Name: preparation and evaluation of 99mtc-labeled tridentate chelates for pre-targeting using bioorthogonal chemistry
Uploaded: 2017-02-04T15:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry at JoVE.com

This work supported by research grant funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Ontario Institute for Cancer Research (OICR, #P.SI.015.8), and the Canadian Cancer Society (CCS, #703857). The authors acknowledge the contributions of Dr. Denis Snider who provided assistance in preparing the manuscript.

In Tierstudien wurden von der Tierforschung Ethikrat an der McMaster University in Übereinstimmung mit Canadian Council on Animal Care (CCAC) Richtlinien zugelassen. 1. Die radioaktive Markierung von Tz-dreizähnigen Liganden mit 99m Tc ACHTUNG: Die folgenden Verfahren erfordern die Verwendung von radioaktiven Verbindungen. Die Arbeiten sollten nur in einem zugelassenen Labor mit der Einhaltung von Sicherheits- und Entsorgungsvorschriften erfolgen. Mikrowellen-Reaktionen sollten in einer Mikrowelle durchgeführt werden, die speziell für die chemische Synthese konstruiert. <ol><li> Synthese von [99m Tc (CO) 3 (H 2 O) 3] + 19, 20 <ol><li> In einem Mikrowellenfläschchen kombinieren 8 mg K 2 [BH 3 CO 2], 15 mg Na 2 CO 3, 20 mg Na 2 B 4 O 7 · 10H 2 O und 25 mg KOCO [CH (OH)]2 COONa · 4H 2 O Purge das Fläschchen für 10 Minuten mit Argongas. </li><li> 4 ml 99m TcO 4 - (~ 1,100 MBq, ~ 30 mCi) in 0,9% Kochsalzlösung in das Fläschchen. </li><li> Die Reaktion wird in einer Mikrowelle für 3,5 min bei 110 ° C nach 10 s Rühren eine gute Durchmischung der Reagenzien zu gewährleisten. </li><li> Der pH-Wert der Lösung auf 3,5-4 mittels ~ 400 &amp; mgr; l von 1 M HCl. Stellen Sie sicher, pH-Papier verwenden. </li></ol></li><li> Die radioaktive Markierung von Tetrazin - Liganden 1-5 <ol><li> Man löst 2 mg jedes Liganden (Verbindungen 1-5) in 250 &amp; mgr; l MeOH 21. </li><li> Nach Eintragen von 250 &amp; mgr; l [99m Tc (CO) 3 (H 2 O) 3] + (~ 74 MBq, ~ 2 mCi) zu jeder Lösung. </li><li> Das Reaktionsgemisch wird eine Mikrowelle für 20 min bei 60 ° C verwendet wird. Hinweis: dieser Schritt für alle 5 Tetrazinen identisch war. </li><li> Für Verbindungen 2- 5, verdampfe das Lösungsmittel und Wieder DISSOLve die resultierenden Produkte in 1 ml 1: 1 v / v DCM: TFA. </li><li> Wärme , die gelösten Reaktionsprodukte (2-5) bei 60 ° C in einer Mikrowelle für 6 min (2-4) oder 10 min (5). </li><li> Nach dem Abkühlen auf Raumtemperatur, dampfe das Lösungsmittel unter Verwendung eines Verdampfers (36 ° C, 8 mbar, 3 min, 6000 rpm) und lösen die getrocknete Verbindung in 1: 1 ACN: H 2 O oder 1: 1 MeOH: H 2 O, vor der HPLC-Reinigung. </li><li> Reinige den 99m Tc-markierten Verbindungen (1-5), einschließlich des markierten Produkts von unmarkiertem Liganden Tetrazin Trennung unter Verwendung von HPLC (C18 Umkehrphase). Typischerweise verwenden eines Elutionsgradienten von 30:70 ACN: H 2 O (beide mit 0,1% TFA) bis 40:60 ACN: H 2 O über 20 min (18 min) und ein C 18 analytisches 4,6 x 100 mm Säule. Verwenden sowohl UV (254 nm) und gamma-Detektion. <ol><li> Nehmen Sie eine kleine Probe jedes Produkts und vergleichen ihre HPLC-Retentionszeit, die der Co-injektiert, nicht-radioaktive, Re-markierten Standards (0,125 mg in 20% Methanol-H 2 O). Die Re-markiertem Standard wird in der UV - HPLC - Spur identifiziert, und zur gleichen Zeit wie die 99m Tc-markierte Verbindung , in der γ-HPLC - Spur eluieren. Diese Co-Injektion zeigt Peaks bei vergleichbaren Retentionszeiten, die Identität der 99m Tc-Verbindung bestätigt gekennzeichnet. </li></ol></li><li> Dampfe das Lösungsmittel von HPLC-Fraktionen unter Verwendung eines Verdampfers (36 ° C, 8 mbar, 3 min, 6.000 rpm). </li><li> Formulieren der gereinigten Verbindung in einer Konzentration von 7,4 kBq / &amp; mgr; l in PBS, enthaltend 0,5% BSA und 0,01% Tween-80. </li><li> Um die markierten Verbindungen sind stabil zu gewährleisten, führen Sie eine in - vitro - Stabilitätsstudie. Inkubieren der formulierten Verbindung bei 37 ° C für 1, 4 und 6 h, eine kleine Menge (3,7 MBq) der Mischung auf dem HPLC an jedem Zeitpunkt Injizieren Stabilität zu bewerten. </li></ol></li></ol> 2. Pre-gezielte Bio-Verteilung Studies <ol><li&gt; Vorbereitung der Tiere <ol><li> Mit 7-9 Wochen alt, weiblich Balb / c-Mäuse (n = 3), zu verwalten TCO-BP in Kochsalzlösung (20 mg / kg) (5 ug / ul) formuliert, über Schwanzveneninjektion. </li><li> Bewegen Sie die Maus in der physischen Rückhaltevorrichtung, und identifizieren die sich Venen an den Seitenflächen des Schwanzes und wischen Sie mit einem Alkoholtupfer. Bei etwa 2 cm vom Ende des Schwanzes, legen Sie eine 30-Gauge-Nadel in einem flachen Winkel parallel zur Ader. Langsam drücken Sie den Kolben Nadel zu injizieren, entfernen und reinigen Gazeschwamm an der Injektionsstelle mit leichtem Druck, bis die Blutung aufhört gelten. </li><li> Bei 1 h nach der Injektion von TCO-BP, verabreichen ~ 0,74 MBq (20 uCi) von 99m Tc-Tetrazin in 100 ul 0,5% BSA formuliert, 0,01% Tween-80 in PBS, via Schwanzveneninjektion. </li></ol></li><li> Bio-Verteilungsstudien <ol><li> Bei dem gewünschten Zeitpunkt (t = 6 h), anästhesieren die Mäuse unter Verwendung von 3% Isofluran und 2% Sauerstoff-Gasgemisch. Demonstrieren Sie ein zue Prise Rückzug auf der narkotisierten Maus, um sicherzustellen, dass sie unter chirurgische Ebene der Anästhesie sind. </li><li> Sammeln Blut (1 ml) über eine Spritze Herzpunktur vorbehandelt mit Heparin verwendet wird. Bewegen Sie die Maus auf dem Rücken mit der Nase in die Nase Kegel für die weitere Anästhesie und suchen Sie den Xiphoidbasis auf das Tier. <ol><li> Legen Sie eine 25 G-Nadel, leicht nach links von der Mittellinie des Tieres unter dem Xiphoidbasis, bei einem Winkel von 20 °. Voll führen Sie die Nadel, und langsam auf den Kolben zurückziehen Blut in der Nadel-Ansatz, um zu sehen, ob das Herz durchbohrt wurde. Etwas die Nadel nachstellen, während der Kolben bei Bedarf halten, um das Herz zu durchbohren. ziehen langsam Blut in die Spritze. </li></ol></li><li> Euthanize das Tier durch Genickbruch, während der Narkose. </li><li> Legen Sie jedes Tier in einen Plastikbeutel und verwenden Sie einen Dosiskalibrators (99m Tc - Einstellung) , um den ganzen Körper Aktivitätsniveau zu messen. </li><li> Sammeln Sie die folgenden Gewebe und Flüssigkeiten in vorge wiegened Zählrohre: Blut, Knochen (Knie und Schulter), Gallenblase, Nieren, Leber, Magen (mit Inhalt), Dünndarm (mit Inhalt), Dickdarm und Blinddarm (mit Inhalt), der Schilddrüse und der Trachea, der Harnblase mit Urin und Schwanz. </li><li> Spülen Sie geeignete Gewebe (ohne Blut, Gallenblase und Harnblase) in PBS Blut zu entfernen und trocken tupfen, bevor das Gewebe in geeigneten Zählrohre platzieren. </li><li> Platzieren Sie Tierkadaver in eine Plastiktüte und messen Rest ganzen Körper Aktivität eine Dosis-Kalibrator verwenden. </li><li> Wiegen Sie jedes Röhrchen eine Gewebeprobe enthält. Subtract Anfangsgewicht des Rohrs Masse des Gewebes zu erhalten. </li><li> Verwenden , um eine Dosis - Kalibrator (99m Tc - Einstellung) die Menge an Aktivität in einer Testprobe (100 ul) zu der Zeit der Einspritzung für jede Maus gemessen. ANMERKUNG: Diese Testprobe ist gleich dem Injektionsvolumen, wodurch die Aktivitätszählung zum Zeitpunkt der Injektion geben. </li><li> Zum Zeitpunkt der Gewebemessung eineliquot 5 ul des zuvor verwendeten Testprobe. Verwenden , um einen Multidetektor - Gammazähler (99m Tc - Einstellung) und zähle die Zählung pro Minute (CPM) für die 5 &amp; mgr; l Testprobe zu erhalten. </li><li> Verwenden Sie die beiden erhaltenen Werte in 2.2.9 und 2.2.10 die Aktivität und CPM - Beziehung 1 unter Verwendung der Gleichung zu berechnen einen Umrechnungsfaktor zu erhalten (CPM uCi -1). (1) <img alt="Gleichung 1" src="/files/ftp_upload/55188/55188eq1.jpg" /></li><li> Verwenden, um die Gamma-Zähler die Menge an Radioaktivität in jedem Gewebe oder Flüssigkeitsprobe zu messen. </li><li> Verwenden der Gleichung 1 die Aktivitätsmenge in jedem Gewebe oder Flüssigkeit, die zum Zeitpunkt der Messung in Bezug auf die gesamten injizierten Dosis berechnet. Dieser Wert wird dann durch Organgewicht normalisiert und als Prozent injizierte Dosis pro Gramm (dh% ID / g) Gewebe berichtet. </li><li> Führen Sie die Schritte 2.1.2 bis 2.2.13 ein negatives Kontrollexperiment durchzuführen unter Verwendung der 99m Tc-markierten Tetrazin - Liganden in der Absence von TCO-BP. Opfer-Mäuse (n = 3) bei 0,5, 1, 4 und 6 h nach der Injektion und zu erhalten Gewebe oder Flüssigkeit, wie oben beschrieben. </li></ol></li></ol>

