Co, Fe and Ga chelates for cell labelling: a potential use in PET imaging?
The radiolabelling of blood cellular elements with PET radionuclides offers a higher sensitivity and resolution than conventional imaging, but short-lived PET radionuclides have limited clinical use in cell labelling. Medium half-life PET radionuclides, such as 55Co (t1/2 = 18.2 h), 52Fe (t1/2 = 8.3 h) and 66Ga (t1/2 = 9.4 h), enable quantitative uptake and cell kinetic studies with radiolabelled blood cellular elements. Co(II) oxine, Co(III) tropolonate, Fe(III) oxine, Ga(III) oxine and Ga(III) MPO were prepared using gamma-emitting radionuclides and a number of cell labelling parameters were investigated. The uptake of 57Co(II) oxine into erythrocytes was only 37%, and 65% of the activity eluted from the cells in cell-free plasma within 30 min. In contrast, high leukocyte and erythrocyte labelling efficiencies (> 90%) were obtained with 57Co(III) tropolonate containing cobalt carrier and the elution in cell-free plasma over 4 h was < 8%. High labelling efficiencies were also observed with 59Fe(III) oxine and 67Ga-MPO and the elution from leukocytes over 4 h was < 25%. We conclude that Co(III) tropolonate, Fe(III) oxine and Ga-MPO may be useful for radiolabelling leukocytes for PET investigations.
Ellis
B L
BL
Department of Nuclear Medicine, Manchester Royal Infirmary, UK. bev.ellis@man.ac.uk
Sharma
H L
HL
D002470:Cell Survival; D002614:Chelating Agents / Q000138:chemical synthesis / Q000378:metabolism*; D003035:Cobalt / Q000097:blood*; D003037:Cobalt Radioisotopes; D004912:Erythrocytes / Q000000981:diagnostic imaging; D005708:Gallium / Q000097:blood*; D005710:Gallium Radioisotopes; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D066298:In Vitro Techniques; D007501:Iron / Q000097:blood*; D007504:Iron Radioisotopes; D007553:Isotope Labeling; D007962:Leukocytes / Q000000981:diagnostic imaging; D016877:Oxidants / Q000494:pharmacology; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed
D002614:Chelating Agents; D003037:Cobalt Radioisotopes; D005710:Gallium Radioisotopes; D007504:Iron Radioisotopes; D016877:Oxidants; D019275:Radiopharmaceuticals; D003035:Cobalt; D006861:Hydrogen Peroxide; D005708:Gallium; D007501:Iron