title: Differential stripping demonstrates a significant reduction of the hair follicle reservoir in vitro compared to in vivo.
abstract: Penetration studies are commonly performed on in vitro models, presumably due to a lack of non-invasive in vivo methods. To date, it is not clear whether in vitro models are suitable to reflect the in vivo conditions for percutaneous penetration. Apart from inter and intraspecies skin differences, the excision of a skin sample may influence the penetration rate inter alia as a result of the contraction of the elastic fibres in the skin during excision. Therefore, the aim of the present study was to investigate the follicular reservoir of the hair follicles of human skin in vivo and in vitro utilizing the method of differential stripping. The results obtained revealed a significantly reduced follicular reservoir in vitro, which was only 9.5+/-10.6% of the in vivo reservoir. These results are important for the interpretation of earlier and future penetration investigations. It can thus be assumed that excised skin models are suitable for penetration studies only to a limited extent, as follicular penetration is greatly diminished due to the contraction of the elastic fibres of the skin.
authors.affiliation: Department of Dermatology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin, Germany. alexa.patzelt@charite.de
authors.forename: Alexa
authors.initials: A
authors.lastname: Patzelt
authors.forename: Heike
authors.initials: H
authors.lastname: Richter
authors.forename: Rolf
authors.initials: R
authors.lastname: Buettemeyer
authors.forename: Hans Joachim Roewert
authors.initials: HJ
authors.lastname: Huber
authors.forename: Ulrike
authors.initials: U
authors.lastname: Blume-Peytavi
authors.forename: Wolfram
authors.initials: W
authors.lastname: Sterry
authors.forename: Juergen
authors.initials: J
authors.lastname: Lademann
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D001706:Biopsy; D003474:Curcumin / Q000008:administration & dosage / Q000378:metabolism*; D062109:Dermatologic Surgical Procedures; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004547:Elastic Tissue / Q000166:cytology; D005260:Female; D018859:Hair Follicle / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D015203:Reproducibility of Results; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D012869:Skin Absorption
chemical_list: D003474:Curcumin