Vascular endothelial growth factor improves recovery of sensorimotor and cognitive deficits after focal cerebral ischemia in the rat

VEGF Modulates the Neural Dynamics of Hippocampal Subregions in Chronic Global Cerebral Ischemia Rats

Theta and gamma rhythms in hippocampus are important to cognitive performance. The cognitive impairments following cerebral ischemia is linked with the dysfunction of theta and gamma oscillations. As the primary mechanism for learning and memory, synaptic plasticity is in connection with these neural oscillations. Although vascular endothelial growth factor (VEGF) is thought to protect synaptic function in the ischemia rats to relieve cognitive impairment, little has been done on its effect of neural dynamics with this process. The present study investigated whether the alternation of neural oscillations in the hippocampus of ischemia rats is one of the potential neuroprotective mechanisms of VEGF. Rats were treated with the intranasal administration of VEGF at 72 h following chronic global cerebral ischemia procedure. Then local field potentials (LFPs) in hippocampal CA1 and CA3 regions were recorded and analyzed. Our results showed that VEGF can improve the power of theta and gamma rhythms in CA1 region after ischemia. Chronic global cerebral ischemia reduced the theta-gamma phase-amplitude coupling (PAC) not only within CA1 area but also in the pathway from CA3 to CA1, while VEGF alleviated the decreased coupling strength. Despite these notable differences, there were no obvious changes in the PAC within CA3 region. Surprisingly, the ischemia state did not affect the phase-phase interaction of hippocampus. In conclusion, our findings demonstrated that VEGF enhanced the theta-gamma PAC strength of CA3-CA1 pathway in ischemia rats, which may futher improve the information transmission within the hippocampus. These results illustrated the potential electrophysiologic mechanism of VEGF on cognitive improvement.

Neurocognition and social cognition in remitted first-episode schizophrenia: correlation with VEGF serum levels

BACKGROUND

Accumulating evidence suggests that serum vascular endothelial growth factor (VEGF) in many neurobiological processes potentially contributes to the pathophysiology of psychiatric disorders, particularly cognitive decline. The purpose of this study was to explore the differences in neurocognition, social cognition and VEGF among remitted first-episode schizophrenic patients, non-remitters and normal control subjects. Moreover, we investigated the association between serum VEGF levels and cognitive functions.

METHOD

65 remission (RS) and 45 nonremission patients (NRS) after first-episode schizophrenia, as well as 58 healthy controls (HC) were enrolled in this study. Social cognition was assessed using the Chinese Facial Emotion Test (CFET); neurocognition was measured with a test battery consisting of Hopkins Verbal Learning Test-Revised, Verbal Fluency Test, Trail Making Tests, Digit Span Tests (DST) and Stroop Tests. Blood samples were collected for VEGF measurements. Data was analyzed with SPSS 22.0 (Chicago, IL, USA).

RESULTS

On nearly all neurocognitive tests (except for DST), RS performed significantly worse than HC but better than NRS (P < 0.05). NRS, but not RS, exhibited markedly poorer social cognition than HC (except for Happiness and Surprise subscales of the CFET) (P < 0.05). VEGF levels showed a gradient change among three groups (HC > RS > NRS).

CONCLUSION

Compared to HC, RS demonstrated poorer neurocognitive but intact social cognition functioning. These results indicate that VEGF levels decreased gradually with the severity of cognitive impairment in schizophrenia. VEGF may be involved in the pathological mechanism of cognitive performance in RS.

Icariin and mesenchymal stem cells synergistically promote angiogenesis and neurogenesis after cerebral ischemia via PI3K and ERK1/2 pathways

Mesenchymal stem cells (MSCs) are one promising candidate for regenerative therapy of ischaemic stroke through transdifferetiation and paracrine actions. Icariin (ICA) has shown great potential in improving cell activity and VEGF, BDNF secretion in vitro. Whether they will synergistically improve therapy effect on cerebral ischemia is unknown. In this study, male SD rats were subjected to transient middle cerebral artery occlusion (MCAO) followed by reperfusion and ICA/MSC treatment. Results showed that ICA and MSCs combined treatment greatly reduced brain infarction volume, improved neurologic deficits of motor and somatosensory function and neurobehavioral outcomes. The combined therapy increased expression of VEGF and BDNF to a maximum through activating PI3K and ERK1/2 pathways in the hippocampus and frontal cortex in response to transient MCAO. They notably promoted angiogenesis and neurogenesis in vivo. Thus, ICA and MSCs combined treatment may represent a feasible approach for improving the beneficial effects of stem cell therapy for cerebral ischemia.

The Role of Capillaries in the Lesser Ailments of Old Age and in Alzheimer's Disease and Vascular Dementia: The Potential of Pro-Therapeutic Angiogenesis

Apart from chronic diseases (arthritis, diabetes, etc.), old age is generally characterized by three lesser ailments: muscle weakness, minor memory lapses, and cold intolerance. This trio of complaints may have a common, underlying cause, namely, the age-associated reduced microcirculation in muscles, brain, skin, and elsewhere in the body. The Angiogenesis Hypothesis proposes that old age is in part a deficiency disease due to the decline in angiogenic (AG) factors, resulting in a reduced capillary density (CD) throughout the body. Over fifty published papers document waning levels of AG factors and/or decreased CD in various organ systems of aged animals and people, including those with Alzheimer's disease. The deficiency of AG factors is analogous to that of certain hormones (e.g., testosterone) whose blood levels also decline with age. In theory, therapeutic angiogenesis employing recombinant AG factors is a tenable treatment for the lesser ailments of old age and may improve the later years of human life. An optimal administration route may be intranasal.

VEGF-Mediated Cognitive and Synaptic Improvement in Chronic Cerebral Hypoperfusion Rats Involves Autophagy Process

Chronic cerebral hypoperfusion (CCH) is associated with various neurodegenerative diseases characterized by cognitive impairment. Dozens of studies including ours have indicated that exogenous administration of vascular endothelial growth factor (VEGF) could exert effective cognitive protection during ischemia. Nevertheless, the underlying mechanism has not been well clarified. To address this issue, we explored the synaptic mechanisms in vivo since hippocampal synaptic function is essential to the learning and memory process. Besides, the role of autophagy in cognitive dysfunction under conditions of CCH is still controversial. And abnormal autophagy could threaten normal neurotransmission at synapse where a large amount of protein synthesis and degradation take place. Hence, we further examined whether the altered synaptic function was associated with autophagy. The results showed that CCH impaired spatial cognition as evidenced in Morris water maze. We further found that VEGF mitigated impaired hippocampal synaptic function including basal synaptic transmission, paired-pulse facilitation, short-term, long-term plasticity, depotentiation, and the level of synaptic proteins as assessed by electrophysiological examination and western blot assay. Furthermore, our results demonstrated that CCH could induce excessive autophagy which could be inhibited by VEGF. Thus, we speculated that VEGF could ameliorate impaired synaptic function induced by CCH because of its ability to inhibit excessive autophagy, and eventually improve spatial learning and memory function. Importantly, our findings shed light on potential therapeutic strategies to be exploited in the usage of VEGF.

