In-vitro investigation of ALA-induced protoporphyrin IX

Protoporphyrin IX (PpIX) induced endogenously by delta-aminolevulinic acid (ALA), can be used to destroy photodynamically tumor cells. The influence of several parameters on the PpIX formation of human skin fibroblasts was investigated by fluorescence spectrophotometry. The PpIX formation increases...

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Bibliographic Details
Published in:Journal of photochemistry and photobiology. B, Biology Biology, 1996-11, Vol.36 (2), p.121-126
Main Authors: Krammer, B, Uberriegler, K
Format: Article
Language:English
Subjects:
Aminolevulinic Acid - pharmacology
Dose-Response Relationship, Drug
Fibroblasts - drug effects
Fibroblasts - metabolism
Humans
Hydrogen-Ion Concentration
Kinetics
Photosensitizing Agents - metabolism
Protoporphyrins - metabolism
Skin - drug effects
Skin - metabolism
Spectrometry, Fluorescence
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Summary:Protoporphyrin IX (PpIX) induced endogenously by delta-aminolevulinic acid (ALA), can be used to destroy photodynamically tumor cells. The influence of several parameters on the PpIX formation of human skin fibroblasts was investigated by fluorescence spectrophotometry. The PpIX formation increases (1) with the pH value of ALA (2) with the ALA incubation time in a moderate sigmoidal manner, and (3) with the ALA concentration up to 700 micrograms ml-1. Other parameters, such as cell washing procedures, have no influence on the PpIX production. ALA has to be applied in a concentration 30 times higher than external protoporphyrin IX and Photosan 3 in order to produce the same cytotoxic damage. Protoporphyrin bleaching and photoproduct generation at 646 nm was observed. Additional information about intracellular PpIX formation kinetics and its topographically correlation to cell structures was gained by a CCD camera mounted on a fluorescence microscope. A few minutes after the onset of incubation with ALA, PpIX generation is observed in the mitochondria, followed by relocalization in the cytoplasm and the nuclear membrane.
ISSN:1011-1344
DOI:10.1016/S1011-1344(96)07358-7