Regenerating Urethral Striated Muscle by CRISPRi/dCas9-KRAB-Mediated Myostatin Silencing for Obesity-Associated Stress Urinary Incontinence.

Overweight females are prone to obesity-associated stress urinary incontinence (OA-SUI), and there are no definitive medical therapies for this common urologic condition. This study was designed to test the hypothesis that regenerative therapy to restore urethral striated muscle (stM) and pelvic floor muscles might represent a valuable therapeutic approach. For the in vitro experiment, single-guide RNAs targeting myostatin (MSTN) were used for CRISPRi/dCas9-Kruppel associated box (KRAB)-mediated gene silencing. For the in vivo experiment, a total of 14 female lean ZUC-Leprfa 186 and 14 fatty ZUC-Leprfa 185 rats were used as control and CRISPRi-MSTN treated groups, respectively. The results indicated that lentivirus-mediated expression of MSTN CRISPRi/dCas9-KRAB caused sustained downregulation of MSTN in rat L6 myoblast cells and significantly enhanced myogenesis in vitro. In vivo, the urethral sphincter injection of lentiviral-MSTN sgRNA and lentiviral-dCas9-KRAB significantly increased the leak point pressure, the thickness of the stM layer, the ratio of stM to smooth muscle, and the number of neuromuscular junctions. Downregulation of MSTN with CRISPRi/dCas9-KRAB-mediated gene silencing significantly enhanced myogenesis in vitro and in vivo. It also improved urethral continence in the OA-SUI rat model.