Help-me signaling: Non-cell autonomous mechanisms of neuroprotection and neurorecovery

Self-preservation is required for life. At the cellular level, this fundamental principle is expressed in the form of molecular mechanisms for preconditioning and tolerance. When the cell is threatened, internal cascades of survival signaling become triggered to protect against cell death and defend against future insults. Recently, however, emerging findings suggest that this principle of self-preservation may involve not only intracellular signals; the release of extracellular signals may provide a way to recruit adjacent cells into an amplified protective program. In the central nervous system where multiple cell types co-exist, this mechanism would allow threatened neurons to "ask for help" from glial and vascular compartments. In this review, we describe this new concept of help-me signaling, wherein damaged or diseased neurons release signals that may shift glial and vascular cells into potentially beneficial phenotypes, and help remodel the neurovascular unit. Understanding and dissecting these non-cell autonomous mechanisms of self-preservation in the CNS may lead to novel opportunities for neuroprotection and neurorecovery.

The role of vascular endothelial growth factor in the regulation of development and functioning of the brain: new target molecules for pharmacotherapy

Vascular endothelial growth factors (VEGFs) have been shown to participate in atherosclerosis, arteriogenesis, cerebral edema, neuroprotection, neurogenesis, angiogenesis, postischemic brain and vessel repair. Most of these actions involve VEGF-A and the VEGFR-2 receptor. VEGF signaling pathways represent an important potential for treatment of neurological diseases affecting the brain

Intracerebral hemorrhage and cognitive impairment

Vascular cognitive impairment and vascular dementia are composed of cognitive deficits resulted from a range of vascular lesions and pathologies, including both ischemic and hemorrhagic. However the contribution of spontaneous intracerebral hemorrhage presumed due to small vessel diseases on cognitive impairment is underestimated, in contrast to the numerous studies about the role of ischemic vascular disorders on cognition. In this review we summarize recent findings from clinical studies and appropriate basic science research to better elucidate the role and possible mechanisms of intracerebral hemorrhage in cognitive impairment and dementia. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

Ginsenoside Rd promotes neurogenesis in rat brain after transient focal cerebral ischemia via activation of PI3K/Akt pathway

AIM

To investigate the effects of ginsenoside Rd (Rd) on neurogenesis in rat brain after ischemia/reperfusion injury (IRI).

METHODS

Male SD rats were subjected to transient middle cerebral artery occlusion (MCAO) followed by reperfusion. The rats were injected with Rd (1, 2.5, and 5 mg·kg(-1)·d(-1), ip) from d 1 to d 3 after MCAO, and with BrdU (50 mg·kg(-1)·d(-1), ip) from d 3 to d 6, then sacrificed on 7 d. The infarct size and neurological scores were assessed. Neurogenesis in the brains was detected by BrdU, DCX, Nestin, and GFAP immunohistochemistry staining. PC12 cells subjected to OGD/reperfusion were used as an in vitro model of brain ischemia. VEGF and BDNF levels were assessed with ELISA, and Akt and ERK phosphorylation was measured using Western blotting.

RESULTS

Rd administration dose-dependently decreased the infarct size and neurological scores in the rats with IRI. The high dose of Rd 5 (mg·kg(-1)·d(-1)) significantly increased Akt phosphorylation in ipsilateral hemisphere, and markedly increased the number of BrdU/DCX and Nestin/GFAP double-positive cells in ischemic area, which was partially blocked by co-administration of the PI3 kinase inhibitor LY294002. Treatment with Rd (25, 50, and 100 μmol/L) during reperfusion significantly increased the expression of VEGF and BDNF in PC12 cells with IRI. Furthermore, treatment with Rd dose-dependently increased the phosphorylation of Akt and ERK, and significantly decreased PC12 cell apoptosis, which were blocked by co-application of LY294002.

CONCLUSION

Rd not only attenuates ischemia/reperfusion injury in rat brain, but also promotes neurogenesis via increasing VEGF and BDNF expression and activating the PI3K/Akt and ERK1/2 pathways.

Systematic review and meta-analysis of efficacy of mesenchymal stem cells on locomotor recovery in animal models of traumatic brain injury

Introduction

The therapeutic potential of mesenchymal stem cells (MSCs) for traumatic brain injury (TBI) is attractive. Conducting systematic review and meta-analyses based on data from animal studies can be used to inform clinical trial design. To conduct a systematic review and meta-analysis to (i) systematically review the literatures describing the effect of MSCs therapy in animal models of TBI, (ii) determine the estimated effect size of functional locomotor recovery after experimental TBI, and (iii) to provide empirical evidence of biological factors associated with greater efficacy.

Methods

We conducted a systematic search of PubMed, EMBASE, and Web of Science and hand searched related references. Studies were selected if they reported the efficacy of MSCs in animal models of TBI. Two investigators independently assessed the identified studies. We extracted the details of individual study characteristics from each publication, assessed study quality, evaluated the effect sizes of MSCs treatment, and performed stratified meta-analysis and meta-regression, to assess the influence of study design on the estimated effect size. The presence of small effect sizes was investigated using funnel plots and Egger’s tests.

Results

Twenty-eight eligible controlled studies were identified. The study quality was modest. Between-study heterogeneity was large. Meta-analysis showed that MSCs exert statistically significant positive effects on sensorimotor and neurological motor function. For sensorimotor function, maximum effect size in studies with a quality score of 5 was found in the weight-drop impact injury TBI model established in male SD rats, to which syngeneic umbilical cord-derived MSCs intracerebrally at cell dose of (1–5) × 10⁶ was administered r 6 hours following TBI, using ketamine as anesthetic agent. For neurological motor function, effect size was maximum for studies with a quality score of 5, in which the weight-drop impact injury TBI models of the female Wistar rats were adopted, with administration syngeneic bone marrow-derived MSCs intravenously at cell dose of 5 × 10⁶ at 2 months after TBI, using sevofluorane as anesthetic agent.

Conclusions

We conclude that MSCs therapy may improve locomotor recovery after TBI. However, additional well-designed and well-reported animal studies are needed to guide further clinical studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0034-0) contains supplementary material, which is available to authorized users.

Effects of ischemic preconditioning on VEGF and pFlk-1 immunoreactivities in the gerbil ischemic hippocampus after transient cerebral ischemia

Ischemia preconditioning (IPC) displays an important adaptation of the CNS to sub-lethal ischemia. In the present study, we examined the effect of IPC on immunoreactivities of VEGF-, and phospho-Flk-1 (pFlk-1) following transient cerebral ischemia in gerbils. The animals were randomly assigned to four groups (sham-operated-group, ischemia-operated-group, IPC plus (+) sham-operated-group, and IPC+ischemia-operated-group). IPC was induced by subjecting gerbils to 2 min of ischemia followed by 1 day of recovery. In the ischemia-operated-group, a significant loss of neurons was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) alone 5 days after ischemia-reperfusion, however, in all the IPC+ischemia-operated-groups, pyramidal neurons in the SP were well protected. In immunohistochemical study, VEGF immunoreactivity in the ischemia-operated-group was increased in the SP at 1 day post-ischemia and decreased with time. Five days after ischemia-reperfusion, strong VEGF immunoreactivity was found in non-pyramidal cells, which were identified as pericytes, in the stratum oriens (SO) and radiatum (SR). In the IPC+sham-operated- and IPC+ischemia-operated-groups, VEGF immunoreactivity was significantly increased in the SP. pFlk-1 immunoreactivity in the sham-operated- and ischemia-operated-groups was hardly found in the SP, and, from 2 days post-ischemia, pFlk-1 immunoreactivity was strongly increased in non-pyramidal cells, which were identified as pericytes. In the IPC+sham-operated-group, pFlk-1 immunoreactivity was significantly increased in both pyramidal and non-pyramidal cells; in the IPC+ischemia-operated-groups, the similar pattern of VEGF immunoreactivity was found in the ischemic CA1, although the VEGF immunoreactivity was strong in non-pyramidal cells at 5 days post-ischemia. In brief, our findings show that IPC dramatically augmented the induction of VEGF and pFlk-1 immunoreactivity in the pyramidal cells of the CA1 after ischemia-reperfusion, and these findings suggest that the increases of VEGF and Flk-1 expressions may be necessary for neurons to survive from transient ischemic damage.

