| Objective:To evaluate the repair ability of human umbilical cord derived-mesenchymal stem cells (hUC-MSCs) transplanted into spinal cord-injured rats via subarachnoid space way and intraspinal cord way directly.Methods:Seventy female Wistar rats which subjected to spinal cord injury at T10 using the MASCIS Impactor Model-Ⅱtype weight drop apparatus were assigned into five groups randomly:plain control group (group A,n=10), DMEM subarachnoid space way transplanted group (groupB, n=10), DMEM intraspinal cord way group (group C, n=10), hUC-MSCs subarachnoid space way transplanted group (group D, n=20), hUC-MSCs intraspinal cord way group (group E, n=20). After a week, the rats of group A were not transplanted anything, only received SCI. Five microliter DMEM were transplanted into spinal cord-injured rats of group B (via subarachnoid space way) and group C (intraspinal cord way directly). Also, five microliter hUC-MSCs (1×106) were isolated and purified in vitro and then transplanted into spinal cord injured rats of group D (via subarachnoid space way) and group E (intraspinal cord way directly) respectively. The recoveries of the lower extremity were observed by Basso-Beattie-Bresnahan (BBB) locomotor scoring system, foot printing, somatosensory evoked potential (SEP) and motor evoked potentials (MEP). Also, lmigration, differentiation and survive of hUC-MSCs in the injury site were observed by immunohistochemistry. The area of glial scar in the injury site was calculated by Immunostaining against GFAP. The coticospinal tract (CST) was observed using the biotinylated dextran amine (BDA) tracing also.Result:BBB score of group E (9.31±0.37) is more higher than another four groups 4 weeks after injury, the statistical difference was significant (p<0.05). Five weeks after injury, the score of group D (9.19±0.26) was higher than group A (8.19±.46),B (8.31±0.37) and C (8.25±0.38), but lower than group E (9.87±0.23) the statistical difference was significant (p<0.05). Foot printing analysis revealed that hindlimb angle of rotation (group D 21.06±2.08°, group E 19.03±1.19°) and interlimb coordination (group D:2.64±0.27cm, group E:2.33±0.28cm) were statistical difference significantly (p<0.05) between group D and E at 6 and 7 weeks after injury respectively, the repairing effect of group E is better than group D. Statistical differences showed in latency period of P40 and wave amplitude in SEP&MEP was obvious in group D and E compare with another three group (p<0.05). Immunohistochemical staining showed hUC-MSCs differentiate into neuronal cells, oligodendrocytes and astrocytes. The area of glial scar in group D (140261.93±9137.56) is smaller than group A (203127.88±16448.84), B (219622.47±18944.89) and C (197995.0335±11628.49), but bigger than group E (94180.74±13078.66), the statistical difference was significant (p<0.05). BDA (biotinylated dextran amine) nerve tracing and microscope observation show that axonal regeneration extension is more obvious in experimental group, corticospinal tract regenerates and extends, part of which can get through the injuried area and reach distal end.Conclusion:Trangplanting hUC-MSCs can repair the spinal cord-injured in rats effectively. After transplanted by subarachnoid space way, hUC-MSCs could migrate into the injured parenchyma of spinal cord and repair spinal cord injury effectively also, but the therapeutic effect inferior to by transplanting cells in to injury site directly.
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