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The authors declare they have no competing financial interests.

Eine Sammlung von Tetrazin-linked dreizähnigen Chelate verschiedener Polaritäten wurde hergestellt, und die Nützlichkeit der 99m Tc - Komplexe in der IEDDA Reaktion mit einer TCO - Derivat in vivo bewertet. Eine effektive und reproduzierbare 99m Tc wurde Markierungsverfahren für fünf Tetrazin-Chelate entwickelt, wobei der Ligand - Konzentration 10 -3 M. war der Markierungsschritt durch Entfernung der Schutzgruppe von t- Butyl - Gruppen (für die Verbindungen <stron...

99m Tc bleibt die dominierende Radioisotop in der diagnostischen Nuklearmedizin verwendet wird , mit mehr als 50 Millionen Bildgebungsverfahren pro Jahr weltweit durchgeführt 1, 2, 3. Die Mehrheit der 99m Tc Mittel werden klinisch Perfusion Radiopharmaka. Es gibt eine begrenzte Anzahl von aktiv gezielte Verbindungen , in denen 99m Tc gerichtet ist eine spezifische Biomarker durch Ligation an ein Targeting - Konstrukt zu binden. Die Erzeugung gezielter 99m Tc - Radiopharmaka wird häufig durch den Einfluß von 99m Tc-Ligand - Komplexe auf die Fähigkeit des dirigierenden Moleküls zu binden , um die Biomarker von Interesse gehinderte oder die Isotopen - Halbwertszeit nicht lang genug ist für die Verwendung mit höherem Molekulargewicht Biomoleküle wie Antikörper. Letzteres erfordert üblicherweise mehrere Tage vor Bildern, um für das Biomolekül erworben werden von Nicht-Ziel zu löschen tiss<html> ues. Pre-Targeting bietet einen alternativen Ansatz, diese Herausforderungen zu überwinden. Pre-Targeting mit bioorthogonale Chemie kombiniert wurde ein effektiver Weg gezeigt werden , für die Entwicklung neuer molekularer Bildgebungssonden sowohl für Fluoreszenz und Radio-Imaging - 4, 5, 6, 7, 8. Die inversem Elektronenbedarf Diels-Alder (IEDDA) Reaktion zwischen 1,2,4,5-Tetrazin (Tz) und trans -Cycloocten (TCO) -Derivate, wie in Figur 1 gezeigt ist , hat sich als besonders wirksam 6 erwiesen. Die IEDDA Reaktion mit diesen Komponenten können schnell Kinetik in PBS (k 2 ≈ 6000 M -1 s -1) und eine hohe Selektivität aufweisen, wodurch es ideal für in - vivo - Pre-Targeting - Anwendungen macht 9, 10. e_content &quot;&gt; Die am häufigsten verwendete Ansatz umfasst ein TCO-derived Targeting - Vektor Verwaltung und eine ausreichende Verzögerung Folgezeit ein radioaktiv markiertes Tetrazin verabreicht. Radiolabeled Tetrazinen basierend auf 11 C, 18 F, 64 Cu, 89 Zr und 111 In gewesen 11 berichtete, 12, 13, 14, 15. im Gegensatz dazu gibt es nur einen Bericht eines 99m ist Tz-Tc markiert, die eine HYNIC - Typ - Liganden wurde unter Verwendung von der Verwendung von Co-Liganden erfordern Protein zu verhindern Bindung und den Abbau in vivo 16. Alternativ berichten wir hier die Synthese von 99m Tc (I) markiertem Tetrazinen eine Familie von Liganden , die mit einem [99m Tc (CO) 3] + Kern stabil dreizähnige Komplexe bilden. Abbildung 1: Die bioorthogonale IEDDA Reaktion zwischen Tetrazin und trans -Cycloocten. <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55188/55188fig1large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="https://ecsource-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55188/55188fig1large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a> Die Familie von Liganden hergestellt enthalten dreizähnigen Chelate , die in der Polarität und der Natur der Linkergruppe zwischen der Metallbindungsbereich und dem Tz (Abbildung 2) variieren. Das Ziel war es, ein 99m zu identifizieren Tc-Tetrazin , dass effektiv lokalisieren und reagieren mit TCO-markierten Stellen in vivo konstruieren konnte und schnell klar , wenn sie nicht gebunden, um eine hohe Ziel-zu-Nichtziel - Verhältnisse zu erhalten. Um die Liganden zu testen, ein TCO-Derivat einer Bisphosphonat (TCO-BP) wurde 17 verwendet. Wir haben bereits gezeigt, dass TCO-BP zu den Bereichen der aktiven Knochenmetabolismus lokalisiert und reagieren mitradiomarkierten Tetrazinen in vivo 18. Es ist eine bequeme Reagenz neue Tetrazinen zu testen, da es in einem einzigen Schritt hergestellt werden können, und Experimente können in normalen Mäusen durchgeführt werden, in denen die Lokalisierung in erster Linie in den Gelenken (Knie und Schultern) auftritt.