In vivo bioluminescence imaging of vascular remodeling after stroke

Thrombolysis remains the only beneficial therapy for ischemic stroke, but is restricted to a short therapeutic window following the infarct. Currently research is focusing on spontaneous regenerative processes during the sub-acute and chronic phase. Angiogenesis, the formation of new blood vessels from pre-existing ones, was observed in stroke patients, correlates with longer survival and positively affects the formation of new neurons. Angiogenesis takes place in the border zones of the infarct, but further insight into the temporal profile is needed to fully apprehend its therapeutic potential and its relevance for neurogenesis and functional recovery. Angiogenesis is a multistep process, involving extracellular matrix degradation, endothelial cell proliferation, and, finally, new vessel formation. Interaction between vascular endothelial growth factor and its receptor 2 (VEGFR2) plays a central role in these angiogenic signaling cascades. In the present study we investigated non-invasively the dynamics of VEGFR2 expression following cerebral ischemia in a mouse model of middle cerebral artery occlusion (MCAO). We used a transgenic mouse expressing firefly luciferase under the control of the VEGFR2 promotor to non-invasively elucidate the temporal profile of VEGFR2 expression after stroke as a biomarker for VEGF/VEGFR2 signaling. We measured each animal repetitively up to 2 weeks after stroke and found increased VEGFR2 expression starting 3 days after the insult with peak values at 7 days. These were paralleled by increased VEGFR2 protein levels and increased vascular volume in peri-infarct areas at 14 days after the infarct, indicating that signaling via VEGFR2 leads to successful vascular remodeling. This study describes VEGFR2-related signaling is active at least up to 2 weeks after the infarct and results in increased vascular volume. Further, this study presents a novel strategy for the non-invasive evaluation of angiogenesis-based therapies.

Delayed VEGF treatment enhances angiogenesis and recovery after neonatal focal rodent stroke

Neonatal stroke occurs in one in 4,000 live births and leads to significant morbidity and mortality. Approximately two thirds of the survivors have long-term sequelae including seizures and neurological deficits. However, the pathophysiological mechanisms of recovery after neonatal stroke are not clearly understood, and preventive measures and treatments are nonexistent in the clinical setting. In this study, we investigated the effect of vascular endothelial growth factor (VEGF) treatment on histological recovery and angiogenic response to the developing brain after an ischemic insult. Ten-day-old Sprague-Dawley rats underwent right middle cerebral arterial occlusion (MCAO) for 1.5 h. Diffusion-weighted MRI during occlusion confirmed focal ischemia that was then followed by reperfusion. On group of animals received 5-bromo-2-deoxyuridine and sacrificed at postnatal day (P)18 or P25. A second group of animals was treated with VEGF (1.5 µg/kg, icv) or phosphate-buffered saline (PBS) at P18 and perfusion fixed at P25. Based on Nissl and iron staining, a single VEGF injection reduced the injury score, compared to the animals that underwent MCAO and PBS injection. Furthermore, neurodegeneration represented by neuronal nuclei staining was markedly diminished. In addition, animals treated with VEGF revealed a positive trend in endothelial proliferation and a significant increase in total vessel volume in the peri-infarct region of the caudate. The number of Iba1-positive microglial cells was significantly reduced after a single VEGF injection, and myelin basic protein expression was enhanced in the caudate after ischemia without an effect of VEGF treatment. In conclusion, delayed treatment with VEGF ameliorates injury, promotes endothelial cell proliferation, and increases total vascular volume following neonatal stroke. These results suggest that VEGF has a neuroprotective effect, in part by enhancing endogenous angiogenesis. These data contribute to a better understanding of neonatal stroke.

Perlecan domain V inhibits amyloid-β induced brain endothelial cell toxicity and restores angiogenic function

In Alzheimer's disease (AD), amyloid-β (Aβ) deposits in the cerebrovasculature can result in neurovascular dysfunction and/or cerebral amyloid angiopathy. The accumulation of Aβ in blood vessels can cause endothelial cell damage, resulting in impaired Aβ clearance by the blood-brain barrier. Additionally, impaired endothelial cell function can result in decreased angiogenesis in the brains of AD patients, affecting cognitive function. VEGF is a crucial mediator of angiogenesis and is deficient in AD brains thus promoting angiogenesis could be an important component of successful AD treatment. The C-terminal portion of the extracellular matrix proteoglycan perlecan, Domain V (DV), promotes brain-derived endothelial cell proliferation and is proangiogenic in that it increases VEGFR2 expression and production of VEGF. In this study, we show that Aβ25-35 reduces proliferation of a mouse brain microvascular endothelial cell line (MBEC) in vitro and that DV and mouse LG3 (C-terminal fragment of DV) block these effects of Aβ25-35. Additionally, we show that DV restores the ability of MBECs to form tube-like structures on Matrigel in the presence of Aβ25-35 and that this is α5β1 dependent. Interestingly, the reduction in tube-like structure formation by Aβ25-35 was not due to endothelial cell death, suggesting that Aβ25-35 induces the downregulation of a cell surface molecule required for adhesion events critical to the angiogenic process. We propose a model suggesting that DV works through both the α5β1 integrin receptor and VEGFR2 to increase VEGF production, causing competition with Aβ25-35 for VEGFR2 binding, thus ultimately increasing VEGF expression and restoring angiogenesis. This supports DV as a potential anti-amyloid therapy.

VEGF ameliorates cognitive impairment in in vivo and in vitro ischemia via improving neuronal viability and function

Vascular endothelial growth factor (VEGF) has recently been proved to be a potential therapeutic drug in ischemic disorders depending on the dose, route and time of administration, especially in focal cerebral ischemia. Whether VEGF could exert protection in a long-term total cerebral ischemic model is still uncertain, and the cellular mechanism has not been clarified so far. In order to answer the above issue, an experiment was performed in non-invasively giving exogenous VEGF to a total cerebral ischemic model rats and examining their spatial cognitive function by performing Morris water maze and long-term potential test. Moreover, we performed in vitro experiment to explore the cellular mechanism of VEGF protection effect. In an in vitro ischemia model oxygen-glucose deprivation (OGD), whole-cell patch-clamp recording was employed to examine neuronal function. Additionally, hematoxylin-eosin and propidium iodide staining were applied in vivo and in vitro in the neuropathological and viability study, separately. Our results showed that intranasal administration of VEGF could improve the cognitive function, synaptic plasticity and damaged hippocampal neurons in a global cerebral ischemia model. In addition, VEGF could retain the membrane potential, neuronal excitability and spontaneous excitatory postsynaptic currents in the early stage of ischemia, which further demonstrated that there was an acute effect of VEGF in OGD-induced pyramidal neurons. Simultaneously, it was also found that the death of CA1 pyramidal neuronal was significantly reduced by VEGF, but there was no similar effect in VEGF coexists with SU5416 group. These results indicated that VEGF could ameliorate cognitive impairment and synaptic plasticity via improving neuronal viability and function through acting on VEGFR-2.

