Olfactory ensheathing cells show promise in preclinical animal models as a
cell transplantation therapy for repair of the injured spinal cord. This is a report of a clinical trial of
autologous transplantation of olfactory ensheathing cells into the spinal cord in six patients with complete, thoracic
paraplegia. We previously reported on the methods of surgery and
transplantation and the safety aspects of the trial 1 year after
transplantation. Here we address the overall design of the trial and the safety of the procedure, assessed during a period of 3 years following the
transplantation surgery. All patients were assessed at entry into the trial and regularly during the period of the trial. Clinical assessments included medical, psychosocial, radiological and neurological, as well as specialized tests of neurological and functional deficits (standard American
Spinal Injury Association and Functional Independence Measure assessments). Quantitative test included neurophysiological tests of sensory and motor function below the level of injury. The trial was a Phase I/IIa design whose main aim was to test the feasibility and safety of
transplantation of autologous olfactory ensheathing cells into the injured spinal cord in human
paraplegia. The design included a control group who did not receive surgery, otherwise closely matched to the transplant recipient group. This group acted as a control for the assessors, who were blind to the treatment status of the patients. The control group also provided the opportunity for preliminary assessment of the efficacy of the
transplantation. There were no adverse findings 3 years after
autologous transplantation of olfactory ensheathing cells into spinal cords injured at least 2 years prior to
transplantation. The magnetic resonance images (MRIs) at 3 years showed no change from preoperative MRIs or intervening MRIs at 1 and 2 years, with no evidence of any tumour of introduced cells and no development of post-traumatic
syringomyelia or other adverse radiological findings. There were no significant functional changes in any patients and no
neuropathic pain. In one transplant recipient, there was an improvement over 3 segments in light touch and pin prick sensitivity bilaterally, anteriorly and posteriorly. We conclude that
transplantation of autologous olfactory ensheathing cells into the injured spinal cord is feasible and is safe up to 3 years of post-implantation, however, this conclusion should be considered preliminary because of the small number of trial patients.