title: Pigmentation of regenerated hairs after wounding.
abstract: BACKGROUND
  After severe wounding, hair follicles were known to be regenerated de novo along with the re-epithelialization. However, the regenerated hairs lack pigmentation.
  
  
  OBJECTIVE
  We aimed to find out the condition to regenerate pigmented hairs after severe wounding.
  
  
  METHODS
  De novo hair regeneration was observed during the re-epithelialization process after the full thickness excision of dorsal skin. Hair pigmentation mechanism was assessed by the modulation of Wnt and Kit signalings.
  
  
  RESULTS
  Stable regeneration of pigmented hairs was demonstrated when a wound was created to the mice during the anagen stage of the hair cycle. A significant increase in the number of melanocyte stem cells in the postnatal 1st anagen interfollicular skin of 5-week-old mice was observed. An increase of Wnt7a of the keratinocytes was observed in the skin at this stage, which may direct melanocyte stem cells to produce pigmented hairs in the regenerating follicles. This was supported by the finding that transgenic mice expressing the melanocyte stimulatory factor Kitl in their skin promoted the regeneration of pigmented hairs irrespective of the stage of the hair cycle.
  
  
  CONCLUSIONS
  Our results provide a new insight into the intimate regulation process between two follicular stem cell systems, keratinocyte stem cells and melanocyte stem cells, during de novo hair regeneration after wounding.
authors.affiliation: Department of Tissue and Organ Development, Regeneration and Advanced Medical Science, Gifu University Graduate School of Medicine, Gifu 5011194, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yuriguchi
authors.affiliation: Department of Tissue and Organ Development, Regeneration and Advanced Medical Science, Gifu University Graduate School of Medicine, Gifu 5011194, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Aoki
authors.affiliation: Department of Tissue and Organ Development, Regeneration and Advanced Medical Science, Gifu University Graduate School of Medicine, Gifu 5011194, Japan; General Reearch & Development Institute, Hoyu Co., Ltd., 1-12, Roboku, Nagakute, Aichi 4801136, Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Taguchi
authors.affiliation: Department of Tissue and Organ Development, Regeneration and Advanced Medical Science, Gifu University Graduate School of Medicine, Gifu 5011194, Japan. Electronic address: tkunisad@gifu-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kunisada
mesh_terms: D000818:Animals; D006197:Hair / Q000502:physiology*; D018859:Hair Follicle / Q000502:physiology*; D006801:Humans; D008544:Melanocytes / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010858:Pigmentation; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D062326:Re-Epithelialization; D012038:Regeneration / Q000502:physiology*; D012867:Skin / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology; D051153:Wnt Proteins / Q000378:metabolism*; D014945:Wound Healing
chemical_list: D051153:Wnt Proteins; C490508:Wnt7a protein, mouse; D019009:Proto-Oncogene Proteins c-kit
keywords: De novo hair regeneration; Keratinocyte stem cell; Kitl; Melanocyte stem cell; Wnt signaing; Wnt7a