scholarly journals Development of the First Aliphatic 18F-Labeled Tetrazine Suitable for Pretargeted PET Imaging – Expanding the Bioorthogonal Tool Box

2021 ◽  
Author(s):  
Umberto Maria Battisti ◽  
Klas Bratteby ◽  
Jesper Tranekjær Jørgensen ◽  
Lars Hvass ◽  
Vladimir Shalgunov ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Blocking Effect ◽  
Structure Property ◽  
Promising Candidate ◽  
Bioorthogonal Reaction ◽  
Radiation Burden ◽  
Small Structure ◽  
Radiochemical Yields ◽  
State Of Art

<p>Pretargeting imaging of nanomedicines have attracted considerable interest in nuclear medicine since it has the potential to increase imaging contrast while simultaneously reducing radiation burden to healthy tissue. Currently, the tetrazine ligation is the fastest bioorthogonal reaction available for this strategy and consequently, the state-of-art choice for <i>in vivo</i>chemistry. We have recently identified key properties for tetrazines to be applied in pretargeting. We have also developed a method to <sup>18</sup>F-label highly reactive tetrazines using an aliphatic nucleophilic substitution strategy.<a> In this study, we combined this knowledge and developed an <sup>18</sup>F-labeled tetrazine for pretargeted imaging. In order to develop this ligand, a small structure-property study was carried out. The most promising compound - with respect to reactivity, hydrophilicity and <i>ex vivo</i> blocking effect - was selected for labeling and subsequent PET <i>in vivo</i> imaging. Radiolabeling was achieved in satisfying radiochemical yields, molar activities as well as in high radiochemical purities. The tracer </a><a>displayed favorable pharmacokinetics and remarkable target-to-background ratios in pretargeted experiments - already one hour post injection.</a> We believe that the developed pretargeting imaging agent is a promising candidate for translation into clinical studies.</p>

scholarly journals Development of the First Aliphatic 18F-Labeled Tetrazine Suitable for Pretargeted PET Imaging – Expanding the Bioorthogonal Tool Box

2021 ◽  
Author(s):  
Umberto Maria Battisti ◽  
Klas Bratteby ◽  
Jesper Tranekjær Jørgensen ◽  
Lars Hvass ◽  
Vladimir Shalgunov ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Blocking Effect ◽  
Structure Property ◽  
Promising Candidate ◽  
Bioorthogonal Reaction ◽  
Radiation Burden ◽  
Small Structure ◽  
Radiochemical Yields ◽  
State Of Art

<p>Pretargeting imaging of nanomedicines have attracted considerable interest in nuclear medicine since it has the potential to increase imaging contrast while simultaneously reducing radiation burden to healthy tissue. Currently, the tetrazine ligation is the fastest bioorthogonal reaction available for this strategy and consequently, the state-of-art choice for <i>in vivo</i>chemistry. We have recently identified key properties for tetrazines to be applied in pretargeting. We have also developed a method to <sup>18</sup>F-label highly reactive tetrazines using an aliphatic nucleophilic substitution strategy.<a> In this study, we combined this knowledge and developed an <sup>18</sup>F-labeled tetrazine for pretargeted imaging. In order to develop this ligand, a small structure-property study was carried out. The most promising compound - with respect to reactivity, hydrophilicity and <i>ex vivo</i> blocking effect - was selected for labeling and subsequent PET <i>in vivo</i> imaging. Radiolabeling was achieved in satisfying radiochemical yields, molar activities as well as in high radiochemical purities. The tracer </a><a>displayed favorable pharmacokinetics and remarkable target-to-background ratios in pretargeted experiments - already one hour post injection.</a> We believe that the developed pretargeting imaging agent is a promising candidate for translation into clinical studies.</p>

