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A Journal on Nuclear Medicine and Molecular Imaging
Affiliated to the and to the International Research Group of Immunoscintigraphy
Indexed/Abstracted in: Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index (SciSearch), Scopus
Impact Factor 2,413
Online ISSN 1827-1936
RADIOPHARMACY AND RADIOPHARMACEUTICALS 2007 UPDATE
Jestin E. 1, Mougin-Degraef M. 1, Faivre-Chauvet A. 1, Remaud-Le Saëc P. 1, Hindre F. 2, Benoit J. P. 2, Chatal J. F. 1, Barbet J. 1, Gestin J. F. 1
1 INSERM, U 601 University of Nantes, Nantes, France
2 INSERM, U 646 University of Angers, Angers, France
Aim. Radioimmunotherapy is limited in some cases by the low radioactive doses delivered to tumor cells by antibodies or pretargeted haptens. In order to increase this dose, lipidic nanocapsules (LNC) with a hydrophobic core are proposed as radionuclide vectors that could be targeted to cancer cells by a bispecific anti-tumor × anti-hapten antibody after incorporation of different haptens in the nanocapsule membrane.
Methods. To bind different radionuclides to the nanocapsules, several bifunctional chelating agents (BCA) were used to form stable complexes with the radionuclides. Some of them are hydrophilic for LNC shell while others are lipophilic to radiolabel the core. Poly(ethylene glycols) (PEG) were used to increase the residence time in blood. Since PEG can modify haptens recognition by the bispecific antibody and radiolabeling efficiency, haptens, BCA or Bolton-Hunter reagent (BH) were attached to the PEG extremity to optimize accessibility. Specific constructs (DSPE-PEG-haptens, DSPE-PEG-BCA, and DSPE-PEG-BH) were synthesized to develop these new radiolabeled vector formulations. Large amounts of PEG have been introduced by a postinsertion method without important change in nanocapsule size and properties. The nanocapsule core was radiolabeled with a lipophilic [99mTc]SSS complex.
Results. Serum stability studies showed that this 99mTc-labeling method was efficient for at least 20 h. Concerning the nanocapsule surface, several methods have been performed for 111In-labeling by using DSPE-PEG-DTPA and for 125I-labeling with DSPE-PEG-BH.
Conclusions. The nanocapsules labeling feasibility with a variety of radionuclides and their stability were demonstrated in this paper.