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Pulsing influences photoradiation outcomes in cell culture
Author(s) -
Brondon Philip,
Stadler Istvan,
Lanzafame Raymond J.
Publication year - 2009
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20740
Subject(s) - melanin , medicine , intense pulsed light , mtt assay , blue light , cell growth , in vitro , pulsed laser , andrology , urology , endocrinology , chemistry , laser , biochemistry , dermatology , materials science , optics , physics , optoelectronics
Background and Objectives Skin pigmentation can adversely affect phototherapy outcomes. Delivering pulsed light has been suggested as a means of enhancing efficacy. Suitable pulse frequencies remain indeterminate, often being selected empirically. This study was undertaken to determine whether pulsed light delivery mitigates the filtering effect of melanin pigment on photomodulation in vitro. Study Design and Methods Human HEP‐2 cells were cultured in complete DMEM media. Photoradiation was delivered through 0.025% melanin filters at 670 nm (5.0 J/cm 2 /treatment/24 hours) for 72 hours at different pulse rates. Group A received no light treatment. Group B received treatments without pulsing. Groups C, D, E, F, and G received treatments at 6, 18, 36, 100, and 600 Hz. Cell proliferation was assessed by MTT assay and oxidative burst was measured using the 2.7 dichloro‐fluorescein‐diacetate assay. Results Cell proliferation was maximally stimulated at 100 Hz at 48 and 72 hours (n = 4, P ≤0.05). Oxidative burst was maximally stimulated at 600 Hz (n = 4, P ≤0.05). All frequencies were stimulatory at 48 and 72 hours (n = 4, P ≤0.05). Conclusion This investigation suggests that light pulsing may improve outcomes by mitigating the filtration effects of cutaneous melanin. Further studies to further define these effects are warranted. Lasers Surg. Med. 41:222–226, 2009. © 2009 Wiley‐Liss, Inc.