Lipophilic rather than hydrophilic photosensitizers show strong adherence to standard cell culture microplates under cell-free conditions.

Analysis of photosensitizer (PS) uptake kinetics into tumor cells is a standard cell culture experiment in photodynamic therapy (PDT) - usually performed in plastic microplates or petri dishes. Organic substances such as PS can potentially interact with the plastic surfaces. In this study, we provide a qualitative comparison of three lipophilic PS (hypericin, Foscan® and Photofrin®) and two rather hydrophilic PS formulations (PVP-hypericin and aluminum (III) phthalocyanine tetrasulfonate chloride) regarding their adherence to the surfaces of 96-well microplates obtained from four different manufacturers.

Comparative in vitro study on the characteristics of different photosensitizers employed in PDT.

At present a wide range of photosensitizers are employed in photodynamic therapy (PDT) that have very different characteristics. Although, countless in vitro studies on the attributes of photosensitizers do exist, a direct comparison of these substances on one cell line are rare and may contribute to the choice of the optimal photoactive substance for a specific application. We therefore evaluated the properties of six widespread photosensitizers, namely Foscan, Fospeg, hypericin, aluminum (III) phthalocyanine tetrasulfonate chloride (AlPcS(4)), 5-aminolevulinic acid (ALA), and Photofrin in terms of: (i) cytotoxicity without illumination, (ii) phototoxicity, (iii) cellular uptake and release, and (iv) apoptosis induction in A431 human epidermoid carcinoma cells using comparable illumination regimens.

Uptake and phototoxicity of meso-tetrahydroxyphenyl chlorine are highly variable in human biliary tract cancer cell lines and correlate with markers of differentiation and proliferation.

Photodynamic therapy (PDT) using Photofrin and, recently, Foscan has gained broad acceptance for palliative treatment of non-resectable cholangiocarcinoma (CC). No information, however, is available whether the phenotype of CC tumour cells has an effect on the efficiency of the treatment. Using a well-characterised set of n = 9 biliary tract cancer cell lines this study investigated the uptake, phototoxicity, and release of meso-tetrahydroxyphenyl chlorine (mTHPC, Foscan) after incubation with 200 or 400 ng ml(-1) mTHPC.

Comparative characterization of the efficiency and cellular pharmacokinetics of Foscan- and Foslip-based photodynamic treatment in human biliary tract cancer cell lines.

Due to the poor prognosis and limited management options for perihilar cholangiocarcinoma (CC) the development of alternatives for treatment is an important topic. Photodynamic therapy (PDT) with porfimer as palliative or neoadjuvant endoscopic treatment of non-resectable perihilar CC has improved quality of life and survival time, but cannot eradicate the primary tumors because of inadequate tumoricidal depth (4 mm only around the tumor stenoses). The use of meta-tetrahydroxyphenyl chlorin (mTHPC) and photoactivation at higher wavelengths (650-660 nm) provides high tumoricidal depth (10 mm) for PDT of pancreatic cancer and should yield similar tumoricidal depth in CC.

Characterization of apoptosis induced by photodynamic treatment with hypericin in A431 human epidermoid carcinoma cells.

Hypericin is a naturally occurring metabolite extracted from Hypericum plants and is regarded as a promising photosensitizing agent for applications in the frame of photodynamic treatment (PDT). This treatment procedure is based on the light-induced formation of reactive oxygen species and subsequent destruction of target cells. We used an in vitro model system consisting of human epidermoid carcinoma cells (A431) and hypericin as a photosensitizer to study the time- and dose-dependent characteristics of hypericin-PDT-based induction of cytotoxicity and apoptotic cell death.

Differential effects of glucose deprivation on the cellular sensitivity towards photodynamic treatment-based production of reactive oxygen species and apoptosis-induction.

Photodynamic treatment (PDT) employs a photosensitizer and the light-induced formation of reactive oxygen species--antagonized by cellular antioxidant systems--for the removal of harmful cells. This study addresses the effect of altered carbohydrate metabolism on the cellular antioxidant glutathione system, and the subsequent responses to PDT. It is shown that glucose-deprivation of 18 h prior to PDT causes a reduced level of intracellular glutathione and an increased cytotoxicity of PDT.