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[Oxygen consumption during photodynamic therapy in vitro]
E O Wandl1, H G Löw, K H Kärcher
1Universitätsklinik für Strahlentherapie und Strahlenbiologie Wien, Osterreich.
Summary
Photodynamic therapy (PDT) in vitro consumes oxygen, with consumption rates increasing with hematoporphyrin derivative (HpD) concentration, serum, and cells. Repeated irradiation reduces oxygen consumption, indicating HpD disaggregation.
Area of Science:
- Biochemistry
- Photochemistry
- Cell Biology
Context:
- Photodynamic therapy (PDT) utilizes photosensitizers like hematoporphyrin derivative (HpD) to generate reactive oxygen species upon light activation.
- Understanding oxygen consumption during PDT is crucial for optimizing treatment efficacy and predicting outcomes.
- In vitro studies provide a controlled environment to investigate the fundamental mechanisms of PDT.
Purpose:
- To quantify dissolved molecular oxygen consumption during in vitro photodynamic therapy.
- To investigate the influence of hematoporphyrin derivative (HpD) concentration, serum, and cell presence on oxygen depletion.
- To explore the effect of repeated irradiation on HpD aggregation state and subsequent oxygen consumption.
Summary:
- Oxygen consumption was measured in aqueous solutions and cell suspensions containing hematoporphyrin derivative (HpD) during light irradiation (610-640 nm).
- The rate of oxygen consumption escalated with increasing HpD concentrations, serum levels, and cell numbers.
- Repeated irradiation led to decreased oxygen consumption, suggesting HpD disaggregation, and consumption occurred even at low oxygen partial pressures.
Impact:
- This study elucidates the oxygen dynamics critical for PDT efficacy, highlighting the role of photosensitizer aggregation.
- Findings provide insights into optimizing PDT protocols by managing photosensitizer concentration and cellular environment.
- The research contributes to a deeper understanding of the biochemical processes underlying photodynamic therapy in vitro.