title: Tranexamic Acid Diminishes Laser-Induced Melanogenesis.
abstract: BACKGROUND
  The treatment of post-inflammatory hyperpigmentation (PIH) remains challenging. Tranexamic acid, a well-known anti-fibrinolytic drug, has recently demonstrated a curative effect towards melasma and ultraviolet-induced PIH in Asian countries. However, the precise mechanism of its inhibitory effect on melanogenesis is not fully understood.
  
  
  OBJECTIVE
  In order to clarify the inhibitory effect of tranexamic acid on PIH, we investigated its effects on mouse melanocytes (i.e., melan-a cells) and human melanocytes.
  
  
  METHODS
  Melan-a cells and human melanocytes were cultured with fractional CO2 laser-treated keratinocyte-conditioned media. Melanin content and tyrosinase activity were evaluated in cells treated with or without tranexamic acid. Protein levels of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 were evaluated in melan-a cells. Signaling pathway molecules involved in melanogenesis in melanoma cells were also investigated.
  
  
  RESULTS
  Tranexamic acid-treated melanocytes exhibited reduced melanin content and tyrosinase activity. Tranexamic acid also decreased tyrosinase, TRP-1, and TRP-2 protein levels. This inhibitory effect on melanogenesis was considered to be involved in extracellular signal-regulated kinase signaling pathways and subsequently microphthalmia-associated transcription factor degradation.
  
  
  CONCLUSIONS
  Tranexamic acid may be an attractive candidate for the treatment of PIH.
authors.affiliation: Department of Dermatology, Inje University, Sanggye Paik Hospital, Seoul, Korea.
authors.forename: Myoung Shin
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Dermatology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Bang
authors.affiliation: Aesthetic Research Team, Amore Pacific Corporation Research and Development Center, Yongin, Korea.
authors.forename: Jeong-Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Aesthetic Research Team, Amore Pacific Corporation Research and Development Center, Yongin, Korea.
authors.forename: Hong-Ju
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: Department of Dermatology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Jee-Ho
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Department of Dermatology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Sung Eun
authors.initials: SE
authors.lastname: Chang
keywords: Hyperpigmentation; Melanocytes; Tranexamic acid