The ESCs-treated animals showed a significant improvement of the recovery of motor function 28 days after lesion, with an average score of 4.61 ± 0.13 points of the Basso Mouse Scale (n = 14), when compared to the average score of vehicle treated mice, 3.58 ± 0.23 (n = 10). The number of identified ESCs found at the lesion site was 0.6 % of the injected cells at 1 week after transplantation, and further reduced to 0.04 % at 1 month. It is, thus, apparent that the promoted hind-limb recovery cannot be correlated to a substitution of the lost tissue performed by the exogenous ESC. The extensive evaluation of production of several neuroprotective and inflammatory cytokines did not reveal any effect by ESC-treatment, but unexpectedly the number of invading macrophages and neutrophils was greatly reduced. This may explain the improved preservation of lesion site ventral myelin, at both 1 week (29 ± 11 % ) and 1 month (106 ± 14 % ) after injury. No teratoma formation was observed, although an inappropriate colonization of the sacral cord by differentiated nestin- and β-tubulin III-positive ESCs was detected.