Post-Treatment Response and Safety of Stem Cell-Based Urethral Injection Therapy for Female Stress Urinary Incontinence: A Systematic Review and Meta-Analysis.

Background/

Objectives

Cell-based therapies have been proposed as a regenerative treatment for female stress urinary incontinence (SUI), but their efficacy, safety, and optimal delivery characteristics remain uncertain. The aim of this review is to systematically evaluate the post-treatment clinical response and safety of cell-based injection therapies for female SUI and explore factors associated with post-treatment response.

Methods

PubMed, Scopus, and the Cochrane Library were searched from inception to 15 February 2026, and the search was subsequently updated through 25 April 2026 to identify newly published studies. Randomized controlled trials and prospective single-arm studies evaluating urethral injection of cell-based therapies in adult women with SUI were included. Random-effects meta-analysis was used to pool study-defined post-treatment response proportions. Subgroup analyses examined response definition, cell source, urinary incontinence type, ultrasound guidance, injection approach, and post-treatment physiotherapy. Continuous moderators were explored using univariable meta-regression. Placebo-controlled randomized trials reporting a common 12-month response endpoint were additionally pooled using risk ratios (RR).

Results

Twenty-one studies involving 885 women were included. Seventeen studies contributed to the pooled post-treatment response analysis. The overall response proportion was 63.7% (95% confidence interval [CI] 56.7-70.5%), with moderate-to-substantial heterogeneity (I2 = 62.6%). Exploratory subgroup analyses showed higher post-treatment response in ultrasound-guided cohorts than non-ultrasound-guided cohorts (78% vs. 57%; p < 0.001), in cohorts restricted to pure SUI compared with those including mixed urinary incontinence (76% vs. 55%; p < 0.001), and in cohorts incorporating post-treatment physiotherapy compared with those without physiotherapy (78% vs. 58%; p < 0.001). Two placebo-controlled randomized trials reporting ≥ 50% reduction in stress incontinence episode frequency at 12 months were included in an exploratory comparative meta-analysis. The analysis showed no significant difference between cell therapy and placebo (RR 1.02, 95% CI 0.85-1.23; p = 0.85). Reported adverse events were predominantly minor and transient, commonly comprising irritative urinary symptoms, urinary tract infection, and biopsy- or injection-site complications. Serious treatment-related adverse events were rare, and no treatment-related deaths were reported.

Conclusions

Stem cell-based injection therapy for female SUI is associated with encouraging post-treatment response rates and a generally favorable short- to medium-term safety profile. However, this estimate cannot be interpreted as treatment-specific efficacy. The available placebo-controlled randomized evidence did not demonstrate a higher 12-month response with cell therapy than placebo. Cell-based therapy should therefore remain investigational, pending adequately powered, controlled trials and long-term follow-up.