BACKGROUNDHuman amniotic epithelial cells (HAECs), which have several characteristics similar to stem cells, therefore could possibly be used in cell therapy without creating legal or ethical problems. In this study, we transplanted HEACs into the injured spinal cord of rats to investigate if the cells can improve the rats' hindlimb motor function.

METHODSHAECs were obtained from a piece of fresh amnion, labeled with Hoechst33342, and transplanted into the site of complete midthoracic spinal transections in adult rats. The rats (n = 21) were randomly divided into three groups: Sham-operation group (n = 7), cells-graft group (n = 7), and PBS group (n = 7). One rat of each group was killed for histological analysis at the second week after the transplantation. The other six rats of each group were killed for histological analysis after an 8-week behavioral testing. Hindlimb motor function was assessed by using the open-field BBB scoring system. Survival rate of the graft cells was observed at second and eighth weeks after the transplantation. We also detected the myelin sheath fibers around the lesions and the size of the axotomized red nucleus. A one-way ANOVA was used to compare the means among the groups. The significance level was set at P < 0.05.

RESULTSThe graft HAECs survived for a long time (8 weeks) and integrated into the host spinal cord without immune rejection. Compared with the control group, HAECs can promote the regeneration and sprouting of the axons, improve the hindlimb motor function of the rats (BBB score: cells-graft group 9.0 +/- 0.89 vs PBS group 3.7 +/- 1.03, P < 0.01), and inhibit the atrophy of axotomized red nucleus [cells-graft group (526.47 +/- 148.42) microm(2) vs PBS group (473.69 +/- 164.73) microm(2), P < 0.01].

CONCLUSIONTransplantation of HAECs can improve the hindlimb motor function of rats with spinal cord injury.