Experimental Evidence in Hair Restoration Procedures: Plucked Hair Survival and Growth Rate

Background: Limitations of hair restoration procedures are the amount of hairs available and the invasiveness of follicular harvesting. Objective: The aim of this study was to compare conventional human micrografts and plucked hair follicles in an in vitro model in order to test hair growth rates for experimentally assessing the soundness of plucked follicle use in hair transplantation procedures. Methods and materials: A total of 100 conventional one-hair micrografts (group A; control) and a total of 80 plucked hair follicles (group B; experimental) were obtained from 14 healthy male patients. The length of each graft was measured immediately following isolation and at the end of the 10-day culture period. The Kruskal-Wallis one-way analysis of variance by ranks test was used in order to statistically analyze the data obtained. Results: A statistically significant difference was found between the growth rate of micrografts in control (mean 10-day shaft growth rate = 0.30mm) and experimental (mean 10-day shaft growth rate = 0.36mm) groups. Conclusion: The obtained data shows a higher plucked hair follicle growth rate compared to one-hair micrografts, which leads us to believe that plucked micrografts could be a useful and less invasive adjunct in the field of hair transplantation surgery.Hair transplantation for correction of androgenetic alopecia is one common aesthetic plastic surgery procedure performed on male patients.1,2 The principal purpose of hair harvesting has always been to obtain the maximum survival and growth rate possible. Micrografting is a method of hair transplantation involving randomly assorted groups of (1-2) hairs, without considering the natural configuration of their follicular units, which are selected under loupe, microscope, or naked eye examination.3 This type of graft is prepared by isolating each follicle as a whole, while maintaining a significant amount of tissue around the entire length of the follicle. Careful patient selection is very important, especially for African Americans and patients of Mediterranean origin on account of the curvilinear direction of their hair shafts, which could make graft preparation more difficult.4 Micrografting technique has been used both for hair restoration of the scalp and the face after burn injuries5,6 and particularly for eyebrow reconstruction7 due to the fine control obtainable with this technique and the natural-looking results. Plucked human hair consists in hair follicles which have been stripped from the donor area, without any dissection or local anesthesia. As demonstrated in the authors’ previous studies,8,9 rapid proliferating hair follicle capacity probably depends on the presence of human hair follicle multipotent stem cells in the bulge region of the outer root sheath. These previously characterized cells10 show an expression of proliferation marker Ki-67 and stem cell marker CD-34 in the follicle bulge region; the authors observed that plucked hair follicles have the same multipotent cell population as adult and fetal scalp hair follicles.9 Although some authors11-13 have recently described the presence of stem cells in plucked hair follicles, this was, to the best of the authors’ knowledge, the very first study specifically designed to assess the survival and growth rates of human plucked hair follicles, hypothesizing their possible use in hair restoration surgery. The aim of this study was to compare conventional human micrografts and human plucked hair follicles in an in vitro model, to experimentally assess the soundness of plucked hair follicle use in hair restoration surgery.