While
photodynamic therapy (
PDT) is an effective treatment for
glioma, induction of apoptotic cell death of
glioma cells is important for ensuring efficacy and safety of
PDT treatment in
glioma patients, as necrotic cell death can induce late appearance of obstacles in treatment. Here, we investigated the relationship between type of cell death and
PDT treatment conditions involved in
laser and
photosensitizer dosage in human
glioblastoma T98G cells.
Photosensitizer talaporfin sodium-mediated
PDT (NPe6-PDT) treatment induced
laser and
NPe6 dose-dependent cell death in T98G cells, whereas almost all cells pretreated with
NPe6 at ≥ 30 µg/mL were killed by
laser irradiation, regardless of
laser dose. Morphological analysis showed that combination of high doses of
NPe6 and
laser irradiation changes the dominant cell death process from apoptosis to
necrosis. Biochemical analysis (detection of
caspase-3 activity and staining of cell surface-exposed
phosphatidylserine) also showed that increasing
laser dose changes the type of cell death from apoptotic to necrotic cell death after high-dose treatment with
NPe6.
Lactate dehydrogenase leakage assay demonstrated that a
laser dose of 5 J/cm(2) induced less leakage than 30 J/cm(2). Our results suggested that type of
glioma cell death in NPe6-PDT changed with fluctuations in
laser and
NPe6 dose, and that combination of 30 µg/mL
NPe6 with 5 J/cm(2)
laser is the best treatment condition for inducing an increase in apoptotic cells while keeping rate of necrotic cell death low in this in vitro study.