in noninjured rats (2 groups, i.e., untreated and animals that received cODNs) revealed a constant cerebral blood flow of approximately 14 mL.min-1.100 g-1, whereas the values from injured animals pretreated with control ODNs (cODNs) or from animals subjected to TBI alone were approximately 8.0 mL.min-1.100 g-1 during the 18-48 h time period post-TBI. After antisense ET-1 ODNs pretreatment, however, cerebral blood flow in injured animals was approximately 17 mL.min-1.100 g-1 during the 6-48 h time period. Antisense ET-1 ODNs-treated animals also had 19%-29% larger microvessel cross-sectional area and approximately one-third less ET-1 immunoreactivity in the 50-75% range after injury than did cODNs-treated animals after TBI. The results indicate that this direct in vivo approach is an effective therapeutic intervention for the restoration of cerebral blood flow after TBI.

Exaggeration of Focal Cerebral Ischemia in Transgenic Mice Carrying Human Renin and Human Angiotensinogen Genes

We examined the possibility that activation of the human brain renin-angiotensin system is involved in enhancement of ischemic brain damage using chimeric transgenic mice with human renin (hRN) and human angiotensinogen (hANG) genes. Chimeric (hRN/hANG-Tg) mice were generated by mating of hRN and hANG transgenic mice. Permanent occlusion of the middle cerebral artery (MCA) by an intraluminal filament technique induced focal ischemic brain lesions. hRN/hANG-Tg mice showed higher angiotensin II levels in the plasma and brain. The ischemic brain area at 24 hours after MCA occlusion was significantly enlarged in hRN/hANG-Tg mice with an enhanced neurological deficit compared to that in wild-type, hRN-Tg and hANG-Tg mice. The reduction of cerebral blood flow in the periphery region of the MCA territory after MCA occlusion was markedly exaggerated in hRN/hANG-Tg mice. Superoxide anion production in the brain and arteries was also increased significantly in hRN/hANG-Tg mice even before MCA occlusion and was further enhanced after MCA occlusion. Treatment with an AT(1) receptor blocker, valsartan (3.0 mg/kg per day), for 2 weeks significantly reduced the ischemic brain area and improved the neurological deficit after MCA occlusion in hRN/hANG-Tg mice, similar to those in wild-type, hRN-Tg, and hANG-Tg mice, with restoration of cerebral blood flow in the peripheral region and decreases in superoxide anion production and blood pressure. These results indicate that activation of the human renin-angiotensin system exaggerates ischemic brain damage mainly through stimulation of the AT(1) receptor and marked reduction of cerebral blood flow and enhanced oxidative stress.

Newborn resuscitation: should we oxygenate or not?

how should we oxygenate newborn and infants suffering from hypoxia and ischemia? Is it harmful to use 100% O2? It may seem odd to question a practice that has been carried out for so long, seemingly without any adverse effects. The case is, however, that after the practice of routinely using 100% O2

Erythropoietin-Induced Neurovascular Protection, Angiogenesis, and Cerebral Blood Flow Restoration after Focal Ischemia in Mice

Restoration of local blood supply in the post-ischemic brain plays a critical role in tissue repair and functional recovery. The present investigation explored beneficial effects of recombinant human erythropoietin (rhEPO) on vascular endothelial cell survival, angiogenesis, and restoration of local cerebral blood flow (LCBF) after permanent focal cerebral ischemia in adult mice. Saline or rhEPO (5,000 U/kg, intraperitoneal) was administered 30 mins before ischemia and once daily after ischemic stroke. Immunohistochemistry showed an enhancing effect of rhEPO on expression of EPO receptor (EPOR) of endothelial cells in the penumbra region 3 to 21 days after the ischemic insult. The treatment with rhEPO decreased ischemia-induced cell death and infarct volume 3 days after stroke. Specifically, rhEPO reduced the number of terminal deoxynucleotidyl transferase biotin-dUPT nick end labeling- and caspase-3-positive endothelial cells in the penumbra region. Colocalization of the vessel marker glucose transporter-1 (Glut-1) and cell proliferation marker 5-bromo-2'-deoxyuridine indicated enhanced angiogenic activity in rhEPO-treated mice 7 to 21 days after stroke. Western blot showed upregulation of the expression of angiogenic factors Tie-2, Angiopoietin-2, and vascular endothelial growth factor in rhEPO-treated animals. Local cerebral blood flow was measured by laser scanning imaging 3 to 21 days after stroke. At 14 days, LCBF in the penumbra was recovered to preischemia levels in rhEPO-treated mice but not in control mice. Our data suggest that rhEPO treatment upregulates the EPOR level in vascular endothelial cells, confers neurovascular protection, and enhances angiogenesis. We further show a promoting effect of rhEPO on LCBF recovery in the ischemic brain. These rhEPO-induced effects may contribute to therapeutic benefits in the treatment of ischemic stroke.

