title: Evaluation of68Ga-labeled peptide tracer for detection of gelatinase expression after myocardial infarction in rat.
abstract: Matrix metalloproteinases 2 and 9 (MMP-2/9) play a role in extracellular matrix remodeling after an ischemic myocardial injury. We evaluated68Ga-DOTA-peptide targeting MMP-2/9 for the detection of gelatinase expression after myocardial infarction (MI) in rat.
  
  
  
  Rats were injected with 43 ± 7.7 MBq of68Ga-DOTA-peptide targeting MMP-2/9 at 7 days (n = 7) or 4 weeks (n = 8) after permanent coronary ligation or sham operation (n = 5 at both time points) followed by positron emission tomography (PET). The left ventricle was cut in frozen sections for autoradiography and immunohistochemistry 30 minutes after tracer injection.
  
  
  
  Immunohistochemical staining showed MMP-2 and MMP-9 expressing cells, CD31-positive endothelial cells, and CD68-positive macrophages in the infarcted myocardium. Autoradiography showed increased tracer uptake in the infarcted area both at 7 days and 4 weeks after MI (MI-to-remote area ratio 2.5 ± 0.46 and 3.1 ± 1.0, respectively). Tracer uptake in damaged tissue correlated with the amount of CD68-positive macrophages at 7 days after MI, and CD31-positive endothelial cells at 7 days and 4 weeks after MI. The tracer was rapidly metabolized, radioactivity in the blood exceeded that of the myocardium, and tracer accumulation in the heart was not detectable by in vivo PET.
  
  
  
  68Ga-DOTA-peptide targeting MMP-2/9 accumulates in the damaged rat myocardium after an ischemic injury, but tracer instability and slow clearance in vivo make it unsuitable for further evaluation.
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.
authors.forename: Max
authors.initials: M
authors.lastname: Kiugel
authors.affiliation: Heart Center, Turku University Hospital, Turku, Finland.|Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Kytö
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Saanijoki
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.|Turku Center for Disease Modeling, University of Turku, Turku, Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Liljenbäck
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Metsälä
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.
authors.forename: Mia
authors.initials: M
authors.lastname: Ståhle
authors.affiliation: Department of Cell Biology and Anatomy, University of Turku, Turku, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Tuomela
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.|Turku PET Centre, Åbo Akademi University, Turku, Finland.
authors.forename: Xiang-Guo
authors.initials: XG
authors.lastname: Li
authors.affiliation: Department of Pathology and Forensic Medicine, University of Turku, Turku, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Saukko
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.|Turku PET Centre, Turku University Hospital, Turku, Finland.
authors.forename: Juhani
authors.initials: J
authors.lastname: Knuuti
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland.|Turku Center for Disease Modeling, University of Turku, Turku, Finland.|Turku PET Centre, Turku University Hospital, Turku, Finland.
authors.forename: Anne
authors.initials: A
authors.lastname: Roivainen
authors.affiliation: Turku PET Centre, University of Turku, 20521, Turku, Finland. antti.saraste@utu.fi.|Heart Center, Turku University Hospital, Turku, Finland. antti.saraste@utu.fi.|Institute of Clinical Medicine, University of Turku, Turku, Finland. antti.saraste@utu.fi.
authors.forename: Antti
authors.initials: A
authors.lastname: Saraste
mesh_terms: D000818:Animals; D001345:Autoradiography; D005710:Gallium Radioisotopes; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000032:analysis*; D020780:Matrix Metalloproteinase 9 / Q000032:analysis*; D009203:Myocardial Infarction / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D049268:Positron-Emission Tomography; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005710:Gallium Radioisotopes; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9
keywords: Matrix metalloproteinase; myocardial infarction; positron emission tomography