Simplified 89Zr-Labeling Protocol of Oxine (8-Hydroxyquinoline) Enabling Prolonged Tracking of Liposome-Based Nanomedicines and Cells

In this work, a method for the preparation of the highly lipophilic labeling synthon [89Zr]Zr(oxinate)4 was optimized for the radiolabeling of liposomes and human induced pluripotent stem cells (hiPSCs). The aim was to establish a robust and reliable labeling protocol for enabling up to one week positron emission tomography (PET) tracing of lipid-based nanomedicines and transplanted or injected cells, respectively. [89Zr]Zr(oxinate)4 was prepared from oxine (8-hydroxyquinoline) and [89Zr]Zr(OH)2(C2O4). Earlier introduced liquid–liquid extraction methods were simplified by the optimization of buffering, pH, temperature and reaction times. For quality control, thin-layer chromatography (TLC), size-exclusion chromatography (SEC) and centrifugation were employed. Subsequently, the 89Zr-complex was incorporated into liposome formulations. PET/CT imaging of 89Zr-labeled liposomes was performed in healthy mice. Cell labeling was accomplished in PBS using suspensions of 3 × 106 hiPSCs, each. [89Zr]Zr(oxinate)4 was synthesized in very high radiochemical yields of 98.7% (96.8% ± 2.8%). Similarly, high internalization rates (≥90%) of [89Zr]Zr(oxinate)4 into liposomes were obtained over an 18 h incubation period. MicroPET and biodistribution studies confirmed the labeled nanocarriers’ in vivo stability. Human iPSCs incorporated the labeling agent within 30 min with ~50% efficiency. Prolonged PET imaging is an ideal tool in the development of lipid-based nanocarriers for drug delivery and cell therapies. To this end, a reliable and reproducible 89Zr radiolabeling method was developed and tested successfully in a model liposome system and in hiPSCs alike.

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Microwave-assisted radiolabelling of 52Mn-porphyrins

10.26434/chemrxiv-2021-v8wm5 ◽

2021 ◽

Author(s):

Peter J. Gawne ◽

Sara M. A. Pinto ◽

Karin M. Nielsen ◽

Mariette M. Pereira ◽

Rafael T. M. de Rosales

Keyword(s):

Lipid Bilayers ◽

Mri Contrast Agents ◽

Mri Contrast ◽

Manganese Porphyrins ◽

Biodistribution Studies ◽

Positron Emission ◽

Radiochemical Yields

Manganese porphyrins have several therapeutic/imaging applications; including their use as radioprotectants (in clinical trials), and as paramagnetic MRI contrast agents. The affinity of porphyrins for lipid bilayers also makes them candidates for cell/liposome labelling. We hypothesised that metalation with the positron emission tomography (PET) radionuclide 52Mn (t1/2 = 5.6 d) would allow long-term in vivo biodistribution studies of Mn-porphyrins as well as a method to label and track cells/liposomes, but methods for fast and efficient radiolabelling are lacking. Several porphyrins were produced and radiolabelled by addition to neutralised [52Mn]MnCl2 and heated at 165 oC for 1 h using a microwave (MW) synthesiser at a ligand concentration of 0.6 – 0.7 mM. These conditions were compared with non-MW heating at 70oC. MW radiosynthesis allowed >95 % radiochemical yields (RCY) in just 1 h. Conversely, non-MW heating at 70 oC for 1 h resulted in low RCY (0 – 25 % RCY) and most porphyrins did not reach completion after 24h. Formation of the 52Mn-complexes were confirmed with radio-HPLC by comparison with their non-radioactive 55Mn counterparts. Following this, several 52Mn-porphyrins were used to radiolabel liposomes by incubation at 50 oC for 30 min resulting in 75 – 86 % labelling efficiency (LE). Two lead 52Mn-porphyrins were taken forward to label MDA-MB-231 cancer cells in vitro, achieving ca. 11 % LE. After 24 h, 32 – 45 % of the 52Mn-porphyrin was retained in cells. In contrast to standard methods, MW heating allows fast synthesis of 52Mn-porphyrins with >95% radiochemical yields that avoid purification. 52Mn-porphyrins also show promising cell/liposome labelling properties. This technique can potentially be exploited for the in vivo imaging of Mn-porphyrin therapeutics, as well as for the accurate in vivo quantification of Mn-porphyrin MRI agents.

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Effect of ethanol and cocaine on [11C]MPC-6827 uptake in SH-SY5Y cells

Molecular Biology Reports ◽

10.1007/s11033-021-06336-7 ◽

2021 ◽

Author(s):

Naresh Damuka ◽

Miranda Orr ◽

Paul W. Czoty ◽

Jeffrey L. Weiner ◽

Thomas J. Martin ◽

...

Keyword(s):

Mechanism Of Action ◽

Ex Vivo ◽

Neuroblastoma Cells ◽

Proper Function ◽

Brain Functions ◽

Biodistribution Studies ◽

Positron Emission ◽

Vitro Binding

AbstractMicrotubules (MTs) are structural units in the cytoskeleton. In brain cells they are responsible for axonal transport, information processing, and signaling mechanisms. Proper function of these processes is critical for healthy brain functions. Alcohol and substance use disorders (AUD/SUDs) affects the function and organization of MTs in the brain, making them a potential neuroimaging marker to study the resulting impairment of overall neurobehavioral and cognitive processes. Our lab reported the first brain-penetrant MT-tracking Positron Emission Tomography (PET) ligand [11C]MPC-6827 and demonstrated its in vivo utility in rodents and non-human primates. To further explore the in vivo imaging potential of [11C]MPC-6827, we need to investigate its mechanism of action. Here, we report preliminary in vitro binding results in SH-SY5Y neuroblastoma cells exposed to ethanol (EtOH) or cocaine in combination with multiple agents that alter MT stability. EtOH and cocaine treatments increased MT stability and decreased free tubulin monomers. Our initial cell-binding assay demonstrated that [11C]MPC-6827 may have high affinity to free/unbound tubulin units. Consistent with this mechanism of action, we observed lower [11C]MPC-6827 uptake in SH-SY5Y cells after EtOH and cocaine treatments (e.g., fewer free tubulin units). We are currently performing in vivo PET imaging and ex vivo biodistribution studies in rodent and nonhuman primate models of AUD and SUDs and Alzheimer's disease.

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Optimised GMP-compliant production of [18F]DPA-714 on the Trasis AllinOne module

EJNMMI Radiopharmacy and Chemistry ◽

10.1186/s41181-021-00133-0 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Klaudia A. Cybulska ◽

Vera Bloemers ◽

Lars R. Perk ◽

Peter Laverman

Keyword(s):

Significant Degree ◽

Translocator Protein ◽

Positron Emission ◽

Leaving Group ◽

Inflammatory Processes ◽

Single Production ◽

Translocator Protein 18 Kda ◽

Radiochemical Yields ◽

Specific Ligand

Abstract Background The translocator protein 18 kDa is recognised as an important biomarker for neuroinflammation due to its soaring expression in microglia. This process is common for various neurological disorders. DPA-714 is a potent TSPO-specific ligand which found its use in Positron Emission Tomography following substitution of fluorine-19 with fluorine-18, a positron-emitting radionuclide. [18F]DPA-714 enables visualisation of inflammatory processes in vivo non-invasively. Radiolabelling of this tracer is well described in literature, including validation for clinical use. Here, we report significant enhancements to the process which resulted in the design of a fully GMP-compliant robust synthesis of [18F]DPA-714 on a popular cassette-based system, Trasis AllinOne, boosting reliability, throughput, and introducing a significant degree of simplicity. Results [18F]DPA-714 was synthesised using the classic nucleophilic aliphatic substitution on a good leaving group, tosylate, with [18F]fluoride using tetraethylammonium bicarbonate in acetonitrile at 100∘C. The process was fully automated on a Trasis AllinOne synthesiser using an in-house designed cassette and sequence. With a relatively small precursor load of 4 mg, [18F]DPA-714 was obtained with consistently high radiochemical yields of 55-71% (n=6) and molar activities of 117-350 GBq/µmol at end of synthesis. With a single production batch, starting with 31-42 GBq of [18F]fluoride, between 13-20 GBq of the tracer can be produced, enabling multi-centre studies. Conclusion To the best of our knowledge, the process presented herein is the most efficient [18F]DPA-714 synthesis, with advantageous GMP compliance. The use of a Trasis AllinOne synthesiser increases reliability and allows rapid training of production staff.

