Rose Bengal and Future Directions in Larynx Tumor Photodynamic Therapy†

Photodynamic Therapy Using a Rose-Bengal Photosensitizer for Hepatocellular Carcinoma Treatment: Proposition for a Novel Green LED-Based Device for In Vitro Investigation

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.

Miniature wireless LED-device for photodynamic-induced cell pyroptosis

The inability of visible light to penetrate far through biological tissue limits its use for phototherapy and photodiagnosis of deep-tissue sites of disease. This is unfortunate because many visible dyes are excellent photosensitizers and photocatalysts that can induce a wide range of photochemical processes, including photogeneration of reactive oxygen species. One potential solution is to bring the light source closer to the site of disease by using a miniature implantable LED. With this goal in mind, we fabricated a wireless LED-based device (volume of 23 mm3) that is powered by RF energy and emits light with a wavelength of 573 nm. It has the capacity to excite the green absorbing dye Rose Bengal, which is an efficient type II photosensitizer. The wireless transfer of RF power is effective even when the device is buried in chicken breast and located 6 cm from the transmitting antenna. The combination of a wireless device as light source and Rose Bengal as photosensitizer was found to induce cell death of cultured HT-29 human colorectal adenocarcinoma cells. Time-dependent generation of protruding bubbles was observed in the photoactivated cells suggesting cell death by light-induced pyroptosis and supporting evidence was gained by cell staining with the fluorescence probes Annexin-V FITC and Propidium Iodide. The results reveal a future path towards a wireless implanted LED-based device that can trigger photodynamic immunogenic cell death in deep-seated cancerous tissue.

Vitamin D and Vitamin D3 Supplementation during Photodynamic Therapy: A Review

Photodynamic therapy is an unconventional yet increasingly common method of treating dermatological diseases and cancer that is implemented more often in adults than in children. Current clinical uses include treatment of actinic keratosis, superficial basal cell carcinomas, and acne. Despite its high efficiency, photodynamic therapy support supplements have recently been reported in the literature, including calcitriol (1,25-dihydroxycholecalciferol), the active form of vitamin D, and vitamin D3 cholecalciferol. In clinical trials, photodynamic therapy enhanced with vitamin D or D3 supplementation has been reported for treatment of squamous cell skin cancers, actinic keratosis, and psoriasis. Experimental research on the effect of photodynamic therapy with vitamin D or D3 has also been carried out in breast cancer cell lines and in animal models. The aim of this review is to evaluate the usefulness and effectiveness of vitamin D and D3 as supports for photodynamic therapy. For this purpose, the Pubmed and Scopus literature databases were searched. The search keyword was: “vitamin D in photodynamic therapy”. In the analyzed articles (1979–2022), the authors found experimental evidence of a positive effect of vitamin D and D3 when used in conjunction with photodynamic therapy. An average of 6–30% (in one case, up to 10 times) increased response to photodynamic therapy was reported in combination with vitamin D and D3 as compared to photodynamic therapy alone. Implementing vitamin D and D3 as a supplement to photodynamic therapy is promising and may lead to further clinical trials and new clinical methodologies.

Photodynamic Therapy-Adjunctive Therapy in the Treatment of Prostate Cancer

The alarming increase in the number of advanced-stage prostate cancer cases with poor prognosis has led to a search for innovative methods of treatment. In response to the need for implementation of new and innovative methods of cancer tissue therapy, we studied photodynamic action in excised prostate tissue in vitro as a model for photodynamic therapy. To ascertain the effects of photodynamic action in prostate tissue, Rose Bengal (0.01 to 0.05 mM) was used as a photosensitizer in the presence of oxygen and light to generate singlet oxygen in tissues in vitro. Five preset concentrations of Rose Bengal were chosen and injected into prostate tissue samples (60 samples with 12 replications for each RB concentration) that were subsequently exposed to 532 nm light. The effects of irradiation of the Rose Bengal infused tissue samples were determined by histopathological analysis. Histopathological examination of prostate samples subjected to photodynamic action revealed numerous changes in the morphology of the neoplastic cells and the surrounding tissues. We conclude that the morphological changes observed in the prostate cancer tissues were a result of the photogeneration of cytotoxic singlet oxygen. The tissue damage observed post photodynamic action offers an incentive for continued in vitro investigations and future in vivo clinical trials.