In anatomical and functional studies of the human and animal urethra, the middle urethral contained rhabdosphincter is critical for maintaining continence. Transplanted stem cells may have the ability to undergo self renewal and multipotent differentiation, leading to sphincter regeneration. In addition, such cells may release, or be engineered to release, neurotrophins with subsequent paracrine recruitment of endogenous host cells to concomitantly promote a regenerative response of nerve-integrated muscle. Cell-based therapies are most often associated with the use of autologous multipotent stem cells, such as the bone marrow stromal cells. However, harvesting bone marrow stromal stem cells is difficult, painful, and may yield low numbers of stem cells upon processing. In contrast, alternative autologous adult stem cells such as muscle derived stem cells (MDSCs) and adipose-derived stem cells (ADSCs) can be easily obtained in large quantities and with minimal discomfort. This chapter aims to discuss the neurophysiology of stress urinary incontinence (highlighting the importance of the middle urethra); current injectable cell sources for endoscopic treatment; and the potential of MDSCs for the delivery of neurotrophic factors.