A study of the effects of phototherapy dose interval on photobiomodulation of cell cultures

✍ Scribed by Philip Brondon; Istvan Stadler; Raymond J. Lanzafame

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 133 KB
• Volume: 36
• Category: Article
• ISSN: 0196-8092
• DOI: 10.1002/lsm.20183

✦ Synopsis

Abstract

Background and Objectives

Dosimetry and treatment frequency are controversial phototherapy issues. Efficacy of dose fractionation on photobiomodulation was evaluated in vitro.

Study Design/Materials and Methods

Human HEP‐2 and murine L‐929 cell lines were cultured in complete DMEM media. Photoradiation (670 nm, 5 J/cm^2^/treatment, 50 J/cm^2^ total energy delivery), was performed varying treatments per 24 hour period: Group I (Controls)—0, Group II‐1/d, Group III‐2/d, Group IV‐4/d. Cell proliferation was measured using Cyquant® (fluorescent DNA content) and MTT (3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyl tetrasolium bromide) assays for 240 hours post therapy. A proliferation index: PI = (#Cells Experimental~t~ ÷ #Cells Control~t~) was computed.

Results

MTT assay results demonstrated maximal response in Group III (P < 0.05, n = 3). Cyquant® maxima occurred in HEP‐2 Groups II and III (P < 0.045) and L‐929 Group III (P < 0.091).

Conclusions

Cellular response to dose frequency varies. More frequent treatments (2/24 hours) increased metabolism and proliferation in both cell lines. Further investigation of dose fractionation in phototherapy is warranted. © 2005 Wiley‐Liss, Inc.