title: Repeated Microneedle Stimulation Induces Enhanced Hair Growth in a Murine Model.
abstract: BACKGROUND
  Microneedle is a method that creates transdermal microchannels across the stratum corneum barrier layer of skin. No previous study showed a therapeutic effect of microneedle itself on hair growth by wounding.
  
  
  OBJECTIVE
  The aim of this study is to investigate the effect of repeated microwound formed by microneedle on hair growth and hair growth-related genes in a murine model.
  
  
  METHODS
  A disk microneedle roller was applied to each group of mice five times a week for three weeks. First, to identify the optimal length and cycle, microneedles of lengths of 0.15 mm, 0.25 mm, 0.5 mm, and 1 mm and cycles of 3, 6, 10, and 13 cycles were applied. Second, the effect of hair growth and hair-growth-related genes such as Wnt3a, β-catenin, vascular endothelial growth factor (VEGF), and Wnt10b was observed using optimized microneedle. Outcomes were observed using visual inspection, real-time polymerase chain reaction, and immunohistochemistry.
  
  
  RESULTS
  We found that the optimal length and cycle of microneedle treatment on hair growth was 0.25 mm/10 cycles and 0.5 mm/10 cycles. Repeated microneedle stimulation promoted hair growth, and it also induced the enhanced expression of Wnt3a, β-catenin, VEGF, and Wnt10b.
  
  
  CONCLUSIONS
  Our study provides evidence that microneedle stimulation can induce hair growth via activation of the Wnt/β-catenin pathway and VEGF. Combined with the drug delivery effect, we believe that microneedle stimulation could lead to new approaches for alopecia.
authors.affiliation: Department of Dermatology, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Yoon Seob
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Dermatology, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Kwan Ho
authors.initials: KH
authors.lastname: Jeong
authors.affiliation: Department of Dermatology, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Kim
authors.affiliation: Department of Dermatology, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Woo
authors.affiliation: Department of Dermatology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Beom Joon
authors.initials: BJ
authors.lastname: Kim
authors.affiliation: Department of Dermatology, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Hoon
authors.initials: H
authors.lastname: Kang
keywords: Alopecia; Hair; Hair follicle; Microneedle