NSCs promote hippocampal neurogenesis, metabolic changes and synaptogenesis in APP/PS1 transgenic mice.

Adult neurogenesis and synaptic remodeling persist as a unique form of structural and functional plasticity in the hippocampal dentate gyrus (DG) and subventricular zone (SVZ) of the lateral ventricles due to the existence of neural stem cells (NSCs). Transplantation of NSCs may represent a promising approach for the recovery of neural circuits. Here, we aimed to examine effects of highly neuronal differentiation of NSCs transplantation on hippocampal neurogenesis, metabolic changes and synaptic formation in APP/PS1 mice. 12-month-old APP/PS1 mice were used for behavioral tests, immunohistochemistry, western blot, transmission electron microscopy and proton magnetic resonance spectroscopy (1H-MRS). The results showed that N-acetylaspartate (NAA) and Glutamate (Glu) levels were increased in the Tg-NSC mice compared with the Tg-PBS and Tg-AD mice 10 weeks after NSCs transplantation. NSC-induced an increase in expression of synaptophysin and postsynaptic protein-95, and the number of neurons with normal synapses was significantly increased in Tg-NSC mice. More doublecortin-, BrdU/NeuN- and Nestin-positive neurons were observed in the hippocampal DG and SVZ of the Tg-NSC mice. This is the first demonstration that engrafted NSCs with a high differentiation rate to neurons can enhance neurogenesis in a mouse model of AD and can be detected by 1H-MRS in vivo. It is suggested that engraft of NSCs can restore memory and promote endogenous neurogenesis and synaptic remodeling, moreover, 1H-MRS can detect metabolite changes in AD mice in vivo. The observed changes in NAA/creatine (Cr) and glutamate (Glu)/Cr may be correlated with newborn neurons and new synapse formation.

The value of whole-brain CT perfusion imaging and CT angiography using a 320-slice CT scanner in the diagnosis of MCI and AD patients.

OBJECTIVES: To validate the value of whole-brain computed tomography perfusion (CTP) and CT angiography (CTA) in the diagnosis of mild cognitive impairment (MCI) and Alzheimer's disease (AD). METHODS: Whole-brain CTP and four-dimensional CT angiography (4D-CTA) images were acquired in 30 MCI, 35 mild AD patients, 35 moderate AD patients, 30 severe AD patients and 50 normal controls (NC). Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and correlation between CTP and 4D-CTA were analysed. RESULTS: Elevated CBF in the left frontal and temporal cortex was found in MCI compared with the NC group. However, TTP was increased in the left hippocampus in mild AD patients compared with NC. In moderate and severe AD patients, hypoperfusion was found in multiple brain areas compared with NC. Finally, we found that the extent of arterial stenosis was negatively correlated with CBF in partial cerebral cortex and hippocampus, and positively correlated with TTP in these areas of AD and MCI patients. CONCLUSIONS: Our findings suggest that whole-brain CTP and 4D-CTA could serve as a diagnostic modality in distinguishing MCI and AD, and predicting conversion from MCI based on TTP of left hippocampus. KEY POINTS: • Whole-brain perfusion using the full 160-mm width of 320 detector rows • Provide clinical experience of 320-row CT in cerebrovascular disorders of Alzheimer's disease • Initial combined 4D CTA-CTP data analysed perfusion and correlated with CT angiography • Whole-brain CTP and 4D-CTA have high value for monitoring MCI to AD progression • TTP in the left hippocampus may predict the transition from MCI to AD.

Neural stem cell transplantation decreases neuroinflammation in a transgenic mouse model of Alzheimer's disease.