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Harnessing PET to track micro- and nanoplastics in vivo

Scientific Reports ◽

10.1038/s41598-021-90929-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Outi Keinänen ◽

Eric J. Dayts ◽

Cindy Rodriguez ◽

Samantha M. Sarrett ◽

James M. Brennan ◽

...

Keyword(s):

Sea Water ◽

Accurate Determination ◽

Nuclear Imaging ◽

Imaging Data ◽

Biodistribution Studies ◽

Positron Emission ◽

20 Nm ◽

Pharmacokinetic Behavior

AbstractThe proliferation of plastics in the environment continues at an alarming rate. Plastic particles have been found to be persistent and ubiquitous pollutants in a variety of environments, including sea water, fresh water, soil, and air. In light of this phenomenon, the scientific and medical communities have become increasingly wary of the dangers posed to human health by chronic exposure to microplastics (< 5 mm diameter) and nanoplastics (< 100 nm diameter). A critical component of the study of the health effects of these pollutants is the accurate determination of their pharmacokinetic behavior in vivo. Herein, we report the first use of molecular imaging to track polystyrene (PS) micro- and nanoplastic particles in mammals. To this end, we have modified PS particles of several sizes—diameters of 20 nm, 220 nm, 1 µm, and 6 µm—with the chelator desferrioxamine (DFO) and radiolabeled these DFO-bearing particles with the positron-emitting radiometal zirconium-89 (89Zr; t1/2 ~ 3.3 d). Subsequently, positron emission tomography (PET) was used to visualize the biodistribution of these radioplastics in C57BL/6J mice at 6, 12, 24, and 48 h after ingestion. The imaging data reveal that the majority of the radioplastics remain in the gastrointestinal tract and are eliminated through the feces by 48 h post-ingestion, a result reinforced by acute biodistribution studies. Ultimately, this work suggests that nuclear imaging—and PET in particular—can be a sensitive and effective tool in the urgent and rapidly growing effort to study the in vivo behavior and potential toxicity of micro- and nanoplastics.

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New 55Co-labeled Albumin-Binding Folate Derivatives as Potential PET Agents for Folate Receptor Imaging

Pharmaceuticals ◽

10.3390/ph12040166 ◽

2019 ◽

Vol 12 (4) ◽

pp. 166 ◽

Cited By ~ 4

Author(s):

Lauren L. Radford ◽

Solana Fernandez ◽

Rebecca Beacham ◽

Retta El Sayed ◽

Renata Farkas ◽

...

Keyword(s):

Folate Receptor ◽

Small Animal ◽

Small Animal Pet ◽

Receptor Imaging ◽

Albumin Binding ◽

Liver Uptake ◽

Biodistribution Studies ◽

Positron Emission

Overexpression of folate receptors (FRs) on different tumor types (e.g., ovarian, lung) make FRs attractive in vivo targets for directed diagnostic/therapeutic agents. Currently, no diagnostic agent suitable for positron emission tomography (PET) has been adopted for clinical FR imaging. In this work, two 55Co-labeled albumin-binding folate derivatives-[55Co]Co-cm10 and [55Co]Co-rf42-with characteristics suitable for PET imaging have been developed and evaluated. High radiochemical yields (≥95%) and in vitro stabilities (≥93%) were achieved for both compounds, and cell assays demonstrated FR-mediated uptake. Both 55Co-labeled folate conjugates demonstrated high tumor uptake of 17% injected activity per gram of tissue (IA/g) at 4 h in biodistribution studies performed in KB tumor-bearing mice. Renal uptake was similar to other albumin-binding folate derivatives, and liver uptake was lower than that of previously reported [64Cu]Cu-rf42. Small animal PET/CT images confirmed the biodistribution results and showed the clear delineation of FR-expressing tumors.

