Quite seriously,
this is important for the expansion of stem cell therapies also. The application here, which is now becoming
practical, can be implemented with the minimum fuss as it is largely a cosmetic
application and the bar is much lower.
Thus stem cell hair restoration is easily rolled out compared to all
other applications.
It also allows a
plausibly youthful head of hair. Thus
even women will quickly opt for this solution.
All this leads quickly to other cosmetic applications including facial
skin replacement. It will not so readily
restore muscle tone but undamaged skin will always be welcome.
The point of course
is that the market for cosmetic application is way larger than for specific medical
procedures to correct damage.
First Study to
Convert Adult Human Cells to Hair-Follicle-Generating Stem Cells has
Implications for Hair Regeneration
PHILADELPHIA — If the content of many a situation
comedy, not to mention late-night TV advertisements, is to be believed, there’s
an epidemic of balding men, and an intense desire to fix their follicular
deficiencies.
One potential approach to reversing hair loss uses
stem cells to regenerate the missing or dying hair follicles. But it hasn’t
been possible to generate sufficient number of hair-follicle-generating stem
cells – until now.
Xiaowei
“George” Xu, MD, PhD, associate professor of Pathology and Laboratory
Medicine and Dermatology at the Perelman
School of Medicine, University of Pennsylvania, and colleagues published
inNature Communications a method for converting adult cells into
epithelial stem cells (EpSCs), the first time anyone has achieved this in
either humans or mice.
The epithelial stem cells, when implanted into
immunocompromised mice, regenerated the different cell types of human skin and
hair follicles, and even produced structurally recognizable hair shaft, raising
the possibility that they may eventually enable hair regeneration in people.
Xu and his team, which includes researchers from
Penn’s departments of Dermatology and Biology, as well as the New Jersey
Institute of Technology, started with human skin cells called dermal
fibroblasts. By adding three genes, they converted those cells into induced
pluripotent stem cells (iPSCs), which have the capability to differentiate into
any cell types in the body. They then converted the iPS cells into epithelial
stem cells, normally found at the bulge of hair follicles.
Starting with procedures other research teams had
previously worked out to convert iPSCs into keratinocytes, Xu’s team
demonstrated that by carefully controlling the timing of the growth factors the
cells received, they could force the iPSCs to generate large numbers of
epithelial stem cells. In the Xu study, the team’s protocol succeeded in
turning over 25% of the iPSCs into epithelial stem cells in 18 days. Those
cells were then purified using the proteins they expressed on their surfaces.
Comparison of the gene expression patterns of the
human iPSC-derived epithelial stem cells with epithelial stem cells obtained
from human hair follicles showed that the team had succeeded in producing the
cells they set out to make in the first place. When they mixed those cells with
mouse follicular inductive dermal cells and grafted them onto the skin of
immunodeficient mice, they produced functional human epidermis (the outermost
layers of skin cells) and follicles structurally similar to human hair
follicles.
“This is the first time anyone has made scalable
amounts of epithelial stem cells that are capable of generating the epithelial
component of hair follicles,” Xu says. And those cells have many potential
applications, he adds, including wound healing, cosmetics, and hair
regeneration.
That said, iPSC-derived epithelial stem cells are
not yet ready for use in human subjects, Xu adds. First, a hair follicle
contains epithelial cells -- a cell type that lines the body’s vessels and
cavities – as well as a specific kind of adult stem cell called dermal
papillae. Xu and his team mixed iPSC-derived EpSCs and mouse dermal cells to
generate hair follicles to achieve the growth of the follicles.
“When a person loses hair, they lose both types of
cells.” Xu explains. “We have solved one major problem, the epithelial
component of the hair follicle. We need to figure out a way to also make new
dermal papillae cells, and no one has figured that part out yet.”
What’s more, the process Xu used to create iPSCs
involves genetic modification of human cells with genes encoding oncogenic
proteins and so needs more refinement. Still, he notes that stem-cell
researchers are developing more workarounds, including strategies using only
chemical agents.
The study was funded by the National Institute of Arthritis and
Musculoskeletal and Skin Diseases (R01-AR054593, P30-AR05721).
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