Stem Cell Transplantation in Traumatic Spinal Cord Injury: A Systematic Review and Meta-Analysis of Animal Studies

Abstract

Author SummarySpinal cord injury is an important cause of disability in young adults, and stem cells have been proposed as a possible treatment. Here we systematically assess the evidence in the scientific literature for the effectiveness of stem-cell–based therapies in animal models of spinal cord injury. More studies reported effects on the ability to move (“motor outcomes”) than on sensation (“sensory outcomes”). Overall, treatment improves both sensory and motor outcomes, and for sensory outcome there was a dose–response effect (which suggests an underlying biological basis). Although more measures were taken to reduce the risk of bias than in other areas of translational neuroscience, unblinded studies tended to overstate the effectiveness of the treatment. The variability observed between the studies is not explained by differences in the stem cells used, but does seem to depend on the different injury models used to emulate human spinal cord injury. This suggests that the mechanism of injury should be an important consideration in the design of future clinical trials. Furthermore, open questions arise about the use of immunosuppressive drugs, and efficacy in female animals; these should be addressed before proceeding to clinical trial.