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Coen G. Gho, MD
International Society of Hair Restoration Surgery
New York, NY 2003
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ABSTRACT
TO
MULTIPLY OR NOT TO MULTIPLY, THAT IS THE QUESTION…
Coen
G. Gho MD., GHO Clinic, Maastricht, The Netherlands
H.A. Martino Neumann MD., PhD., Department of Dermatology,
Erasmus Medical Center and Erasmus University Rotterdam
Rotterdam, The Netherlands
Scientific
background
Stem
cells in general are protected against apoptosis. Bcl-2
is known to protect cells against apoptosis, while Bax promotes
cell death. Reports in the literature have indicated that
stem cell populations are cytokeratin (CK) 19 positive. The
presence of CK19 and Bcl-2 and absence of Bax expression, may
therefore be used as an indicator of stem cell populations in hair
follicle cultures.
A
considerable portion of the hair follicle remains attached to a
plucked hair and this can be used for follicular cell culture. We
found co-expression of CK19 and Bcl-2, but not Bax in two areas of
the mid-portion of the outer root sheath of the hair follicle from
skin biopsies, as well as of the plucked hair, while proliferation
markers were negative in these areas. This marker combination,
indicative of stem cells, could not be found in the dermal papilla
(partly Ki-67 positive) or the proximal part of the plucked hair.
CK19 and Bcl-2 were also present in a fraction of the follicular
cell culture.
We
conclude that CK19-, Bcl-2-positive and Bax-negative cells can be
obtained from plucked hair and remain present in follicular cell
cultures. If this phenotype indeed represents follicular stem cells,
our finding endorses the assumption that stem cells are located in
the bulge area of the hair follicle; they were not found in or near
the dermal papilla.
Slides
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Follicle transplantation
We
have shown that follicular stem cells are present in two areas of
the mid-portion of the outer root sheath of hair follicles obtained
from skin biopsies. The question therefore arises whether or not
both areas are necessary to induce hair growth. Kim
et al. found that
the proximal part of the hair follicle cannot regenerate into a
differentiated hair follicle, but the distal part of the follicle
can (Kim et al, 1995), eventually resulting in a fully developed
hair follicle (Kim et al, 1996). However, Reynolds et al. found
that, although the dermal papillae of human hair cannot induce new
hair growth, the sheath of the lower part of the hair follicle can
(Reynolds et al, 1999). These apparently contradictory studies
indicate that both proximal as well as distal areas of the hair
follicle have the potential to induce hair growth, which corresponds
with our finding that there are two stem cell locations in the
mid-portion of the outer root sheath.
This
knowledge is used in the technique of follicle
transplantation. While a part of the follicle which can induce hair growth remains in
the dermis, the extracted distal part of the hair follicle can also
induce hair growth. Because the exact location of the two
areas of stem cell varies between patients,
the potential for multiplication of the transplanted hair follicle
also varies between patients.
Slides
- click to enlarge
copyrighted materials, all rights reserved!
Hair multiplication
We
have shown in several studies that follicular stem cells derived
from plucked hair can be cultured. Hair multiplication is a technique whereby cultured follicular stem cells derived
from plucked hair from the occipital side of the head are used
to regenerate new hairs in bald areas. Because
the role of the
connective tissue or extracellular matrix surrounding the epithelial
portion of the hair follicle is very important for the survival of
the implanted cells, we implant the cultured cells into hair
follicles which remain in the recipient area.
The
future of hair restoration
Hair
multiplication may be the next step in hair restoration. The main
advantage is the preservation of hair growth in the donor area.
Although this advantage is very important, one has to bear in mind
that there are also disadvantages. For example, the patient has to
come to the clinic several times to donate the hairs, and laboratory
facilities are necessary to culture the cells. Also, as in other
tissue engineering projects, the consistency of the result cannot be
guaranteed. Although we have improved the consistency since
commencing our study programme, the results are still not
satisfactory enough to offer hair multiplication as a regular
commercial treatment.
References
Kim JC, Choi YC. Regrowth
of grafted human scalp hair after removal of the bulb. Dermatol Surg
1995; 21:312-3.
Kim JC, Kim MK, Choi YC.
Regeneration of the human scalp hair follicle after horizontal
sectioning: implications for pluripotent stem cells and melanocyte reservoir. In:
Van Neste DJJ, Randall VA, eds. Hair restoration for the next millennium: Elsevier Science B.V.,
1996:135-139.
Reynolds AJ, Lawrence C,
Cserhalmi Friedman PB, Christiano AM, Jahoda CA. Trans-gender
induction of hair follicles. Nature
1999; 402:33-4.
Earlier
coverage on Dr. Gho
HAIR
MULTIPLICATION FORUM
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