Urinary Stem Cells and Their Therapeutic Potential


Yuanyuan Zhang, assistant professor of regenerative medicine at Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine, has extended earlier work on stem cells from urine that suggests that these cells might be more therapeutically useful than previously thought.

These urinary stem cells can be isolated from a patient’s urine sample, and they can be induced, in the laboratory, to form bladder-type cells; smooth muscle and urothelial (bladder-lining) cells. Such stem cells could certainly be used to treat urinary tract problems, even though a good deal more work is required to confirm that they can do just that.

Nevertheless, Zhang and his co-workers have discovered that these urinary tract stem cells are much more plastic than previously thought. In the laboratory, Zhang and others have managed to differentiate urinary tract stem cells into bone, cartilage, fat, skeletal muscle, nerve, and endothelial cells (the cells that line blood vessels). This suggests that urine-derived stem cells could be used in a variety of therapies.

USCs undergo multipotential differentiation in vitro. (a-c) endothelial differentiation of USCs. USCs (p3) were induced to endothelial lineage by culture in EBM-2 medium containing VEGF 50 ng/ml for 14 days. (a) In vitro vessel formation. Endothelial differentiated USCs were cultured on Matrigel for 18h to form branched networks (angiogenesis) and tubular structures. Scale bar = 100μm. (b) Expression analysis of endothelial-specific transcripts by RT-PCR. (c) Immunofluorescence staining using endothelial-specific markers revealed enhanced staining of the markers with differentiation (middle row) compared to the non-treated control (top row). Scale bar = 50μm.
USCs undergo multipotential differentiation in vitro. (a-c) endothelial differentiation of
USCs. USCs (p3) were induced to endothelial lineage by culture in EBM-2 medium containing
VEGF 50 ng/ml for 14 days. (a) In vitro vessel formation. Endothelial differentiated USCs were
cultured on Matrigel for 18h to form branched networks (angiogenesis) and tubular structures. Scale
bar = 100μm. (b) Expression analysis of endothelial-specific transcripts by RT-PCR. (c)
Immunofluorescence staining using endothelial-specific markers revealed enhanced staining of the
markers with differentiation (middle row) compared to the non-treated control (top row). Scale bar =
50μm.

Zhang said that urinary tract stem cells could be used to treat urological disorders such a kidney disease, urinary incontinence, and erectile dysfunction. However, Zhang is optimistic that they can also be used to treat a wider variety of treatment options, such as making replacement bladders, urine tubes, and other urologic organs.

Since these stem cells come from the patient’s own body, they can have a low chance of being rejected by the immune system. Also, they do not cause tumors when implanted into laboratory animals.

In their latest work, Zhang and his colleagues obtained urine samples from 17 healthy individuals whose ages ranged from five to 75 years old. Even though these stem cells are only one of a large collection of cells in urine, isolating urinary stem cells from urine only requires minimal processing.

A single USC (inset) is followed through different passages (p0-p12). The cells were expanded to a colony were cultured in KSFM-EFM medium with 5% serum and images recorded with passage. Images shown at x100
A single USC (inset)
is followed through different passages (p0-p12). The cells were expanded to a colony were cultured in
KSFM-EFM medium with 5% serum and images recorded with passage. Images shown at x100

In the laboratory, Zhang and his team differentiated the cells into derivatives of all three embryological layers (endoderm – skin and nervous tissue; mesoderm – bone, muscle, glands, and blood vessels; and endoderm – digestive system).

Differentiation of one USC clone into UCs and SMCs. (a) USCs (p3) t were used to differentiate into two distinct lineages. Culture in SMCs-lineage differentiation (2.5 ng/ml TGF-􀈕1 and 5 ng/ml PDGF-BB) and UCs-lineage differentiation (30 ng/ml EGF) medium was used for 14 days.
Differentiation of one USC clone into UCs and SMCs. (a) USCs (p3) t were used to
differentiate into two distinct lineages. Culture in SMCs-lineage differentiation (2.5 ng/ml TGF-􀈕1 and
5 ng/ml PDGF-BB) and UCs-lineage differentiation (30 ng/ml EGF) medium was used for 14 days.

After showing the multipotent nature of urinary tract stem cells in the laboratory, Zhang and others took smooth muscle cells and urothelial cells made from urinary tract stem cells and transplanted them into mice with tissue scaffolds that had been made from decellularized pig intestine. The scaffolds only had extracellular molecules and not cells. After one month, the implanted cells had formed multi-layered, tissue-like structures.

