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ABSTRACT: BACKGROUND AND PURPOSE: GW3965, a synthetic liver X receptor agonist, elevates high-density lipoprotein cholesterol and has antiatherosclerosis and anti-inflammation properties. We tested the hypothesis that GW3965 treatment of stroke increases vascular remodeling, promotes synaptic protein expression and axonal growth in the ischemic brain, and improves functional outcome in mice. METHODS: Mice were subjected to transient middle cerebral artery occlusion and treated without or with different doses of GW3965 (5, 10, or 20 mg/kg) starting 24 hours after middle cerebral artery occlusion daily for 14 days. Neurological functional tests, blood high-density lipoprotein cholesterol measurement, and immunostaining were performed. Mouse brain endothelial cells, primary cultured artery explants, and primary cortical neurons cultures were also used in vitro. RESULTS: GW3965 treatment of stroke significantly increased blood high-density lipoprotein cholesterol level, synaptic protein expression, axonal density, angiogenesis and arteriogenesis, and Angiopoietin1, Tie2, and occludin expression in the ischemic brain and improved functional outcome compared with middle cerebral artery occlusion control animals (n=10; P<0.05). In vitro, GW3965 and high-density lipoprotein cholesterol also significantly increased capillary-like tube formation and artery explant cell migration as well as neurite outgrowth. Inhibition of Angiopoietin-1 attenuated GW3965-induced tube-formation, artery cell migration, and neurite outgrowth (n=6 per group; P<0.05). CONCLUSIONS: These data indicate, for the first time, that GW3965 promotes synaptic protein expression and axonal growth and increases vascular remodeling, which may contribute to improvement of functional outcome after stroke. Increasing Angiopoietin-1/Tie2 signaling activity may play an important role in GW3965-induced brain plasticity and neurological recovery from stroke.
Stroke 11/2012; · 5.73 Impact Factor
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ABSTRACT: Background and purpose: Diabetes mellitus (DM) is a major stroke risk factor and is associated with poor recovery compared with nondiabetic stroke patients. In the present study, we investigated the effects of tissue plasminogen activator (tPA) treatment of stroke in diabetic and non-diabetic rats. Methods: Type-1 diabetes (T1DM) was induced by injection of streptozotocin. Non-T1DM and T1DM rats were subjected to embolic middle cerebral artery occlusion (MCAo) and treated with or without tPA 2h after MCAo. Functional outcomes and immunostaining for advanced glycation endproducts receptor (RAGE), matrix metalloproteinase-9 (MMP-9) and toll-like receptor 4 (TLR4) and Western blotting were performed. Results: tPA treatment of WT-MCAo rats significantly improved the functional outcome and reduced the lesion volume compared with non-treatment WT-MCAo rats (p<0.05). There was no significant difference between treatment with or without tPA in the WT-MCAo group in brain hemorrhage, BBB leakage and expression of inflammatory mediators, RAGE, MMP-9 and TLR4. However, tPA treatment in T1DM-MCAo rats (T1DM-MCAo+tPA) significantly enlarged brain hemorrhage, augmented BBB leakage, and failed to decrease lesion volume and improve functional outcome after stroke compared to T1DM-MCAo control. tPA treatment also significantly increased the expression of RAGE, MMP-9 and TLR4 in the ischemic brain in T1DM-MCAo rats compared with T1DM-MCAo control rats (p<0.05). Brain hemorrhage was significantly correlated with functional deficit and RAGE and TLR4 expression, respectively. Conclusions: Treatment of stroke with tPA increased brain hemorrhage, BBB leakage and failed to improve functional outcome in T1DM rats. The increased inflammatory response may contribute to the failed neuroprotective effects of tPA treatment in T1DM rats.
Neuroscience 07/2012; 222:326-32. · 3.38 Impact Factor
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ABSTRACT: Biotinidase deficiency is an autosomal recessively inherited disorder characterized by neurological and cutaneous abnormalities. We have developed a transgenic knock-out mouse with biotinidase deficiency to better understand aspects of pathophysiology and natural history of the disorder in humans. Neurological deficits observed in symptomatic mice with biotinidase deficiency are similar to those seen in symptomatic children with the disorder. Using a battery of functional neurological assessment tests, the symptomatic mice performed poorly compared to wild-type mice. Demyelination, axonal degeneration, ventriculomegaly, and corpus callosum compression were found in the brains of untreated, symptomatic enzyme-deficient mice. With biotin treatment, the symptomatic mice improved neurologically and the white matter abnormalities resolved. These functional and anatomical findings and their reversal with biotin therapy are similar to those observed in untreated, symptomatic and treated individuals with biotinidase deficiency. The mouse with biotinidase deficiency appears to be an appropriate animal model in which to study the neurological abnormalities and the effects of treatment of the disorder.