Inflammatory processes are considered to play an important role in the progression of neurodegenerative changes in Alzheimer's disease (AD). A number of studies have reported that inflammatory processes are highly correlated with cognitive deficits in AD-like mice. Transplantation of neural stem cells (NSCs) has been considered as a potential new therapy for the treatment of AD because of its effects in improving cognitive ability. However, NSCs have not been evaluated for their protective effects against inflammatory changes in AD. Here, we injected NSCs into amyloid precursor protein (APP)/PS1 transgenic mice to analyse cognitive function and to measure glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor molecule-1 (Iba-1) and toll-like receptors 4(TLR4) activation. We also quantified TLR-4 pathway-related agents, Aß concentration and the levels of proinflammatory mediators. Our results showed that in NSC-injected APP/PS1 mice, activation of GFAP, Iba-1, TLR4 and TLR4 pathway-related agents (MyD88, TRIF, P38 MAPK and NF-κB P65) were significantly decreased with decreased expression of proinflammatory mediators (IL-1, IL-6, TNF-α and PGE2). These changes were associated with the amelioration of cognitive deficits, but no difference was found in Aß concentration. Our results provide novel evidence that NSC transplantation in APP/PS1 mice significantly improved cognitive deficits and was accompanied by the attenuation of inflammatory injury via suppression of glial and TLR4-mediated inflammatory pathway activation. Our data indicate that these pathways may potentially be important therapeutic targets to prevent or delay AD. This study investigated the neuroprotective effect of neural stem cell (NSC) transplantation against Alzheimer's disease (AD) inflammation. We found that NSC treatment in APP/PS1 mice significantly improved cognitive deficits and was accompanied by the attenuation of inflammatory injury via suppression of glial and toll-like receptor 4 (TLR4) activation and its downstream signalling pathways. Our findings indicate that these pathways may be potentially important therapeutic targets to prevent or delay AD.

[Effects of neural stem cells transplanted into an animal model of Alzheimer disease on Aß plaques].

OBJECTIVE: To explore the effects on Aß plaques of neural stem cells transplanted into an Alzheimer disease mouse model. METHODS: A total of twenty 12-months-old APP+PS1 double transgenic AD mice were randomly divided into two groups.One group received neural stem cells transplantation, that was NSC group, another mice received an equal quantity 0.01 mol/L PBS, as positive control group. After 5 weeks transplantation, the total number of Aß plaques examined by immunohistochemistry, the ratio of compact of Aß plaques by TS staining, and whether NSCs migrate into Aß plaques by immunofluorescence monitoring. RESULTS: There was no difference in total number of Aß plaques between NSC group (181 ± 12) and PBS (179 ± 14) group after transplantation (P > 0.05). There was no difference in the number of TS+ plaques between NSC group (54.9%) and PBS (55.7%) group after eight weeks NSCs transplantation (P > 0.05). (2) However, engrafted NSCs showed partial chemotaxis toward Aß plaques. CONCLUSION: NSCs transplantation did not have a significant impact on Aß plaques of AD mice, but the tropism of engrafted NSCs may be capable of replacing lost or damaged cells and reverse the course of AD mice in some extent.

Mechanism of ischemic tolerance induced by hyperbaric oxygen preconditioning involves upregulation of hypoxia-inducible factor-1alpha and erythropoietin in rats.

We studied the effect of hyperbaric oxygen (HBO) preconditioning on the molecular mechanisms of neuroprotection in a rat focal cerebral ischemic model. Seventy-two male Sprague-Dawley rats were pretreated with HBO (100% O(2), 2 atmospheres absolute, 1 h once every other day for 5 sessions) or with room air. In experiment 1, HBO-preconditioned rats and matched room air controls were subjected to focal cerebral ischemia or sham surgery. Postinjury motor parameters and infarction volumes of HBO-preconditioned rats were compared with those of controls. In experiment 2, HBO-preconditioned rats and matched room air controls were killed at different time points. Brain levels of hypoxia-inducible factor-1alpha (HIF-1alpha) and its downstream target gene erythropoietin (EPO) analyzed by Western blotting and RT-PCR as well as HIF-1alpha DNA-binding and transcriptional activities were determined in the ipsilateral hemisphere. HBO induced a marked increase in the protein expressions of HIF-1alpha and EPO and the activity of HIF-1alpha, as well as the expression of EPO mRNA. HBO preconditioning dramatically improved the neurobehavioral outcome at all time points (3.0 +/- 2.1 vs. 5.6 +/- 1.5 at 4 h, 5.0 +/- 1.8 vs. 8.8 +/- 1.4 at 8 h, 6.4 +/- 1.8 vs. 9.7 +/- 1.3 at 24 h; P < 0.01, respectively) and reduced infarction volumes (20.7 +/- 4.5 vs. 12.5 +/- 3.6%, 2,3,5-Triphenyltetrazolium chloride staining) after cerebral ischemia. This observation indicates that the neuroprotection induced by HBO preconditioning may be mediated by an upregulation of HIF-1alpha and its target gene EPO.

