- Vie Abr 01, 2011 8:55 am
#228174
ORIGINAL ARTICLE
Donor hair follicle preservation by partial follicular unit extraction.
A method to optimize hair transplantation
COEN G. GHO1 & H. A. MARTINO NEUMANN2
1Hair Science Institute, Amsterdam, The Netherlands and 2Department of Dermatology and Venerology, Erasmus
University Rotterdam, The Netherlands
Abstract
Background: There are different stem cell pools located in the hair follicle. Objective: To try to determine whether follicular units can survive a partial extraction and whether this partial extracted follicular unit can regenerate new hairs. Methods: From five individuals, between 100 and 150 grafts were harvested from the occipital area of the scalp. Suitable grafts were implanted into the recipient area. Hair growth and characteristics in the donor area and the recipient area were observed at different intervals.
Results: After 3 months, between 92.1% and 104.1% (mean 97.7%) of the partial follicular units in the donor sites survived and produced hairs with the same characteristics. After 1 year, 91.1–101.7% (mean 95.9%) of the implanted partial follicular units regenerated hair growth with the same characteristics as the hairs in the donor area. Conclusions: We revealed that extracted partial longitudinal follicular units transplanted to the recipient area can be used as complete follicular units to regenerate completely differentiated hair growth with the same characteristics as in the donor area. We also revealed that the partial follicular units in the donor area can survive and produce the same number of hairs with the same characteristics. This technique enables us to generate two hair follicles from one follicle with consistent results and preserve the donor area.
Key words: alopecia, androgenetic alopecia, esthetics, hair restoration, hair transplantation, humans Introduction. Over 60% of men and 50% of women suffer from androgenetic alopecia (1,2). Since this type of hair loss is a semi-natural process, and medication can only inhibit this temporarily, hair transplantation is the only method to restore hair permanently. There are different techniques of hair transplantation, all with their advantages and disadvantages. The most common and known hair transplantation method is the so-called ‘strip’ method (3). A strip of skin containing hair follicles is removed, cut into grafts and implanted in the recipient area. In recent years, new methods have developed, of which the most promising is the follicular unit extraction (FUE) method (4). With this method, whole follicle units are extracted one by one and implanted one by one back into the recipient area. The FUE method is a major step towards perfecting hair transplantation. Although the FUE method is more patient friendly and leaves only tiny scars compared to the strip method, which leaves visible linear scars at the donor area, the major disadvantage of both methods is that the extracted hair follicles are removed and the source of potential grafts will be consumed in time. Hair transplantations with the described methods will always be limited by the availability of donor hair follicles because no re-grow will occur in the donor area. The cosmetic result depends not only on the graft type (single-hair grafts or follicular units), the survival rate of the transplantation and the skill of the surgeon, but also on the number of grafts one can transplant. To date, no multiplication of human hair follicles in vitro is possible. The only theoretical way to preserve a significant part of the donor hair follicles could be partial FUE. This idea is not unrealistic and is supported by different experiments (5,6). Kim and Choi (5) found that, in humans, the proximal part of the hair follicle cannot regenerate into a differentiated hair follicle, but the distal part of the follicle can, eventually resulting in a fully developed hair follicle (7). Reynolds et al. found that, although the dermal papillae of humans cannot induce new hair growth, the sheath of the lower part of the hair follicle can (6). These apparently contradictory results indicate that both proximal and distal areas of the hair follicle should contain follicular stem cells that can induce hair growth.
In an earlier study we revealed that hair follicles from skin biopsies expressed CK19 and Bcl-2 in cells from the upper to the lower third of the follicle (8). Commo et al. also observed that distinct areas in the
hair follicle from skin biopsies are positive for CK19 (9). The fact that these areas are also Bcl-2 positive and Bax negative is a strong indication for different follicular stem cell sites which can induce hair growth. Positivity for CK19 and Bcl-2 corresponds to infrequent cell division in these areas, as concluded from the absence of Ki-67 staining (10,11). The fact that these cells are positive for Bcl-2 and CK 19, but Ki-67and Bax negative, is a strong indication that they represent follicular stem cells in the hair follicle. In case of partial longitudinal FUE, where follicular stem cells remain at the donor site as well as in the partial extracted follicle, a donor site capable of multiple hair transplantations should become possible. The main objectives of this study are: (i) to determine the percentage of re-growth and characteristics of hairs from transplanted partial longitudinal follicular units in the recipient area; and (ii) to determine the survival rate and the percentage of re-growth of the partial follicular units remaining in the donor area; the characteristics of the re-grown hairs are also evaluated.
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