Lin, 1998 (ruby hair removal & growth cycle)

Lin, 1998

Title: Hair growth cycle affects hair follicle destruction by ruby laser pulses.

Authors: Lin TY, Manuskiatti W, Dierickx CC, Farinelli WA, Fisher ME, Flotte T, Baden HP, Anderson RR

Journal: J Invest Dermatol 1998 Jul;111(1):107-13

PMID: 9665395, UI: 98328332

Affiliated institution: Wellman Laboratories of Photomedicine, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.

It has been shown that normal mode ruby laser pulses (694 nm) are effective in selectively destroying brown or black pigmented hair follicles in adult Caucasians. This study investigated how the various stages of the hair follicle growth cycle influence follicle destruction by ruby laser treatment, using a model of predictable synchronous hair growth cycles in the infantile and adolescent mice. A range of ruby laser pulse fluences was delivered during different stages of the hair growth cycle, followed by histologic and gross observations of the injury and regrowth of hair. Actively growing and pigmented anagen stage hair follicles were sensitive to hair removal by normal mode ruby laser exposure, whereas catagen and telogen stage hair follicles were resistant to laser irradiation. Selective thermal injury to follicles was observed histologically, and hair regrowth was fluence dependent. In animals exposed during anagen, intermediate fluences induced nonscarring alopecia, whereas high fluences induced scarring alopecia. The findings of this study suggest treatment strategies for optimal laser hair removal.

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