Detection of microlesions induced by heavy ions using liposomes filled with fluorescent dye

In cells irradiation by heavy ions has been hypothesized to produce microlesions, regions of local damage. In cell membranes this damage is thought to manifest itself in the form of holes. The primary evidence for microlesions comes from morphological studies of cell membranes, but this evidence is...

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Bibliographic Details
Published in:Advances in space research 2004, Vol.34 (6), p.1373-1377
Main Authors: Koniarek, J.P., Thomas, J.L., Vazquez, M.
Format: Article
Language:English
Subjects:
1,2-Dipalmitoylphosphatidylcholine
Cell irradiation
Cell Membrane - radiation effects
Cholesterol
Detection of microlesions
Egg Yolk
Fluoresceins
Fluorescent dye
Fluorescent Dyes
Heavy Ions
Iron
Liposomes - radiation effects
Membranes, Artificial
Phosphatidylcholines
Radiation risk
Space life sciences
Synchrotrons
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Summary:In cells irradiation by heavy ions has been hypothesized to produce microlesions, regions of local damage. In cell membranes this damage is thought to manifest itself in the form of holes. The primary evidence for microlesions comes from morphological studies of cell membranes, but this evidence is still controversial, especially since holes also have been observed in membranes of normal, nonirradiated, cells. However, it is possible that damage not associated with histologically discernable disruptions may still occur. In order to resolve this issue, we developed a system for detecting microlesions based on liposomes filled with fluorescent dye. We hypothesized that if microlesions form in these liposomes as the result of irradiation, then the entrapped dye will leak out into the surrounding medium in a measurable way. Polypropylene vials containing suspensions of vesicles composed of either dipalmitoyl phosphatidylcholine, or a combination of egg phosphatidylcholine and cholesterol were irradiated at the Brookhaven National Laboratory using 56Fe ions at 1 GeV/amu. In several cases we obtained a significant loss of the entrapped dye above the background level. Our results suggest that holes may form in liposomes as the result of heavy ion irradiation, and that these holes are large enough to allow leakage of cell internal contents that are at least as large as a 1 nm diameter calcein molecule.
ISSN:0273-1177
1879-1948
DOI:10.1016/j.asr.2004.01.012