title: Binding, transcytosis and biodistribution of anti-PECAM-1 iron oxide nanoparticles for brain-targeted delivery.
abstract: OBJECTIVE
  Characterize the flux of platelet-endothelial cell adhesion molecule (PECAM-1) antibody-coated superparamagnetic iron oxide nanoparticles (IONPs) across the blood-brain barrier (BBB) and its biodistribution in vitro and in vivo.
  
  
  METHODS
  Anti-PECAM-1 IONPs and IgG IONPs were prepared and characterized in house. The binding affinity of these nanoparticles was investigated using human cortical microvascular endothelial cells (hCMEC/D3). Flux assays were performed using a hCMEC/D3 BBB model. To test their immunospecificity index and biodistribution, nanoparticles were given to Sprague Dawley rats by intra-carotid infusion. The capillary depletion method was used to elucidate their distribution between the BBB and brain parenchyma.
  
  
  RESULTS
  Anti-PECAM-1 IONPs were ~130 nm. The extent of nanoparticle antibody surface coverage was 63.6 ± 8.4%. Only 6.39 ± 1.22% of labeled antibody dissociated from IONPs in heparin-treated whole blood over 4 h. The binding affinity of PECAM-1 antibody (KD) was 32 nM with a maximal binding (Bmax) of 17 × 10(5) antibody molecules/cell. Anti-PECAM-1 IONP flux across a hCMEC/D3 monolayer was significantly higher than IgG IONP's with 31% of anti-PECAM-1 IONPs in the receiving chamber after 6 h. Anti-PECAM-1 IONPs showed higher concentrations in lung and brain, but not liver or spleen, than IgG IONPs after infusion. The capillary depletion method showed that 17±12% of the anti-PECAM-1 IONPs crossed the BBB into the brain ten minutes after infusion.
  
  
  CONCLUSIONS
  PECAM-1 antibody coating significantly increased IONP flux across the hCMEC/D3 monolayer. In vivo results showed that the PECAM-1 antibody enhanced BBB association and brain parenchymal accumulation of IONPs compared to IgG. This research demonstrates the benefit of anti-PECAM-1 IONPs for association and flux across the BBB into the brain in relation to its biodistribution in peripheral organs. The results provide insight into potential application and toxicity concerns of anti-PECAM-1 IONPs in the central nervous system.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America ; Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Mo
authors.initials: M
authors.lastname: Dan
authors.forename: David B
authors.initials: DB
authors.lastname: Cochran
authors.forename: Robert A
authors.initials: RA
authors.lastname: Yokel
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Dziubla
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D042783:Endothelial Cells; D005290:Ferric Compounds / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008297:Male; D053768:Metal Nanoparticles / Q000737:chemistry; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D014018:Tissue Distribution; D057900:Transcytosis
chemical_list: D000911:Antibodies, Monoclonal; D005290:Ferric Compounds; D007074:Immunoglobulin G; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C000499:ferric oxide