The role of stem cell secretome on spinal cord injury regeneration: a systematic review and meta-analysis

Abstract

The treatment of spinal cord injuries (SCIs) is a controversial topic and is not yet effective. Stem cell secretome is an emerging alternative treatment that uses the paracrine effect of stem cells. Although there have been many studies on this subject, there are still differences regarding the origin, dose, route of secretome administration, type of experimental animal, phase of the SCI, and outputs evaluated. The topic needs a systematic review and meta-analysis. Methods: This systematic review and meta-analysis were reported based on criteria from Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The authors searched PubMed, ScienceDirect, Cochrane Library, and Google Scholar with multiple electronic databases until October 2021. Results:Twenty-eight studies that met the inclusion criteria were included in this research. The stem cell secretome was very beneficial as the axonal regeneration agent (n=12); it increases the locomotor recovery (n=28) and growth factors (n=2) and reduces the size of the cystic cavity (n=1) and lesion extension (n=14). We recognized 28 studies that met our inclusion criteria. Stem cell secretome therapies showed improvement in the locomotor score (standard mean difference [SMD]: 0.94; 95% confidence interval [CI]: 0.75–1.13, p<0.000001, I2 =90%) and reduction in the lesion size (SMD: 5.06; 95% CI: 3.44– 6.67, p<0.00001, I2 =94%). Conclusion:The stem cell secretome greatly affects treating SCI rodent models. Future studies should focus on chronic SCIs in the primary research, translational research, and neurological research stage of stem cell secretome.