Age-Related Changes in Urethral Structure and Responds to Injury: Single-Cell Atlas of a Rat Model of Vaginal Birth Injury induced Stress Urinary Incontinence

Stress urinary incontinence (SUI) greatly affects the daily life of numerous women and is closely related to a history of vaginal delivery and aging. We used vaginal balloon dilation to simulate vaginal birth injury in young and middle-aged rats to produce a SUI animal model, and found that young rats restored urethral structure and function well, but not the middle-aged rats. To identify the characteristics of cellular and molecular changes in the urethral microenvironment during the repair process of SUI. We profiled 51,690 individual female rat urethra cells from 24 and 48 weeks old, with or without simulated vaginal birth injury. Cell interaction analysis showed that signal networks during repair process changed from resting to active, and aging altered the distribution but not the overall level of cell interaction in the repair process. Similarity analysis showed that muscle, fibroblasts, and immune cells underwent large transcriptional changes during aging and repair. In middle-aged rats, cell senescence occurs mainly in the superficial and middle urothelium due to cellular death and shedding, and the basal urothelium expressed many Senescence-Associated Secretory Phenotype (SASP) genes. In conclusion, we established the aging and vaginal balloon dilation (VBD) model of female urethral cell anatomy and the signal network landscape, which provides an insight into the normal or disordered urethra repair process and the scientific basis for developing novel SUI therapies.