Ready for human spinal cord repair?

We are in an exciting time where, based on successfully established animal models, a partial repair of the damaged human CNS appears to be feasible. A paper in the present issue of Brain (Mackay-Sim et al., 2008) deals with the outcome after transplantation of olfactory ensheathing cells (OEC) in subjects with chronic spinal cord injury. An earlier report described the surgical and safety procedures in this trial (Feron et al., 2005). Presently, rehabilitation of spinal cord injury is limited to exploiting neuronal plasticity by functional training (Dietz, 2002). The combination of functional training and regenerative therapies, even if only limited structural repair is achieved, would certainly make an improved impact on outcome. There is an impressive number of promising approaches for inducing regeneration or limiting neuronal damage by neuroprotective treatments based on rodent experiments (for review see One is the application of regeneration-facilitating OEC at the lesion site. Convincing evidence was found that this approach leads to some spinal cord repair in rodent spinal cord injury (Li et al. The present article (Mackay-Sim et al., 2008) reports on the effect of this approach in six chronic complete (ASIA A) spinal cord injury subjects (phase I/IIa design) with regular follow-up using clinical, electrophysiological (MEP), imaging (MRI) and functional (Functional Independence Measure, FIM) examinations over 3 years. Thus, the present study, in contrast to other OEC trials (Huang et al., 2003; Lima et al., 2006), was carefully designed on the basis of standards established during the past few years (Steeves et al., 2007). Such a study design is in line with the consensus that clinical examinations alone are insufficient reliably to monitor any therapeutic effect of a new interventional therapy (Curt et al., 2004). Additional neurophysiological and functional examinations allow for some differentiation between compensation , neuronal plasticity and regeneration as principal factors underlying an improvement of function after a spinal cord injury (Curt et al., 2008). Meanwhile, the Spinal Cord Independence Measure (SCIM) has been established for functional testing in spinal cord injury subjects (Catz et al., 2001). The results described by Mackay et al. (2008) must be considered preliminary because of the small number of spinal cord injury subjects included. In addition, the therapeutic effect of cell transplantation on outcome was not the primary goal of this study, although a comparison was made with a control group of spinal cord injury subjects. Overall, there were no adverse findings 3 years …