Limited functional recovery in rats with complete spinal cord injury after transplantation of whole-layer olfactory mucosa

Abstract

Object The olfactory mucosa (OM) consists of 2 layers, the epithelium and the lamina propria. Attempts have been made to restore motor function in rat models of spinal cord injury (SCI) by transplanting olfactory ensheathing cells from the lamina propria, but there has been no attempt to transplant the OM in animal models. To investigate the potential of the OM to restore motor function, the authors developed a rat model of SCI and delayed transplantation of syngenic OM. Methods Two weeks after complete transection of the spinal cord at the T-10 level in Wistar rats, pieces of syngenic whole-layer OM were transplanted into the lesion. Rats that underwent respiratory mucosa transplantation were used as controls. The authors evaluated the locomotor activity according to the Basso-Beattie-Bresnahan scale for 8 weeks after transplantation. Obtained spinal cords were analyzed histologically. Results The OM transplantation rats showed significantly greater hindlimb locomotor recovery than the respiratory mucosa–transplanted rats. However, the recovery was limited according to the Basso-Beattie-Bresnahan scale. In the histological examination, the serotonergic raphespinal tract was regenerated. The pseudocyst cavity volume in the vicinity of the SCI lesion correlated negatively with the functional recovery. Conclusions Transplantation of whole-layer OM in rats contributes to functional recovery from SCI, but the effect is limited. In addition to OM transplantation, other means would be necessary for better outcomes in clinical situations.