3D lung spheroid cultures for evaluation of photodynamic therapy (PDT) procedures in microfluidic Lab-on-a-Chip system

- Microchip for study of PDT procedures efficiency on lung spheroids is presented.
- PDT procedures on 3D spheroids model during long-term culture is investigated.
- Verification of spheroid viability, ALA accumulation, ROS generation.
- High PDT effectiveness on lung spheroids required additional time after treatment.

The purpose of this paper is to present a fully integrated microchip for the evaluation of PDT procedures efficiency on 3D lung spheroid cultures. Human lung carcinoma A549 and non-malignant MRC-5 spheroids were utilized as culture models. Spheroid viability was evaluated 24 h after PDT treatment, in which 5-aminolevulinic acid (ALA) had been used as a precursor of a photosensitizer (protoporphyrin IX - PpIX). Moreover, spheroid viability over a long-term (10-day) culture was also examined. We showed that the proposed PDT treatment was toxic only for cancer spheroids. This could be because of a much-favoured enzymatic conversion of ALA to PpIX in cancer as opposed normal cells. Moreover, we showed that to obtain high effectiveness of ALA-PDT on lung cancer spheroids additional time of spheroid after light exposure was required. It was found that PDT had been effective 5 days after PDT treatment with 3 mM ALA. To the best of our knowledge this has been the first presentation of such research performed on a 3D lung spheroids culture in a microfluidic system.

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