| Paraplegia below the level of injury resulted from traumatic spinal cord injury (SCI) is one of the tough problems in the world, which is still lack of effective method in clinical treatment. Unfortunately, injured axons in the mammalian central nervous system (CNS) do not regenerate normally. In recent years, substantial evidence has suggested that the failure of injured axons to regenerate within the mature central nervous system (CNS) can be overcome by providing growth-permissive environment at the injury site. Several strategies have been developed to achieve this goal including adding growth factors and transplanting functional cells. Since little of these strategies alone have been sufficient in repair of adult CNS, two or more strategies might be used in combination to obtain adequate structural and functional rebuilt.Potential therapeutic role of olfactory ensheathing cells (OECs) for repair of spinal cord injuries has been highlighted by recent reports. OECs are thought to play a key role in promoting and guiding the olfactory axons regenerate into CNS. In recent years, many studies have shown that transplants of OECs into lesions in spinal cord are also able to stimulate the growth of axons and in some cases restore functional connections.Glial cell line-derived neurotrophic factor (GDNF), a transforming growth factor (TGF)-P super-family trophic factor for midbrain dopaminergic neurons, has been found to support the survival of several neuronal cells including cultured spinal motoneurons and sensory neurons. GDNF is the most potent motor neuron trophic factor among NTFs found so far. GDNF might be useful in the treatment of neurodegenerative diseases and nerve injuries.In present paper, primary cultures of olfactory ensheathing cells (OECs) were dissociated from new born and 2.5 month old rat firstly. Purification of OECs was developed with cytosine arabinoside (Ara-C) treatment and differential adhesion method. OECs were stimulated to propagate by BPE or forskolin. The purity of OECswas determined according to immunostaining positively for p75 at different time. Viability and purity of OECs at distinct time was observed and compared. Adult OECs culture was selected for further experiment. Secondly, adult SD rats receiving Tg spinal cord hemisection were treated with GDNF and/or OECs, and the ability to promote axon regeneration and prevent neuron atrophy after spinal cord injury (SCI) was investigated. Animals were behaviorally tested for 8 weeks using the Basso, Beattie, Bresnahan locomotor rating scale and inclined plane test. At the end of 8 weeks, horseradish (HRP) labeled rubrospinal neurons (RSN) and corticospinal neurons (CSN) were counted and the mean soma size of RSN and CSN were quantified. Finally, the survival promoting effect and the possible intracellular signal transduction way of GDNF on OECs culture were examed to further investigate the mechanism of synergistic effect of GDNF and OECs.The main results of our research are as follows:1. Primary cultured OECs with high purityPrimary cultures of OECs were dissociated from new born and 2.5 month old rat. Purification of OECs was developed with cytosine arabinoside (Ara-C) treatment and differential adhesion method. OECs were stimulated to proliferate by BPE or forskolin. The purity of OECs was determined according to immunostaining positively for p75 at different time. Furthermore, viability of OECs with distinct derivation was observed and compared. The result demonstrated that the time for purification of OECs derived from new born rats was 5d with 80-85% purity, and the cell viability decreased about 18-20 days after purification. Meanwhile, total purification time of OECs derived from adult rats was 10d with more than 95% purity, and cell viability decreased about 12-14 days after purification. Adult OECs culture was selected for our experiment because of the high purity.2. Neuronal protection effects of GNDF and OECs after SCISD rats receiving T8 spinal cord hemisection were divided into 4 groups: cont...
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