Donor hair follicle preservation by partial follicular unit extraction. A method to optimize hair transplantation.

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.