Protection of Vascular Endothelial Growth Factor to Brain Edema Following Intracerebral Hemorrhage and Its Involved Mechanisms: Effect of Aquaporin-4

Vascular endothelial growth factor (VEGF) has protective effects on many neurological diseases. However, whether VEGF acts on brain edema following intracerebral hemorrhage (ICH) is largely unknown. Our previous study has shown aquaporin-4 (AQP4) plays an important role in brain edema elimination following ICH. Meanwhile, there is close relationship between VEGF and AQP4. In this study, we aimed to test effects of VEGF on brain edema following ICH and examine whether they were AQP4 dependent. Recombinant human VEGF165 (rhVEGF165) was injected intracerebroventricularly 1 d after ICH induced by microinjecting autologous whole blood into striatum. We detected perihemotomal AQP4 protein expression, then examined the effects of rhVEGF165 on perihemotomal brain edema at 1 d, 3 d, and 7 d after injection in wild type (AQP4^+/+) and AQP4 knock-out (AQP4^−/−) mice. Furthermore, we assessed the possible signal transduction pathways activated by VEGF to regulate AQP4 expression via astrocyte cultures. We found perihemotomal AQP4 protein expression was highly increased by rhVEGF165. RhVEGF165 alleviated perihemotomal brain edema in AQP4^+/+ mice at each time point, but had no effect on AQP4^−/− mice. Perihemotomal EB extravasation was increased by rhVEGF165 in AQP4^−/− mice, but not AQP4^+/+ mice. RhVEGF165 reduced neurological deficits and increased Nissl’s staining cells surrounding hemotoma in both types of mice and these effects were related to AQP4. RhVEGF165 up-regulated phospharylation of C-Jun amino-terminal kinase (p-JNK) and extracellular signal-regulated kinase (p-ERK) and AQP4 protein in cultured astrocytes. The latter was inhibited by JNK and ERK inhibitors. In conclusion, VEGF reduces neurological deficits, brain edema, and neuronal death surrounding hemotoma but has no influence on BBB permeability. These effects are closely related to AQP4 up-regulation, possibly through activating JNK and ERK pathways. The current study may present new insights to treatment of brain edema following ICH.

Hypoxia-inducible factor and vascular endothelial growth factor are targets of dietary soy during acute stroke in female rats

Dietary soy and soy isoflavones are neuroprotective in experimental cerebral ischemia. Because these isoflavones have estrogenic properties, we hypothesized that, like estrogens, they would inhibit acute vascular injury and the detrimental acute increase in hypoxia-induced vascular endothelial growth factor (VEGF) that leads to cerebral edema after stroke. Mature ovariectomized female Sprague Dawley rats were fed soy-free or soy-containing diets for 4 weeks followed by 90 minutes of transient middle cerebral artery occlusion. Similar to estrogens, dietary soy significantly reduced cerebral edema and vascular apoptosis 24 hours after stroke. Soy also inhibited the ischemia-induced increase in cortical VEGF and VEGF receptor (VEGFR)-2 protein expression observed 4 and 24 hours after stroke, although mRNA levels increased. The reduction in VEGF/VEGFR-2 was associated both with decreases in receptor phosphorylation and signaling to AKT and endothelial nitric oxide synthase. Furthermore degradation of the VEGFR-2 was increased with dietary soy. The primary ischemic stimulus for VEGF, hypoxia-inducible factor 1α (HIF1α), was similarly reduced by dietary soy 4 hours after transient middle cerebral artery occlusion in both the cortex and striatum. The inhibition of HIF1α activity was further confirmed by a significant decrease in the HIF1α-activated apoptotic mediator BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (Nip3-like protein X). These data suggest that soy isoflavones target events early in the ischemic cascade as part of their neuroprotective actions and counterbalance some of the detrimental effects of the endogenous response to cerebral injury.

Vascular endothelial growth factors (VEGFs) and stroke

Vascular endothelial growth factors (VEGFs) have been shown to participate in atherosclerosis, arteriogenesis, cerebral edema, neuroprotection, neurogenesis, angiogenesis, postischemic brain and vessel repair, and the effects of transplanted stem cells in experimental stroke. Most of these actions involve VEGF-A and the VEGFR-2 receptor, but VEGF-B, placental growth factor, and VEGFR-1 have been implicated in some cases as well. VEGF signaling pathways represent important potential targets for the acute and chronic treatment of stroke.

VEGF reverts the cognitive impairment induced by a focal traumatic brain injury during the development of rats raised under environmental enrichment

The role of VEGF in the nervous system is extensive; apart from its angiogenic effect, VEGF has been described as a neuroprotective, neurotrophic and neurogenic molecule. Similar effects have been described for enriched environment (EE). Moreover, both VEGF and EE have been related to improved spatial memory. Our aim was to investigate the neurovascular and cognitive effects of intracerebrally-administered VEGF and enriched environment during the critical period of the rat visual cortex development. Results showed that VEGF infusion as well as enriched environment induced neurovascular and cognitive effects in developing rats. VEGF administration produced an enhancement during the learning process of enriched animals and acted as an angiogenic factor both in primary visual cortex (V1) and dentate gyrus (DG) in order to counteract minipump implantation-induced damage. This fact revealed that DG vascularization is critical for normal learning. In contrast to this enriched environment acted on the neuronal density of the DG and V1 cortex, and results showed learning enhancement only in non-operated rats. In conclusion, VEGF administration only has effects if damage is observed due to injury. Once control values were reached, no further effects appeared, showing a ceiling effect. Our results strongly support that in addition to neurogenesis, vascularization plays a pivotal role for learning and memory.

Neuroprotection by hypoxic preconditioning involves upregulation of hypoxia-inducible factor-1 in a prenatal model of acute hypoxia

The molecular pathways underlying the neuroprotective effects of preconditioning are promising, potentially drugable targets to promote cell survival. However, these pathways are complex and are not yet fully understood. In this study we have established a paradigm of hypoxic preconditioning based on a chick embryo model of normobaric acute hypoxia previously developed by our group. With this model, we analyzed the role of hypoxia-inducible factor-1α (HIF-1α) stabilization during preconditioning in HIF-1 signaling after the hypoxic injury and in the development of a neuroprotective effect against the insult. To this end, we used a pharmacological approach, based on the in vivo administration of positive (Fe(2+), ascorbate) and negative (CoCl(2)) modulators of the activity of HIF-prolyl hydroxylases (PHDs), the main regulators of HIF-1. We have found that preconditioning has a reinforcing effect on HIF-1 accumulation during the subsequent hypoxic injury. In addition, we have also demonstrated that HIF-1 induction during hypoxic preconditioning is necessary to obtain an enhancement in HIF-1 accumulation and to develop a tolerance against a subsequent hypoxic injury. We provide in vivo evidence that administration of Fe(2+) and ascorbate modulates HIF accumulation, suggesting that PHDs might be targets for neuroprotection in the CNS.

Growth factors in ischemic stroke

Data from pre-clinical and clinical studies provide evidence that colony-stimulating factors (CSFs) and other growth factors (GFs) can improve stroke outcome by reducing stroke damage through their anti-apoptotic and anti-inflammatory effects, and by promoting angiogenesis and neurogenesis. This review provides a critical and up-to-date literature review on CSF use in stroke. We searched for experimental and clinical studies on haemopoietic GFs such as granulocyte CSF, erythropoietin, granulocyte-macrophage colony-stimulating factor, stem cell factor (SCF), vascular endothelial GF, stromal cell-derived factor-1α and SCF in ischemic stroke. We also considered studies on insulin-like growth factor-1 and neurotrophins. Despite promising results from animal models, the lack of data in human beings hampers efficacy assessments of GFs on stroke outcome. We provide a comprehensive and critical view of the present knowledge about GFs and stroke, and an overview of ongoing and future prospects.

