title: Effect of IGF-I on Hair Growth Is Related to the Anti-Apoptotic Effect of IGF-I and Up-Regulation of PDGF-A and PDGF-B.
abstract: BACKGROUND
  Insulin-like growth factor-I (IGF-I) shares a high degree of structural and functional homology with insulin and is a potent mitogen supporting cell growth and survival in many kinds of the tissues and cells. It also plays a role in some differentiation and anti-apoptotic functions. In previous reports, it has been shown that IGF-I stimulates hair follicle (HF) growth, maintains the anagen stage, and postpones the catagen stage.
  
  
  OBJECTIVE
  The exact mechanism of the effect of IGF-I on HF growth is not yet established. Therefore, we investigated the relationships between IGF-I and various other factors (i.e. apoptosis related molecules, pro-inflammatory cytokines, other growth factors, etc.) in the control of HF growth.
  
  
  METHODS
  The effect of IGF-I on human hair growth was measured using an organ culture model of human HFs and compared with a control group that did not receive IGF-I. We also measured mRNA expression of factors related to hair growth and apoptosis (which was determined by reverse transcription polymerase chain reaction (RT-PCR). RT-PCR was done on days 2, 4, 6, and 8 of organ culture.
  
  
  RESULTS
  In organ cultured human hair follicles, IGF-I had a positive effect on the rate of linear hair growth. IGF-I maintained the anagen phase. IGF-I increased the expression of platelet-derived growth factor (PDGF)-A, PDGF-B and the expression ratio of Bcl-2/Bax.
  
  
  CONCLUSIONS
  The effect of IGF-I on hair growth appears to be related to the upregulation of PDGF-A and PDGF-B and to the anti-apoptotic effect of IGF-I.
authors.affiliation: Department of Dermatology and Institute of Hair and Cosmetic Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Seok-Yong
authors.initials: SY
authors.lastname: Ahn
authors.forename: Long-Quan
authors.initials: LQ
authors.lastname: Pi
authors.forename: Sungjoo Tommy
authors.initials: ST
authors.lastname: Hwang
authors.forename: Won-Soo
authors.initials: WS
authors.lastname: Lee