RESEARCH REPORT POSTER DISPLAY

Number: 08-17
Physiotherapy 2007;93(S1):S189
Monday 4 June 09:00
VCEC Exhibit Hall B & C

THE EFFECTS OF LASER IRRADIATION ON PROLIFERATION IN OSTEOSARCOMA CELL LINES (MG63 AND U2OS). Renno A1, Mcdonnell A2, Laakso L3, Parizotto N4; 1Federal University of São Carlos, Sao Carlos, Brazil. 2Griffith University, Brisbane, Australia. 3Griffith University, Gold Coast, Australia. 4Federal University of São Carlos, Sao Carlos, Brazil

PURPOSE: In order to progress our understanding of the physiological processes and clinical parameters involved in the field of laser therapy, and to determine the responses of malignant bone cells to laser irradiation, we investigated the dose-response effects of 670nm, 780 nm and 830 nm laser on cell proliferation of two osteosarcoma (MG63 and U2OS) cell lines in vitro. RELEVANCE: Low level laser therapy (LLLT) has been used as a treatment in many clinical conditions and with effects on reducing post-injury inflammation and accelerating soft and hard tissue healing. LLLT stimulates mitochondrial respiration, increases the synthesis of DNA, RNA and regulatory proteins, and promotes cell proliferation in normal and malignant cells. However, the mechanism by which LLLT acts on cells is not fully understood. PARTICIPANTS: Human osteosarcoma cell lines: MG63 and U2OS METHODS: Cell lines were grown and passaged using standard aseptic tissue culture protocols. For laser irradiation, the wells of 96-well plates were seeded with 1x104 cells in fresh growth medium then incubated for 24hr at 37°C in 5%CO2. A single dose of irradiation was performed (670nm, 780 nm and 830 nm, 30 mW) at the intensities of 0.5, 1, 5 and 10 J/cm2. Cell proliferation was assessed 24hr after treatment by colorimetric spectrophotometry ANALYSIS: Data were described as means and standard deviation (SD) of the percentage. A 2-way ANOVA test was used to assess the significance of differences between the percentage of increase or decrease of irradiated groups compared with negative (untreated) controls, and the Duncan’s test to identify the differences. A p value of 0.05 was set for determining statistical significance. RESULTS: It was observed that MG63 osteosarcoma cell proliferation increased significantly after 670nm (at 5 J/cm2) and 780nm laser irradiation (at 1, 5 and 10 J/cm2, p≤ 0.05), but did not alter after 830nm laser irradiation. In contrast, U2OS cell proliferation was found significantly increased after irradiation with all laser wavelengths studied and at all doses (p≤ 0.05). CONCLUSIONS: The results of the present study suggest that laser irradiation has stimulatory effects on osteosarcoma cell proliferation. However, these data highlight that different osteosarcoma cell lines have different responses to different types of laser using specific irradiation parameters. Further investigations are required to investigate possible response mechanisms that may explain the outcomes obtained when examining laser irradiation of cultured cells. IMPLICATIONS: Such future studies will undoubtedly contribute to a better understanding of the safety and efficacy of LLLT in clinical oncology. KEYWORDS: cell proliferation, low level laser therapy, osteosarcoma. FUNDING ACKNOWLEDGEMENTS: Capes-Coordenação de Aperfeiçoamento de pessoal de Nivel Superior. CONTACT: acmr_ft@yahoo.com.br