VEGF-induced angiogenesis ameliorates the memory impairment in APP transgenic mouse model of Alzheimer's disease

Vascular endothelial growth factor (VEGF) was investigated in the present study to see whether it could provide a therapeutic opportunity for the treatment of Alzheimer's disease (AD). PDGF-hAPP(V717I) transgenic mice were treated with VEGF or PBS by intraperitoneal injection for three consecutive days. The results showed that VEGF ameliorated the memory impairment of mice, accompanied by CD34(+) cells increasing in peripheral blood, vWF(+) vessels increasing in hippocampus, and CD34(+)/VEGFR2(+), vWF(+)/VEGFR2(+) and BrdU(+)/vWF(+) cells expressing in hippocampus. Furthermore, the level of choline acetyltransferase (ChAT) was considerably enhanced and Aβ deposition was decreased in the brains of mice upon VEGF treatment. These observations suggest that VEGF should be pursued as a novel therapeutic agent for treatment of AD.

Neural stem cells modified by a hypoxia-inducible VEGF gene expression system improve cell viability under hypoxic conditions and spinal cord injury

STUDY DESIGN

An in vitro neural hypoxia model and rat spinal cord injury (SCI) model were used to assess the regulation of therapeutic vascular endothelial growth factor (VEGF) gene expression in mouse neural stem cells (mNSCs) by the EPO (erythropoietin) enhancer or RTP801 promoter.

OBJECTIVE

To increase VEGF gene expression in mNSCs under hypoxic conditions in SCI lesions but avoid unwanted overexpression of VEGF in normal sites, we developed a hypoxia-inducible gene expression system consisting of the EPO enhancer and RTP801 promoter fused to VEGF or the luciferase gene, then transfected into mNSCs.

SUMMARY OF BACKGROUND DATA

On the basis of the ischemic response in the injured area, poor cell survival at the transplantation site is a consistent problem with NSC transplantation after SCI. Although VEGF directly protects neurons and enhances neurite outgrowth, uncontrolled overexpression of VEGF in uninjured tissue may cause serious adverse effects. To effectively improve NSC survival in ischemic sites after transplantation, we evaluated mNSCs modified by a hypoxia-inducible VEGF gene expression system in an SCI model.

METHODS

Hypoxia-inducible luciferase or VEGF plasmids were constructed using the EPO enhancer or RTP801 promoter. The effect of these systems on targeted gene expression and cell viability was evaluated in mNSCs in both hypoxic in vitro injury and a rat SCI model in vivo.

RESULTS

The gene expression system containing the EPO enhancer or RTP801 promoter significantly increased the expression of the luciferase reporter gene and therapeutic VEGF gene under hypoxic conditions. The Epo-SV-VEGF plasmid transfection group had significantly fewer apoptotic cells in vitro. This system also augmented cell viability in the in vivo SCI model.

CONCLUSION

These results strongly suggest the potential utility of mNSCs modified by a hypoxia-inducible VEGF gene expression system in the development of effective stem cell transplantation protocols in SCI.

Acute hepatocyte growth factor treatment induces long-term neuroprotection and stroke recovery via mechanisms involving neural precursor cell proliferation and differentiation

Hepatocyte growth factor (HGF) is an interesting candidate for acute stroke treatment as shown by continuous infusion or gene delivery protocols. However, little is known about HGF-mediated long-term effects. The present study therefore analyzed long-term effects of an acute intrastriatal HGF treatment (5 μg) after a 45-minute stroke, with regard to brain injury and neurologic recovery. Hepatocyte growth factor induced long-term neuroprotection as assessed by infarct volume and neuronal cell death analysis for as long as 4 weeks after stroke, which was associated with sustained neurologic recovery as evidenced by corner-turn and tight-rope tests. Analyzing underlying mechanisms of HGF-induced sustained neuroprotection, enhanced cell proliferation followed by increased neuronal differentiation of neural precursor cells (NPCs) was observed in the ischemic striatum of HGF-treated mice, which persisted for up to 4 weeks. In line with this, HGF promoted neurosphere formation as well as proliferation of NPC and decreased caspase-3-dependent hypoxic injury in vitro. Preservation of blood-brain barrier integrity 24  hours after stroke was furthermore noticed in animals receiving HGF, which was associated with the inhibition of matrix metalloproteases (MMP)-2 and MMP-9 at 4 and 24  hours, respectively. We suggest that sustained recruitment of proliferating cells together with improved neurovascular remodeling provides an explanation for HGF-induced long-term neuroprotection.

The role of angiogenesis in damage and recovery from ischemic stroke

Ischemic stroke is burdened with a high morbidity and mortality in our society. However, there are few effective and largely available therapies for this devastating disease. In additon to advancing acute reperfusion therapies, there is a need to develop treatments aimed to promote repair and regeneration of brain tissue damaged by ischemia (neurorecovery). Therapeutic angiogenesis and vasculogenesis represent novel approaches of regenerative medicine that may help in the cure of patients with acute ischemic stroke. Translation of our knowledge about these processes from the bench to bedside is still underway. Although angiogenesis (the sprouting of new blood vessels from pre-existing vascular structures) is likely to contribute to neurorepair, the finality of the angiogenic response in acute ischemic stroke has not been fully elucidated. The first therapeutic approach to angiogenesis after ischemic stroke would be the modulation of the endogenous angiogenic response. In this setting, early instauration of physical activity, statins, and peroxisome proliferator-activated receptor-gamma agonists may enhance angiogenesis and neuroregeneration. Gene therapy with vascular growth factors has been successfully tested in patients affected by chronic myocardial and peripheral ischemia. Regarding brain ischemia, experiments in animal models have shown that the effect of these growth factors is critically affected by the dosage, route of delivery, and time of administration in relation to stroke onset. In addition, the optimal angiogenic substance is unknown. Finally, vectors for gene transfer should be further optimized. Therapeutic vasculogenesis consists of the administration of exogenous endothelial progenitor cells in order to enhance brain repair processes. Endothelial progenitor cells may be recruited in response to cerebral ischemia and participate in reparative vasculogenesis after acute ischemic stroke. Further research is needed to clarify their role and therapeutic applicability in human brain ischemia.

Neuroprotective effect of combined hypoxia-induced VEGF and bone marrow-derived mesenchymal stem cell treatment

PURPOSES

To avoid unwanted adverse effects of higher doses of single treatment of stem cells and gene therapy and increase the therapeutic efficacies, we hypothesized the combined therapy with stem cells and gene therapy. This study assessed the neuroprotective effects of combined gene therapy and stem cell treatment under ischemic hypoxia conditions using hypoxia-inducible vascular endothelial growth factor (VEGF) and bone marrow-derived mesenchymal stem cells (BMSC).

METHODS

Experimental groups included the control which was N2A cells transfected with empty vectors, the transfection only group which was N2A cells treated with pEpo-SV-VEGF alone, the BMSC only group which was N2A cells transfected with empty vectors and cocultured with BMSCs, and the combined treatment group which was N2A cells treated with pEpo-SV-VEGF and cocultured with BMSCs. Each group was transfected for 4 h and cultured at 37 degrees C and 5% CO2 for 24 h. Each group was then cultivated under hypoxic conditions (1% O2) for 12 h. Neuroprotective effects were assessed by reverse transcription polymerase chain reaction, annexin V, and cytotoxicity assay.

