Human umbilical cord blood-derived mesenchymal stem cell therapy in experimental spinal cord injury: A systematic review and meta-analysis

Figure 3 Forest plot of subgroup analyses for functional recovery. The plot presents pooled standardized mean differences (SMDs) with 95% confidence intervals for predefined subgroups investigating potential sources of heterogeneity. Significant effects were observed in canine models (P = 0.015), subacute intervention timing (P = 0.033), low-dose therapy (P < 0.001), and compression injury models (P = 0.033). All outcomes have been harmonized to the convention that higher values indicate better recovery; positive SMD values favor human umbilical cord blood-derived mesenchymal stem cell therapy. The dashed vertical line at SMD = 0 represents the null effect. Note: No studies administered human umbilical cord blood-derived mesenchymal stem cells in the chronic phase (> 2 weeks post-injury); therefore, the “timing of intervention” subgroup includes only acute (≤ 24 hours) and subacute (> 24 hours to ≤ 2 weeks) categories. The low-dose subgroup comprised only four studies using absolute cell counts without interspecies dose normalization; the observed I² = 0% should not be interpreted as evidence of true biological homogeneity (see the Limitations section for details). CI: Confidence interval; SMD: Standardized mean difference; hUCB-MSCs: Human umbilical cord blood-derived mesenchymal stem cells.