Neurobiology of Disease 05/2012; 47(3):428-35. · 5.40 Impact Factor
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Jieli Chen,
Amjad Shehadah,
Ajai Pal,
Alex Zacharek, Xu Cui,
Yishen Cui,
Cynthia Roberts,
Mei Lu,
Andrew Zeitlin,
Robert Hariri,
Michael Chopp
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ABSTRACT: Background: Human placenta-derived adherent (PDA001) cells are mesenchymal-like stem cells isolated from postpartum human placenta. In this study, we tested whether intravenously-infused PDA001 improves neurological functional recovery after stroke in rats. In addition, potential mechanisms underlying the PDA001-induced neuroprotective effect were investigated.Methods: Young adult male rats (2-3 months) were subjected to 2h of middle cerebral artery occlusion (MCAo) and treated with PDA001 (4x10⁶) or vehicle controls (Dextran vehicle or phosphate buffer saline (PBS)) via intravenous (IV) administration initiated at 4h after MCAo. A battery of functional tests and measurements of lesion volume and apoptotic cells were performed. Immunostaining and ELISA assays for vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) and brain-derived neurotrophic factor (BDNF) were performed in the ischemic brain to test the potential mechanisms underlying the neuroprotective effects of PDA001 cell treatment of stroke.Results: PDA001 cell treatment at 4h post stroke significantly improved functional outcome, and as well as significantly decreased lesion volume, TUNEL and cleaved-Caspase-3 positive cell number in the ischemic brain, compared to MCAo-vehicle and MCAo-PBS control. Treatment of stroke with PDA001 cells also significantly increased HGF and VEGF expression in the ischemic border zone (IBZ) compared to controls. Using ELISA assays, treatment of stroke with PDA001 cells significantly increased VEGF, HGF and BDNF levels in the ischemic brain compared to controls.Conclusion: When administered intravenously at 4h after MCAo, PDA001 cells promoted neuroprotective effects. These effects induced by PDA001 cell treatment may be related to the increase of VEGF, HGF and BDNF expression and a decrease of apoptosis. PDA001 cells may provide a viable cell source to treat stroke.
Cell Transplantation 03/2012; · 5.13 Impact Factor
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Jieli Chen,
Xinchun Ye,
Tao Yan,
Chunling Zhang,
Xiao-Ping Yang, Xu Cui,
Yishen Cui,
Alex Zacharek,
Cynthia Roberts,
Xinfeng Liu,
Xiangguo Dai,
Mei Lu,
Michael Chopp
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ABSTRACT: Cell therapy with bone marrow stromal cells (BMSCs) improves functional recovery after stroke in nondiabetic rats. However, its effect on diabetics with stroke is unknown. This study investigated the effect of BMSCs on stroke outcome in Type 1 diabetic (T1DM) rats.
T1DM was induced in adult male Wistar rats by injecting streptozotocin. Nondiabetic and T1DM rats were subjected to 2 hours of middle cerebral artery occlusion (MCAO), treated with or without BMSCs (3×10(6)) at 24 hours after MCAO, and monitored for 14 days.
Functional benefit was not detected in T1DM-MCAO treated with BMSC rats compared with corresponding T1DM-MCAO controls. BMSC treatment in T1DM-MCAO rats had increased mortality, blood-brain barrier leakage, brain hemorrhage, and angiogenesis. Internal carotid artery neointimal formation and cerebral arteriole narrowing/occlusion were also observed in T1DM-MCAO+BMSCs rats compared with T1DM-MCAO controls (P<0.05), but not in nondiabetic stroke rats. We further studied the underlying mechanisms responsible for BMSC-induced blood-brain barrier leakage and accelerated vascular damage in T1DM-MCAO rats. We found that the expression of angiogenin (an angiogenic factor) and ED1 (a marker for macrophages) was significantly increased in the T1DM-MCAO+BMSC rats in the ischemic brain and internal carotid artery compared with nontreated T1DM-MCAO rats, but not in nondiabetic stroke rats.
