Preliminary Toxicity Evaluation of a Porphyrin Photosensitizer in an Alternative Preclinical Model

In photodynamic therapy (PDT), a photosensitizer (PS) excited with a specific wavelength, and in the presence of oxygen, gives rise to photochemical reactions that lead to cell damage. Over the past few years, larval stages of the G. mellonella moth have proven to be an excellent alternative animal model for in vivo toxicity testing of novel compounds and virulence testing. In this article, we report a series of preliminary studies on G. mellonella larvae to evaluate the photoinduced stress response by a porphyrin (PS) (TPPOH). The tests performed evaluated PS toxicity on larvae and cytotoxicity on hemocytes, both in dark conditions and following PDT. Cellular uptake was also evaluated by fluorescence and flow cytometry. The results obtained demonstrate how the administration of PS and subsequent irradiation of larvae affects not only larvae survival rate, but also immune system cells. It was also possible to verify PS's uptake and uptake kinetics in hemocytes, observing a maximum peak at 8 h. Given the results obtained in these preliminary tests, G. mellonella appears to be a promising model for preclinical PS tests.

Automated summary

In photodynamic therapy (PDT), a photosensitizer excited by a specific wavelength and oxygen leads to photochemical reactions and cell damage. This article reports preliminary studies on G. mellonella larvae to evaluate the stress response induced by a porphyrin photosensitizer (TPPOH). The tests showed the impact of photosensitizer administration and irradiation on larvae's survival rate and immune system cells, and observed a maximum peak of cellular uptake at 8 hours. The results suggest G. mellonella as a promising model for preclinical photosensitizer tests.