Stepwise Revascularization for Prevention of Postoperative Hyperperfusion

Abrupt normalization of cerebral blood flow (CBF) after surgical procedures to improve excessive cerebral hypoperfusion can cause irreversible brain parenchymal damage. Such hyperperfusion, which is caused by inflow at normal blood pressure into maximally dilated fine vessels, is an important complication following carotid endarterectomy (CEA). Strict control of blood pressure in the perioperative period can prevent this complication except in a few patients, who have severe cerebral hypoperfusion and poor cerebrovascular reserve due to extremely severe stenosis of the ipsilateral or the bilateral carotid arteries, for which CEA is indicated. The requirement for improved CBF and the risk of postoperative hyperperfusion conflict in the pathogenesis of these patients. We tried to prevent abrupt improvement in perfusion by attempting gradual restoration of CBF. Superficial temporal artery-middle cerebral artery anastomosis was first performed to improve the poor cerebrovascular reserve by allowing insufficient blood flow. A few weeks later, CEA was performed to completely restore CBF. This surgical approach obtained good results without postoperative problems in four patients. The indications of this surgical management and efficacy of stepwise restoration of CBF to prevent postoperative hyperperfusion depend on careful preoperative evaluation of perfusion studies.

Power Doppler imaging in detection of surgically induced indirect neoangiogenesis in adult moyamoya disease

Moyamoya is a rare, chronic disease that leads to the progressive narrowing and/or occlusion of the distal internal carotid and proximal cerebral arteries. Chronic cerebral ischemia ensues due to insufficient collateral blood supply. One potential treatment consists of the restoration of regional cerebral blood flow by direct or indirect revascularization surgery. The extent of neovascularization, especially in indirect procedures such as encephalomyosynangiosis (EMS), is currently evaluated with conventional angiography. Because this method is invasive and carries some risks, the authors investigated power Doppler imaging as an alternative noninvasive bedside procedure that can be used to assess surgically induced indirect revascularization in adult patients with moyamoya disease. Twelve symptomatic patients with adult moyamoya disease (seven women and five men, mean age 38 +/- 17 years) underwent combined (direct and indirect) revascularization. They were then examined using conventional angiography and power Doppler imaging to assess the extent of revascularization within 120 days postsurgery. According to the number of intracranial vessels demonstrating opacification on conventional angiography and power Doppler imaging studies, EMS was graded as follows: 1, absent (0 vessels); 2, moderate (one-four vessels); and 3, extensive (> four vessels) for both methods. Examiners were blinded to the classification results for the procedure that they did not grade. All 24 hemispheres were examined. The visual grading of EMS revealed a highly significant agreement between conventional angiography and power Doppler imaging (Spearman rank coefficient, r = 0.92; p < 0.001) and there was 100% agreement of patency of the bypass between the direct and indirect methods. The authors found excellent agreement between the two methods. Therefore, power Doppler imaging is a valid noninvasive alternative to carotid artery angiography in evaluating direct and indirect revascularization.

急性期にＳＴＡ‐ＭＣＡ吻合術を施行した頭蓋内内頚動脈閉塞症の１例

A 25-year-old right-handed woman presented with sudden-onset aphasia and right hemiparesis. She was restless, and her GCS score was E4V1M5 on admission. Diffusion-weighted MRI showed high intensity areas in the left insular cortex, frontal lobe, and corona radiata. Perfusion CT showed a large hypoperfusion area almost identical to the left MCA distribution. Cerebral angiography disclosed occlusion of the left internal carotid artery bifurcation. Emergency superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis was performed. She showed progressive recovery in verbal function following surgery, and reached a GCS score of E4V4M6 at Day 3. Postoperative perfusion CT confirmed restoration of cerebral blood flow in the left MCA distribution. She became ambulatory with a cane 2 months later. In spite of thorough examination, the cause of the internal carotid artery occlusion remains unclear. STA-MCA anastomosis in the acute stage may be beneficial in neurological recovery in a selected group of patients with intracranial internal carotid artery occlusion.

Bone marrow grafts restore cerebral blood flow and blood brain barrier in stroke rats

We monitored alterations in cerebral blood flow (CBF) and blood–brain barrier (BBB) permeability following middle cerebral artery occlusion (MCAo) and intrastriatal transplantation of mouse bone marrow stromal cells (BMSCs) or saline infusion in adult Sprague–Dawley rats. Laser Doppler and Evans Blue assay revealed that BMSC grafts dose-dependently restored CBF and BBB to near normal levels at a much earlier period (Days 4–5 post-MCAo) in transplanted stroke animals compared to stroke animals that received saline infusion (Days 11–14 post-MCAo). Xenografted BMSCs survived in the absence of immunosuppression, and elevated levels of transforming growth factor-beta superfamily of neurotrophic factors were detected in transplanted stroke animals. These data suggest that early restoration of CBF and BBB following transplantation of BMSCs could mediate the reported functional outcomes in stroke animals.