Role of follicular stem cells in wound healing
The research in hair growth and skin care has taken new strides
with the discovery of adult stem cells, which are sometimes also
referred to as progenitor cells. The scientific world got a major
boost with the findings that stem cells can be used to cure genetic
diseases by replacing damaged cells. And no wonder that the area
of the body that has maximum frequency of wounds, the skin, is
benefiting from this theory.
Scientists and researchers have tried their hardest to find a
way to correct or replace skin that has been burnt or damaged
through wounds by using cosmetic and plastic surgery. So far though
the success of new methods of surgery and treatment for extensive
skin damage have been mixed. But stem cells have given new hope
to the scientists as well as to the patients that receive such
burns and wounds. With advanced scientific techniques, researchers
have been able to make new discoveries, which can be used in the
science of skin care and dermatology.
It is a well known fact that epidermal cells cover the human
skin. Hair follicle cells and these epidermal cells are under
the constant microscope of dermatologists and skin specialists,
as there are some contrasting and insufficient theories about
the involvement of epidermal cells for production of hair follicle
cells in the cases of burnt skin of patients.
• Some theories state that if epidermal cells are lost,
there are chances of keratinocytes migrating from hair follicles
and re-establishing the lost epidermis.
Some theories, however, maintain the fact that there is no such
trafficking between epidermis cells and hair follicle cells, and
they are both independently self-sufficient.
Which basic theory is correct is a topic of hot debate, and no
conclusive evidence has yet been found in support of one or other.
Some recent investigations suggest that there are chances of some
traffic of cells between the epidermis and the hair follicles.
However, the research data is not conclusive due to the limited
number of subjects that have been examined by the researchers.
Utmost care needs to be taken while taking observations in experiments
and it is a well-known fact that the environment effects the skin
of the subjects, which can alter the nature of results, significantly.
Techniques used for checking the traffic
There is a particular biological property that can be used to
identify the keratinocyte stem cells. They are normally very slow
cycling and researchers can identify these sow growing keratinocyte
stem cells with some special scientific techniques. In this study,
the scientists used a technique to identify these keratinocyte
stem cells known as the label retention technique.
Though the overall reliability of this technique still remains
to be vindicated, the technique has received wide support from
dermatological scientists, and some important results have been
obtained by using this technique. This technique inovles exposing
skin cells to a supply of tritiated thymidine (a radioactive substance).
All the cells take up the radioactive thymidine and incorporate
it into themselves. Then the tritiated thymidine is taken away
and the cells get normal non-tritiated thymidine for the rest
of the experiment. As cells grow and multiply, the tritiated thymdine
gets spread progressively thinner between the daughter cells.
The radioactivity subsides and eventually disappears in growing
cells. However, stem cells don’t grow and proliferate much,
so the tritiated thymidine in these cells stays in them at fairly
high concentrations (I.e. they retain the “label” of
radioactivity – they are label retaining cells). The radioactive
cells can be tracked over a long time period and only the slow
cycling cells retain the label while others eventually lose it.
In this way the scientists can follow the stem cells and see where
The questions that arise from the results of this technique are
both interesting and important, as they may present a total new
face to the theories that deal with the formation of epidermis
cells with the migration of keratinocyte cells from hair follicles
and also the ones that state that no such thing happened and epidermis
cells and hair follicles are distinct and there is no connection
between the two.
Recent studies about the connection
Some very recent studies have suggested and supported the fact
that there may be a chance of some trafficking of keratinocyte
stem cells from a part of the hair follicle which is known as
Bulge. What makes these findings more striking is the fact that
they also suggest formation of epidermal cells with these bulge
stem cells. The data and the investigation results can be used
for further examination to establish a clear and permanent relationship
between the formation of hair follicles and epidermal cells with
the help of Bulge stem cells.
This property could actually help a lot in the field of skin
care. These studies support the idea that, though the epidermal
cells are self-sufficient under normal conditions, if the need
arises, stem cells can move from Bulge area of hair follicles
to form epidermal cells. The conditions under which this trafficking
may occur may include neonatal expansion of the skin and during
adult skin wound repair. The main point to be taken care of is
that the subjects that are examined in these studies have different
kinds of skin on different parts of the body. In humans, there
are some parts which have no hair follicles on the skin surface
like the palms and soles of the feet. In these areas clearly wounds
cannot be supplied with stem cells from hair follicles because
there are no hair follicles nearby.
The similarities of microenvironment and other properties between
epidermal cells and hair follicle cells present a clear picture
that the trafficking of stem cells does happen under certain circumstances.
The authenticity of the label retention technique has also been
supported by the fact that researchers are able to examine the
stem cells from epidermis cells and hair follicle cells. This
gives an added advantage to researchers for further studies and
investigation about stem cells and their microenvironment. So,
in the end we can say that there is a definite role played by
follicular cells in the formation of epidermal skin during a time
Role of follicular stem cells in wound healing references