Urine as a source of stem cells.

Traditionally, clinicians and researchers have relied on a skin biopsy or blood extraction as relatively accessible supplies for in vitro cell expansion and biological studies. Perhaps surprisingly, limited attention has been given to a totally noninvasive source, urine, which eliminates the discomfort associated with other procedures. This may arise from the perception that urine is merely a body waste. Yet, the analysis of urine is a longstanding fundamental test for diagnostic purposes and nowadays there is growing interest in using urine for detecting biomarkers. In addition, recent work including ours reinforces the idea that urine contains a variety of viable cell types with relevant applications. In this review, we describe those cell types and their potential uses.