Dataset Information

Investigation of the complexation of natZr(iv) and 89Zr(iv) by hydroxypyridinones for the development of chelators for PET imaging applications.

ABSTRACT: Three hydroxypyridinone (HOPO) positional isomers - 1,2-HOPO (L1H) and its water soluble analogue (L1'H), 3,2-HOPO (L2H) and 3,4-HOPO (L3H) have been investigated for the complexation of Zr(iv). Potentiometric and UV-Vis spectrometric studies show a higher thermodynamic stability for the formation of Zr(L1')4 in comparison with Zr(L2)4 and Zr(L3)4 as well as a higher kinetic inertness in competition studies with EDTA or Fe3+ at a radiotracer concentration with 89Zr. Besides the low pKa of L1H or L1'H (pKa = 5.01) in comparison with L2H and L3H (pKa = 8.83 and 9.55, respectively), the higher stability of Zr(L1')4 can be attributed in part to the presence of the amide group next to the chelating oxygen that induces intramolecular H-bond and amide/? interactions that were observed by X-ray crystallography and confirmed by quantum chemical calculations. The data presented here indicate that the 1,2-HOPO L1' exhibits the best characteristics for Zr(iv) complexation. However, 3,2-HOPO and 3,4-HOPO patterns, if appropriately tuned, for instance with the addition of an amide group as in the 1,2-HOPO ligand, may also become interesting alternatives for the design of Zr(iv) chelators with improved characteristics for applications in nuclear imaging with 89Zr.

SUBMITTER: Guerard F

PROVIDER: S-EPMC5488699 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

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Investigation of the complexation of natZr(iv) and 89Zr(iv) by hydroxypyridinones for the development of chelators for PET imaging applications.

Guérard F F Beyler M M Lee Y-S YS Tripier R R Gestin J-F JF Brechbiel M W MW

Dalton transactions (Cambridge, England : 2003) 20170401 14

Three hydroxypyridinone (HOPO) positional isomers - 1,2-HOPO (L1H) and its water soluble analogue (L1'H), 3,2-HOPO (L2H) and 3,4-HOPO (L3H) have been investigated for the complexation of Zr(iv). Potentiometric and UV-Vis spectrometric studies show a higher thermodynamic stability for the formation of Zr(L1')4 in comparison with Zr(L2)4 and Zr(L3)4 as well as a higher kinetic inertness in competition studies with EDTA or Fe3+ at a radiotracer concentrat ...[more]

PMID: 28338136

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Project description:The encapsulation of Glucocorticoids (GCs) into long-circulating liposomes (LCLs) is a proven strategy to reduce the side effects of glucocorticoids and improve the treatment of inflammatory diseases, such as rheumatoid arthritis (RA). With the aim of supporting the development of GC-loaded LCLs, and potentially predict patient response to therapy clinically, we evaluated a direct PET imaging radiolabelling approach for preformed GC-LCLs in an animal model of human inflammatory arthritis. Methods: A preformed PEGylated liposomal methylprednisolone hemisuccinate (NSSL-MPS) nanomedicine was radiolabelled using [89Zr]Zr(oxinate)4 (89Zr-oxine), characterised and tracked in vivo using PET imaging in a K/BxN serum-transfer arthritis (STA) mouse model of inflammatory arthritis and non-inflamed controls. Histology and joint size measurements were used to confirm inflammation. The biodistribution of 89Zr-NSSL-MPS was compared to that of free 89Zr in the same model. A therapeutic study using NSSL-MPS using the same time points as the PET/CT imaging was carried out. Results: The radiolabelling efficiency of NSSL-MPS with [89Zr]Zr(oxinate)4 was 69 ± 8 %. PET/CT imaging of 89Zr-NSSL-MPS showed high uptake (3.6 ± 1.5 % ID; 17.4 ± 9.3 % ID/mL) at inflamed joints, with low activity present in non-inflamed joints (0.5 ± 0.1 % ID; 2.7 ± 1.1 % ID/mL). Importantly, a clear correlation between joint swelling and high 89Zr-NSSL-MPS uptake was observed, which was not observed with free 89Zr. STA mice receiving a therapeutic dose of NSSL-MPS showed a reduction in inflammation at the time points used for the PET/CT imaging compared with the control group. Conclusions: PET imaging was used for the first time to track a liposomal glucocorticoid, showing high uptake at visible and occult inflamed sites and a good correlation with the degree of inflammation. A subsequent therapeutic response matching imaging time points in the same model demonstrated the potential of this radiolabeling method as a theranostic tool for the prediction of therapeutic response - with NSSL-MPS and similar nanomedicines - in the treatment of inflammatory diseases.

