Subcellular phototoxicity of 5-aminolaevulinic acid (ALA).
OBJECTIVE
5-aminolaevulinic acid (ALA) is a new, promising photosensitizer for PDT of cancer. Subcellular toxicity induced by ALA and light exposure in single cells was studied to elucidate the mechanism of cell damage.


METHODS
CPAE, PTK2, and rat neonatal myocardial cells treated with ALA were examined for localization using fluorescence microscopy and for subcellular phototoxicity using 630 nm laser microbeam irradiation of specific subcellular regions.


RESULTS
In CPAE and PTK2 cells, a large amount of fluorescence was detected in the peri-nuclear cytoplasm. In rat neonatal myocardial cells, the sensitizer selectively localized in the large mitochondria. In both cell types, there was little phototoxicity when the peripheral cytoplasmic region was exposed, as compared to considerable phototoxicity with exposure of either the perinuclear or nuclear regions.


CONCLUSIONS
Both the CPAE and PTK2 cells demonstrated that the nucleus followed by the perinuclear cytoplasm are the most sensitive cell areas with no sensitivity in the peripheral cytoplasm.
Liang
H
H
Beckman Laser Institute and Medical Clinic, University of California, Irvine 92612, USA.
Shin
D S
DS
Lee
Y E
YE
Nguyen
D C
DC
Trang
T C
TC
Pan
A H
AH
Huang
S L
SL
Chong
D H
DH
Berns
M W
MW
D000622:Aminolevulinic Acid / Q000633:toxicity*; D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000187:drug effects; D002478:Cells, Cultured; D003593:Cytoplasm / Q000187:drug effects; D004173:Dipodomys; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D005260:Female; D006321:Heart / Q000187:drug effects*; D007668:Kidney / Q000166:cytology / Q000187:drug effects*; D007834:Lasers; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects; D009206:Myocardium / Q000166:cytology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000633:toxicity*; D051381:Rats
D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid