In vivo 212Pb/212Bi generator using indium-DTPA-tagged liposomes

• Published in: Radiochimica acta Vol. 99; no. 11; pp. 743 - 749
• Main Authors: Le Du, A., Mougin-Degraef, M., Botosoa, E., Rauscher, A., Faivre Chauvet, A., Barbet, Jacques, Montavon, G.
• Format: Journal Article
• Language: English
• Published: Oldenbourg Wissenschaftsverlag GmbH 01.11.2011; Oldenbourg Wissenschaftsverlag
• Subjects: 212 Pb; 212Bi; Chemical Sciences; Generator; Liposomes; Radiochemistry; Targeted alpha therapy; In vivo; 212Pb; Targeted alpha therapy; liposomes; 212Bi; Generator
• ISSN: 0033-8230; 2193-3405
• DOI: 10.1524/ract.2011.1871

Indium-DTPA-tagged liposomes were studied in the present work as carriers of Pb/ Bi generator to be used in targeted alpha therapy. The liposomal uptake of Pb, into preformed liposomes, was investigated using different lipophilic chelate (DCP, 2,3-dimercapto-1-propanol (BAL), sodium acetate, and A23187), as a function of various parameters (temperature, concentrations of lipids, Pb, DTPA, ...) with Pb as a tracer. Different formulations of liposomes were tested to evaluate the radiolabeling efficiency. No complexing agent was necessary for the passage of Pb through the membrane. It occurs naturally a partial permeability of the lipid bilayer, which increases with the temperature. A complexing agent (DTPA) appears necessary to concentrate Pb in the internal compartment of the liposomes. Conditions were found ( =65 ºC, internal DTPA concentration of 0.025 M, pH 7.4, ...) yielding a high and rapid uptake of Pb in liposomes. The protocol established provides a novel method for the efficient entrapment of about 2–3 Pb atoms per liposome with a yield of 75% in conditions relevant for nuclear medicine.