BMSC therapy in T1DM-MCAO rats does not improve functional outcome. On the contrary, it increases blood-brain barrier leakage and cerebral artery neointimal formation, and arteriosclerosis, which possibly is due to increased expression of angiogenin. Thus, BMSC treatment starting 24 hours after MCAO may not be beneficial for diabetic subjects with stroke.
Stroke 09/2011; 42(12):3551-8. · 5.73 Impact Factor
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Xinchun Ye,
Michael Chopp, Xu Cui,
Alex Zacharek,
Yisheng Cui,
Tao Yan,
Amjad Shehadah,
Cynthia Roberts,
Xinfeng Liu,
Mei Lu,
Jieli Chen
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ABSTRACT: We investigated the changes and the molecular mechanisms of cerebral vascular damage and tested the therapeutic effects of Niaspan in type-1 streptozotocin induced diabetic (T1DM) rats after stroke. T1DM-rats were subjected to transient middle cerebral artery occlusion (MCAo) and treated without or with Niaspan. Non-streptozotocin rats (WT) were also subjected to MCAo. Functional outcome, blood-brain-barrier (BBB) leakage, brain hemorrhage, immunostaining, and rat brain microvascular endothelial cell (RBEC) culture were performed. Compared to WT-MCAo-rats, T1DM-MCAo-rats did not show an increase lesion volume, but exhibited significantly increased brain hemorrhage, BBB leakage and vascular damage as well as decreased functional outcome after stroke. Niaspan treatment of stroke in T1DM-MCAo-rats significantly attenuated BBB damage, promoted vascular remodeling and improved functional outcome after stroke. T1DM-MCAo-rats exhibited significantly increased Angiopoietin 2 (Ang2) expression, but decreased Ang1 expression in the ischemic brain compared to WT-MCAo-rats. Niaspan treatment attenuated Ang2, but increased Ang1 expression in the ischemic brain in T1DM-MCAo-rats. In vitro data show that the capillary-like tube formation in the WT-RBECs marginally increased compared to T1DM-RBEC. Niaspan and Ang1 treatment significantly increased tube formation compared to non-treatment control. Inhibition of Ang1 attenuated Niacin-induced tube formation in T1DM-RBECs. Niaspan treatment of stroke in T1DM-rats promotes vascular remodeling and improves functional outcome. The Ang1/Ang2 pathway may contribute to Niaspan induced brain plasticity. Niaspan warrants further investigation as a therapeutic agent for the treatment of stroke in diabetics.
Experimental Neurology 09/2011; 232(2):299-308. · 4.70 Impact Factor
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ABSTRACT: We investigated the changes and the molecular mechanisms of cerebral vascular damage after stroke in type-2 diabetic (T2DM) mice. Adult male db/db T2DM and wild-type (WT) mice were subjected to transient middle cerebral artery occlusion (MCAo) and sacrificed 24 hours after MCAo. T2DM-mice exhibited significantly increased blood glucose, brain hemorrhagic rate, mortality and cerebrovascular density, but decreased cerebrovascular diameter, arteriolar density and arterial mural cell numbers in the ischemic brain compared with WT mice. The hemorrhagic rate was significantly correlated with the mortality (r = 0.85). T2DM-mice also exhibited increased blood-brain barrier leakage and concomitantly, increased Angiopoietin2, but decreased Angiopoietin1, Tie2 and tight junction protein expression in the ischemic brain. Angiopoietin1 gene expression also significantly decreased in the common carotid artery (CCA) in T2DM-mice compared with WT mice after stroke. To further test the effects of T2DM on cerebrovascular damage, we performed in vitro studies. The capillary-like tube formation of primary cultured mouse brain endothelial cells (MBECs) significantly increased, but artery cell migration in the primary CCA cultures significantly decreased both in Sham and MCAo T2DM-mice compared with the WT mice. Angiopoietin1 treatment significantly increased artery cell migration in T2DM-CCA after MCAo. Tie2-FC, a neutralized Tie2 antibody, significantly decreased artery cell migration in WT-CCA after MCAo. Therefore, decreased Angiopoietin1/Tie2 and increased Angiopoietin2 expression may contribute to diabetes-induced vascular damage after stroke.