<table><tbody><tr><td>Argon gas</td><td>Alphagaz</td><td>---</td><td>---</td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;CO&lt;sub&gt;3&lt;/sub&gt;</td><td>EMD Millipore</td><td>106395</td><td>---</td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;B&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt;&amp;#183;10H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Anachemia</td><td>S9640</td><td>---</td></tr><tr><td>KNaC&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt;&amp;#183;4H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Anachemia</td><td>217255</td><td>---</td></tr><tr><td>Technelite &lt;sup&gt;99m&lt;/sup&gt;Tc generator</td><td>Lantheus medical imaging</td><td>---</td><td>Source of &lt;sup&gt;99m&lt;/sup&gt;TcO&lt;sup&gt;4-&lt;/sup&gt;</td></tr><tr><td>0.9% Saline</td><td>Lantheus medical imaging</td><td>---</td><td>To elute generator</td></tr><tr><td>1 M HCl</td><td>Lab Chem</td><td>---</td><td>---</td></tr><tr><td>MeOH</td><td>Caledon</td><td>---</td><td>---</td></tr><tr><td>ACN</td><td>Caledon</td><td>---</td><td>HPLC grade</td></tr><tr><td>Millipore H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Thermo Fisher Scientific</td><td>Barnstead Nanopure</td><td>---</td></tr><tr><td>DCM</td><td>Caledon</td><td>---</td><td>---</td></tr><tr><td>TFA</td><td>Caledon</td><td>---</td><td>---</td></tr><tr><td>PBS</td><td>Thermo Fisher Scientific</td><td>10010023</td><td>pH 7.4 1x</td></tr><tr><td>BSA</td><td>Sigma Aldrich</td><td>A7906</td><td>---</td></tr><tr><td>Tween80</td><td>Sigma Aldrich</td><td>P8047</td><td>---</td></tr><tr><td>Isoflurane</td><td>CDMV</td><td>108737</td><td>Supplier: Fresenius Kabi Animal Health</td></tr><tr><td>HPLC</td><td>Waters</td><td>1525 Binary Pump, 2998 Photodiodde Array Detector, E-SAT/IN, Bioscan Flowcount PMT detector (item # 15590)</td><td>---</td></tr><tr><td>HPLC column for analysis and purification of compounds 2-4</td><td>Phenomenex</td><td>00G-4435-E0</td><td>Gemini&amp;reg; 5 &amp;micro;m C18 110&amp;nbsp;&amp;Aring;, LC Column 250 x 4.6 mm</td></tr><tr><td>HPLC column for analysis and purification of compounds 1 and 5</td><td>Waters&amp;nbsp;</td><td>186003115</td><td>XBridge BEH C18 Column, 130 &amp;Aring;, 5 &amp;micro;m, 4.6 mm x 100 mm</td></tr><tr><td>Microwave Reactor&amp;nbsp;</td><td>Biotage&amp;nbsp;</td><td>Initiator 8</td><td>---</td></tr><tr><td>Biotage V10 Evaporator</td><td>Biotage&amp;nbsp;</td><td>Serial # V1041</td><td>---</td></tr><tr><td>Dose calibrator</td><td>Capintec, Inc.&amp;nbsp;</td><td>CRC-25R</td><td>---</td></tr><tr><td>Gamma counter</td><td>Perkin Elmer</td><td>Wizard 1470 Automatic Gamma Counter</td><td>---</td></tr><tr><td>Animal room scale&amp;nbsp;</td><td>Mettler Toledo</td><td>XP105 Delta Range</td><td>---</td></tr><tr><td>Microwave vials&amp;nbsp;</td><td>Biotage&amp;nbsp;</td><td>355629</td><td>0.5-2 mL&amp;nbsp;</td></tr></tbody></table>

preparation and evaluation of 99mtc-labeled tridentate chelates for pre-targeting using bioorthogonal chemistry

Pre-targeting combined with bioorthogonal chemistry is emerging as an effective way to create new radiopharmaceuticals. Of the methods available, the inverse electron demand Diels-Alder (IEDDA) cycloaddition between a radiolabeled tetrazines and trans-cyclooctene (TCO) linked to a biomolecule has proven to be a highly effective bioorthogonal approach to imaging specific biological targets. Despite the fact that technetium-99m remains the most widely used isotope in diagnostic nuclear medicine, there is a scarcity of methods for preparing 99mTc-labeled tetrazines. Herein we report the preparation of a family of tridentate-chelate-tetrazine derivatives and their Tc(I) complexes. These hitherto unknown compounds were radiolabeled with 99mTc using a microwave-assisted method in 31% to 83% radiochemical yield. The products are stable in saline and PBS and react rapidly with TCO derivatives in vitro. Their in vivo pre-targeting abilities were demonstrated using a TCO-bisphosphonate (TCO-BP) derivative that localizes to regions of active bone metabolism or injury. In murine studies, the 99mTc-tetrazines showed high activity concentrations in knees and shoulder joints, which was not observed when experiments were performed in the absence of TCO-BP. The overall uptake in non-target organs and pharmacokinetics varied greatly depending on the nature of the linker and polarity of the chelate.

