Regenerative medicine and injection therapies in stress urinary incontinence.

Stress urinary incontinence (SUI) is a common and bothersome condition. Anti-incontinence surgery has high cure rates, but concerns about mesh tapes have resulted in the resurgence of surgical procedures that involve increased abdominopelvic dissection and morbidity. Injection therapy with urethral bulking agents or stem cell formulations have been developed as minimally invasive alternatives. Many synthetic and biological bulking agents have been trialled, but several have been discontinued owing to safety concerns. The use of Macroplastique and Contigen has the largest evidence base, but, overall, success rates seem to be similar between the various agents and positive outcomes are poorly sustained for more than 6 months. Furthermore, subjective cure rates, although initially high, also deteriorate over time. The available data consistently demonstrate manifestly poorer outcomes for injection therapies than for surgery. Stem cell treatments are thought to functionally regenerate the urethral sphincter in patients with suspected intrinsic sphincter deficiency. Autologous adipose and muscle-derived stem cells seem to be the intuitive cell source, as they are comparatively abundant, can be harvested and cause minimal donor site morbidity. To date, only a few small clinical studies have been reported and most data are derived from animal models. The success rates of stem cell injection therapies seem to be comparable with those of bulking agents.