Effects of transplantation of olfactory ensheathing cells in chronic spinal cord injury: a systematic review and meta-analysis

The debate on the effects and outcome of olfactory ensheathing cell (OEC) transplantation for the treatment of spinal cord injury (SCI) has remained unresolved for nearly 20 years. This study aimed to evaluate the safety and efficacy of OEC transplantation in chronic SCI patients. Electronic databases, including PubMed, the Cochrane Library, EMBASE, and MEDLINE, were searched to identify clinical therapeutic trials studying the use of OEC transplantation for SCI in humans. Each trial was analyzed in accordance with the criteria of the Cochrane Handbook 5.1.0 and MOOSE. Data were analyzed with Review Manager 5.2 and Meta-Analyst Beta 3.13 software. Eleven articles concerning 10 studies of 1,193 patients with chronic SCI treated with OEC transplantation were selected for review. All the articles had low methodological quality. Studies reported their outcomes using the American Spinal Injury Association (ASIA) Impairment Scale; the AISA motor, light touch, pinprick score; the Functional Independence Measure and (or) other measure methods. According to the available relevant data, the incidences of total adverse events and mortality were 7.68 % (n = 742) and 0.35 % (n = 566), respectively. The most frequently reported adverse events were fever, mild anemia, and syringomyelia; however, the statistical adverse events occurring in different studies were cerebrospinal fluid leakage (7.00 %, n = 586, 2 trials), sensory deterioration (0.70 %, n = 573, 2 trials), and both motor and sensory deterioration (0.68 %, n = 586, 2 trials). Given the results from our study, we conclude that OEC transplantation appears to be safe, although the evidence for efficacy is modest and requires the support of prospective, randomized trials in larger cohorts of patients. Further randomized controlled trials utilizing strict therapy programs and implanted cell selections are needed to confirm these findings.