Neurobiology of Disease 07/2011; 43(1):285-92. · 5.40 Impact Factor
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ABSTRACT: Diabetes mellitus leads to a higher risk of ischemic stroke and worse outcome compared to the general population. However, there have been few studies on white matter (WM) damage after stroke in diabetes mellitus. We therefore investigated WM damage after stroke in mice with diabetes mellitus.
BKS.Cg-m(+/+)Lepr(db)/J (db/db) type 2 diabetes mellitus mice and db(+) non-diabetes mellitus mice were subjected to middle cerebral artery occlusion. Functional outcome, immunostaining, zymography, Western blot, and polymerase chain reaction were used.
After stroke, mice with diabetes mellitus exhibited significantly increased lesion volume and brain hemorrhagic and neurological deficits compared to mice without diabetes mellitus. Bielshowsky silver, luxol fast blue, amyloid precursor protein, and NG2 expression were significantly decreased, indicating WM damage, and matrix metalloproteinase (MMP)-9 activity was significantly increased in the ischemic brain of mice with diabetes mellitus. Subanalysis of similar lesions in mice with and without diabetes mellitus demonstrated mice with diabetes mellitus had significantly increased WM damage than in mice without diabetes mellitus (P<0.05). To investigate the mechanism underlying diabetes mellitus-induced WM damage, oxygen-glucose deprivation-stressed premature oligodendrocyte and primary cortical neuron cultures were used. High glucose increased MMP-2, MMP-9, cleaved caspase-3 levels, and apoptosis, as well as decreased cell survival and dendrite outgrowth in cultured primary cortical neuron. High glucose increased MMP-9, cleaved caspase-3 level, and apoptosis, and decreased cell proliferation and cell survival in cultured oligodendrocytes. Inhibition of MMP by GM6001 treatment significantly decreased high glucose-induced cell death and apoptosis in cultured primary cortical neuron and oligodendrocytes but did not alter dendrite outgrowth in primary cortical neuron.
Mice with diabetes mellitus have increased brain hemorrhage and show more severely injured WM than mice without diabetes mellitus after stroke. MMP-9 upregulated in mice with diabetes mellitus may exacerbate WM damage after stroke in mice with diabetes mellitus.
Stroke 02/2011; 42(2):445-52. · 5.73 Impact Factor
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ABSTRACT: Niacin is the most effective medication in current clinical use for increasing high-density lipoprotein cholesterol. We tested the hypothesis that niacin treatment of stroke promotes synaptic plasticity and axon growth in the ischemic brain.
Male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion and treated with or without Niaspan (a prolonged-release formulation of niacin, 40 mg/kg) daily for 14 days starting 24 hours after middle cerebral artery occlusion. The expression of synaptophysin, Nogo receptor, Bielschowsky silver, brain-derived neurotrophic factor, and its receptor tropomyosin-related kinase B were measured by immunohistostaining and Western blot, respectively, in the ischemic brain. Complementing in vivo studies, primary cultured neurons were used to test the effect of niacin and high-density lipoprotein on neurite outgrowth and brain-derived neurotrophic factor/tropomyosin-related kinase B expression.
Niaspan treatment of stroke significantly increased synaptophysin, Bielschowsky silver, brain-derived neurotrophic factor/tropomyosin-related kinase B expression, and decreased Nogo receptor expression in the ischemic brain compared with middle cerebral artery occlusion control animals (P<0.05, n=8/group). Niacin and high-density lipoprotein treatment significantly increased neurite outgrowth and brain-derived neurotrophic factor/tropomyosin-related kinase B expression in primary cultured neurons. Tropomyosin-related kinase B inhibitor attenuated niacin-induced neurite outgrowth (P<0.05, n=6/group).
Niacin treatment of stroke promotes synaptic plasticity and axon growth, which is mediated, at least partially, by the brain-derived neurotrophic factor/tropomyosin-related kinase B pathways.
