Neural stem cells isolated from amyloid precursor protein-mutated mice for drug discovery.

AIM: To develop an in vitro model based on neural stem cells derived from transgenic animals, to be used in the study of pathological mechanisms of Alzheimer's disease and for testing new molecules. METHODS: Neural stem cells (NSCs) were isolated from the subventricular zone of Wild type (Wt) and Tg2576 mice. Primary and secondary neurosphere generation was studied, analysing population doubling and the cell yield per animal. Secondary neurospheres were dissociated and plated on MCM Gel Cultrex 2D and after 6 d in vitro (DIVs) in mitogen withdrawal conditions, spontaneous differentiation was studied using specific neural markers (MAP2 and TuJ-1 for neurons, GFAP for astroglial cells and CNPase for oligodendrocytes). Gene expression pathways were analysed in secondary neurospheres, using the QIAGEN PCR array for neurogenesis, comparing the Tg2576 derived cell expression with the Wt cells. Proteins encoded by the altered genes were clustered using STRING web software. RESULTS: As revealed by 6E10 positive staining, all Tg2576 derived cells retain the expression of the human transgenic Amyloid Precursor Protein. Tg2576 derived primary neurospheres show a decrease in population doubling. Morphological analysis of differentiated NSCs reveals a decrease in MAP2- and an increase in GFAP-positive cells in Tg2576 derived cells. Analysing the branching of TuJ-1 positive cells, a clear decrease in neurite number and length is observed in Tg2576 cells. The gene expression neurogenesis pathway revealed 11 altered genes in Tg2576 NSCs compared to Wt. CONCLUSION: Tg2576 NSCs represent an appropriate AD in vitro model resembling some cellular alterations observed in vivo, both as stem and differentiated cells.

Neurogenesis in temporal lobe epilepsy: relationship between histological findings and changes in dentate gyrus proliferative properties.

OBJECTIVE: The relationship between hippocampal histopathological abnormalities, epileptogenesis and neurogenesis remains rather unclear. METHODS: Tissue samples including the subgranular zone of dentate gyrus (DG) were freshly collected for tissue culture for neurospheres generation in 16 patients who underwent surgery for drug-resistant temporal lobe epilepsy. Remaining tissues were histologically examined to assess the presence of mesial temporal sclerosis (MTS) and focal cortical dysplasia. RESULTS: MTS was detected in 8 cases. Neurospheres were formed in 10/16 cases. Only three out of these 10 cases exhibited MTS; on the contrary 5/6 cases lacking neurosphere proliferation presented MTS. There was a significant correlation between presence of MTS and absence of proliferation (p = 0.0389). We also observed a correlation between history of febrile seizures (FS) and presence of MTS (p = 0.0004) and among the 6 cases lacking neurosphere proliferation, 4 cases (66.6%) had experienced prolonged FS. Among "proliferating" cases the percentage of granular cells pathology (GCP) was lower (20% vs 50%) compared to "non proliferating" cases. CONCLUSION: A decreased potential to generate neurosphere from the SGZ is related to MTS and to alterations of dentate gyrus granule cells, especially in MTS type 1b and GCP type 1. These histological findings may have different prognostic implications, regarding seizure and neuropsychological outcome, compared to patients with other epileptogenic lesions (such as FCD, glioneuronal tumours, vascular lesions).

Prenatal glucocorticoid exposure affects learning and vulnerability of cholinergic neurons.

Prenatal treatment with synthetic glucocorticoids is commonly used as a treatment for women at risk of preterm delivery. However, little is known about the life-long consequences of these treatments on the fetus. In the present study, we evaluated cognitive function as well as susceptibility of cholinergic neurons to (192)IgG-saporin immunolesion in adult rats after prenatal glucocorticoid treatment. Morris water maze results revealed a significant difference in learning and memory function in adult rats that were prenatally exposed to dexamethasone, and further cognitive deficits after (192)IgG-saporin exposure. Choline acetyl transferase activity was decreased in the cortex of dexamethasone-treated rats compared with controls. In addition, rats prenatally exposed to either dexa, or betamethasone revealed a dramatic decrease in choline acetyl transferase activity compared to control rats after (192)IgG-saporin lesion. We report behavioral and biochemical evidence for altered cognitive function and increased susceptibility of cholinergic neurons to (192)IgG-saporin in adult rats after prenatal glucocorticoid treatment. Taken together, these results suggest that prenatal treatment with dexamethasone could affect cognitive functions and render cholinergic neurons more vulnerable to challenges later in life.

Thyroid hormone and remyelination in adult central nervous system: a lesson from an inflammatory-demyelinating disease.

Re-myelination in the adult CNS has been demonstrated in different experimental models of demyelinating diseases. However, there is no clear evidence that re-myelination is effective in multiple sclerosis (MS), the most diffuse demyelinating disease. Moreover, chronic disabilities in MS are believed to be due to remyelination failure and consequent neuron damage and degeneration. Due to the presence of numerous oligodendrocyte precursors inside demyelination plaques, reasons for remyelination failure are unknown. In this paper, we reviewed data from embryonic development and in vitro studies supporting the primary role of thyroid hormone in oligodendrocyte maturation. We also reviewed personal data on the possibility of promoting myelination in chronic experimental allergic encephalomyelitis (EAE), a widely used experimental model of MS, by recruiting progenitors and channeling them into oligodendroglial lineage through the administration of thyroid hormone.

Cognitive deficit associated with cholinergic and nerve growth factor down-regulation in experimental allergic encephalomyelitis in rats.

Clinical symptoms in multiple sclerosis include cognitive dysfunction. Difficulties in learning and remembering new information represent the most common cognitive deficit and are associated with a general and progressive brain pathology. Possible pathogenetic mechanisms for neuronal damage such as neuroprotective strategies are under active investigation also in experimental allergic encephalomyelitis, the most widely used experimental model for multiple sclerosis. In this paper we demonstrate that a selective deficit in learning and memory performance, as investigated by the Morris water maze test, is a consistent feature in rat encephalomyelitis, which correlates with a decline in choline acetyltransferase activity and nerve growth factor mRNA level in cerebral cortex, hippocampus, and basal forebrain. Treatment aimed to restore acetylcholine content through chronic administration of selective acetylcholinesterase inhibitors (rivastigmine and donepezil) restores cognitive performance, choline acetyltransferase activity, and nerve growth factor mRNA expression.