RESULTS

Neurons exposed to hypoxic conditions exhibited neuronal apoptosis. Compared to single treatments, the combined hypoxia-inducible VEGF and BMSC treatment demonstrated a significant increase in VEGF expression and decreased neuronal apoptosis.

CONCLUSIONS

These results suggest that combined pEpo-SV-VEGF and BMSC treatment is effective in protecting neurons against hypoxic ischemic injury.

Role of the oxygen-dependent degradation domain in a hypoxia-inducible gene expression system in vascular endothelial growth factor gene therapy

STUDY DESIGN.: An in vitro neural hypoxia model and rat spinal cord injury (SCI) model were used to assess the regulation effect of a reporter or therapeutic gene expression by an oxygen-dependent degradation (ODD) domain in a hypoxia-inducible gene expression system with or without the erythropoietin (EPO) enhancer. OBJECTIVE.: To increase vascular endothelial growth factor (VEGF) gene expression in SCI lesions but avoid unwanted overexpression of VEGF in normal sites, we developed a hypoxia-inducible gene expression system consisting of the EPO enhancer upstream of the SV promoter and an ODD domain C-terminally fused to VEGF. SUMMARY OF BACKGROUND DATA.: ODD domain plays a major role in the degradation of hypoxia-inducible factor 1alpha and has been used in a hypoxia-specific gene expression system as a post-translational regulatory factor. METHODS.: The hypoxia-inducible luciferase or VEGF plasmid was constructed using the EPO enhancer combined with or without the ODD domain. The constructed plasmid was transfected into mouse Neuro 2a (N2a) neuroblastoma cells by Lipofectamine 2000, followed by a 24-hour incubation in hypoxia or normoxia. For in vivo analysis, the naked plasmid DNA was directly injected into the injured rat spinal cord. The gene expression was evaluated by luciferase activity assay, enzyme-linked immunosorbent assay, reverse transcriptase-polymerase chain reaction, and immunofluorescence staining. RESULTS.: The EPO enhancer/ODD domain-combined hypoxia-inducible gene expression system clearly increased the expression of the reporter luciferase gene and therapeutic VEGF gene specifically under hypoxic conditions and SCI, and quickly downregulated protein expression to a very low level after reoxygenation. CONCLUSION.: These results strongly suggest the potential applicability of this EPO enhancer/ODD domain-based hypoxia-inducible gene expression system in the development of a safer and more effective VEGF gene therapy for SCI.

Pivotal role for beta-1 integrin in neurovascular remodelling after ischemic stroke

beta1 integrin is a cell surface molecule that is critical for endothelial cell adhesion, migration and survival during angiogenesis. In the present study we employed in vivo and in vitro models to elucidate the role of beta1 integrin in vascular remodelling and stroke outcomes. At 24 h after cerebral ischemia and reperfusion (I/R), the ischemic cortex (ipsilateral area) exhibited modest beta1 integrin immunoreactivity and a robust increase was observed at 72 h. Double-label immunohistochemical analysis for beta1 integrin with neuronal (NeuN), microglial (Iba-1), astrocyte (GFAP), progenitor cell (Ng2) and blood vessel (collagen 4) markers showed that beta1 integrin expression only localized to blood vessels. In vitro studies using cultured endothelial cells and a beta1 integrin blocking antibody confirmed that beta1 integrin is required for endothelial cell migration, proliferation and blood vessel formation. In vivo studies in the cerebral I/R model using the beta1 integrin blocking antibody further confirmed that beta1 integrin signaling is involved in vascular formation and recovery following ischemic stroke. Finally, we found that beta1 integrin is critically involved in functional deficits and survival after a stroke. These results suggest that beta1 integrin plays important roles in neurovascular remodelling and functional outcomes following stroke, and that targeting the beta1 integrin signalling may provide a novel strategy for modulating angiogenesis in ischemic stroke and other pathological conditions.

Role and therapeutic potential of VEGF in the nervous system

The development of the nervous and vascular systems constitutes primary events in the evolution of the animal kingdom; the former provides electrical stimuli and coordination, while the latter supplies oxygen and nutrients. Both systems have more in common than originally anticipated. Perhaps the most striking observation is that angiogenic factors, when deregulated, contribute to various neurological disorders, such as neurodegeneration, and might be useful for the treatment of some of these pathologies. The prototypic example of this cross-talk between nerves and vessels is the vascular endothelial growth factor or VEGF. Although originally described as a key angiogenic factor, it is now well established that VEGF also plays a crucial role in the nervous system. We describe the molecular properties of VEGF and its receptors and review the current knowledge of its different functions and therapeutic potential in the nervous system during development, health, disease and in medicine.

Glibenclamide improves neurological function in neonatal hypoxia-ischemia in rats

Recent studies demonstrated that sulfonylurea receptor 1 (SUR 1) regulated nonselective cation channel, the NC(Ca-ATP) channel, is involved in brain injury in rodent models of stroke. Block of SUR 1 with sulfonylurea such as glibenclamide has been shown to be highly effective in reducing cerebral edema, infarct volume and mortality in adult rat models of ischemic stroke. In this study, we tested glibenclamide in both severe and moderate models of neonatal hypoxia-ischemia (HI) in postnatal day 10 Sprague-Dawley rat pups. A total of 150 pups were used in the present study. Pups were subjected to unilateral carotid artery ligation followed by 2.5 or 2 h of hypoxia in the severe and moderate HI models, respectively. In the severe HI model, glibenclamide, administered immediately after HI and on postoperative Day 1, was not effective in attenuating short-term effects (brain edema and infarct volume) or long-term effects (brain weight and neurological function) of neonatal HI. In the moderate HI model, when injected immediately after HI and on postoperative Day 1, glibenclamide at 0.01 mg/kg improved several neurological parameters at 3 weeks after HI. We conclude that glibenclamide provided some long-term neuroprotective effect after neonatal HI.

Netrin-4 enhances angiogenesis and neurologic outcome after cerebral ischemia

Functional recovery after cerebral ischemia is mediated by the regeneration of vascular networks and the restoration of synaptic architecture. Netrins have been implicated in neuronal pathfinding and angiogenesis. In this study, we investigated the expression of Netrin-4 and its putative receptors, deleted in colorectal cancer (DCC), Unc5A, and Unc5B after distal middle cerebral artery occlusion in mice. Netrin-4 protein was also administered intracerebroventricularly to examine its effect on angiogenesis and behavioral recovery. Netrin-4 protein was highly upregulated in the ischemic core as soon as 1 day after cerebral ischemia, with subsequent downregulation after 1 week. Its expression was limited to the area of blood-brain barrier damage and was seen on both blood vessels and astrocytic foot processes. Although there was not a significant upregulation of the putative Netrin-4 receptor Unc5A and Unc5B, there was a significant increase in expression of the DCC receptor on neuronal processes in the peri-infarct cortex. Intracerebroventricular administration of Netrin-4 into the ischemic brain increased blood vessel density, endothelial proliferation, and improved behavioral recovery at 1 week after stroke, but did not have an effect on blood-brain barrier permeability or infarct size. These findings suggest that Netrin-4 may improve poststroke functional recovery by enhancing blood vessel proliferation.

Positron Emission Tomography Imaging of Poststroke Angiogenesis

Background and Purpose— Vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) play important roles during neurovascular repair after stroke. In this study, we imaged VEGFR expression with positron emission tomography (PET) to noninvasively analyze poststroke angiogenesis.

