5-aminolevulinic-acid-hexyl-ester and Osteosarcoma

We observed that two osteosarcoma cell lines from the same tumor displayed marked differences in their sensitivities to photodynamic therapy (PDT) with aminolevulinic acid hexyl ester (hALA-PDT). We investigated why these two closely related lines had different hALA-PDT sensitivities and whether the PDT phototoxicity of the less sensitive cell line could be increased by a simultaneous application of hyperthermia (HT).. Flow cytometry was used to evaluate the intracellular accumulation of protoporphyrin IX (PpIX), a metabolic product of aminolevulinic acid, in two human mandibular osteosarcoma cell lines (HOSM-1 and HOSM-2) treated with HT, hALA-PDT, or hALA-PDT combined with HT (PDT + HT). With hALA-PDT, cells treated with 0.2 mM hALA were irradiated with a light dose of 10-80 J/cm(2) from a near-infrared irradiator. With PDT + HT, the cells were treated as for hALA-PDT except that the temperature was raised to 43.5 degrees C during irradiation.. At 6 h after hALA treatment, HOSM-2 cells carried about 1.53-fold more PpIX than HOSM-1 cells. With hALA-PDT, the survival rate for HOSM-1 cells treated with 80 J/cm(2) irradiation was 35.7%, while that for HOSM-2 cells treated with 40-80 J/cm(2) was below 12%. With PDT + HT, the survival rate for HOSM-1 and HOSM-2 cells treated with 80 J/cm(2) irradiation was 14.1% and 10.7%, respectively.. A combination therapy comprising hALA-PDT + HT treatment may be very useful for the treatment of tumors containing cells that are insensitive to hALA-PDT, such as the HOSM-1 cell line described in this study.

Topics: Aminolevulinic Acid; Cell Line, Tumor; Combined Modality Therapy; Humans; Hyperthermia, Induced; Infrared Rays; Mandibular Neoplasms; Osteosarcoma; Photochemotherapy; Photosensitizing Agents; Protoporphyrins