title: Sensitive angiogenesis imaging of orthotopic bladder tumors in mice using a selective magnetic resonance imaging contrast agent containing VEGF121/rGel.
abstract: OBJECTIVE
  To investigate the efficiency of magnetic resonance imaging (MRI) contrast agents employing vascular endothelial growth factor (VEGF121)/rGel conjugated MnFe2O4 nanocrystals for imaging of neovasculature using a bladder tumor model.
  
  
  METHODS
  VEGF121/rGel was conjugated to MnFe2O4 nanoparticles (MNPs). The targeting efficiency and detection capability of the VEGF121/rGel-MNPs were investigated in both KDR-deficient (253JB-V) and KDR-overexpressing (PAE/KDR) cells using MRI. The internalization of VEGF121/rGel-MNPs into cells was confirmed by electron microscopy. Their phosphorylation ability and cytotoxicity were compared with unconjugated VEGF121/rGel. The orthotopic tumor mice were established by implanting low KDR-expressing 253JB-V cells into the bladder dome. After tail-vein injection of VEGF121/rGel-MNPs, the MR signal enhancement of intratumoral vessels by VEGF121/rGel-MNPs was observed and inhibition test using VEGF121 was also conducted. Ex vivo MR imaging of tumor tissue, and a fluorescence immunostaining study was also performed.
  
  
  RESULTS
  The water-soluble VEGF121/rGel-MNPs (44.5 ± 1.2 nm) were stably suspended in the biologic media and exhibited a high relaxivity coefficient (423 mMs). They demonstrated sufficient targeting capability against KDR-overexpressing PAE/KDR cells, as confirmed by dose-dependent MR images and VEGF121 inhibition tests. The phosphorylation activity of KDR and cytotoxicity of VEGF121/rGel-MNPs were evaluated. VEGF121/rGel-MNPs successfully targeted the tumor and provided accurate anatomic details through (i) acquisition of clear neoangiogenic vascular distributions and (ii) obvious enhancement of the MR signal in T2*-weighted images. Immunostaining and blocking studies demonstrated the specific targeting ability of VEGF121/rGel-MNPs toward intratumoral angiogenesis.
  
  
  CONCLUSIONS
  Synthesized VEGF121/rGel-MNPs as targeted MR imaging contrast agents can be specifically delivered to tumors and bind to KDR-expressing angiogenic tumor vessels.
authors.affiliation: Department of Radiology, College of Medicine, Yonsei University, Seoul 120-752, Republic of Korea.
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Cho
authors.forename: Jaemoon
authors.initials: J
authors.lastname: Yang
authors.forename: Khalid A
authors.initials: KA
authors.lastname: Mohamedali
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Lim
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Kim
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Farhangfar
authors.forename: Jin-Suck
authors.initials: JS
authors.lastname: Suh
authors.forename: Seungjoo
authors.initials: S
authors.lastname: Haam
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rosenblum
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Huh
mesh_terms: D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D005290:Ferric Compounds; D008297:Male; D017895:Manganese Compounds; D051379:Mice; D008807:Mice, Inbred BALB C; D058726:Nanoconjugates; D009389:Neovascularization, Pathologic; D054789:Ribosome Inactivating Proteins, Type 1; D012680:Sensitivity and Specificity; D001749:Urinary Bladder Neoplasms / Q000098:blood supply* / Q000175:diagnosis*; D042461:Vascular Endothelial Growth Factor A
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D017895:Manganese Compounds; D058726:Nanoconjugates; D054789:Ribosome Inactivating Proteins, Type 1; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C551151:manganese ferrite; C025674:GEL protein, Gelonium multiflorum