Non-invasive imaging of glycoprotein VI binding to injured arterial lesions

2005 ◽  
Vol 93 (05) ◽  
pp. 910-913 ◽  
Author(s):  
Ildiko Konrad ◽  
Andrea Hauser ◽  
Suzanne Sauer ◽  
Zhongyan Li ◽  
Hans-Jürgen Wester ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Critical Role ◽  
Vascular Lesions ◽  
Glycoprotein Vi ◽  
Non Invasive ◽  
Arterial Lesions ◽  
Ex Vivo Autoradiography ◽  
Radiochemical Yields ◽  
Collagen Receptor

SummaryGlycoprotein VI (GPVI) is the major platelet collagen receptor and plays a critical role in the process of thrombosis at sites of atherosclerotic lesions. This study evaluates the feasibility of radiolabeled soluble GPVI to identify injured arterial lesions. Radiolabeling was carried out using the iodogen method and resulted in the radioiodinated GPVI in radiochemical yields between 97–100%. The biodistribution of [125I]GPVI was determined in normal mice and demonstrated a blood clearance halftime of approximately 5.5 hours. Vascular lesions were induced in the carotid artery in wild type and ApoE -/- mice. Immediately after injury radioiodinated GPVI was injected intravenously. Binding of [123I]GPVI to carotid lesions was assessed by szinti-graphic in vivo imaging. Carotid arteries were explanted for ex vivo autoradiography and histological characterization of the lesion. In vivo and ex vivo imaging revealed substantial accumulation of radioiodinated GPVI in the injured artery wall, with a ratio of lesion to control vessel of 3:1 and 7:1, respectively. Because GPVI is the critical collagen receptor that mediates platelet adhesion to vascular lesions, soluble radiolabeled GPVI may be an agent for non-invasive imaging of thrombogenic thus, vulnerable atherosclerotic plaques.

scholarly journals Design, Synthesis, In Vitro and In Vivo Evaluation of Heterobivalent SiFAlin-Modified Peptidic Radioligands Targeting Both Integrin αvβ3 and the MC1 Receptor—Suitable for the Specific Visualization of Melanomas?

2021 ◽  
Vol 14 (6) ◽  
pp. 547
Author(s):  
Xia Cheng ◽  
Ralph Hübner ◽  
Valeska von von Kiedrowski ◽  
Gert Fricker ◽  
Ralf Schirrmacher ◽  
...  
Keyword(s):  
Malignant Melanoma ◽  
Ex Vivo ◽  
Integrin Αvβ3 ◽  
In Vivo Evaluation ◽  
Design Synthesis ◽  
Pet Ct ◽  
In Vivo Testing ◽  
Radiochemical Yields

Combining two peptides addressing two different receptors to a heterobivalent peptidic ligand (HBPL) is thought to enable an improved tumor-targeting sensitivity and thus tumor visualization, compared to monovalent peptide ligands. In the case of melanoma, the Melanocortin-1 receptor (MC1R), which is stably overexpressed in the majority of primary malignant melanomas, and integrin αvβ3, which is involved in lymph node metastasis and therefore has an important role in the transition from local to metastatic disease, are important target receptors. Thus, if a radiolabeled HBPL could be developed that was able to bind to both receptor types, the early diagnosis and correct staging of the disease would be significantly increased. Here, we report on the design, synthesis, radiolabeling and in vitro and in vivo testing of different SiFAlin-modified HBPLs (SiFA = silicon fluoride acceptor), consisting of an MC1R-targeting (GG-Nle-c(DHfRWK)) and an integrin αvβ3-affine peptide (c(RGDfK)), being connected by a symmetrically branching framework including linkers of differing length and composition. Kit-like 18F-radiolabeling of the HBPLs 1–6 provided the labeled products [18F]1–[18F]6 in radiochemical yields of 27–50%, radiochemical purities of ≥95% and non-optimized molar activities of 17–51 GBq/µmol within short preparation times of 25 min. Besides the evaluation of radiotracers regarding logD(7.4) and stability in human serum, the receptor affinities of the HBPLs were investigated in vitro on cell lines overexpressing integrin αvβ3 (U87MG cells) or the MC1R (B16F10). Based on these results, the most promising compounds [18F]2, showing the highest affinity to both target receptors (IC50 (B16F10) = 0.99 ± 0.11 nM, IC50 (U87MG) = 1300 ± 288 nM), and [18F]4, exhibiting the highest hydrophilicity (logD(7.4) = −1.39 ± 0.03), were further investigated in vivo and ex vivo in a xenograft mouse model bearing both tumors. For both HBPLs, clear visualization of B16F10, as well as U87MG tumors, was feasible. Blocking studies using the respective monospecific peptides demonstrated both peptide binders of the HBPLs contributing to tumor uptake. Despite the somewhat lower target receptor affinities (IC50 (B16F10) = 6.00 ± 0.47 nM and IC50 (U87MG) = 2034 ± 323 nM) of [18F]4, the tracer showed higher absolute tumor uptakes ([18F]4: 2.58 ± 0.86% ID/g in B16F10 tumors and 3.92 ± 1.31% ID/g in U87MG tumors; [18F]2: 2.32 ± 0.49% ID/g in B16F10 tumors and 2.33 ± 0.46% ID/g in U87MG tumors) as well as higher tumor-to-background ratios than [18F]2. Thus, [18F]4 demonstrates to be a highly potent radiotracer for the sensitive and bispecific imaging of malignant melanoma by PET/CT imaging and impressively illustrates the suitability of the underlying concept to develop heterobivalent integrin αvβ3- and MC1R-bispecific radioligands for the sensitive and specific imaging of malignant melanoma by PET/CT.

