Effect of argon laser and Photofrin II on murine neuroblastoma cells

Laser-induced fluorescence (LIF) of photosensitizers is used to detect cancer. The effect of argon laser light with an average irradiance of 31 mW cm-2 and Photofrin II (Dihematoporphyrin ether, DHE) at concentrations of 1.0 and 5.0 micrograms ml-1 on C1300 murine neuroblastoma cells (MNB, NB41A3) in vitro was investigated. Growth curves and cell viability (trypan blue dye exclusion) were determined at 1, 24, 96, and 144 hr post-irradiation. Light doses of 1.8 and 9.0 J cm-2 combined with 5.0 micrograms DHE ml-1 decreased both cell numbers and viability, immediately and up to 144 hr postirradiation. Argon laser light alone at a fluence of 9.0 J cm-2 caused reversible injury to the cells. This in vitro study shows that both low energy argon laser light and low dose DHE are cytocidal to C1300 MNB cells. LIF promises to aid in the detection and destruction of neuroblastoma. Surgeons should be aware that tissue irreversible damage is likely to occur when performing LIF detection of neuroblastoma. The doses of laser light and of Photofrin II found to be toxic to neuroblastoma cells in culture may provide guidelines for photodynamic therapy ablation of neuroblastoma clinically.