Is violet LED light-based PDT efficient to treat superficial lesions such as a low-grade cervical intraepithelial neoplasia?

Abstract

Photosensitizers utilized in photodynamic therapy (PDT) can be exited with light of any wavelengths matching their absorption bands. Thus, superficial lesions, such as those involved in cervical intraepithelial neoplasias (CINs) might be treated with a light of shorter wavelength than red despite the smaller penetration depth in tissue. We review basic aspects of PDT and some investigations related to the use of light-emitting diodes (LEDs) of different wavelength mainly applied to superficial lesions, and highlight the benefits of the use of violet light and cellular spheroids as a PDT dosage model. Our previous results from spheroids of cervix carcinoma cells, suggest that the violet light from a LED source is appropriate for performing PDT of neoplastic lesions involving about 300 μm in depth. In this work we present a high fluence light source emitting at 420 nm and apply it to perform PDT treatment of a HeLa cell tumor model implanted in BALB/c nude mice. The photodynamic reaction is inferred from the fluorescence evolution measured at the tumor and the temperature evolution of the treated surface. Violet LED light could be a promising alternative for treating CINs involving superficial dysplasia, with reduced side effects.