Stroke 09/2010; 41(9):2044-9. · 5.73 Impact Factor
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ABSTRACT: We investigated axonal plasticity in the bilateral motor cortices in rats after unilateral stroke and bone marrow stromal cell (BMSC) treatment. Rats were subjected to permanent right middle cerebral artery occlusion followed by intravenous administration of phosphate-buffered saline or BMSCs 1 day later. Adhesive-removal test and modified neurologic severity score were performed weekly to monitor limb functional deficit and recovery. Anterograde tracing with biotinylated dextran amine injected into the right motor cortex was used to assess axonal sprouting in the contralateral motor cortex and ipsilateral rostral forelimb area. Animals were killed 28 days after stroke. Progressive functional recovery was significantly enhanced by BMSCs. Compared with normal animals, axonal density in both contralateral motor cortex and ipsilateral rostral forelimb area significantly increased after stroke. Bone marrow stromal cells markedly enhanced such interhemispheric and intracortical connections. However, labeled transcallosal axons in the corpus callosum were not altered with either stroke or treatment. Both interhemispheric and intracortical axonal sprouting were significantly and highly correlated with behavioral outcome after stroke. This study suggests that, after stroke, cortical neurons surviving in the peri-infarct motor cortex undergo axonal sprouting to restore connections between different cerebral areas. Bone marrow stromal cells enhance axonal plasticity, which may underlie neurologic functional improvement.
Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 07/2010; 30(7):1288-95. · 5.46 Impact Factor
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ABSTRACT: In this study we examined the effect of combination treatment of experimental stroke with Niaspan, a prolonged-release formulation of Niacin (vitamin B3), and Simvastatin, a cholesterol-lowering drug, on functional outcome, axonal damage, axonal density and the of Iba-1 immunoreactive microglia expression in the ischemic brain of rats. Adult male rats were subjected to 2 h middle cerebral artery occlusion (MCAo) and treated with or without Niaspan alone, Simvastatin alone and combination Niaspan and Simvastatin starting 24 h after MCAo and daily for 14 days. Neurological functional tests were performed. Axonal damage and density were evaluated by Amyloid Precursor Protein (APP) and Bielschowsky silver, respectively. Nogo66 Receptor (NgR) expression and immunoreactive microglia (Iba-1) were also measured in the ischemic brain. Niaspan and Simvastatin monotherapy and combination treatment significantly promote functional outcome after stroke (p<0.05) compared to MCAo control animals. Combination treatment with Niaspan and Simvastatin induces additive but not synergetic effects when compared to Niaspan or Simvastatin monotherapy groups. Combination treatment significantly decreased APP expression and increased Bielschowsky silver expression. NGR and Iba-1 expression were significantly decreased in the ischemic brain. These data suggest that treatment of experimental stroke with combination of Niaspan and Simvastatin significantly improves functional outcome, reduces axonal damage and increases axonal density. Decreased expression of the NGR and reduced activated microglia may contribute to functional recovery after stroke.
Journal of the neurological sciences 07/2010; 294(1-2):107-11. · 2.32 Impact Factor
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ABSTRACT: We compared the effect of treatment of stroke with bone marrow stromal cells from stroke rats (Isch-BMSC) and normal rats (Nor-BMSC) on functional outcome.
Isch-BMSCs and Nor-BMSCs were intravenously injected into rats 24 hours after middle cerebral artery occlusion. To test the mechanism of Isch-BMSC-enhanced neurorestoration, Isch-BMSC and Nor-BMSC cultures were used.
Isch-BMSC significantly promoted functional outcome and enhanced angiogenesis, arterial density, and axonal regeneration compared with Nor-BMSC treatment animals. Isch-BMSCs exhibited increased Angiopoietin-1, Tie2, basic fibroblast growth factor, glial cell-derived neurotrophic factor, vascular endothelial growth factor, and Flk1 gene expression compared with Nor-BMSC. Using transwell coculture of BMSCs with brain-derived endothelial cells, Isch-BMSCs increased phosphorylated-Tie2 activity in brain-derived endothelial cells and enhanced brain-derived endothelial cells capillary tube formation compared with Nor-BMSCs. Inhibition of Tie2 gene expression in brain-derived endothelial cells using siRNA significantly attenuated BMSC-induced capillary tube formation.
These data suggest that Isch-BMSCs are superior to Nor-BMSCs for the neurorestorative treatment of stroke, which may be mediated by the enhanced trophic factor and angiogenic characteristics of Isch-BMSCs.
