Stem cell therapy for erectile dysfunction: a systematic review and meta-analysis

Erectile dysfunction (ED) is a prevalent sexual dysfunction, and due to the limited efficacy of conventional treatments, stem cell (SC)-based regenerative approaches are being extensively investigated. We aimed to investigate the overall effect of SC therapy (SCT) on ED by consolidating findings from clinical studies and offering a general overview of the intervention content and design of these studies.

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We systematically reviewed MEDLINE, PubMed, Web of Science and ClinicalTrials.gov from inception to July 26, 2024. The outcomes were analyzed using the Comprehensive Meta-Analysis software version 3.0. The Q statistic and I² statistics were used to evaluate heterogeneity.

In this meta-analysis, a total of 11 studies evaluated International Index of Erectile Function (IIEF) levels, with an overall mean effect estimated at 16.872 [95% confidence interval (CI): 13.311-20.432]. The findings demonstrated statistically significant improvements in IIEF (Z=9.288, P<0.001), peak systolic velocity (PSV) (Z=5.384, P<0.001), end-diastolic velocity (EDV) (Z=4.604, P<0.001), erection hardness score (EHS) (Z=4.341, P<0.001), and resistive index (RI) (Z=22.302, P<0.001) levels. The pooled analysis demonstrated a significant improvement in IIEF-5 scores, although heterogeneity was extremely high (I²=92.59%). Furthermore, subgroup analyses revealed significant differences in patient diagnosis (z=3.29, P=0.017), baseline IIEF values (z=-3.64, P=0.003), and the type of SCs applied (z=-2.38, P=0.019).

This study suggests that SCT may represent a promising alternative approach for the treatment of ED. However, the current evidence is primarily derived from early-phase studies characterized by small sample sizes, heterogeneous populations, lack of control groups, and short follow-up durations. Therefore, while preliminary findings indicate a potential improvement in erectile function following treatment, the overall level of certainty remains low. Further well-designed, randomized controlled trials with larger sample sizes are required before definitive conclusions can be reached and broader clinical implementation can be recommended.