Application of photodynamic therapy in the sterilisation of tumour cells transplanted into laboratory animals

In this study, we tried to estimate the effectiveness of the antimicrobial activity of photodynamic therapy (PDT) without the destruction of tumour cells. Chlorin e6 in concentrations from 0.05 to 1.0 µg/mL and total dose of light 100 J/sq.cm were used. Samples from different tumours were tested for a presence of bacteria. Next, cells from the same tumours were treated with chlorin e6-PDT, chlorin e6, and light alone, or not treated. The survival rate was counted, and the cells were injected back into the animals. PDT caused the eradication of bacteria such as Proteus sp., Streptococcus α-haemolyticus, and others: the specimen became aseptic. After Ce6-PDT treatment and in control groups, tumour growth was observed in all rats 7-10 d after transplantation. The tumours were palpable and macroscopically visible. Our studies showed that PDT kills bacterial flora without the destruction of tumour cells. Thus, tumour cells free of bacteria could be used for other experiments.