Stroke 03/2010; 41(3):524-30. · 5.73 Impact Factor
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ABSTRACT: In this study, we tested the hypothesis that TO901317 promotes synapse plasticity and axonal regeneration after stroke. Adult male C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAo) and treated with or without TO901317 starting 24 h after MCAo daily for 14 days. Axonal damage and regeneration were evaluated by immunostaining. TO901317 significantly increased synaptophysin expression and axonal regeneration, as well as decreased the expressions of amyloid betaA4 precursor protein and Nogo receptor (NgR) in the ischemic brain. To test whether TO901317 regulates the phosphorylation of phosphatidylinositol 3-kinase (p-PI3K) and Akt (p-Akt) activity in the ischemic brain, MCAo mice were treated with or without TO901317 starting 24 h after MCAo daily for 4 days and were then killed at 5 days after MCAo. TO901317 treatment significantly increased p-PI3K and p-Akt activity, but did not increase total PI3K expression in the ischemic brain. Using primary cortical neuron (PCN) culture, TO901317 significantly increased synaptophysin expression, p-PI3K activity, and decreased NgR expression compared with nontreated controls. TO901317 also significantly increased neurite outgrowth, and inhibition of the PI3K/Akt pathway by LY294002 decreased neurite outgrowth in both controls and TO901317-treated groups in cultured hypoxic PCN. These data indicate that TO901317 promotes synaptic plasticity and axonal regeneration, and that PI3K/Akt signaling activity contributes to neurite outgrowth.
Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 09/2009; 30(1):102-9. · 5.46 Impact Factor
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ABSTRACT: Marrow stromal cells (MSCs) are capable of differentiating into various cell types including endothelial cells. Microenvironment is important in cell fate determination. Tumor necrosis factor-alpha converting enzyme (TACE), a well-characterized "sheddase," participates in the differentiation process of multiple lineages by the proteolytic release of membrane-bound proteins such as tumor necrosis factor-alpha (TNF-alpha). We investigated the endothelial differentiation of MSCs under two coculture conditions: 1) direct MSCs-rat brain microvascular endothelial cells (rBMECs) contact coculture; and 2) indirect coculture of MSCs and rBMECs. Also, we examined the role of TACE/TNF-alpha signaling in the process of differentiation under direct coculture condition. We found that endothelial differentiation of MSCs was substantially enhanced in MSCs-rBMECs direct contact coculture, but not in indirect transwell coculture condition. Transcript levels of TACE and TNF-alpha as well as TACE protein expression were significantly upregulated in direct, but not in indirect, coculture condition. Addition of human recombinant TACE promoted gene expression of endothelial specific markers including vWF, CD31, VE-cadherin, Flk-1, and Flt-1 in the differentiating MSCs. Furthermore, inhibition of TACE with TAPI-2 or inhibition of TNF-alpha with Etanercept attenuated endothelial differentiation of MSCs in the direct coculture condition. We demonstrated for the first time that direct MSCs-rBMECs interaction stimulated the endothelial differentiation of MSCs via TACE/TNFalpha signaling.
Cell Transplantation 09/2009; 19(1):43-53. · 5.13 Impact Factor
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ABSTRACT: We investigated the additive therapeutic effect of the combination treatment of stroke with sub-therapeutic doses of Simvastatin, a HMG-CoA reductase inhibitor, and bone marrow stromal cells (BMSCs). Rats were administered Simvastatin (0.5 mg/kg), BMSCs (1x10(6)) or combination of Simvastatin and BMSCs starting at 24 h after stroke. Combination treatment significantly improved neurological outcome, enhanced angiogenesis and arteriogenesis, and increased the number of engrafted-BMSCs in the ischemic brain. The number of engrafted-BMSCs and arteriogenesis was significantly correlated with functional outcome. Simvastatin significantly increased stromal cell-derived factor-1 (SDF1) expression in the ischemic brain and chemokine (CXC motif) receptor-4 (CXCR4) in BMSCs, and increased BMSC migration to RBMECs and astrocytes. Combination treatment of stroke upregulates the SDF1/CXCR4 axis and enhances BMSC migration into the ischemic brain, amplifies arteriogenesis and angiogenesis, and improves functional outcome after stroke.
