Thrombo-occlusive cerebrovascular disease resulting in stroke and permanent neuronal loss is an important cause of morbidity and mortality. Because of the unique properties of cerebral vasculature and the limited reparative capability of neuronal tissue, it has been difficult to devise effective neuroprotective therapies in cerebral ischemia. Our results demonstrate that systemic administration of human cord blood-derived CD34 + cells to immunocompromised mice subjected to stroke 48 hours earlier induces neovascularization in the ischemic zone and provides a favorable environment for neuronal regeneration. Endogenous neurogenesis, suppressed by an antiangiogenic agent, is accelerated as a result of enhanced migration of neuronal progenitor cells to the damaged area, followed by their maturation and functional recovery. Our data suggest an essential role for CD34 + cells in promoting directly or indirectly an environment conducive to neovascularization of ischemic brain so that neuronal regeneration can proceed.

Although amyloid ␤ (A␤) oligomers are presumed to cause synaptic and cognitive dysfunction in Alzheimer's disease (AD), their contribution to other pathological features of AD remains unclear. To address the latter, we generated APP transgenic mice expressing the E693⌬ mutation, which causes AD by enhanced A␤ oligomerization without fibrillization. The mice displayed age-dependent accumulation of intraneuronal A␤ oligomers from 8 months but no extracellular amyloid deposits even at 24 months. Hippocampal synaptic plasticity and memory were impaired at 8 months, at which time the presynaptic marker synaptophysin began to decrease. Furthermore, we detected abnormal tau phosphorylation from 8 months, microglial activation from 12 months, astrocyte activation from 18 months, and neuronal loss at 24 months. These findings suggest that A␤ oligomers cause not only synaptic alteration but also other features of AD pathology and that these mice are a useful model of A␤ oligomer-induced pathology in the absence of amyloid plaques.

Thrombo-occlusive cerebrovascular disease resulting in stroke and permanent neuronal loss is an important cause of morbidity and mortality. Because of the unique properties of cerebral vasculature and the limited reparative capability of neuronal tissue, it has been difficult to devise effective neuroprotective therapies in cerebral ischemia. Our results demonstrate that systemic administration of human cord blood-derived CD34 + cells to immunocompromised mice subjected to stroke 48 hours earlier induces neovascularization in the ischemic zone and provides a favorable environment for neuronal regeneration. Endogenous neurogenesis, suppressed by an antiangiogenic agent, is accelerated as a result of enhanced migration of neuronal progenitor cells to the damaged area, followed by their maturation and functional recovery. Our data suggest an essential role for CD34 + cells in promoting directly or indirectly an environment conducive to neovascularization of ischemic brain so that neuronal regeneration can proceed.

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Amnestic mild cognitive impairment (MCI) describes the condition of memory-impaired individuals who otherwise function well and do not meet the clinical criteria for dementia. Such individuals are considered to represent a transitional stage between normal aging and dementia of Alzheimer type (DAT). Neurobiologic changes in amnestic MCI, and their significance for psychophysiologic function, are poorly understood. In this study, the authors compared acoustic prepulse inhibition (PPI) between subjects with amnestic MCI and mild DAT to characterize sensorimotor gating. The acoustic startle reflex, which the authors measured using an accelerometer and electromyogram, involves whole-body movement and eye blink in response to a sudden loud noise (115 dB). PPI is inhibition of this reflex by a softer noise (prepulse; 85 dB) preceding the startle stimulus by 30 ms. PPI was examined in 30 controls, 20 subjects with amnestic MCI, and 20 subjects with mild DAT. Neither amnestic MCI nor mild DAT affected startle movement amplitude. Subjects with amnestic MCI showed significantly enhanced PPI (gating facilitation), while subjects with mild DAT exhibited significantly less PPI than controls (gating deficit). This pattern of PPI changes suggests that neuropathologic changes in the limbic cortex, mainly the entorhinal cortex, at the earliest stage of DAT might be responsible for PPI abnormalities via disturbed regulation of the limbic cortico-striato-pallido-pontine circuitry. Startle PPI changes could be used as a biologic marker for amnestic MCI and mild DAT.