scholarly journals A novel therapeutic peptide targeting myocardial reperfusion injury

2019 ◽  
Vol 116 (3) ◽  
pp. 633-644 ◽  
Author(s):  
Prisca Boisguérin ◽  
Aurélie Covinhes ◽  
Laura Gallot ◽  
Christian Barrère ◽  
Anne Vincent ◽  
...  
Keyword(s):  
Bolus Injection ◽  
Ex Vivo ◽  
Therapeutic Application ◽  
Promising Candidate ◽  
Ischaemia Reperfusion ◽  
Regulated Cell Death ◽  
Cardioprotective Effects ◽  
Peptide Targeting ◽  
Apoptotic Signal

Abstract Aims Regulated cell death is a main contributor of myocardial ischaemia-reperfusion (IR) injury during acute myocardial infarction. In this context, targeting apoptosis could be a potent therapeutical strategy. In a previous study, we showed that DAXX (death-associated protein) was essential for transducing the FAS-dependent apoptotic signal during IR injury. The present study aims at evaluating the cardioprotective effects of a synthetic peptide inhibiting FAS:DAXX interaction. Methods and results An interfering peptide was engineered and then coupled to the Tat cell penetrating peptide (Tat-DAXXp). Its internalization and anti-apoptotic properties were demonstrated in primary cardiomyocytes. Importantly, an intravenous bolus injection of Tat-DAXXp (1 mg/kg) 5 min before reperfusion in a murine myocardial IR model decreased infarct size by 48% after 24 h of reperfusion. In addition, Tat-DAXXp was still efficient after a 30-min delayed administration, and was completely degraded and eliminated within 24 h thereby reducing risks of potential side effects. Importantly, Tat-DAXXp reduced mouse early post-infarction mortality by 67%. Mechanistically, cardioprotection was supported by both anti-apoptotic and pro-survival effects, and an improvement of myocardial functional recovery as evidenced in ex vivo experiments. Conclusions Our study demonstrates that a single dose of Tat-DAXXp injected intravenously at the onset of reperfusion leads to a strong cardioprotection in vivo by inhibiting IR injury validating Tat-DAXXp as a promising candidate for therapeutic application.

scholarly journals Clickable Radiocomplexes With Trivalent Radiometals for Cancer Theranostics: In vitro and in vivo Studies

2021 ◽  
Vol 8 ◽  
Author(s):  
Alice D'Onofrio ◽  
Francisco Silva ◽  
Lurdes Gano ◽  
Urszula Karczmarczyk ◽  
Renata Mikołajczak ◽  
...  
Keyword(s):  
Specific Activity ◽  
Ex Vivo ◽  
High Specific Activity ◽  
In Vivo Studies ◽  
Tumor Uptake ◽  
Biodistribution Studies ◽  
Radiochemical Yields ◽  
Analysis Of The Images

