Abstract: 【Abstract】 Objective To compare the efficacy and safety of a domestic hair follicle extraction system versus traditional follicular unit excision （FUE） in extracting hair follicles for the treatment of androgenetic alopecia （AGA）. Methods A multicenter, randomized, self-controlled clinical trial was conducted on AGA patients aged 18 - 59 years who were recruited from the Huashan Hospital, Fudan University, the Affiliated Hangzhou First People's Hospital, and the China-Japan Friendship Hospital between June 2023 and September 2024. Each patient′s scalp was randomly divided into two sides （experimental side vs. control side） using an envelope method. The experimental side underwent robotic hair transplantation with a domestic hair follicle extraction system, and the control side underwent traditional FUE. Hair follicles were extracted from the safe donor area in the occipital region, and implanted into the ipsilateral hair loss area. The primary outcome was the hair transection rate which was calculated immediately after follicular extraction. The secondary outcomes included the hair follicle unit loss rate and the change in hair density at the recipient site on postoperative day 14. Safety was evaluated by assessing the incidence of folliculitis at the donor site on postoperative day 14 and the overall incidence of adverse events. Surgical outcomes were evaluated at 9 months after surgery. Comparisons of evaluation indicators among groups were performed by using a paired t test or Wilcoxon signed-rank test. Results A total of 55 patients with AGA （51 males and 4 females, aged 32.71 ± 5.75 years） completed the hair follicle transplantation and postoperative follow-up. The hair transection rate （M ［Q1, Q3］） was 6.65%（4.56%，10.16%） in the experimental group and 5.28%（3.04%，8.89%） in the control group （difference = 1.24%, 95% CI：-0.24%，2.65%）. The hair follicle unit loss rate was 2.00%（1.00%，3.50%） in the experimental group and 0.50%（0，2.00%） in the control group, with a significant difference between the two groups （P =0.008）. On postoperative day 14, there was no significant difference in the hair density between the experimental group and control group （72.20 ± 25.95 per cm2 vs. 76.49 ± 30.84 per cm2, P = 0.173）. At 9-month follow-up, both groups showed improvement in the investigator's overall score in the recipient areas. Seven adverse events occurred in 7 subjects （12.72%） in each group, and all were mild folliculitis. Conclusion The domestic hair follicle extraction system demonstrated comparable efficacy and safety to the traditional FUE in hair transplantation.

Key words: Alopecia, Androgenetic alopecia, Hair follicle, Hair transplantation, Robotic hair transplantation, Follicular unit excision, Randomized controlled trial