Objective To explore the methods of isolation, cultivation and expansion in vitro of rat O-2A progenitor cells. To explore the possible mechanisms for the repair of spinal cord hemisection by transplanting O-2A progenitor cells. Methods Unicellular suspension was obtained from the brain tissues of postnatal SD rats by mechanical dissociation. A serum free medium containing bFGF and PDGF was used to culture, expand and passage O-2A progenitor cells in vitro. Expression of A2B5 (maker for O-2A progenitor) or GFAP (maker for differentiated type-2 astrocyte) was identified by Immunocytochemistry staining. 80 SD rats were randomized to four groups: normal (Group A, n=30), and injury (Group B, group C and Group D; Given T9 laminectomy with spinal cord left-hemisection, each group n=30). Group B was control group (given saline in injured spinal cord), Group C (given 50% O-2A and 50% T1A) and Group D (given purified O-2A) were transplanted groups. Combined Behavioral Scores (CBS) and BBB of each group were assessed by blinder observers at 3, 7, 14, 21, 28 days after surgery; GAP-43 and NF-200 expression were detected by immunohistochemistry labeling in each group after injury. Results Cells derived from the cerebral cortex of postnatal 1~2 days SD rats show the oval-shape and typical bipolar process; the results of immunohistochemistry staining show A2B5 antibody positive and the purity of cells can reach 95%. Expression of GAP-43 and NF-200 increased at 14 days after injury. Expression of GAP-43 and NF-200 in the gray matter of normal group was significantly lower than in the injured area of group B, C, D (P<0.05). GAP-43 and NF-200 expression in the injured area were much higher in Group D than in Group B or C (P<0.01), with significant difference between Group C and Group B (P<0.05); The CBS of Group A was 100. Certain neurological recovery in the hindlimb was observed in injured groups after hemisection. CBS of the left hindlimbs was much higher than that of the right ones of the injured groups (P<0.01). CBS evaluation showed significant difference between Group D and Group C (P<0.05), whereas it was similar in both groups (P>0.05). Conclusion Cells obtained from the cerebral cortex of postnatal SD rats and isolated by shaking have the characteristic morphology of O-2A progenitor cells and can be specificaly marked by A2B5 antibody. Transplantation of O-2A progenitor cells can promote neurological recovery after spinal cord injury. Increasing expression of GAP-43 and NF-200 possibly play an important role in the neurological recovery after injury.
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