Die Liganden wurden unter Verwendung von verschiedenen Linkern synthetisiert und Chelatoren über eine einfache reduktive Aminierung Strategie (Abbildung 2), gefolgt von Kupplung des Produktes mit einem handelsüblichen Tetrazin 22, 23. Die radioaktive Markierung wurde mit der gleichen Methode für alle Verbindungen durchgeführt und war in hohem Maße reproduzierbar. Das Verfahren wurde durch Variieren des pH, d...

Watch this Scientific Journal Video about Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry at JoVE.com

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

Here, we describe a protocol for radiolabeling and in vivo testing of tridentate 99mTc(I) chelate-tetrazine derivatives for pre-targeting and bioorthogonal chemistry.

Herstellung und Auswertung der<sup&gt; 99m</sup&gt; Tc-markierte Dreizähnige Chelate für Pre-Targeting Bioorthogonale Chemie

Pre-targeting combined with bioorthogonal chemistry is emerging as an effective way to create new radiopharmaceuticals. Of the methods available, the ...

preparation-evaluation-99mtc-labeled-tridentate-chelates-for-pre

Universidad San Sebastian

Research

JoVE Journal

Chemistry

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

8.1K Aufrufe.  McMaster University. Here, we describe a protocol for radiolabeling and in vivo testing of tridentate 99mTc(I) chelate-tetrazine derivatives for pre-targeting and bioorthogonal chemistry. 

Serie: Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

Microfluidic On-chip Capture-cycloaddition Reaction to Reversibly Immobilize Small Molecules or Multi-component Structures for Biosensor Applications

Methods for rapid surface immobilization of bioactive small molecules with control over orientation and immobilization density are highly desirable for biosensor and microarray applications. In this Study, we use a highly efficient covalent bioorthogonal [4+2] cycloaddition reaction between trans-cyclooctene (TCO) and 1,2,4,5-tetrazine (Tz) to enable the microfluidic immobilization of TCO/Tz-derivatized molecules. We monitor the process in real-time under continuous flow conditions using surface plasmon resonance (SPR). To enable reversible immobilization and extend the experimental range of the sensor surface, we combine a non-covalent antigen-antibody capture component with the cycloaddition reaction. By alternately presenting TCO or Tz moieties to the sensor surface, multiple capture-cycloaddition processes are now possible on one sensor surface for on-chip assembly and interaction studies of a variety of multi-component structures. We illustrate this method with two different immobilization experiments on a biosensor chip; a small molecule, AP1497 that binds FK506-binding protein 12 (FKBP12); and the same small molecule as part of an immobilized and in situ-functionalized nanoparticle.

We present a method for rapid, reversible immobilization of small molecules and functionalized nanoparticle assemblies for Surface Plasmon Resonance (SPR) studies, using sequential on-chip bioorthogonal cycloaddition chemistry and antibody-antigen capture.

Mikrofluidik-On-Chip-Capture-Cycloaddition reversibel Unbeweglichkeitseffekt kleine Moleküle oder Mehrkomponenten-Strukturen für Biosensor-Anwendungen

Methods  for rapid surface immobilization of bioactive small molecules with control over  orientation and immobilization density are highly desirable for ...

Forschung

Chemie

The Bioconjugation and Radiosynthesis of 89Zr-DFO-labeled Antibodies

The exceptional affinity, specificity, and selectivity of antibodies make them extraordinarily attractive vectors for tumor-targeted PET radiopharmaceuticals. Due to their multi-day biological half-life, antibodies must be labeled with positron-emitting radionuclides with relatively long physical decay half-lives. Traditionally, the positron-emitting isotopes 124I (t1/2 = 4.18 d), 86Y (t1/2 = 14.7 hr), and 64Cu (t1/2 = 12.7 hr) have been used to label antibodies for PET imaging. More recently, however, the field has witnessed a dramatic increase in the use of the positron-emitting radiometal 89Zr in antibody-based PET imaging agents. 89Zr is a nearly ideal radioisotope for PET imaging with immunoconjugates, as it possesses a physical half-life (t1/2 = 78.4 hr) that is compatible with the in vivo pharmacokinetics of antibodies and emits a relatively low energy positron that produces high resolution images. Furthermore, antibodies can be straightforwardly labeled with 89Zr using the siderophore-derived chelator desferrioxamine (DFO). In this protocol, the prostate-specific membrane antigen targeting antibody J591 will be used as a model system to illustrate (1) the bioconjugation of the bifunctional chelator DFO-isothiocyanate to an antibody, (2) the radiosynthesis and purification of a 89Zr-DFO-mAb radioimmunoconjugate, and (3) in vivo PET imaging with an 89Zr-DFO-mAb radioimmunoconjugate in a murine model of cancer.

