| Spinal cord injury (SCI) is one of the tough problems in the world, which is still lack of effective method in clinical treatment. Injured axons in the adult mammalian central nervous system (CNS) can sprout and grow long distance into peripheral transplantation. But because of inhibitory effects of peripheral glial cells, the regenerating axons fail to grow within the adult mammalian CNS, which does not apply to olfactory bulb(OB). A remarkable difference between an axonal growth-permissive structure such as the OB and the remaining CNS resides in the presence of ensheathing glia in the former. Therefore, optimizing local microenvironment of CNS can promote axons regeneration.Decades years ago , people used many methods such as cells transplantation, embryo-tissure transplantation, neurotrophic factors administration, genetic treatment, and so on to treat SCI and received many inspiring results . In recent years, people have found that olfactory ensheathing cells (OECs) is a kind of glial cells between schwanns cells and as-trocytes , which can promote and guide the olfactory axons to regenerate into CNS. OECs can go though the CNS-PNS transitional zone and exist in the CNS. OECs may produce neurotrophic factors , neurotrophic nexin and express neuronal-cell adhesion molecules. In recent years, many studies have shown that transplantation of OECs into lesions in spinal cord is able to stimulate the growth of axons and in some cases restore functional connections. More and more people are interested in these characters of OECs and look on them as main transplanted cells.Glial cell line-derived neurotrophic factor (GDNF), a member of transforming growth factor (TGF)-β super-family trophic factor ,is a new kind of neurotrophic factor, which was extracted and purified from B49 cells of adult rats by Lin and so on in 1993. GDNF is the most potent motor neurontrophic factor among NTFs found so far. GDNF has been found to support not only the programme-death of developmental motor neurons ,but also the survival of the injured corticospinal neurons (CSN). It supports sensory neurons, motor neurons and peripheral sympathetic neurons as well as midbrain dopamine neurons.In present paper, we adopted genetic technology to treat SCI, which is advanced in the world. At first, olfactory ensheathing cells (OECs) were primarily cultured and purified in vitro. Then OECs-GDNF was built and transplanted into spinal cord injury site. We investigated from three points such as axons regeneration, neurons protection and be-havior test.The main results of our research are as follows:(1) Primary cultured OECs with high purityPrimary cultures of OECs were dissociated from 2. 5 month old rat. We employed different purification methods to contrast cells purity . The result demonstrated that the differential adhesion method was more effective than arabinoside (Ara-C) treatment method. OECs were stimulated to proliferate by bFGF. OECs was determined according to immu-nostaining positively for p75NGFR,S100 and GFAP.(2) Successfully build engineered OECs-GDNFFirst, we used molecule biology techniques to build virus vector PN2A-GDNF. Then, we transfected GDNF into PA317 cells with positive-ion liposome, and built PA317-GDNF cells by using G418 to select positive clones. Second, we got virus titres by 3T3 cells, and used high titres to infect OECs. Finally, we assayed GDNF activation and quantity. So the OECs secreting high quantity GDNF were geneticly engineered cells.(3) Promoting effect of OECs-GDNF on functional recovery after SCIPurified OECs-GDNF were transplanted into complete transected zone of spinal cord at T10 level. According to different treatment, SD rats were divided into three groups; control group , OECs group and OECs -GDNF group . After injury, animals were behav-iorally tested for 8 weeks using the inclined plane (IP) test to valuate the ability of OECs-GDNF to promote functional recovery. It is demonstrated that rats treated with OECs-GDNF regained more improvements in hindlimb funct...
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