68Ga-DOTA-RGD peptide: biodistribution and binding into atherosclerotic plaques in mice.
OBJECTIVE
Increased expression of αvβ3/αvβ5 integrin is involved in angiogenesis and the inflammatory process in atherosclerotic plaques. The novel 68Ga-DOTA-RGD peptide binds with high affinity to αvβ3/αvβ5 integrin. The aim of this study was to investigate the uptake of the 68Ga-DOTA-RGD peptide in atherosclerotic plaques.


METHODS
Uptake of intravenously administered 68Ga-DOTA-RGD peptide was studied ex vivo in excised tissue samples and aortic sections of LDLR-/-ApoB100/100 atherosclerotic mice. The uptake of the tracer in aortic cryosections was examined by using digital autoradiography. Subsequently, the autoradiographs were combined with histological and immunohistological analysis of the sections.


RESULTS
DOTA-RGD peptide was successfully labelled with the generator-produced 68Ga. The tracer had reasonably good specific radioactivity (8.7 ± 1.1 GBq/μmol) and was quite stable in vivo. According to ex vivo biodistribution results, 68Ga-DOTA-RGD was cleared rapidly from the blood circulation and excreted through the kidneys to the urine with high radioactivity in the intestine, lungs, spleen and liver. Autoradiography results showed significantly higher uptake of 68Ga-DOTA-RGD peptide in the atherosclerotic plaques compared to healthy vessel wall (mean ratio ± SD 1.4 ± 0.1, p = 0.0004). Conclusion We observed that 68Ga-DOTA-RGD is accumulated into the plaques of atherosclerotic mice. However, this data only shows the feasibility of the approach, while the clinical significance still remains to be proven. Further studies are warranted to assess the uptake of this tracer into human atherosclerotic plaques.
Johanna Haukkala
Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland.
Iina Laitinen
Pauliina Luoto
Peter Iveson
Ian Wilson
Hege Karlsen
Alan Cuthbertson
Jukka Laine
Pia Leppänen
Ylä-Herttula
Seppo
S
Knuuti
Juhani
J
Roivainen
Anne
A
D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D053299:Apolipoprotein B-100 / Q000378:metabolism; D001345:Autoradiography; D001692:Biological Transport; D016616:Cryoultramicrotomy; D004355:Drug Stability; D005240:Feasibility Studies; D005710:Gallium Radioisotopes / Q000737:chemistry; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D007249:Inflammation / Q000473:pathology; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D008297:Male; D051379:Mice; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics*; D058226:Plaque, Atherosclerotic / Q000378:metabolism* / Q000473:pathology; D019030:Receptors, Vitronectin / Q000378:metabolism; D015203:Reproducibility of Results
D053299:Apolipoprotein B-100; D005710:Gallium Radioisotopes; D006573:Heterocyclic Compounds, 1-Ring; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; C047981:arginyl-glycyl-aspartic acid