Project description:BackgroundIn vivo monitoring of cell biodistribution using positron emission tomography (PET) provides a quantitative non-invasive method to further optimize cell therapies and related new developments in the field. Our group has earlier optimized and evaluated the in vitro properties of two radiotracers,[89Zr]Zr-(oxinate)4 and [89Zr]Zr-DFO-NCS, for the radiolabelling of different cell types. Here, we performed a microPET study to assess the in vivo biodistribution of cells in rats using these two radiotracers. Human decidual stromal cells (hDSC) and rat macrophages (rMac) were radiolabelled with [89Zr]Zr-(oxinate)4 or [89Zr]Zr-DFO-NCS. Rats were intravenously injected with radiolabelled cells, and the in vivo biodistribution was monitored with microPET/CT imaging for up to day 7. Organ uptake was evaluated and presented as a percentage of injected activity per gram tissue (%IA/g) and total absorbed organ doses (mSv/MBq).ResultsThe biodistribution in vivo showed an immediate uptake in the lungs. Thereafter, [89Zr]Zr-(oxinate)4 labelled cells migrated to the liver, while the signal from [89Zr]Zr-DFO-NCS labelled cells lingered in the lungs. The differences in the in vivo behaviour for the same cell type appeared related to the radiotracer labelling. After 24 h, [89Zr]Zr-(oxinate)4 labelled cells had over 70% higher liver uptake for both hDSC and rMac compared to [89Zr]Zr-DFO-NCS labelled cells, whereas [89Zr]Zr-DFO-NCS labelled cells showed over 60% higher uptake in the lungs compared to [89Zr]Zr-(oxinate)4 labelled cells. This difference in both lung and liver uptake continued until day 7. Dosimetry calculations showed a higher effective dose (mSv/MBq) for [89Zr]Zr-DFO-NCS compared to [89Zr]Zr-(oxinate)4, for both cell types. Although the bone uptake was higher for [89Zr]Zr-(oxinate)4 labelled cells, the prolonged uptake in the lungs contributed to a significant crossfire to bone marrow resulting in a higher bone dose.ConclusionThe [89Zr]Zr-DFO-NCS labelled cells suggest a prolonged accumulation in the lungs, while [89Zr]Zr-(oxinate)4 suggests quicker clearance of the lungs followed by accumulation in the liver. Accumulation of radiolabelled cells in the liver corresponds to other cell-tracking methods. Further studies are required to determine the actual location of the [89Zr]Zr-DFO-NCS labelled cell.

Project description:BackgroundThere is a need to better characterise cell-based therapies in preclinical models to help facilitate their translation to humans. Long-term high-resolution tracking of the cells in vivo is often impossible due to unreliable methods. Radiolabelling of cells has the advantage of being able to reveal cellular kinetics in vivo over time. This study aimed to optimise the synthesis of the radiotracers [89Zr]Zr-oxine (8-hydroxyquinoline) and [89Zr]Zr-DFO-NCS (p-SCN-Bn-Deferoxamine) and to perform a direct comparison of the cell labelling efficiency using these radiotracers.ProceduresSeveral parameters, such as buffers, pH, labelling time and temperature, were investigated to optimise the synthesis of [89Zr]Zr-oxine and [89Zr]Zr-DFO-NCS in order to reach a radiochemical conversion (RCC) of >95 % without purification. Radio-instant thin-layer chromatography (iTLC) and radio high-performance liquid chromatography (radio-HPLC) were used to determine the RCC. Cells were labelled with [89Zr]Zr-oxine or [89Zr]Zr-DFO-NCS. The cellular retention of 89Zr and the labelling impact was determined by analysing the cellular functions, such as viability, proliferation, phagocytotic ability and phenotypic immunostaining.ResultsThe optimised synthesis of [89Zr]Zr-oxine and [89Zr]Zr-DFO-NCS resulted in straightforward protocols not requiring additional purification. [89Zr]Zr-oxine and [89Zr]Zr-DFO-NCS were synthesised with an average RCC of 98.4 % (n = 16) and 98.0 % (n = 13), respectively. Cell labelling efficiencies were 63.9 % (n = 35) and 70.2 % (n = 30), respectively. 89Zr labelling neither significantly affected the cell viability (cell viability loss was in the range of 1-8 % compared to its corresponding non-labelled cells, P value > 0.05) nor the cells' proliferation rate. The phenotype of human decidual stromal cells (hDSC) and phagocytic function of rat bone-marrow-derived macrophages (rMac) was somewhat affected by radiolabelling.ConclusionsOur study demonstrates that [89Zr]Zr-oxine and [89Zr]Zr-DFO-NCS are equally effective in cell labelling. However, [89Zr]Zr-oxine was superior to [89Zr]Zr-DFO-NCS with regard to long-term stability, cellular retention, minimal variation between cell types and cell labelling efficiency.

Dataset Information

Investigation of the complexation of natZr(iv) and 89Zr(iv) by hydroxypyridinones for the development of chelators for PET imaging applications.

Publications

Investigation of the complexation of <sup>nat</sup>Zr(iv) and <sup>89</sup>Zr(iv) by hydroxypyridinones for the development of chelators for PET imaging applications.

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