Laser effect in photodynamic therapy of tumors

摘要

Photodynamic therapy is a method that provides a reasonable alternative to other treatment modalities for patients with certain cancers, and in some cases may be the preferred treatment. The therapy implies the intravenous administration of a light-sensitive substance, the photosensitizer. The used sensitizer must absorb at long wavelength. For these purposes, the carbon dioxide laser, He-Ne and the argon laser are particularly suitable. In this study we evaluate in vitro the cytotoxic activity of three synthesized metallo-phthalocyanines with absorption bands in the red part of the spectrum: zinc-di-sulphonated phthalocyanine (ZnS2Pc), zinc-tri-sulphonated phthalocyanine (ZnS3Pc) and zinc-tetrasulphonated phthalocyanine (ZnS4Pc). Some cellular models have been used in this paper, in order to optimize the conditions of this method, as we are presenting in this paper (LSR-SF(SR) - transplantable sarcoma in rat induced by Rous sarcoma virus strain Schmidt-Ruppin; LSCC-SF(Mc29) - transplantable chicken hepatoma induced by the myelocytomatosis virus Mc29, MCF-7 cell line (human breast adenocarcinoma) derived from a patient with metastatic breast cancer, 8-MG-BA - glioblastoma multiforme 8-MG-BA, KS62 - lymphoblastic human cell line, LLC-WRC 256 -Walker epithelial carcinoma. Activation of these photosensitizers retained in the cancerous cells, by red light emitted from a He-Ne laser at X= 632.8 nm laser system, or by a diode laser emitting at 672 nm, produces a photochemical reaction that results in the selective destruction of tumor cells.