Scientists from the United States and China have identified stem cells in urine that can be directed to become multiple cell types.
This image shows immunofluorescent staining of in vitro cultured urine-derived stem cells (Shaofeng Wu et al., 2011).
“These cells can be obtained through a simple, non-invasive low-cost approach that avoids surgical procedures,” explained Dr Yuanyuan Zhang from the Wake Forest Institute of Regenerative Medicine in Winston-Salem, NC, who is a senior author of the study published in the journal STEM CELLS.
Dr Zhang’s team successfully directed stem cells from urine to become bladder-type cells, such as smooth muscle and urothelial, the cells that line the bladder.
But the urine-derived cells could also form bone, cartilage, fat, skeletal muscle, nerve, and endothelial cells, which line blood vessels. The multipotency of the cells suggests their use in a variety of therapies.
Being able to use a patient’s own stem cells for therapy is considered advantageous because they do not induce immune responses or rejection. However, because tissue-specific cells are a very small subpopulation of cells, they can be difficult to isolate from organs and tissues.
The scientists first identified the cells, which are a small subset of the many cells found in urine, in 2006.
The current study builds on earlier studies by confirming the multipotency of the cells. In addition, the research found that unlike iPS cells or embryonic stem cells, the urine derived-stem cells do not form tumors when implanted in the body, indicating they may be safe for use in patients.
The scientists obtained urine samples from 17 healthy individuals ranging in age from five to 75 years. Next, they evaluated the cells’ ability to become multiple cell types.
The cells differentiated into the three tissue layers (endoderm, ectoderm and mesoderm) that are a hallmark of true stem cells and also differentiated into the specific cell types mentioned earlier.
The scientists then placed cells that had been differentiated into smooth muscle and urothelial cells onto scaffolds made of pig intestine. When implanted in mice for one month, the cells formed multi-layer, tissue-like structures.
The urine-derived stem cells have markers of mesenchymal cells, which are adult stem cells from connective tissue such as bone marrow. They also have markers for pericytes, a subset of mesenchymal cells found in small blood vessels. Where do the cells come from? Researchers suspect that the cells originate from the upper urinary tract, including the kidney.
“Identifying the origins of the cells will lead to a better understanding of the biology of this multipotent population of mesenchymal cells within the urinary tract system,” Dr Zhang concluded.
______
Bibliographic information: Shantaram Bharadwaj et al. 2013. Multi-Potential Differentiation of Human Urine-Derived Stem Cells: Potential for Therapeutic Applications in Urology. STEM CELLS, published online; doi: 10.1002/stem.1424