The Bioconjugation and Radiosynthesis of 89Zr-DFO-labeled Antibodies

Due to its multi-day radioactive half-life and favorable decay properties, the positron-emitting radiometal 89Zr is extremely well-suited for use in antibody-based radiopharmaceuticals for PET imaging. In this protocol, the bioconjugation, radiosynthesis, and preclinical application of 89Zr-labeled antibodies will be described.

Die Biokonjugation und Radiosynthese<sup&gt; 89</sup&gt; Zr-DFO-markiertem Antikörper

The exceptional affinity, specificity, and selectivity of antibodies make them extraordinarily attractive vectors for tumor-targeted PET ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Ein optimiertes Protokoll für die effiziente radioaktive Markierung von Gold-Nanopartikeln durch eine Verwendung von<sup&gt; 125</sup&gt; I-markiertem Azide prosthetische Gruppe

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

Harnessing the Bioorthogonal Inverse Electron Demand Diels-Alder Cycloaddition for Pretargeted PET Imaging

Due to their exquisite affinity and specificity, antibodies have become extremely promising vectors for the delivery of radioisotopes to cancer cells for PET imaging. However, the necessity of labeling antibodies with radionuclides with long physical half-lives often results in high background radiation dose rates to non-target tissues. In order to circumvent this issue, we have employed a pretargeted PET imaging strategy based on the inverse electron demand Diels-Alder cycloaddition reaction. The methodology decouples the antibody from the radioactivity and thus exploits the positive characteristics of antibodies, while eschewing their pharmacokinetic drawbacks. The system is composed of four steps: (1) the injection of a mAb-trans-cyclooctene (TCO) conjugate; (2) a localization time period during which the antibody accumulates in the tumor and clears from the blood; (3) the injection of the radiolabeled tetrazine; and (4) the in vivo click ligation of the components followed by the clearance of excess radioligand. In the example presented in the work at hand, a 64Cu-NOTA-labeled tetrazine radioligand and a trans-cyclooctene-conjugated humanized antibody (huA33) were successfully used to delineate SW1222 colorectal cancer tumors with high tumor-to-background contrast. Further, the pretargeting methodology produces high quality images at only a fraction of the radiation dose to non-target tissue created by radioimmunoconjugates directly labeled with 64Cu or 89Zr. Ultimately, the modularity of this protocol is one of its greatest assets, as the trans-cyclooctene moiety can be appended to any non-internalizing antibody, and the tetrazine can be attached to a wide variety of radioisotopes.

The bioorthogonal inverse electron demand Diels-Alder cycloaddition has been harnessed to create an effective and modular pretargeted PET imaging strategy for cancer. In this protocol, the steps of this methodology are described in the context of a model system employing the colorectal cancer targeted antibody huA33 and a 64Cu-labeled radioligand.

Die Nutzung der Bioorthogonale inversem Elektronenbedarf Diels-Alder-Cycloaddition für Pretargeted PET Imaging

Due to their exquisite affinity and specificity, antibodies have become extremely promising vectors for the delivery of radioisotopes to cancer cells for ...

Biotechnik

MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent

Tumor extracellular matrix has abundance of cancer related proteins that can be used as biomarkers for cancer molecular imaging. In this work, we demonstrated effective MR cancer molecular imaging with a small molecular peptide targeted Gd-DOTA monoamide complex as a targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma. We performed the experiment of evaluating the effectiveness of the agent for non-invasive detection of prostate tumor with MRI in a mouse orthotopic PC-3 prostate cancer model. The targeted contrast agent was effective to produce significant tumor contrast enhancement at a low dose of 0.03 mmol Gd/kg. The peptide targeted MRI contrast agent is promising for MR molecular imaging of prostate tumor.

To demonstrate MR cancer molecular imaging with a small peptide targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma in a mouse prostate cancer model.

MR Molekulare Bildgebung von Prostatakrebs mit einem kleinen Molecular Targeted CLT1 Peptid-Kontrastmittel

Tumor extracellular  matrix has abundance of cancer related proteins that can be used as biomarkers  for cancer molecular imaging. In this work,  we ...

Medizin

Pretargeted Radioimmunotherapy Based on the Inverse Electron Demand Diels-Alder Reaction

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can result in high radiation doses to healthy tissues. Perhaps not surprisingly, several different strategies have been developed to circumvent this troubling limitation. One of the most promising of these approaches is pretargeted radioimmunotherapy (PRIT). PRIT is predicated on decoupling the radionuclide from the immunoglobulin, injecting them separately, and then allowing them to combine in vivo at the target tissue. This approach harnesses the exceptional tumor-targeting properties of antibodies while skirting their pharmacokinetic drawbacks, thereby lowering radiation doses to non-target tissues and facilitating the use of radionuclides with half-lives that are considered too short for use in traditional radioimmunoconjugates. Over the last five years, our laboratory and others have developed an approach to in vivo pretargeting based on the inverse electron-demand Diels-Alder (IEDDA) reaction between trans-cyclooctene (TCO) and tetrazine (Tz). This strategy has been successfully applied to pretargeted positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a variety of antibody-antigen systems. In a pair of recent publications, we have demonstrated the efficacy of IEDDA-based PRIT in murine models of pancreatic ductal adenocarcinoma and colorectal carcinoma. In this protocol, we describe protocols for PRIT using a 177Lu-DOTA-labeled tetrazine radioligand ([177Lu]Lu-DOTA-PEG7-Tz) and a TCO-modified variant of the colorectal cancer targeting huA33 antibody (huA33-TCO). More specifically, we will describe the construction of huA33-TCO, the synthesis and radiolabeling of [177Lu]Lu-DOTA-PEG7-Tz, and the performance of in vivo biodistribution and longitudinal therapy studies in murine models of colorectal carcinoma.

