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Green Tea Linked To
Skin Cell Rejuvenation
 Research
into the health-promoting
properties of green tea is
yielding information that may
lead to new treatments for skin
diseases and wounds.
Dr. Stephen Hsu, a cell
biologist in the Medical College
of Georgia Department of Oral
Biology, has uncovered a wealth
of information about green tea
in the last few years. Most
importantly, he helped determine
that compounds in green tea
called polyphenols help
eliminate free radicals, which
can cause cancer by altering
DNA. He also found that
polyphenols safeguard healthy
cells while ushering cancer
cells to their death.
He recently began studying the
most abundant green tea
polyphenol, EGCG. Using pooled
human keratinocytes (skin
cells), he and his colleagues
studied the normal growth of the
skin cells and compared it to
the growth of the cells when
exposed to EGCG.
To their astonishment, they
found that EGCG reactivated
dying skin cells. "Cells that
migrate toward the surface of
the skin normally live about 28
days, and by day 20, they
basically sit on the upper layer
of the skin getting ready to
die," Dr. Hsu said. "But EGCG
reactivates them. I was so
surprised."
The skin consists of three
layers: the epidermis (outer
layer), dermis (mid-layer) and
hypodermis (inner layer). Dr.
Hsu learned that green tea
polyphenols aren't absorbed
beyond the epidermis, so any
benefits are limited to that
outer layer of skin. But the
benefits, he stressed, seem
significant.
Cells in the epidermis, or
keratinocytes, are in a constant
state of renewal. The newly
formed cells, stem cells, are
undifferentiated but rapidly
dividing. As they push through
the epidermis, they begin
differentiating. During this
migration and differentiation
process, the cells are very
active, expending and consuming
vast amounts of energy.
Once they reach the surface of
the skin, their metabolic
activity slows dramatically and
they prepare to die, while
forming a water-proof,
sheet-like structure. As they
die off about a month into their
life cycle, they are replaced by
another wave of migrating cells
supplied by stem cells, starting
the process all over again.
 But
EGCG seems to be a fountain of
youth for skin cells. "When
exposed to EGCG, the old cells
found in the upper layers of the
epidermis appear to start
dividing again," Dr. Hsu said.
"They make DNA and produce more
energy. They are reactivated.
There are lots of unknowns-this
is the first step into the
door-but if we can energize
dying skin cells, we can
probably improve the skin
condition."
In addition, the researchers
found that EGCG accelerates the
differentiation process among
new cells.
Combining these effects of EGCG
on skin cells in different
layers of the epidermis, Dr. Hsu
noted potential benefits for
skin conditions as diverse as
aphthous ulcers, psoriasis,
rosascea, wrinkles and wounds.
"If skin cells surrounding
wounds or infections don't heal
in time, fibroblasts in the
connective tissue may rush in to
fill the void and cause scar
tissue formation," he said. "If
we can spur the skin cells to
differentiate and proliferate,
we can potentially accelerate
the wound-healing process and
prevent scarring."
This potential benefit is
particularly exciting for
conditions such as diabetes,
which stubbornly inhibits the
wound-healing process, Dr. Hsu
said.
He and his colleagues hope to
identify dermatologists
interested in collaborating on
clinical studies of EGCG and
other polyphenols on patients.
Dr. Hsu's research, which is
excerpted on the online version
of the Journal of Pharmacology
and Experimental Therapeutics,
is funded by the Dental Research
Foundation, the MCG School of
Dentistry and MCG Research
Institute.
Source: Medical College Of
Georgia
Date: 2003-04-25
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