GDF11 Rejuvenates Cerebrovascular Structure and Function in an Animal Model of Alzheimer's Disease.

Cerebral amyloid angiopathy (CAA) is present in up to 90% of patients with Alzheimer's disease (AD), and may interact with classical neuropathology to exacerbate cognitive decline. Since growth differentiation factor 11 (GDF11) can activate vascular remodeling, we tested its effects on cognitive function and neuroinflammatory changes of AD model mice. We intravenously administered GDF11 or vehicle daily to 12-month-old transgenic mice overexpressing the amyloid-ß protein precursor (AßPP)/PS1). Cognitive function was monitored using the Morris water maze, and after conclusion of the treatment, we assessed the morphology and presence of inflammatory markers in the cerebral vasculature. Subchronic treatment of adult AßPP/PS1 mice with GDF11 rescued cognitive function and ameliorated cerebrovascular function. In particular, the de novo genesis of small blood vessels and the expression of vascular-related proteins were significantly higher than in the vehicle-treated AßPP/PS1 mice, whereas the expressions of the inflammatory markers Iba-1 and GFAP significantly decreased in proportion to the lower ratio of two forms of amyloid-ß (Aß40/42). Daily intravenous treatment with GDF11-injection can rejuvenate respects of cognition and cerebrovascular changes in AD mice.

Therapeutic effects of hyperbaric oxygen in a rat model of endothelin-1-induced focal cerebral ischemia.

It has been established that hyperbaric oxygen (HBO) treatment reduces brain edema, decreases infarct volume, contributes to neurological functional recovery and suppresses apoptosis in suture-induced focal cerebral ischemic animal models. In the present study, we evaluated the therapeutic effect of HBO in an endothelin-1-induced focal cerebral ischemia in rats and explored the associated mechanisms of HBO-induced brain protection. One hundred twenty male Sprague-Dawley rats (280 to 320 g) were randomly assigned to sham, focal cerebral ischemia and focal cerebral ischemia treated with HBO groups. Brain water content, neurological function, morphology and molecular biological markers were assessed. HBO (100% O2, 2.5 atmosphere absolute for 2 h) was initiated at 1 h after focal cerebral ischemia. Rats were killed at 24 h to harvest tissues for Western blot or for histology. In HBO-treated animals, an enhanced ratio of Bcl-2 and Bax and a reduced expression of hypoxia-inducible factor-1alpha (HIF-1alpha) in the hippocampus after focal cerebral ischemia were observed. These results indicate that HBO provides brain protection that is probably associated with the inhibition of HIF-1alpha and the elevation of Bcl-2.

[Changes in the activities of enzymes involved in starch synthesis and accumulation in caryopsis of transgenic rice with antisense Wx gene].

