This study aims to investigate the effect of adenoviral vector-mediated neurotrophine-3 (NT-3) gene transfer and retinoic acid (RA) pretreatmenton inducing neuronal differentiation of bone marrow mesenchymal stem cells (MSCs) in vitro. MSCs could be efficiently transduced by NT-3gene via recombinant adenoviral vectors (Adv). Combination of AdvNT-3 and RA significantly promoted MSCs to differentiate into cell typesassociated with phenotypes of neural lineages, which included neural markers nestin, NF, MAP2 and PSD95 as detected by immunocytochemistry.But the expressions of GFAP in these cells were not obvious. RT-PCR analysis revealed that AdvNT-3 in combination with RA pretreatment couldinitiate the transcription of TrkC mRNA. These results demonstrate that the combination of AdvNT-3 and RA pretreatment may promote neuronaldifferentiation of MSCs, which may serve as ideal seed cells for the repair of spinal cord injury.

To investigate the synergistic effect of Schwann cells (SCs) and retinoic acid (RA) on differentiation andsynaptogenesis of neural stem cells (NSCs) derived from hippocampus of neonatal rats. Methods The classical methodfor 2

Dendrites and spines undergo dynamic changesin physiological conditions, such as learning and memory, and in pathological conditions, such as Alzheimer's diseaseand epilepsy. Long-term dendritic plasticity has also beenreported after ischemia/hypoxia, which might be compensatoryeffects of surviving neurons for the functional recoveryafter the insults. However, the dendritic changes shortly afterischemia, which might be associated with the pathogenesisof ischemic cell death, remain largely unknown. To reveal themorphological changes of ischemia-vulnerable neurons after ischemia, the present study investigated the alteration ofdendritic arborization of CA1 pyramidal neurons in rats aftertransient cerebral ischemia using intracellular staining techniquein vivo. The general appearance of dendritic arborizationof CA1 neurons within 48 h after ischemia was similar tothat of control neurons. However, a dramatic increase ofdendritic disorientation was observed after ischemia withmany basal dendrites coursed into the territory of apicaldendrites and apical dendrites branched into the region ofbasal dendrites. In addition, a significant increase of apicaldendritic length was found 24 h after ischemia. The increaseof dendritic length after ischemia was mainly due to thedendritic sprouting rather than the extension of individualdendrites, which mainly occurred in the middle segment ofthe apical dendrites. These results reveal a plasticity changein dendritic arborization of CA1 neurons shortly after cerebralischemia.

The present study investigates whether Schwann cells(SCs) could promote the survival and differentiation ofneural stem cells in the injured spinal cord. Neural stemcells were dissociated and cloned from the hippocampaltissue of newborn rats. SCs were also dissociated andpurified simultaneously from the sciatic nerves of 4-dayoldrats. The results showed that the number of survivingneural stem cells and differentiated neuron-like cells wassignificantly increased in the co-grafted (SCs and neuralstem cells) group compared with the control group (neuralstem cells only). Neuron-like cells that developedaxon-like processes were observed more commonly inthe cograftedgroup. These results demonstrate thatSCs can promote the survival and differentiation oftransplanted neural stem cells in the injured spinal cord.

Morphological changes of CA1 and CA3 pyramidal neurons in rat hippocampus at different intervals following transientforebrain ischemia were examined to determine the nature of post-ischemic cell death in these regions. In the CA1 region, swellingof small dendrites occurred at 24h reperfusion. At 48 h reperfusion, swelling was found in large dendrites of many CA1neurons and the mitochondria and endoplasmic reticulum (ER) were dilated. A small portion of neurons showed chromatinaggregation and nuclear indentation without swelling signs. At 60h reperfusion, swelling of somata was evident in manyneurons. Large dense chromatin clumps with round or ovoid contour were found in other neurons. At 72 and 96 h after ischemia,many large vacuoles and glias with active phagocytosis were observed. At 7 days after ischemia, the tissue was compact and manyglias were found in the region. Most of theCA3 neurons had normal appearance after ischemia. A total of 5-10% CA3 neuronsexhibited shrinking nuclei and chromatin aggregation at 24h reperfusion. The number of these neurons decreased overtime anddisappeared at 72h after ischemia. These results demonstrate the co-existence of necrosis andapoptosis in the CA1 region aftertransient forebrain ischemia. Most CA3 neurons remained intact after ischemia while a small portion of them showed apoptoticcell death.