Methods— Female Sprague-Dawley rats after distal middle cerebral artery occlusion surgery were subjected to weekly MRI, 18 F-FDG PET, and 64 Cu-DOTA-VEGF 121 PET scans. Several control experiments were performed to confirm the VEGFR specificity of 64 Cu-DOTA-VEGF 121 uptake in the stroke border zone. VEGFR, BrdU, lectin staining, and 125 I-VEGF 165 autoradiography on stroke brain tissue slices were performed to validate the in vivo findings.

Results— T2-weighed MRI correlated with the “cold spot” on 18 F-FDG PET for rats undergoing distal middle cerebral artery occlusion surgery. The 64 Cu-DOTA-VEGF 121 uptake in the stroke border zone peaked at ≈10 days after surgery, indicating neovascularization as confirmed by histology (VEGFR-2, BrdU, and lectin staining). VEGFR specificity of 64 Cu-DOTA-VEGF 121 uptake was confirmed by significantly lower uptake of 64 Cu-DOTA-VEGF mutant in vivo and intense 125 I-VEGF 165 uptake ex vivo in the stroke border zone. No appreciable uptake of 64 Cu-DOTA-VEGF 121 was observed in the brain of sham-operated rats.

Conclusions— For the first time to our knowledge, we successfully evaluated the VEGFR expression kinetics noninvasively in a rat stroke model. In vivo imaging of VEGFR expression could become a significant clinical tool to plan and monitor therapies aimed at improving poststroke angiogenesis.

Direct transport of VEGF from the nasal cavity to brain

The aim of the present study was to assess the potential of delivering VEGF directly into the central nervous system (CNS) following intranasal administration. Adult Sprague-Dawley rats were randomized into two groups, given [(125)I]-VEGF intranasally or intravenously. VEGF was intranasally administered in both nares alternately, the single dose is 10 microl with time interval of 2 min for about 18.5 min. The intravenous (IV) group was treated with 100 microl [(125)I]-VEGF intravenously. Thirty minutes after administration, rats were killed following blood sample collections, then the brains were removed, and olfactory bulb, striatum corpora, cortex, thalamus, pons, cerebella, medulla, hippocampus, cervical cord and other tissues were collected, weighted, under auto gamma counting and autoradiography analysis. Cisternal sampling of cerebrospinal fluid (CSF) was performed in an additional group of animals. Both gamma counting and high resolution phosphor imaging of tissue sections showed that intranasal administration of [(125)I]-VEGF resulted in substantial delivery throughout the CNS. The highest CNS tissue concentration following IN delivery was found in the trigeminal nerve, followed by the optic nerve, olfactory bulbs, olfactory tubercle, striatum, medulla, frontal cortex, midbrain, pons, appendix cerebri, thalamus, hippocampus, cerebellum. Intranasal administration of [(125)I]-VEGF also targeted the deep cervical lymph nodes. CSF did not contain [(125)I]-VEGF following intranasal administration. Intravenous [(125)I]-VEGF resulted in blood and peripheral tissue exposure higher concentrations than that intranasal administration, but CNS concentrations were significantly lower. The results suggest intranasally delivered VEGF can bypass the blood-brain barrier via olfactory- and trigeminal-associated extracellular pathways to directly entry into the CNS. Intranasal administration of VEGF may provide an effective way for the treatments of CNS diseases.

VEGF overexpression improves mice cognitive abilities after unilateral common carotid artery occlusion

Angiogenesis and neurogenesis are adaptive responses protecting cerebral tissue from hypoxic-ischemic injury. Both processes seem to be governed by hypoxia-induced growth factors, of which vascular endothelial growth factor (VEGF) is a prominent example. The aim of this study was to investigate the influence of VEGF overexpression (V1 mice) on mice cognitive function and cerebral structure under moderate cerebral oligemia. In 33 V1 and wild-type (wt) mice, the left common carotid artery was permanently occluded (CCAO) under acute (48 h) and subchronic (12 days) conditions. Sham operation was performed in 35 mice (controls). Psychometric testing was done using holeboard test and Morris Water Maze system, immunohistochemistry was performed for detection of cerebral apoptosis, nestin and CD31 expression. The results show that under control conditions V1 mice showed better spatial cognitive abilities as compared to their wt littermates. During CCAO, time and distance to reach a hidden platform in Water Maze were shorter in V1 mice as compared to wt animals, indicative of faster learning and better spatial memory processes. While no signs of necrosis or apoptosis were detected, immunohistochemistry showed that VEGF transgenity was related to higher number of nestin-positive precursor cells. Finally, acute CCAO was paralleled by a reduction of CD31 staining in wt but not V1 mice. We conclude that VEGF overexpression led to a protective effect on cognitive function, because V1 mice showed evidence for faster spatial learning and better memory, as well as an increased number of neuronal precursor cells and a prevention of endothelial cell loss after CCAO.

Mannose binding lectin gene deficiency increases susceptibility to traumatic brain injury in mice

Mannose binding lectin (MBL) initiates complement activation and exacerbates tissue damage after systemic ischemia/reperfusion. We tested the hypothesis that MBL activates complement and worsens outcome using two levels of controlled cortical impact (CCI) in mice. After moderate CCI (0.6 mm depth), MBL immunostaining was detected on injured endothelial cells of wild-type (WT) mice and C3d was detected in MBL KO (deficient in MBL A/C) and WT mice, suggesting that MBL is dispensable for terminal complement activation after CCI. Brain neutrophils, edema, blood-brain barrier permeability, gross histopathology, and motor dysfunction were similar in injured MBL KO and WT mice. In mice subjected to mild CCI (0.2 mm), MBL KO mice had almost two-fold increased acute CA3 cell degeneration at 6 h (P<0.01 versus WT). Naive MBL KO mice had decreased brain volume but performed similar to WT mice in two distinct Morris water maze (MWM) paradigms. However, injured MBL KO mice had impaired performance in cued platform trials (P<0.05 versus WT), suggesting a transient nonspatial learning deficit in injured MBL KO mice. The data suggest that MBL deficiency increases susceptibility to CCI through C3-independent mechanisms and that MBL-deficient patients may be at increased risk of poor outcome after traumatic brain injury.

Evidence for neuroprotective properties of human umbilical cord blood cells after neuronal hypoxia in vitro

Background

One of the most promising options for treatment of stroke using adult stem cells are human umbilical cord blood (HUCB) cells that were already approved for therapeutic efficacy in vivo. However, complexity of animal models has thus far limited the understanding of beneficial cellular mechanisms. To address the influence of HUCB cells on neuronal tissue after stroke we established and employed a human in vitro model of neuronal hypoxia using fully differentiated vulnerable SH-SY5Y cells. These cells were incubated under an oxygen-reduced atmosphere (O₂< 1%) for 48 hours. Subsequently, HUCB mononuclear cells (MNC) were added to post-hypoxic neuronal cultures. These cultures were characterized regarding to the development of apoptosis and necrosis over three days. Based on this we investigated the therapeutic influence of HUCB MNC on the progression of apoptotic cell death. The impact of HUCB cells and hypoxia on secretion of neuroprotective and inflammatory cytokines, chemokines and expression of adhesion molecules was proved.

Results

Hypoxic cultivation of neurons initially induced a rate of 26% ± 13% of apoptosis. Hypoxia also caused an enhanced expression of Caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP). Necrosis was only detected in low amounts. Within the next three days rate of apoptosis in untreated hypoxic cultures cumulated to 85% ± 11% (p ≤ 0.001). Specific cytokine (VEGF) patterns also suggest anti-apoptotic strategies of neuronal cells. Remarkably, the administration of MNC showed a noticeable reduction of apoptosis rates to levels of normoxic control cultures (7% ± 3%; p ≤ 0.001). In parallel, clustering of administered MNC next to axons and somata of neuronal cells was observed. Furthermore, MNC caused a pronounced increase of chemokines (CCL5; CCL3 and CXCL10).

