Response: Clinical trials for the treatment of spinal cord injury: Cervical and lumbar enlargements versus thoracic area

Dr Rahimi-Movaghar raises several important issues when considering cell transplantation therapies in spinal cord injuries, particularly when considering ‘the next steps’ in olfactory ensheathing cell transplantation. The animal model data continue to indicate efficacy for these cells, so what is the logical next step in taking them through the clinical trial process? Our first study was a Phase I design with aspects of Phase II, namely a single blind study with an unoperated control group and blinded assessors (Mackay-Sim et al ., 2008). One logical progression is to repeat the trial with a larger cohort. Our first trial had group sizes of three, chosen because the risk was unknown. Clearly a larger number is required to be totally confident that the procedure is safe. Another logical progression is to move to a Phase II trial design to examine efficacy. A large Phase II trial design with staggered entry may fulfil requirement for further testing of both the safety and efficacy. The next part of …