Experimental stroke in rodents stimulates neurogenesis and migration of newborn neurons from their sites of origin into ischemic brain regions. We report that in patients with stroke, cells that express markers associated with newborn neurons are present in the ischemic penumbra surrounding cerebral cortical infarcts, where these cells are preferentially localized in the vicinity of blood vessels. These findings suggest that stroke-induced compensatory neurogenesis may occur in the human brain, where it could contribute to postischemic recovery and represent a target for stroke therapy.ischemia ͉ stem cells ͉ penumbra ͉ infarct ͉ vascular niche
CorrectionsAGRICULTURAL SCIENCES. For the article ''Characterization of capsaicin synthase and identification of its gene (csy1) for pungency factor capsaicin in pepper (Capsicum sp.),'' by B. C. Narasimha
New neurons are generated continuously in the subventricular zone and dentate gyrus of the adult brain. Neuropathologic processes, including cerebral ischemia, can enhance neurogenesis, as can growth factors and other physiologic stimuli. Vascular endothelial growth factor (VEGF) is an angiogenic and neuroprotective growth factor that can promote neurogenesis, but it is unknown whether VEGF can enhance migration of newborn neurons toward sites of ischemic injury, where they might be able to replace neurons that undergo ischemic death. In the present study we produced permanent focal cerebral ischemia in transgenic (Tg) mice that overexpress VEGF. Cell proliferation and neurogenesis were assessed with bromodeoxyuridine (Brdu) labeling and immunostaining for cell type-specific markers. In VEGF-Tg mice, brains examined 7-28 days after cerebral ischemia showed markedly increased subventricular zone (SVZ) neurogenesis, chains of neuroblasts extending from the SVZ to the peri-infarct cortex, and an increase in the number of newly generated cortical neurons at 14-28 days after ischemia. In concert with these effects, VEGF overexpression reduced infarct volume and improved postischemic motor function. These findings provide evidence that VEGF increases SVZ neurogenesis and neuromigration, consistent with a possible role in repair. Our data suggest that in addition to its neuroprotective effects, which are associated with improved outcome in the acute phase after cerebral ischemia, VEGF enhances postischemic neurogenesis, which could provide a therapeutic target for more chronic brain repair.
We sought genetic evidence for the involvement of neuronal vascular endothelial growth factor (VEGF) in amyotrophic lateral sclerosis (ALS). Mice expressing human ALS mutant superoxide dismutase-1 (SOD1) were crossed with mice that overexpress VEGF in neurons (VEGF ϩ/ϩ ). We report that SOD1
G93A/VEGF ϩ/ϩ double-transgenic mice show delayed motor neuron loss, delayed motor impairment, and prolonged survival compared with SOD1 G93A single transgenics. These findings indicate that neuronal VEGF protects against motor neuron degeneration, and may have therapeutic implications for ALS.
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