Neurobiology of Disease 08/2009; 36(1):35-41. · 5.40 Impact Factor
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ABSTRACT: TO901317, a synthetic liver X receptor agonist, elevates high-density lipoprotein cholesterol (HDL-C) in mice. We tested the hypothesis that TO901317 treatment of stroke promotes angiogenesis and vascular maturation and improves functional outcome after stroke by increasing endothelial nitric oxide synthase (eNOS) phosphorylation.
C57BL/6J mice were subjected to middle cerebral artery occlusion and were treated with or without TO901317 (30 mg/kg) starting 24 hours after middle cerebral artery occlusion and daily for 14 days.
TO901317 significantly increased serum HDL-C level, promoted angiogenesis and vascular stabilization in the ischemic brain, and improved functional outcome after stroke. The increased HDL-C level significantly correlated with functional recovery after stroke. TO901317 also increased eNOS phosphorylation in the ischemic brain. Mechanisms underlying the TO901317-induced angiogenesis were investigated using eNOS knockout (eNOS-/-) mice. TO901317 treatment of eNOS-/- mice significantly increased HDL-C level but failed to increase angiogenesis and functional outcome after stroke. In vitro studies demonstrated that TO901317 and HDL-C significantly increased capillary tube formation and promoted eNOS phosphorylation activity in cultured mouse brain endothelial cells compared with nontreatment controls. However, TO901317 and high-density lipoprotein treatment-induced capillary tube formation were absent in eNOS-deficient mouse brain endothelial cell.
These data indicate that TO901317 treatment increases serum HDL-C level, which promotes angiogenesis through eNOS and leads to improvement of functional outcome after stroke.
Stroke 06/2009; 40(7):2532-8. · 5.73 Impact Factor
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ABSTRACT: We tested the hypothesis that Niaspan (a prolonged release formulation of niacin) increases tumor necrosis factor-alpha-converting enzyme (TACE) expression and Notch signaling activity and promotes arteriogenesis after stroke. Rats were subjected to middle cerebral artery occlusion and were treated with or without Niaspan. Niaspan significantly elevated local cerebral blood flow, and increased arteriogenesis as indicated by increased arterial diameter and vascular smooth muscle cell (VSMC) proliferation in the ischemic brain after stroke. The increased arteriogenesis significantly correlated with the functional outcome after stroke. Niaspan treatment of stroke upregulated TACE, Notch1, and Notch intracellular domain expression in the ischemic brain. To further investigate the mechanisms of Niaspan-induced arteriogenesis, a primary brain arterial culture was used. Niacin treatment significantly increased arterial sprouting and VSMC migration compared with control nontreated arterial cells. Inhibition of TACE by the TACE inhibitor or knockdown of TACE gene expression in brain arterial culture significantly attenuated Niacin-induced arterial sprouting and VSMC migration. In addition, TACE treatment of arterial culture significantly increased arterial VSMC migration and arterial sprouting. Knockdown of Notch1 marginally decreased arterial sprouting and VSMC migration compared with scrambled control. Niaspan promotes arteriogenesis, which is mediated, in part, by TACE.
Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 02/2009; 29(5):911-20. · 5.46 Impact Factor
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ABSTRACT: Bone marrow stromal cells (BMSCs) are capable of differentiating into multiple cell lineages including endothelial cells. Simvastatin, an HMG-CoA reductase inhibitor that is used as a cholesterol-lowering agent, promotes endothelial differentiation from epithelial progenitor cells (EPC). The Notch signaling pathway, which plays a key role in multiple cell functions such as differentiation, proliferation, and apoptosis, can be regulated by simvastatin. Therefore, we examined the effect of simvastatin on BMSC differentiation into endothelial cells and the underlying mechanisms involved in this process. We observed that simvastatin stimulation of rat BMSCs resulted in significantly increased expression of endothelial-specific genes and proteins, including von Willebrand factor (vWF), CD31, vascular endothelial-cadherin (VE-cadherin), vascular endothelial growth factor receptor-2 (VEGFR2, Flk-1), and VEGF receptor 1 (VEGFR-1, Flt-1). Simvastatin also significantly increased capillary tubelike formation of the BMSCs. In addition, the intracellular cleavage of Notch (NICD) was markedly enhanced by simvastatin in BMSCs. Incubation of BMSCs with a gamma-secretase inhibitor, or Notch1 small interfering RNA (siRNA) that significantly inhibited the formation of NICD, blocked the expression of endothelial-specific markers in BMSCs and their differentiation into functional endothelial cells. These data suggest that simvastatin induces rat BMSCs differentiation into endothelial cells via a Notch signaling pathway.
