New technique uses 89Zr-radiolabelling of mixed leukocytes for PET imaging of inflammation

Positron emission tomography (PET) constitutes a highly sensitive molecular imaging technique that allows to precisely quantify the signal produced by radiolabelled molecules. The diagnosis and monitoring of inflammatory conditions via trafficking of mixed leukocytes, or white blood cells (WBCs), using this technique has been a growing target of interest. In this context, newly published research [1] has assessed the radiolabeling of WBCs with 89Zr or 64Cu and their advantages for PET imaging.

Nanoparticles
For this purpose, WBCs freshly isolated from whole human blood were conjugated with Chitosan nanoparticles (CNs), used to deliver radiometals into the cells. The radiolabeling efficiency of each radioisotope was determined.

Radiolabeling of WBCs was more efficient with [89Zr]-loaded than with [64Cu]-loaded CN (mean 76.8% vs. 26.3%, respectively). After 2 h, [89Zr]-WBCs had an initial radioactivity loss of 28.4%, which was followed by a plateau as 89Zr remains stable in the cells. Differently, [64Cu]-WBCs had a radioactivity loss of 85% already after 1 h, which increased to 96% after 3 h.

Conclusion
Considering the fast kinetics of cell association and high labeling efficiency of WBCs with [89Zr]-loaded CN, as well as superior retention of the radioactivity, radiolabeling with the radioisotope 89Zr shows great potential application for PET imaging of inflammation.

References
(Click on the PMID to see abstracts from PubMed/NCBI)

[1] Fairclough M, Prenant C, Ellis B, Boutin H, McMahon A, Brown G, Locatelli P, Jones AK. A new technique for the radiolabelling of mixed leukocytes with zirconium-89 for inflammation imaging with positron emission tomography. J Labelled Comp Radiopharm. 2016 Jun 15; 59(7): 270-6. PMID: 27061114.