STIMULATORY EFFECT OF 660 NM LOW-LEVEL LASER ENERGY ON HYPERTROPHIC SCAR-DERIVED FIBROBLASTS - POSSIBLE MECHANISMS FOR INCREASE IN CELL COUNTS

Background and Objective: Varying effects of red light wavelengths on in vitro cells have been reported. Low level lasers (LLL) are employed to assist wound healing especially for indolent ulcers. On healing, b urn wounds may become hypertrophic, resulting in excessive wound contr action, poor cosmesis, and functional impairment. This study enquired whether 660 nm LLL affected hypertrophic scar-derived fibroblasts. Stu dy Design/Materials and Methods: The experiments investigated the effe ct of a 660 nm, 17 mW laser diode at dosages of 2.4 J/cm(2) and 4 J/cm (2) on cell counts of two human fibroblast cell lines, derived from hy pertrophic scar tissue (HSF) and normal dermal (NDF) tissue explants, respectively. The protocol avoided transfer of postirradiated cells. E stimation of fibroblasts utilized the methylene blue bioassay. Results /Conclusion: The post-660 nm-irradiated HSFs exhibited very significan tly higher cell counts than controls P < 0.01 on days 1-4 (Mann-Whitne y U-test), and P < 0.01 on days 1-3 for similarly irradiated NDFs. (C) 1998 Wiley-Liss, Inc.