title: Effect of caffeine and testosterone on the proliferation of human hair follicles in vitro.
abstract: BACKGROUND
  Androgenetic alopecia (AGA) is a common problem in men of all ages, affecting approximately 50% at 50 years of age. The underlying cause is an androgen-dependent miniaturization of genetically predetermined hair follicles. Here, the hair organ culture model was used to investigate the effects of testosterone and caffeine; the latter being a promising candidate for hair growth stimulation.
  
  
  METHODS
  Hair follicles from 14 biopsies, taken from the vertex areas from male AGA patients, were cultivated for 120-192 h in vitro with normal William's E medium (control) or William's E medium containing different concentrations of testosterone and/or caffeine. Hair shaft elongation was measured daily and at the end of cultivation, cryosections of follicles were stained with Ki-67 to evaluate the degree and localization of keratinocyte proliferation.
  
  
  RESULTS
  Significant growth suppression was found in hair follicles treated with 5 microg/ml testosterone. This was counteracted by caffeine in concentrations of 0.001% and 0.005%. Moreover, caffeine alone led to a significant stimulation of hair follicle growth. These results were confirmed immunohistochemically by Ki-67 staining.
  
  
  CONCLUSIONS
  Androgen-dependent growth inhibition of ex vivo hair follicles from patients suffering from AGA was present in the human hair organ culture model, a constellation which may serve for future studies to screen new substances against androgen-dependent hair loss. Caffeine was identified as a stimulator of human hair growth in vitro; a fact which may have important clinical impact in the management of AGA.
authors.affiliation: Department of Dermatology and Allergology, Friedrich-Schiller-University, Jena, Germany. tobias.fischer@derma.uni-jena.de
authors.forename: T W
authors.initials: TW
authors.lastname: Fischer
authors.forename: U C
authors.initials: UC
authors.lastname: Hipler
authors.forename: P
authors.initials: P
authors.lastname: Elsner
mesh_terms: D000328:Adult; D000505:Alopecia / Q000378:metabolism / Q000473:pathology*; D000728:Androgens / Q000494:pharmacology*; D001706:Biopsy; D002110:Caffeine / Q000494:pharmacology*; D018859:Hair Follicle / Q000187:drug effects* / Q000254:growth & development; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D012535:Scalp / Q000473:pathology; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D000728:Androgens; D019394:Ki-67 Antigen; D010726:Phosphodiesterase Inhibitors; D002110:Caffeine; D013739:Testosterone