Pascal Deleporte

This article describes a new photodynamic therapy (PDT) device for evaluating the efficacy of Rose Bengal (RB)-mediated PDT in vitro. The device, called CELL-LED-550/3, consists of two 3D-printed parts, one generating a 550 nm green light from a single LED (the light source part) and the other distributing this light to a 96-well cell culture plate (the light distributor part). The light source part is controlled by a driver with three different modes, enabling the light distributor part to deliver three different irradiance levels to the bottom exterior surface of the wells: 0.02 mW/cm2, 0.23 mW/cm2, or 0.62 mW/cm2. The light distributor part was designed to illuminate the wells individually and simultaneously. To demonstrate the relevance of the CELL-LED-550/3 device, its ability to induce cell death by RB-mediated PDT on HepG2 hepatocellular carcinoma cells was evaluated. First, HepG2 cells were treated for 2 h with increasing concentrations of Rose Bengal, a photosensitizer with an absorption peak (the highest one) at around 550 nm. The treated cells were then illuminated using the CELL-LED-550/3 device set to its maximum irradiance level at light doses of 0.3 J/cm2, 0.6 J/cm2, and 1.2 J/cm2 (respectively, with illumination times of 8 min and 4 s, 16 min and 8 s, and 32 min and 16 s). Finally, viability was measured using Cell-Titer Glo at 24 h post-PDT. The experimental results show that RB-mediated PDT using the CELL-LED-550/3 device is capable of inducing a decrease in the viability of HepG2 cells, in a manner dependent both on the concentration of Rose Bengal and on the administered dose of light. Based on the proof of concept presented in this article, the CELL-LED-550/3 device adds a further tool to the study of RB-mediated PDT.

This article describes a new photodynamic therapy (PDT) device for evaluating the efficacy of Rose Bengal (RB)-mediated PDT in vitro. The device, called CELL-LED-550/3, consists of two 3D-printed parts, one generating a 550 nm green light from a single LED (the light source part) and the other distributing this light to a 96-well cell culture plate (the light distributor part). The light source part is controlled by a driver with three different modes, enabling the light distributor part to deliver three different irradiance levels to the bottom exterior surface of the wells: 0.02 mW/cm2, 0.23 mW/cm2, or 0.62 mW/cm2. The light distributor part was designed to illuminate the wells individually and simultaneously. To demonstrate the relevance of the CELL-LED-550/3 device, its ability to induce cell death by RB-mediated PDT on HepG2 hepatocellular carcinoma cells was evaluated. First, HepG2 cells were treated for 2 h with increasing concentrations of Rose Bengal, a photosensitizer with an absorption peak (the highest one) at around 550 nm. The treated cells were then illuminated using the CELL-LED-550/3 device set to its maximum irradiance level at light doses of 0.3 J/cm2, 0.6 J/cm2, and 1.2 J/cm2 (respectively, with illumination times of 8 min and 4 s, 16 min and 8 s, and 32 min and 16 s). Finally, viability was measured using Cell-Titer Glo at 24 h post-PDT. The experimental results show that RB-mediated PDT using the CELL-LED-550/3 device is capable of inducing a decrease in the viability of HepG2 cells, in a manner dependent both on the concentration of Rose Bengal and on the administered dose of light. Based on the proof of concept presented in this article, the CELL-LED-550/3 device adds a further tool to the study of RB-mediated PDT.

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Despite new treatments, the HCC rate remains important, making it necessary to develop novel therapeutic strategies. Photodynamic therapy (PDT) using a Rose-Bengal (RB) photosensitizer (RB-PDT) could be a promising approach for liver tumor treatment. However, the lack of standardization in preclinical research and the diversity of illumination parameters used make comparison difficult across studies. This work presents and characterizes a novel illumination device based on one green light-emitting diode (CELL-LED-550/3) dedicated to an in vitro RB-PDT. The device was demonstrated to deliver a low average irradiance of 0.62 mW/cm² over the 96 wells of a multi-well plate. Thermal characterization showed that illumination does not cause cell heating and can be performed inside an incubator, allowing a more rigorous assessment of cell viability after PDT. An in vitro cytotoxic study of the RB-PDT on an HCC cell line (HepG2) demonstrated that RB-PDT induces a significant decrease in cell viability: almost all the cells died after a light dose irradiation of 0.3 J/cm² using 75 µM of RB (<10% of viability). In conclusion, the RB-PDT could be a therapeutic option to treat unresectable liver lesions and subclinical disease remaining in the post-resection tumor surgical margin.

Photodynamic therapy (PDT) appears to be a promising strategy in biomedical applications. However, the complexity of its parameters prevents wide acceptance. This work presents and characterizes a novel optical device based on knitted light-emitting fabrics and dedicated to in vitro PDT involving low irradiance over a long illumination period. Technical characterization of this device, called CELL-LEF, is performed. A cytotoxic study of 5-ALA-mediated PDT on human cancer cell lines is provided as a proof of concept. The target of delivering an irradiance of 1 mW/cm² over 750 cm² is achieved (mean: 0.99 mW/cm²; standard deviation: 0.13 mW/cm²). The device can maintain a stable temperature with the mean thermal distribution of 35.1 °C (min: 30.7 °C; max: 38.4 °C). In vitro outcomes show that 5-ALA PDT using CELL-LEF consistently and effectively induced a decrease in tumor cell viability: Almost all the HepG2 cells died after 80 min of illumination, while less than 60% of U87 cell viability remained. CELL-LEF is suitable for in vitro PDT involving low irradiance over a long illumination period.