title: cNGR: a novel homing sequence for CD13/APN targeted molecular imaging of murine cardiac angiogenesis in vivo.
abstract: OBJECTIVE
  Previously, the peptide sequence cNGR has been shown to home specifically to CD13/APN (aminopeptidase N) on tumor endothelium. Here, we investigated the feasibility of selective imaging of cardiac angiogenesis using the cNGR-CD13/APN system.
  
  
  RESULTS
  CD13/APN induction and cNGR homing were studied in the murine myocardial infarction (MI) model. By real-time polymerase chain reaction (PCR) at 7 days after MI, CD13/APN expression was 10- to 20-fold higher in the angiogenic infarct border zone and the MI area than in non-MI areas. In vivo fluorescence microscopy confirmed specific homing of fluorophore-tagged cNGR to the border zone and MI territory at 4 and 7 days after MI with a local advantage of 2.3, but not at 1 or 14 days after MI. Tissue residence half-life was 9.1+/-0.3 hours, whereas the half-life in plasma was 15.4+/-3.4 minutes. Pulse chase experiments confirmed reversible binding of cNGR in the infarct area. Fluorescent labeled cNGR conjugates or antibodies were injected in vivo, and their distribution was studied ex vivo by 2-photon laser scanning microscopy (TPLSM). cNGR co-localized exclusively with CD13/APN and the endothelial marker CD31 on vessels.
  
  
  CONCLUSIONS
  In cardiac angiogenesis endothelial CD13/APN is upregulated. It can be targeted specifically with cNGR conjugates. In the heart cNGR binds its endothelial target only in angiogenic areas.
authors.affiliation: CARIM, University of Maastricht, Maastricht, The Netherlands. abuehler@prdbe.jnj.com
authors.forename: Alexandra
authors.initials: A
authors.lastname: Buehler
authors.forename: Marc A M J
authors.initials: MA
authors.lastname: van Zandvoort
authors.forename: Bram J
authors.initials: BJ
authors.lastname: Stelt
authors.forename: Tilman M
authors.initials: TM
authors.lastname: Hackeng
authors.forename: Bianca H G J
authors.initials: BH
authors.lastname: Schrans-Stassen
authors.forename: Abdelkader
authors.initials: A
authors.lastname: Bennaghmouch
authors.forename: Leo
authors.initials: L
authors.lastname: Hofstra
authors.forename: Jack P M
authors.initials: JP
authors.lastname: Cleutjens
authors.forename: Adriaan
authors.initials: A
authors.lastname: Duijvestijn
authors.forename: Mirjam B
authors.initials: MB
authors.lastname: Smeets
authors.forename: Dominique P V
authors.initials: DP
authors.lastname: de Kleijn
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Post
authors.forename: Ebo D
authors.initials: ED
authors.lastname: de Muinck
mesh_terms: D000818:Animals; D018826:CD13 Antigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods; D009203:Myocardial Infarction / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053758:Nanoparticles; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D021382:Protein Sorting Signals
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1; D021382:Protein Sorting Signals; D018826:CD13 Antigens