The amylose content of rice caryopsis is determined by Wx protein, one kind of granule-bound starch synthetase which is encoded by Wx gene. Different rice types and species have different levels of Wx gene expression and have different amylose contents in their caryopsis. Wuyunjing No.7 (2200), the japonica rice with an amylose content 17% and its transgenic rice lines with antisense Wx gene (2201 and 2203, with amylose contents 8.5% and 2% respectively), and Longtefu (LP03), the indica rice with a high amylose content (28%) and its transgenic rice with antisense Wx gene (A199, with an amylose content 9%) were used to investigate the effects of Wx protein content decrease on the activities of enzymes involved in starch synthesis and thereby starch accumulation. The results indicated that with the decrease in Wx protein, the amylose content in transgenic caryopsis was reduced accordingly, whereas the amylopectin content per caryopsis (mg/grain) was not affected, and made the total starch content in transgenic caryopsis markedly lower than their parents. With the development of caryopsis, the amylose/total starch ratio was not changed significantly in the two parent caryopses, LP03 and 2200, but it went down gradually in their transgenic caryopses. The amylose/total starch ratio in transgenic caryopses was very significantly lower than their parents in the same period. The activities of ADP-glucose pyrophosphorylase (ADPG-PPase), granule-bound starch synthase (GBSS), soluble starch synthase (SSS) and starch branching enzyme (SBE) rose rapidly in early periods of grain filling, and soon reached their maximum, then reduced quickly until the middle and later periods of grain filling. Compared with the parents, the GBSS activity in transgenic caryopsis was significantly lowered, and correlated with the amylose reduction. Besides, the maximum activity of GBSS appeared earlier, and the range of the activity was smaller. In transgenic caryopsis, the activities of ADPG-PPase and SSS were higher than their parents in early and middle periods of grain filling, while the SBE activity was higher than their parents in middle and late periods.

Neural stem cell transplantation enhances mitochondrial biogenesis in a transgenic mouse model of Alzheimer's disease-like pathology.

Mitochondrial dysfunction, especially a defect in mitochondrial biogenesis, is an early and prominent feature of Alzheimer's disease (AD). Previous studies demonstrated that the number of mitochondria is significantly reduced in susceptible hippocampal neurons from AD patients. Neural stem cell (NSC) transplantation in AD-like mice can compensate for the neuronal loss resulting from amyloid-beta protein deposition. The effects of NSC transplantation on mitochondrial biogenesis and cognitive function in AD-like mice, however, are poorly understood. In this study, we injected NSCs or vehicle into 12-month-old amyloid precursor protein (APP)/PS1 transgenic mice, a mouse model of AD-like pathology. The effects of NSC transplantation on cognitive function, the amount of mitochondrial DNA, the expression of mitochondrial biogenesis factors and mitochondria-related proteins, and mitochondrial morphology were investigated. Our results show that in NSC-injected APP/PS1 (Tg-NSC) mice, the cognitive function, number of mitochondria, and expression of mitochondria-related proteins, specifically the mitochondrial fission factors (dynamin-related protein 1 [Drp1] and fission 1 [Fis1]) and the mitochondrial fusion factor optic atrophy 1 (OPA1), were significantly increased compared with those in age-matched vehicle-injected APP/PS1 (Tg-Veh) mice, whereas the expression of mitochondrial fusion factors mitofusion 1 (Mfn1) and Mfn2 was significantly decreased. These data indicate that NSC transplantation may enhance mitochondria biogenesis and further rescue cognitive deficits in AD-like mice.

Neural stem cell transplants improve cognitive function without altering amyloid pathology in an APP/PS1 double transgenic model of Alzheimer's disease.

Neural stem cells (NSCs) are capable of self-renewal and are multipotent. Transplantation of NSCs may represent a promising approach for treating neurodegenerative disorders associated with cognitive decline, such as Alzheimer disease (AD) characterized by extensive loss of neurons. In this study, we investigated the effect of NSC transplantation on cognitive function in the amyloid precursor protein/presenilin-1 (APP/PS1) transgenic mouse, an AD mouse model with age-dependent cognitive deficits. We found that NSCs bilaterally transplanted into hippocampal regions improved spatial learning and memory function in these mice, but did not alter Aß pathology. Immunohistochemical analyses determined that NSCs proliferated, migrated, and differentiated into three neuronal cell types. The improvement in cognitive function was correlated with enhanced long-term potentiation (LTP) and an increase in the neuron expression of proteins related to cognitive function: N-methyl-D-aspartate (NMDA) 2B unit, synaptophysin (SYP), protein kinase C ζ subtypes (PKCζ), tyrosine receptor kinase B (TrkB), and brain-derived neurotrophic factor (BDNF). Taken together, our data indicated that injected NSCs can rescue cognitive deficits in APP/PS1 transgenic mice by replacing neuronal cell types expressing multiple cognition-related proteins that enhance LTP.