This protocol describes the synthesis and characterization of a trans-cyclooctene (TCO)-modified antibody and a 177Lu-labeled tetrazine (Tz) radioligand for pretargeted radioimmunotherapy (PRIT). In addition, it details the use of these two constructs for in vivo biodistribution and longitudinal therapy studies in a murine model of colorectal cancer.

Pretargeted Radioimmuntherapie basierend auf die Inverse Elektron Nachfrage Diels-Alder-Reaktion

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can ...

Synthesis and Bioconjugation of Thiol-Reactive Reagents for the Creation of Site-Selectively Modified Immunoconjugates

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. Yet maleimide-based conjugates display limited stability in vivo because the succinimidyl thioether linkage can undergo a retro-Michael reaction. This, of course, can lead to the release of the radioactive payload or its exchange with thiol-bearing biomolecules in circulation. Both of these processes can produce elevated activity concentrations in healthy organs as well as decreased activity concentrations in target tissues, resulting in reduced imaging contrast and lower therapeutic ratios. In 2018, we reported the creation of a modular, stable, and easily accessible phenyloxadiazolyl methyl sulfone reagent &#8212; dubbed &#8216;PODS&#8217; &#8212; as a platform for thiol-based bioconjugations. We have clearly demonstrated that PODS-based site-selective bioconjugations reproducibly and robustly create homogenous, well-defined, highly immunoreactive, and highly stable radioimmunoconjugates. Furthermore, preclinical experiments in murine models of colorectal cancer have shown that these site-selectively labeled radioimmunoconjugates exhibit far superior in vivo performance compared to radiolabeled antibodies synthesized via maleimide-based conjugations. In this protocol, we will describe the four-step synthesis of PODS, the creation of a bifunctional PODS-bearing variant of the ubiquitous chelator DOTA (PODS-DOTA), and the conjugation of PODS-DOTA to the HER2-targeting antibody trastuzumab.

In this protocol, we will describe the synthesis of PODS, a phenyoxadiazolyl methyl sulfone-based reagent for the site-selective attachment of cargos to the thiols of biomolecules, particularly antibodies. In addition, we will describe the synthesis and characterization of a PODS-bearing bifunctional chelator and its conjugation to a model antibody.

Synthese und Biokonjugaten der Thiol-reaktive Reagenzien für die Erstellung der Website selektiv geändert Immunokonjugate

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. ...

Positron Emission Tomography Imaging of Cell Trafficking: A Method of Cell Radiolabeling

Stem cell and chimeric antigen receptor (CAR) T-cell therapies are emerging as promising therapeutics for organ regeneration and as immunotherapy for various cancers. Despite significant progress having been made in these areas, there is still more to be learned to better understand the pharmacokinetics and pharmacodynamics of the administered therapeutic cells in the living system. For noninvasive, in vivo tracking of cells with positron emission tomography (PET), a novel [89Zr]Zr-p-isothiocyanatobenzyl-desferrioxamine ([89Zr]Zr-DBN)-mediated cell radiolabeling method has been developed utilizing 89Zr (t1/2 78.4 h). The present protocol describes a [89Zr]Zr-DBN-mediated, ready-to-use, radiolabeling synthon for direct radiolabeling of variety of cells, including mesenchymal stem cells, lineage-guided cardiopoietic stem cells, liver regenerating hepatocytes, white blood cells, melanoma cells, and dendritic cells. The developed methodology enables noninvasive PET imaging of cell trafficking for up to 7 days post-administration without affecting the nature or the function of the radiolabeled cells. Additionally, this protocol describes a stepwise method for the radiosynthesis of [89Zr]Zr-DBN, biocompatible formulation of [89Zr]Zr-DBN, preparation of cells for radiolabeling, and finally the radiolabeling of cells with [89Zr]Zr-DBN, including all the intricate details needed for the successful radiolabeling of cells.

Presented here is a protocol to radiolabel cells with a positron emission tomography (PET) radioisotope, 89Zr (t1/2 78.4 h), using a ready-to-use radiolabeling synthon, [89Zr]Zr-p-isothiocyanatobenzyl-desferrioxamine ([89Zr]Zr-DBN). Radiolabeling cells with [89Zr]Zr-DBN allows noninvasive tracking and imaging of administered radiolabeled cells in the body with PET for up to 7 days post-administration.

Positronen-Emissions-Tomographie-Bildgebung des Zelltransports: Eine Methode der radioaktiven Markierung von Zellen

Stem cell and chimeric antigen receptor (CAR) T-cell therapies are emerging as promising therapeutics for organ regeneration and as immunotherapy for ...