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Synthesis of a new 18F labeled porphyrin for potential application in positron emission tomography. In vivo imaging and cellular uptake

RSC Advances ◽

10.1039/c5ra16103g ◽

2015 ◽

Vol 5 (120) ◽

pp. 99540-99546 ◽

Cited By ~ 12

Author(s):

Ana V. C. Simões ◽

Sara M. A. Pinto ◽

Mário J. F. Calvete ◽

Célia M. F. Gomes ◽

Nuno C. Ferreira ◽

...

Keyword(s):

In Vivo Imaging ◽

Bladder Tumor ◽

Radiochemical Purity ◽

Cell Uptake ◽

Emission Tomography ◽

Human Bladder ◽

Biodistribution Studies ◽

Biodistribution Data ◽

Positron Emission

Synthesis, labeling and initial biodistribution studies of a new [18F] radiolabeled meso-tetraphenylporphyrin (radiochemical purity >95%). Includes human bladder tumor cell uptake and biodistribution data.

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Radiosynthesis of [18F]-Labelled Pro-Nucleotides (ProTides)

Molecules ◽

10.3390/molecules25030704 ◽

2020 ◽

Vol 25 (3) ◽

pp. 704

Author(s):

Alessandra Cavaliere ◽

Katrin C. Probst ◽

Stephen J. Paisey ◽

Christopher Marshall ◽

Abdul K. H. Dheere ◽

...

Keyword(s):

Total Synthesis ◽

Pet Imaging ◽

Early Stage ◽

Proof Of Concept ◽

Synthesis Time ◽

Positron Emission ◽

Anti Cancer ◽

Radiochemical Yields ◽

Radiochemical Synthesis

Phosphoramidate pro-nucleotides (ProTides) have revolutionized the field of anti-viral and anti-cancer nucleoside therapy, overcoming the major limitations of nucleoside therapies and achieving clinical and commercial success. Despite the translation of ProTide technology into the clinic, there remain unresolved in vivo pharmacokinetic and pharmacodynamic questions. Positron Emission Tomography (PET) imaging using [18F]-labelled model ProTides could directly address key mechanistic questions and predict response to ProTide therapy. Here we report the first radiochemical synthesis of [18F]ProTides as novel probes for PET imaging. As a proof of concept, two chemically distinct radiolabelled ProTides have been synthesized as models of 3′- and 2′-fluorinated ProTides following different radiosynthetic approaches. The 3′-[18F]FLT ProTide was obtained via a late stage [18F]fluorination in radiochemical yields (RCY) of 15–30% (n = 5, decay-corrected from end of bombardment (EoB)), with high radiochemical purities (97%) and molar activities of 56 GBq/μmol (total synthesis time of 130 min.). The 2′-[18F]FIAU ProTide was obtained via an early stage [18F]fluorination approach with an RCY of 1–5% (n = 7, decay-corrected from EoB), with high radiochemical purities (98%) and molar activities of 53 GBq/μmol (total synthesis time of 240 min).

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Automated Synthesis of Fluorine-18 Labeled CXCR4 Ligand via the Conjugation with Nicotinic Acid N-Hydroxysuccinimide Ester (6-[18F]SFPy)

Molecules ◽

10.3390/molecules25173924 ◽

2020 ◽

Vol 25 (17) ◽

pp. 3924

Author(s):

Falguni Basuli ◽

Xiang Zhang ◽

Tim E. Phelps ◽

Elaine M. Jagoda ◽

Peter L. Choyke ◽

...

Keyword(s):