AJP Cell Physiology 01/2009; 296(3):C535-43. · 3.54 Impact Factor
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ABSTRACT: Notch signaling activity regulates arteriogenesis. Presenilin 1 (PS1) mediates Notch signaling activity via cleavage of Notch, liberating Notch intracellular domain (NICD). We tested the hypothesis that simvastatin enhances arteriogenesis after stroke by increasing PS1 activation of the Notch signaling pathway.
Rats were subjected to middle cerebral artery occlusion (MCAo) and treated with or without simvastatin (1 mg/kg) starting 24 hours after stroke and daily for 7 days; they were euthanized 14 days after stroke. Immunostaining, Western blot, and real-time polymerase chain reaction assays were performed.
Simvastatin significantly increased arterial diameter, density, and vascular smooth muscle cell proliferation, and upregulated PS1, Notch1, and NICD expression in the ischemic border tissue and in the cerebral arteries compared with MCAo control rats, respectively. However, simvastatin did not increase arteriogenesis, PS1, and NICD expression in sham control animals. To investigate the mechanisms of simvastatin-induced arteriogenesis, primary cerebral artery cultures were used. Rats were subjected to MCAo and treated with or without simvastatin daily for 7 days. The cerebral arteries derived from these stroke rats were cultured in matrigel and treated with or without a gamma40-secretase inhibitor II, which blocks Notch signaling activity, inhibiting NICD production. Arterial cell migration was measured. simvastatin treatment significantly increased arterial cell migration compared to control MCAo artery, whereas inhibition of Notch signaling activity by the gamma40-secretase inhibitor II significantly attenuated simvastatin-induced arterial cell migration.
These data indicate that simvastatin increases arteriogenesis after stroke, and that simvastatin upregulation of PS1 expression and Notch signaling activity may facilitate an increase in arteriogenesis.
Stroke 11/2008; 40(1):254-60. · 5.73 Impact Factor
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ABSTRACT: We tested the hypothesis that a nitric oxide donor, DETA-NONOate, up-regulates stromal cell-derived factor-1 (SDF1) and angiopoietin 1 (Ang1) in the ischemic brain and their respective receptors chemokine CXC motif receptor 4 (CXCR4) and Tie2 in the subventricular zone (SVZ) and thereby promote SVZ neuroblast cell migration after stroke. C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAo), and 24 hr later DETA-NONOate (0.4 mg/kg) or phosphate-buffered solution was intravenously administered. Mice were sacrificed at 14 days for histological assessment or sacrificed at 3 days for analysis by real-time polymerase chain reaction and migration after MCAo. To elucidate whether SDF1/CXCR4 and Ang1/Tie2 pathways mediate DETA-NONOate-induced SVZ migration after stroke, SDF1alpha, Ang1 peptide, a specific antagonist of CXCR4 (AMD3100), and a neutralizing antibody of Tie2 (anti-Tie2) were used in vitro. DETA-NONOate significantly increased the percentage area of doublecortin (DCX, a marker of migrating neuroblasts)-immunoreactive cells in the SVZ and ischemic boundary zone. DETA-NONOate significantly increased the expression of SDF1 and Ang1 in the ischemic border and up-regulated CXCR4 and Tie2 in the SVZ compared with MCAo control. DCX-positive cell migration from SVZ explants was significantly increased in the DETA-NONOate treatment group compared with MCAo-alone animals. In vitro, SDF1alpha and Ang1 significantly increased SVZ explants cell migration. In addition, inhibition of CXCR4 or Tie2 significantly attenuated DETA-NONOate-induced SVZ cell migration. Our data indicate that treatment of stroke with a nitric oxide donor up-regulates SDF1/CXCR4 and Ang1/Tie2 pathways and thereby likely increases SVZ neuroblast cell migration.
Journal of Neuroscience Research 09/2008; 87(1):86-95. · 2.74 Impact Factor