Pre-targeting approaches based on the inverse-electron-demand Diels-Alder (iEDDA) reaction between strained trans-cyclooctenes (TCO) and electron-deficient tetrazines (Tz) have emerged in recent years as valid alternatives to classic targeted strategies to improve the diagnostic and therapeutic properties of radioactive probes. To explore these pre-targeting strategies based on in vivo click chemistry, a small family of clickable chelators was synthesized and radiolabelled with medically relevant trivalent radiometals. The structure of the clickable chelators was diversified to modulate the pharmacokinetics of the resulting [111In]In-radiocomplexes, as assessed upon injection in healthy mice. The derivative DOTA-Tz was chosen to pursue the studies upon radiolabelling with 90Y, yielding a radiocomplex with high specific activity, high radiochemical yields and suitable in vitro stability. The [90Y]Y-DOTA-Tz complex was evaluated in a prostate cancer PC3 xenograft by ex-vivo biodistribution studies and Cerenkov luminescence imaging (CLI). The results highlighted a quick elimination through the renal system and no relevant accumulation in non-target organs or non-specific tumor uptake. Furthermore, a clickable bombesin antagonist was injected in PC3 tumor-bearing mice followed by the radiocomplex [90Y]Y-DOTA-Tz, and the mice imaged by CLI at different post-injection times (p.i.). Analysis of the images 15 min and 1 h p.i. pointed out an encouraging quick tumor uptake with a fast washout, providing a preliminary proof of concept of the usefulness of the designed clickable complexes for pre-targeting strategies. To the best of our knowledge, the use of peptide antagonists for this purpose was not explored before. Further investigations are needed to optimize the pre-targeting approach based on this type of biomolecules and evaluate its eventual advantages.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Antithrombotic Effects and Bleeding Time Prolongation with Synthetic Platelet GPIIb/llla Inhibitors in Animal Models of Platelet-Mediated Thrombosis

1994 ◽  
Vol 71 (01) ◽  
pp. 095-102 ◽  
Author(s):  
Désiré Collen ◽  
Hua Rong Lu ◽  
Jean-Marie Stassen ◽  
Ingrid Vreys ◽  
Tsunehiro Yasuda ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Bolus Injection ◽  
Cell Injury ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Thrombotic Occlusion ◽  
Antithrombotic Effects

SummaryCyclic Arg-Gly-Asp (RGD) containing synthetic peptides such as L-cysteine, N-(mercaptoacetyl)-D-tyrosyl-L-arginylglycyl-L-a-aspartyl-cyclic (1→5)-sulfide, 5-oxide (G4120) and acetyl-L-cysteinyl-L-asparaginyl-L-prolyl-L-arginyl-glycyl-L-α-aspartyl-[0-methyltyrosyl]-L-arginyl-L-cysteinamide, cyclic 1→9-sulfide (TP9201) bind with high affinity to the platelet GPIIb/IIIa receptor.The relationship between antithrombotic effect, ex vivo platelet aggregation and bleeding time prolongation with both agents was studied in hamsters with a standardized femoral vein endothelial cell injury predisposing to platelet-rich mural thrombosis, and in dogs with a carotid arterial eversion graft inserted in the femoral artery. Intravenous administration of G4120 in hamsters inhibited in vivo thrombus formation with a 50% inhibitory bolus dose (ID50) of approximately 20 μg/kg, ex vivo ADP-induccd platelet aggregation with ID50 of 10 μg/kg, and bolus injection of 1 mg/kg prolonged the bleeding time from 38 ± 9 to 1,100 ± 330 s. Administration of TP9201 in hamsters inhibited in vivo thrombus formation with ID50 of 30 μg/kg, ex vivo platelet aggregation with an ID50 of 50 μg/kg and bolus injection of 1 mg/kg did not prolong the template bleeding time. In the dog eversion graft model, infusion of 100 μg/kg of G4120 over 60 min did not fully inhibit platelet-mediated thrombotic occlusion but was associated with inhibition of ADP-induccd ex vivo platelet aggregation and with prolongation of the template bleeding time from 1.3 ± 0.4 to 12 ± 2 min. Infusion of 300 μg/kg of TP9201 over 60 min completely prevented thrombotic occlusion, inhibited ex vivo platelet aggregation, but was not associated with prolongation of the template bleeding time.TP9201, unlike G4120, inhibits in vivo platelet-mediated thrombus formation without associated prolongation of the template bleeding time.