Krebsforschung

Initial Evaluation of Antibody-conjugates Modified with Viral-derived Peptides for Increasing Cellular Accumulation and Improving Tumor Targeting

Antibody-conjugates (ACs) modified with virus-derived peptides are a potentially powerful class of tumor cell delivery agents for molecular payloads used in cancer treatment and imaging due to increased cellular accumulation over current ACs. During early AC in vitro development, fluorescence techniques and radioimmunoassays are sufficient for determining intracellular localization, accumulation efficiency, and target cell specificity. Currently, there is no consensus on standardized methods for preparing cells for evaluating AC intracellular accumulation and localization. The initial testing of ACs modified with virus-derived peptides is critical especially if several candidates have been constructed. Determining intracellular accumulation by fluorescence can be affected by background signal from ACs at the cell surface and complicate the interpretation of accumulation. For radioimmunoassays, typically treated cells are fractionated and the radioactivity in different cell compartments measured. However, cell lysis varies from cell to cell and often nuclear and cytoplasmic compartments are not adequately isolated. This can produce misleading data on payload delivery properties. The intravenous injection of radiolabeled virus-derived peptide-modified ACs in tumor bearing mice followed by radionuclide imaging is a powerful method for determining tumor targeting and payload delivery properties at the in vivo phase of development. However, this is a relatively recent advancement and few groups have evaluated virus-derived peptide-modified ACs in this manner. We describe the processing of treated cells to more accurately evaluate virus-derived peptide-modified AC accumulation when using confocal microscopy and radioimmunoassays. Specifically, a method for trypsinizing cells to remove cell surface bound ACs. We also provide a method for improving cellular fractionation. Lastly, this protocol provides an in vivo method using positron emission tomography (PET) for evaluating initial tumor targeting properties in tumor-bearing mice. We use the radioisotope 64Cu (t1/2 = 12.7 h) as an example payload in this protocol.

Viral-derived peptides coupled to antibody-conjugates (ACs) is an approach gaining momentum due to the potential of delivering molecular payloads with increased tumor cell accumulation. Utilizing common methods to evaluate peptide conjugation, AC and payload intracellular accumulation, and tumor targeting, this protocol helps researchers during the key initial development phases.

Erstbewertung der Antikörper-Konjugate mit Viral-abgeleitete Peptide zur Erhöhung der zellulären Akkumulation und Verbesserung der Tumor gezielt modifiziert

Antibody-conjugates (ACs) modified with virus-derived peptides are a potentially powerful class of tumor cell delivery agents for molecular payloads used ...

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo Cell Trafficking by PET/CT

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte cell culture and 64Cu-antibody receptor targeting of the cells. In vitro evaluation of the radiolabel and non-invasive in vivo cell tracking in an animal model of an airway delayed-type hypersensitivity reaction (DTHR) by PET/CT are described.
In detail, the conjugation of a mAb with the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is shown. Following the production of radioactive 64Cu, radiolabeling of the DOTA-conjugated mAb is described. Next, the expansion of chicken ovalbumin (cOVA)-specific CD4+ interferon (IFN)-&#947;-producing T helper cells (cOVA-TH1) and the subsequent radiolabeling of the cOVA-TH1 cells are depicted. Various in vitro techniques are presented to evaluate the effects of 64Cu-radiolabeling on the cells, such as the determination of cell viability by trypan blue exclusion, the staining for apoptosis with Annexin V for flow cytometry, and the assessment of functionality by IFN-&#947; enzyme-linked immunosorbent assay (ELISA). Furthermore, the determination of the radioactive uptake into the cells and the labeling stability are described in detail. This protocol further describes how to perform cell tracking studies in an animal model for an airway DTHR and, therefore, the induction of cOVA-induced acute airway DHTR in BALB/c mice is included. Finally, a robust PET/CT workflow including image acquisition, reconstruction, and analysis is presented.
The 64Cu-antibody receptor targeting approach with subsequent receptor internalization provides high specificity and stability, reduced cellular toxicity, and low efflux rates compared to common PET-tracers for cell labeling, e.g.64Cu-pyruvaldehyde bis(N4-methylthiosemicarbazone) (64Cu-PTSM). Finally, our approach enables non-invasive in vivo cell tracking by PET/CT with an optimal signal-to-background ratio for 48 h. This experimental approach can be transferred to different animal models and cell types with membrane-bound receptors that are internalized.

Murine Lymphocyte Labeling by 64Cu-Antibody Receptor Targeting for In Vivo  Cell Trafficking by PET/CT

Following the preparation of a 64Cu-modified monoclonal antibody binding to a transgenic murine T cell receptor, T cells are radiolabeled in vivo, analyzed for viability, functionality, labeling stability and apoptosis, and adoptively transferred into mice with an airway delayed-type hypersensitivity reaction for non-invasive imaging by positron emission tomography/computed tomography (PET/CT).

Murine Lymphocyte Kennzeichnung von<sup&gt; 64</sup&gt; Cu-Antikörper-Rezeptor-Targeting für<em&gt; In Vivo</em&gt; Zellhandel von PET / CT

This protocol illustrates the production of 64Cu and the chelator conjugation/radiolabeling of a monoclonal antibody (mAb) followed by murine lymphocyte ...

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