PA) - Researchers at the University of Pennsylvania School
of Medicine have isolated a new source of adult stem cells
that appear to have the potential to differentiate into several
cell types. If their approach to growing these cells can be scaled
up and proves to be safe and effective in animal and human studies,
it could one day provide the tissue needed by an individual for
treating a host of disorders, including peripheral nerve disease,
Parkinson’s disease, and spinal cord injury.
“We are very excited about this new source of adult stem cells
that has the potential for a variety of applications,” says
senior author Xiaowei (George) Xu, MD, PhD, Assistant
Professor of Pathology. “A number of reports have pointed
to the fact that adult stem cells may be more flexible in what they
become than previously thought, so we decided to look in the hair
follicle bulge, a niche for these cells.” Xu and colleagues
report their findings in the latest issue of the American Journal
Hair follicles are well known to be a source for adult stem cells.
Using human embryonic stem cell culture conditions, the researchers
isolated and grew a new type of multipotent adult stem cell from
scalp tissue obtained from the National Institute of Health’s
Cooperative Human Tissue Network.
The mutipotent stem cells grow as masses the investigators call
hair spheres. After growing the “raw” cells from the
hair spheres in different types of growth factors, the investigators
were able to differentiate the stem cells into multiple lineages,
including nerve cells, smooth muscle cells, and melanocytes (skin
The differentiated cells acquired lineage-specific markers and demonstrated
appropriate functions in tissue culture, according to each cell
type. For example, after 14 days, 20% to 40% of the cells in the
melanocyte media took on a weblike shape typical of melanocytes.
The new cells also expressed biomarkers typical of pigment cells
and when placed in an artificial human skin construct, produced
melanin and responded to chemical cues from normal epidermis skin
After 14 days, about 10% of the stem cells in the neuronal cell
line -- a type of cell not present in skin or hair -- grew dendrites,
the long extensions typical of nerve cells and expressed neuronal
proteins. The neurotransmitter glutamate was also present in the
cells, but the neurotransmitter dopamine was not detected.
Thirdly, about 80% of the stem cells grown in the muscle media differentiated
into smooth muscle cells. These new muscle cells also contracted
when placed in a collagen matrix.
Overall, the researchers showed that human embryonic stem cell media
could be used to isolate and expand a novel population of multipotent
adult stem cells from human hair follicles. “Although we are
just at the start of this research, our findings suggest that human
hair follicles may provide an accessible, individualized source
of stem cells,” says Xu. The researchers are now working on
inducing other cell types from the hair sphere cells and testing
the cells in animal models.
Study co-authors are Hong Yu, Suresh M. Kumar, and Geza Acs, all
from Penn; and Dong Fang, Ling Li, Thiennga K. Nguyen, and Meenhard
Herlyn, all from the Wistar Institute, Philadelphia.
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