Nicotinic Acid ◽

Specific Binding ◽

Automated Synthesis ◽

Bone Marrow Niche ◽

Positron Emission ◽

Straightforward Method ◽

Radiochemical Yields ◽

Chemokine Receptor 4

The C-X-C motif chemokine receptor 4 (CXCR4) is a seven-transmembrane G protein-coupled receptor that is overexpressed in numerous diseases, particularly in various cancers and is a powerful chemokine, attracting cells to the bone marrow niche. Therefore, CXCR4 is an attractive target for imaging and therapeutic purposes. The goal of this study is to develop an efficient, reproducible, and straightforward method to prepare a fluorine-18 labeled CXCR4 ligand. 6-[18F]Fluoronicotinic acid-2,3,5,6-tetrafluorophenyl ester (6-[18F]FPy-TFP) and nicotinic acid N-hydroxysuccinimide ester (6-[18F]SFPy) have been prepared using ‘fluorination on the Sep-Pak’ method. Conjugation of 6-[18F]SFPy or 6-[18F]FPy-TFP with the alpha-amino group at the N terminus of the protected T140 precursor followed by deprotection, yielded the final product 6-[18F]FPy-T140. The overall radiochemical yields were 6–17% (n = 15, decay-corrected) in a 90-min radiolabeling time with a radiochemical purity >99%. 6-[18F]FPy-T140 exhibited high specific binding and nanomolar affinity for CXCR4 in vitro, indicating that the biological activity of the peptide was preserved. For the first time, [18F]SFPy has been prepared using ‘fluorination on the Sep-Pak’ method that allows rapid automated synthesis of 6-[18F]FPy-T140. In addition to increased synthetic efficiency, this construct binds with CXCR4 in high affinity and may have potential as an in vivo positron emission tomography (PET) imaging agent. This radiosynthesis method should encourage wider use of this PET agent to quantify CXCR4 in both research and clinical settings.

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124I-Radiolabeling of a Au(III)-NHC Complex for in Vivo Biodistribution Studies

10.26434/chemrxiv.11996970 ◽

2020 ◽

Author(s):

Federica Guarra ◽

Alessio Terenzi ◽

Christine Pirker ◽

Rossana Passannante ◽

Dina Baier ◽

...

Keyword(s):

Anticancer Agents ◽

Direct Evidence ◽

Heterocyclic Carbenes ◽

Emission Tomography ◽

Direct Oxidation ◽

In Vivo Biodistribution ◽

Biodistribution Studies ◽

Positron Emission

Au(III) complexes with N-Heterocyclic Carbenes (NHCs) ligands have shown remarkable potential as anticancer agents, yet their fate in vivo has not been thoroughly examined and understood. Herein we report on the synthesis of new Au(III)-NHC complexes via direct oxidation with radioactive [124I]I2 as a valuable strategy to monitor the in vivo biodistribution of this class of compounds using positron emission tomography (PET) and, in combination with in vitro analyses, to provide direct evidence of the importance of Au(III)-to-Au(I) reduction for achieving full anticancer activity.

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Radiopharmaceutical Stem Cell Tracking for Neurological Diseases

BioMed Research International ◽

10.1155/2014/417091 ◽

2014 ◽

Vol 2014 ◽

pp. 1-12 ◽

Cited By ~ 6

Author(s):

Paulo Henrique Rosado-de-Castro ◽

Pedro Moreno Pimentel-Coelho ◽

Bianca Gutfilen ◽

Sergio Augusto Lopes de Souza ◽

Gabriel Rodriguez de Freitas ◽

...

Keyword(s):

Stem Cell ◽

Cell Tracking ◽

Imaging Techniques ◽

Neurological Diseases ◽

Cell Labeling ◽

Pharmacological Agents ◽

Cell Therapies ◽

Causes Of Disease ◽

Potential Applications

Although neurological ailments continue to be some of the main causes of disease burden in the world, current therapies such as pharmacological agents have limited potential in the restoration of neural functions. Cell therapies, firstly applied to treat different hematological diseases, are now being investigated in preclinical and clinical studies for neurological illnesses. However, the potential applications and mechanisms for such treatments are still poorly comprehended and are the focus of permanent research. In this setting, noninvasivein vivoimaging allows better understanding of several aspects of stem cell therapies. Amongst the various methods available, radioisotope cell labeling has become one of the most promising since it permits tracking of cells after injection by different routes to investigate their biodistribution. A significant increase in the number of studies utilizing this method has occurred in the last years. Here, we review the different radiopharmaceuticals, imaging techniques, and findings of the preclinical and clinical reports published up to now. Moreover, we discuss the limitations and future applications of radioisotope cell labeling in the field of cell transplantation for neurological diseases.

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