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Effect of intense pulsed light treatment on human skin in vitro : analysis of immediate effects on dermal papillae and hair follicle stem cells
Author(s) -
Larouche D.,
Kim D.H.,
Ratté G.,
Beaumont C.,
Germain L.
Publication year - 2013
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/bjd.12477
Subject(s) - hair follicle , dermal papillae , vellus hair , stem cell , epidermis (zoology) , biology , hair shaft , keratin , human skin , melanin , dermis , pathology , microbiology and biotechnology , anatomy , scalp , medicine , genetics
Summary Background Hair follicles house a permanent pool of epithelial stem cells. Intense pulsed light ( IPL ) sources have been successfully used for hair removal, but long‐term hair reduction may require several treatments. Many questions remain regarding the impact of IPL treatment on the structure of the hair follicle, more specifically on hair follicular stem cells and dermal papilla cells, a group of specialized cells that orchestrate hair growth. Objectives To characterize the destruction of human hair follicles and surrounding tissues following IPL treatment, with more attention paid to the bulge and the bulb regions. Methods Human scalp specimens of F itzpatrick skin phototype II were exposed ex vivo to IPL pulses and were then processed for histological analysis, immunodetection of stem cell‐associated keratin 19, and revelation of the endogenous alkaline phosphatase activity expressed in dermal papilla cells. Results Histological analysis confirmed that pigmented structures, such as the melanin‐rich matrix cells of the bulb in anagen follicles and the hair shaft, are principally targeted by IPL treatment, while white hairs and epidermis remained unaffected. Damage caused by heat sometimes extended over the dermal papilla cells, while stem cells were mostly spared. Conclusions IPL epilation principally targets pigmented structures. Our results suggest that, under the tested conditions, collateral damage does not deplete stem cells. Damage at the dermal papilla was observed only with high‐energy treatment modalities. Extrapolated to frequently treated hairs, these observations explain why some hairs grow back after a single IPL treatment.