Wei Liu

By Wei Liu and Hong Cai

Photodynamic therapy (PDT) employs light activation of tissue‐localized photosensitizer in an oxygen‐dependent process which initiates oxidative stress, inflammation, and cell death. Photodynamic therapy (PDT) involves the activation of a previously administered photosensitizing agent by visible light to induce tumor necrosis. Photosensitizers are topically applied in the treatment of skin tumors to avoid systemic side effects. The main dermatology indications for topical PDT are superficial nonmelanoma skin cancer and dysplasia, notably superficial basal carcinoma (BCC), Bowen's disease (BD), and actinic keratosis (AK). In this chapter, we evaluated the feasibility and efficacy of aminolevulinic acid (ALA) as a photosensitizer (ALA‐PDT) in combination with CO2 laser in the treatment of dermatological disease from basics to clinic research.

Part of the book: Photomedicine

By Gu Weijie, Liu Hongmei and Liu Wei

Intense pulsed light (IPL) is one of the most effective nonablative approaches to treat skin photoaging. The broad range of wavelengths (500–1200 nm) emitted from IPL devices effectively target both melanin and hemoglobin in the skin. Numerous trials show the effectiveness and compatibility of IPL devices in a variety of skin conditions, especially in cosmetic indications such as hypertrichosis and telangiectasias. Compared with the wide clinical use of IPL, the biochemical and molecular mechanism is not clear. Both in vivo and in vitro studies demonstrate that IPL could increase the production of extracellular matrix, promote the proliferation of fibroblasts, and increase the secretion of TGF-β and matrix metalloproteinases, which play important roles in the photorejuvenation effects of IPL. However, investigations regarding the detailed underlying mechanism are necessary.

Part of the book: Photomedicine