USCs were infected with BMP9 or control GFP and were injected subcutaneously into nude mice. i) Bony masses were only observed in mice implanted with BMP-transduced USCs at week 4. ii) The harvested bony masses were subjected to microCT imaging revealing the isosurface (left) and density heat maps (right).
USCs were infected with BMP9 or control GFP and were
injected subcutaneously into nude mice. i) Bony masses were only observed in mice implanted with
BMP-transduced USCs at week 4. ii) The harvested bony masses were subjected to microCT imaging
revealing the isosurface (left) and density heat maps (right).

Urinary tract stem cells or as Zhang calls them, urine-derived stem cells or USCs, have many cell surface characteristics of mesenchymal stem cells from bone marrow, but they are also like pericytes, which are cells on the outside of small blood vessels. Zhang and others suspect that USCs come from the upper urinary tract, including the kidney. Patients who have had kidney transplants from male donors have USCs with a Y chromosome in them, which suggests that the kidney is a source or one of the sources of these cells.

Determination of USC source. Several clones of USCs (p3) were cultured and analyzed for expression of kidney-lineage marker. (a) FISH (left) and amelogenin gene PCR analysis (right) analysis of USCs isolated from urine obtained from a male donor-to-female recipient kidney transplant for presence of Y-chromosome (L: DNA ladder, M: male control, F: female control, A4: USC from male donor-to-female recipient urine sample, N: negative control).
Determination of USC source. Several clones of USCs (p3) were cultured and analyzed for
expression of kidney-lineage marker. (a) FISH (left) and amelogenin gene PCR analysis (right)
analysis of USCs isolated from urine obtained from a male donor-to-female recipient kidney transplant
for presence of Y-chromosome (L: DNA ladder, M: male control, F: female control, A4: USC from
male donor-to-female recipient urine sample, N: negative control).

Even more work needs to be done before we can truly become over-the-moon excited about these cells as a source of material for regenerative medicine, Zhang’s work is certainly an encouraging start.

See Shantaram Bharadwaj, et al., Multi-Potential Differentiation of Human Urine-Derived Stem Cells: Potential for Therapeutic Applications in Urology. Stem Cells 2013 DOI: 10.1002/stem.1424.

Neural Stem Cell Found in Skeletal Muscle


Scientists at the Wake Forest School of Medicine have more fully characterized a stem cell that was isolated from muscle, but does not differentiate into muscle. Instead, this stem cells expresses several genes normally found in cells that inhabit the nervous system. These cells might serve as a source of material for the treatment of neurodegenerative diseases.

Osvaldo Delbono, professor of internal medicine at Wake Forest University and the senior author of this study said this: “Reversing brain degeneration and trauma lesions will depend on cell therapy, but we can’t harvest neural stem cells from the brain or spinal cord without harming the donor.”

Delbono continued, “Skeletal muscle tissue, which makes up 50% of the body, is easily accessible and biopsies of muscle are relatively harmless to the donor, so we think it may be an alternative source of neural-like cells that potentially could be used to treat brain or spinal cord injury, neurodegenerative disorders, brain tumors and other diseases, although more studies are needed.”

In 2011, Delbono and his colleagues isolated a stem cell from skeletal muscle that expressed several genes that you usually find in very young nervous tissue (the early neural marker Tuj1, light and heavy neurofilament for those who are interested). These cells did not express genes normally expressed in other tissues, such as smooth muscle or blood vessels.

Upon further characterization, the muscle-derived stem cells were able to respond to the neurotransmitter glutamate. This strongly intimates that these stem cells express the types of ion channels normally found in neurons. Also, these neural-like stem cells from muscle were clearly not derived from muscle satellite cells (another muscle stem cell population that produces skeletal muscle in response to muscle injury). Instead this stem cell is  interspersed in between muscle fibers. These cells were also able to proliferate and survive in culture (see Birbrair, et al., PLoS ONE 6(2): e16816. doi:10.1371/journal.pone.0016816).

In this new publication, Delbono’s group isolated muscle-specific neural stem cells from non-human primates and aging mice and injected them into the brain. The injected cells not only survived in the brain, but also migrated the those areas of the brain where neural stem cells are located.

The next issue they addressed was whether or not these stem cells will induce tumors upon injection. Neither stem cells from non-human primates nor those from aged mice produced tumors upon injection into the brain or when injected under the skin.

Alexander Birbrair, a postdoctoral student in Debono’s laboratory and the first author in this paper said, “Right now, patients with glioblastomas or other brain tumors have a very poor outcomes and relatively few treatment options.” Birbrair continued: “Because our cells survived and migrated in the brain, we may be able to use them as drug-delivery vehicles in the future, not only for brain tumors but also for other central nervous system diseases.”

Delbono’s team is also investigating whether these neural-like cells also have the capability to differentiate into functional neurons in the central nervous system.

See Alexander Birbrair, et al., Skeletal muscle neural progenitor cells exhibit properties of NG2-glia. http://dx.doi.org/10.1016/j.yexcr.2012.09.008,