PhPad Prism 4.0c for Macintosh (GraphPad Software program Inc.) for statistical evaluation. P value of 0.05 was deemed to be statistically significant.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptRESULTSAgent synthesis, pharmacokinetics and validation We first established a protocol that permitted us to image infarct healing by PET/MRI. MPOGd served as a targeted molecular MRI agent due to the fact inflammatory Ly-6Chigh monocytes express high amounts of MPO26 and dominate the MR imaging signal in infarcts 90 minutes after injection of MPO-Gd, at a time when traditional Gd-DTPA has washed out13. To image extracellular matrix cross-linking by PET, we created and validated a fluorine-18 version of a FXIII transglutaminase substrate peptide. To this end, we modified the lysine residue with the 2-antiplasmin13-24 substrate peptide27 using the amine-reactive tetrazine linker to give FXIII-Tz with a yield of 66 . The radiolabeled prosthetic group 18F-TCO was synthesized in 56 decay-corrected radiochemical yield. 18F-TCO ( 94 pure right after HPLC purification) and FXIII-Tz have been then combined in a `click’ reaction resulting in 18F-FXIII (Figure 1A). HPLC purification with the reaction mixture provided 2.eight 1.9 mCi of 18F-FXIII in 58 decay-corrected radiochemical yield and 95 radiochemical purity (Figure 1B). We injected 18F-FXIII into B6 mice to measure the agent’s blood-half life and biodistribution (n = five). 18F-FXIII had a blood half-life of 13.Cordycepin Technical Information 2 0.β-Endorphin, human Protocol 94 minutes (R2 = 0.95; Figure 1C). Biodistribution at 75 minutes immediately after injection was as follows (expressed as ID/ g): liver, two.83 0.22; kidney, 1.26 0.06; lymph node, 0.60 0.1; spleen, 0.49 0.05; blood, 0.49 0.03; tail, 0.41 0.03; skin, 0.31.05; bone, 0.31 0.03; heart, 0.23 0.03; intestines, 0.25 0.04; fat, 0.17 0.01; and muscle, 0.15 0.01 (Figure 1D). To assess the presence of 18F-FXIII in myocardial infarcts, we injected B6 mice with or devoid of MI with 18F-FXIII on day four after coronary ligation (n = 4-5 per group). Scintillation counting revealed that B6 mice with MI had substantially larger 18F-FXIII signal inside the heart when compared with handle mice (Figure 2A). Next, we assessed 18F-FXIII specificity by injecting 18F-FXIII into FXIII-/- mice with and without having MI. Signal intensity in hearts of FXIII-/- mice with MI was significantly decrease and comparable to non-infarcted wild-type B6 and FXIII-/- mice (p0.05, Figure 2A). In B6 mice, TTC staining correlated pale infarct places with enhanced 18F-FXIII signal on autoradiography (Figure 2B). PET/MRI on day 4 just after coronary ligation permitted assessment of transglutaminase activity by 18F-FXIII and infarct inflammation with MPO-Gd (Figure 2C-E).PMID:23849184 Monocytes aren’t a dominant source of infarct transglutaminase activity The active subunit A of FXIII is synthesized within the bone marrow and circulates in plasma bound towards the subunit B. Cellular FXIII lacks the B subunit and may be found in platelets and monocytes28. Transglutaminase activity inside the infarct is crucial for wound healing, as even heterozygous FXIII deficient mice rupture their left ventricles14. A single objective of our study was to cut down monocyte recruitment in apoE-/- mice in which blood monocytosis leads toCirculation. Author manuscript; offered in PMC 2013 May well 22.Majmudar et al.Pageexaggerated and prolonged monocyte recruitment and impaired wound healing7. We consequently wondered to what degree monocytes contribute to transglutaminase activity in infarcts. If they contributed substantially, curbing.