Significance of Platelet β-Adrenoceptors for Platelet Responses In Vivo and In Vitro

1992 ◽  
Vol 68 (06) ◽  
pp. 687-693 ◽  
Author(s):  
P T Larsson ◽  
N H Wallén ◽  
A Martinsson ◽  
N Egberg ◽  
P Hjemdahl
Keyword(s):  
Ex Vivo ◽  
High Dose ◽  
Platelet Aggregability ◽  
Adrenoceptor Agonist ◽  
Dose Infusion ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThe significance of platelet β-adrenoceptors for platelet responses to adrenergic stimuli in vivo and in vitro was studied in healthy volunteers. Low dose infusion of the β-adrenoceptor agonist isoprenaline decreased platelet aggregability in vivo as measured by ex vivo filtragometry. Infusion of adrenaline, a mixed α- and β-adrenoceptor agonist, increased platelet aggregability in vivo markedly, as measured by ex vivo filtragometry and plasma β-thromboglobulin levels. Adrenaline levels were 3–4 nM in venous plasma during infusion. Both adrenaline and high dose isoprenaline elevated plasma von Willebrand factor antigen levels β-Blockade by propranolol did not alter our measures of platelet aggregability at rest or during adrenaline infusions, but inhibited adrenaline-induced increases in vWf:ag. In a model using filtragometry to assess platelet aggregability in whole blood in vitro, propranolol enhanced the proaggregatory actions of 5 nM, but not of 10 nM adrenaline. The present data suggest that β-adrenoceptor stimulation can inhibit platelet function in vivo but that effects of adrenaline at high physiological concentrations are dominated by an α-adrenoceptor mediated proaggregatory action.

In Vivo Effect of Suloctidil as an Antiplatelet Agent

1979 ◽  
Vol 41 (03) ◽  
pp. 465-474 ◽  
Author(s):  
Marcia R Stelzer ◽  
Thomas S Burns ◽  
Robert N Saunders
Keyword(s):  
Ex Vivo ◽  
Antiplatelet Agent ◽  
Ratio Method ◽  
Platelet Aggregate ◽  
Permanent Effect ◽  
Platelet Aggregates ◽  
5 Ht Uptake ◽  
High Doses

SummaryThe relationship between the effects of suloctidil in vivo as an antiplatelet agent and in vitro as a modifier of platelet serotonin (5-HT) parameters was investigated. Suloctidil was found to be effective in reducing platelet aggregates formation in the retired breeder rat as determined using the platelet aggregate ratio method (PAR) with an ED50 of 16.1 mg/kg 24 hours post administration. In contrast to the hypothesis that 5-HT depletion is involved in the anti-aggregatory mechanism of suloctidil, no correlation was found between platelet 5- HT content and this antiplatelet activity. Reduction of platelet 5-HT content required multiple injections of high doses (100 mg/kg/day) of suloctidil. Suloctidil administration for 8 days at 100 mg/kg/day, which lowered platelet 5-HT content by 50%, resulted in no permanent effect on ex vivo platelet 5-HT uptake or thrombin-induced release, nor alteration in the plasma 5-HT level. However, these platelets exhibited a short-lived, significant increase in percent leakage of 5-HT after 30 minutes of incubation. Therefore, suloctidil treatment at high doses may with time result in platelet 5-HT depletion, however this effect is probably not related to the primary anti-aggregatory activity of the drug.

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