Conclusion

We established an in vitro model of neuronal hypoxia that affords the possibility to investigate both, apoptotic neuronal cell death and neuroprotective therapies. Here we employed the therapeutic model to study neuroprotective properties of HUCB cells.

We hypothesize that the neuroprotective effect of MNC was due to anti-apoptotic mechanisms related to direct cell-cell contacts with injured neuronal cells and distinct changes in neuroprotective, inflammatory cytokines as well as to the upregulation of chemokines within the co-cultures.

High levels of erythropoietin are associated with protection against neurological sequelae in African children with cerebral malaria

Cerebral malaria (CM) in children is associated with a high mortality and long-term neurocognitive sequelae. Both erythropoietin (Epo) and vascular endothelial growth factor (VEGF) have been shown to be neuroprotective. We hypothesized that high plasma and cerebrospinal fluid (CSF) levels of these cytokines would prevent neurological sequelae in children with CM. We measured Epo, VEGF, and tumor necrosis factor in paired samples of plasma and CSF of Kenyan children admitted with CM. Logistic regression models were used to identify risk and protective factors associated with the development of neurological sequelae. Children with CM (n = 124) were categorized into three groups: 76 without sequelae, 32 with sequelae, and 16 who died. Conditional logistic regression analysis matching the 32 patients with CM and neurological sequelae to 64 patients with CM without sequelae stratified for hemoglobin level estimated that plasma Epo (>200 units/liter) was associated with >80% reduction in the risk of developing neurological sequelae [adjusted odds ratio (OR) 0.18; 95% C.I. 0.05-0.93; P = 0.041]. Admission with profound coma (adjusted OR 5.47; 95% C.I. 1.45-20.67; P = 0.012) and convulsions after admission (adjusted OR 16.35; 95% C.I. 2.94-90.79; P = 0.001) were also independently associated with neurological sequelae. High levels of Epo were associated with reduced risk of neurological sequelae in children with CM. The age-dependent Epo response to anemia and the age-dependent protective effect may influence the clinical epidemiology of CM. These data support further study of Epo as an adjuvant therapy in CM.

Buyang Huanwu Decoction can improve recovery of neurological function, reduce infarction volume, stimulate neural proliferation and modulate VEGF and Flk1 expressions in transient focal cerebral ischaemic rat brains

Buyang Huanwu Decoction is a classic formula for treating stroke-induced disability in traditional Chinese medicine (TCM). To explore its pharmacological basis, we investigated the effects of the whole formula and its herbal components on the neurological behavior performance and infarction volume in focal cerebral ischaemia rats. The neurological deficit scores and infarction volume were measured at days 3, 7 and 14 after 30 min of occlusion of middle cerebral artery. The results showed that Buyang Huanwu Decoction and its herbal components significantly improved the neurological behavior performances and reduced the infarction volume in the ischaemic brains. To elucidate the potential therapeutic mechanisms, we investigated the proliferation of progenitors by detecting the immunohistochemical staining of thymidine analog 5-bromo-2'-deoxyuridine (BrdU) and found that the formula stimulated the proliferation of the progenitors at hippocampus and subventricular zone (SVZ) in the ischaemic brains. As vascular endothelial growth factor (VEGF) and its receptor fetal liver kinase (Flk1) are important neurotrophic, neuroprotective and neuroproliferative factors, we studied the expressions of VEGF and Flk1 in the hippocampus, SVZ and cortex in the ischaemic brains and found that the formula led to increase the numbers of VEGF-positive and Flk1-positive cells in the SVZ and cortex in the ischaemic brains. The results indicate that the therapeutic effects of Buyang Huanwu Decoction for recovery of neurological deficits are associated with the stimulation of the proliferation of progenitors and the enhancement of the expressions of VEGF and Flk in ischaemic brains.

Safety monitoring in bevacizumab (Avastin) treatment: retinal function assessed by psychophysical (visual fields, colour vision) and electrophysiological (ERG/EOG) tests in two subgroups of patients

BACKGROUND

Bevacizumab (Avastin) has been used as off-label treatment for the specific inhibition of the vascular endothelial growth factor (VEGF). Although only intravenous administration of the drug is approved in combination therapy of colorectal carcinoma, promising short-term results have been reported about its intravitreal administration. However, VEGF is also known to exhibit neurotrophic capabilities. Therefore, blockage of all VEGF isoforms by bevacizumab could induce toxic effects. Missing randomized controlled studies and unclear long-term risks require further evaluation.

METHODS

Intensified monitoring of bevacizumab treatment was performed in consecutive patients. In ten patients, the functional field score was calculated after obtaining Goldmann visual fields at baseline and 1 year after injection. The other subgroup was examined by means of EOG, ERG and colour testing at baseline and 4 months following treatment. Naka-Rushton plots were calculated to enable statements about retinal function. Lanthony desaturated D15 test was used for repeated colour testing.

RESULTS

Baseline parameters already disclosed predominant cone dysfunction. Drug-related effects caused a significant improvement of visual acuity. There was no sign of clinically relevant retinal toxicity following the bevacizumab injection. No progression of visual field defects was seen within the follow-up of 1 year. Performance in EOG testing was affected by restricted fixation stability, but no parameter indicated deterioration within the 4-month-period.

CONCLUSIONS

Short-term results underline that intraocular bevacizumab injection promises to be not only a cost-effective, but safe treatment option. Assessed functional parameters as error scores (e.g., Lanthony) corresponded to the impaired retinal function which was presumed to be disease-related. Further long-term results have to confirm the good tolerability in repeated treatment.

Multiple effects of 2ME2 and D609 on the cortical expression of HIF-1alpha and apoptotic genes in a middle cerebral artery occlusion-induced focal ischemia rat model

Despite 2-methoxyestradiol (2ME2) and tricyclodecan-9-yl-xanthogenate (D609) having multiple effects on cancer cells, mechanistically, both of them down-regulate hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF). We hypothesize HIF-1alpha plays an essential role in cerebral ischemia as a pro-apoptosis regulator; 2ME2 and D609 decrease the levels of HIF-1alpha and VEGF, that might contribute to protecting brain from ischemia injury. A total of 102 male Sprague-Dawley rats were split into five groups: sham, middle cerebral artery occlusion (MCAO), MCAO + dimethyl sulfoxide, MCAO + 2ME2, and MCAO + D609. 2ME2 and D609 were injected intraperitoneally 1 h after reperfusion. Rats were killed at 24 h and 7 days. At 24 h, 2ME2 and D609 reduce the levels of HIF-1alpha and VEGF (enzyme-linked immunosorbent assay), depress the expression of HIF-1alpha, VEGF, BCL2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3) and cleaved caspase 3 (western blot and immunohistochemistry) in the brain infarct area. Double fluorescence labeling shows HIF-1alpha positive immunoreactive materials are co-localized with BNIP3 and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling inside the nuclei of neurons. At 7 days, 2ME2 and D609 reduce the infarct volume (2,3,7-triphenyltetrazolium chloride) and blood-brain barrier extravasation, decrease the mortality and improve the neurological deficits. In conclusion, 2ME2 and D609 are powerful agents to protect brain from cerebral ischemic injury by inhibiting HIF-1alpha expression, attenuating the superfluous expression of VEGF to avoid blood-brain barrier disruption and suppressing neuronal apoptosis via BNIP3 pathway.