AIM: To explore the photosensitization of 5-aminolevulinic acid (ALA) in myeloid leukemia cell line. METHODS: Using the
technique of fluorescence spectra, the ALA induced protoporphyrin IX (PpIX) was measured in myeloid leukemia JCS cells. Cofocal laser scanning
microscopy (CLSM) combined with fluorescence organelle probe was used to detecte the localization of PpIX in JCS cells at the subcellular levels.
MIT assay was used to measure the cell survival after light irradiation. RESULTS: ALA successfully produced endogenous PpIX in leukemia JCS cells.
PpIX was observed to be distributed in the cyloplasm and mitochondria was exhibited as the one of binding sites of PpIX. As a photosensitizer, PpIX
initiated photodynamic reaction after light irradiation and effectivily photodamaged leukemia cells. CONCLUSION: ALA-based photosensitization could be
used for inactivation of leukemia cells.
5-Aminolevulinic Acid–Based Photodynamic Therapy in Leukemia Cell HL60
Author(s): Su-Juan Zhang and Zhen-Xi Zhang
A study to explore the optimal experimental parameters and the photosensitization of 5-aminolevulinic acid (ALA)–based
photodynamic therapy (PDT) in promyelocytic leukemia cell HL60 has been conducted, in which HL60 cells and their control groups, peripheral blood
mononuclear cell (PBMC), first are incubated with different concentrations of ALA in dark for different periods of time and then followed by irradiating
with different wavebands for different fluences. Fluorescence microscope and spectrofluorometer have been used to detect the fluorescence of protoporphyrin
IX (PpIX) endogenously produced by ALA. The response of the cells to ALA-PDT was evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2-5-diphenyl-2H-tetrazolium
bromide (MTT) assay (interval between irradiation and the MTT assay is 24 h) and by flow cytometry (the length of time between irradiation and the flow
assay is 30 min). MTT results will reflect the relative number of metabolically active mitochondria in the population. Propidium iodide uptake in flow
cytometry will test for membrane damage. The results of parameter experiments were obtained: 1 × 105/mL HL60 cell was first incubated with 1 mmol/L ALA
in dark for 4 h and the maximum fluorescence of PpIX level appeared; then irradiated with 410 nm (4 mW/cm2) for 14.4 J/cm2 and maximum photodamage to
membrane and mitochondrial function of HL60 cell resulted. With the normal granulocytes, such response was not detected. Therefore a hypothetical idea
can be brought forward that ALA-based PDT can be used for inactivation of leukemia cell HL60 and these optimal parameters may be useful for clinical