title: A new alternative method for testing skin irritation using a human skin model: a pilot study.
abstract: BACKGROUND
  Studies assessing skin irritation to chemicals have traditionally used laboratory animals; however, such methods are questionable regarding their relevance for humans. New in vitro methods have been validated, such as the reconstructed human epidermis (RHE) model (Episkin®, Epiderm®). The comparison (accuracy) with in vivo results such as the 4-h human patch test (HPT) is 76% at best (Epiderm®). There is a need to develop an in vitro method that better simulates the anatomo-pathological changes encountered in vivo.
  
  
  OBJECTIVE
  To develop an in vitro method to determine skin irritation using human viable skin through histopathology, and compare the results of 4 tested substances to the main in vitro methods and in vivo animal method (Draize test).
  
  
  METHODS
  Human skin removed during surgery was dermatomed and mounted on an in vitro flow-through diffusion cell system. Ten chemicals with known non-irritant (heptylbutyrate, hexylsalicylate, butylmethacrylate, isoproturon, bentazon, DEHP and methylisothiazolinone (MI)) and irritant properties (folpet, 1-bromohexane and methylchloroisothiazolinone (MCI/MI)), a negative control (sodiumchloride) and a positive control (sodiumlaurylsulphate) were applied. The skin was exposed at least for 4h. Histopathology was performed to investigate irritation signs (spongiosis, necrosis, vacuolization).
  
  
  RESULTS
  We obtained 100% accuracy with the HPT model; 75% with the RHE models and 50% with the Draize test for 4 tested substances. The coefficients of variation (CV) between our three test batches were <0.1, showing good reproducibility. Furthermore, we reported objectively histopathological irritation signs (irritation scale): strong (folpet), significant (1-bromohexane), slight (MCI/MI at 750/250ppm) and none (isoproturon, bentazon, DEHP and MI).
  
  
  CONCLUSIONS
  This new in vitro test method presented effective results for the tested chemicals. It should be further validated using a greater number of substances; and tested in different laboratories in order to suitably evaluate reproducibility.
authors.affiliation: Dermatology Clinic, Canton Vaud University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Miles
authors.affiliation: Institute of Work and Health (IST), University of Lausanne and Geneva, Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Berthet
authors.affiliation: Institute of Work and Health (IST), University of Lausanne and Geneva, Lausanne, Switzerland.
authors.forename: N B
authors.initials: NB
authors.lastname: Hopf
authors.affiliation: Dermatology Clinic, Canton Vaud University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Gilliet
authors.affiliation: Reconstructive and Plastic Surgery Clinic, Canton Vaud University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: W
authors.initials: W
authors.lastname: Raffoul
authors.affiliation: Institute of Work and Health (IST), University of Lausanne and Geneva, Lausanne, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Vernez
authors.affiliation: Dermatology Clinic, Canton Vaud University Hospital (CHUV), Lausanne, Switzerland. Electronic address: Philipp.Spring@chuv.ch.
authors.forename: P
authors.initials: P
authors.lastname: Spring
mesh_terms: D000328:Adult; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007509:Irritants / Q000633:toxicity*; D008875:Middle Aged; D008954:Models, Biological; D009336:Necrosis; D010865:Pilot Projects; D012867:Skin / Q000473:pathology*; D012871:Skin Diseases / Q000139:chemically induced / Q000473:pathology*; D023422:Skin Irritancy Tests / Q000379:methods*; D014617:Vacuoles / Q000473:pathology
chemical_list: D007509:Irritants
keywords: 1-Bromohexane; Bentazon; Butylmethacrylate; DEHP; Draize test; Epiderm®; Episkin®; Folpet; Heptylbutyrate; Hexylsalicylate; Irritation scale; Isoproturon; Methylchloroisothiazolinone (MCI/MI); Methylisothiazolinone (MI); NaCl; Sodiumlaurylsulfate