Safety evaluation of low level light therapy on cancer cells

Objective: Low level light therapy (LLLT) is being widely used in wound healing and pain relief, and its use is expected to be expanded rapidly to treatment of other disorders as well in a foreseeable future. However, before its expansion, the fear that LLLT could initiate or promote metastasis must be addressed thoroughly. As an initial effort towards this end, the current study evaluates the safety of LLLT in vitro using two different human cancer cell lines (Michigan Cancer Foundation-7 (MCF-7) and Jurkat E6-1) by determining the viability of cells after low level light (LLL) application while treatment under anti-cancer chemotherapeutic drugs (5-fluorouracil (5-FU) and cisplatin) separately on each cell line. Methods: Two human cancer cell lines (MCF-7 and Jurkat E6-1) were cultured throughout the experiments. Two different anti-cancer chemotherapeutic drugs (5-FU and cisplatin) were used to treat both cell lines. The half maximal inhibitory concentration (IC50) of each drug on each cell line was determined by treating each cell line with varying concentrations of each drug. A total of 3 or 4 trials were done for each cell line with each drug, and the range of concentration was narrowed closer to the IC50 value at each successive trial. Once the IC50 concentrations were determined, each cell line was treated with 808 nm LLL at varying energy densities in a single dose using a light emitting diode (LED) source both in the absence and the presence of each drug at one