title: Serial block-face scanning electron microscopy applied to study the trafficking of 8D3-coated gold nanoparticles at the blood-brain barrier.
abstract: Due to the physical and physiological properties of the blood-brain barrier (BBB), the transport of neurotherapeutics from blood to brain is still a pharmaceutical challenge. We previously conducted a series of experiments to explore the potential of the anti-transferrin receptor 8D3 monoclonal antibody (mAb) to transport neurotherapeutics across the BBB. In that study, gold nanoparticles (AuNPs) were coated with the 8D3 antibody and administered intravenously to mice. Transmission electron microscopy was used and a two-dimensional (2D) image analysis was performed to detect the AuNPs in the brain capillary endothelial cells (BCECs) and brain parenchyma. In the present work, we determined that serial block-face scanning electron microscopy (SBF-SEM) is a useful tool to study the transcytosis of these AuNPs across the BBB in three dimensions and we, therefore, applied it to gain more knowledge of their transcellular trafficking. The resulting 3D reconstructions provided additional information on the endocytic vesicles containing AuNPs and the endosomal processing that occurs inside BCECs. The passage from 2D to 3D analysis reinforced the trafficking model proposed in the 2D study, and revealed that the vesicles containing AuNPs are significantly larger and more complex than described in our 2D study. We also discuss tradeoffs of using this technique for our application, and conclude that together with other volume electron microscopy imaging techniques, SBF-SEM is a powerful approach that is worth of considering for studies of drug transport across the BBB.
authors.affiliation: Secció de Fisiologia, Departament de Bioquímica i Fisiologia, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Av. Joan XXIII 27-31, 08028, Barcelona, Spain.|Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.|Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Itsaso
authors.initials: I
authors.lastname: Cabezón
authors.affiliation: Secció de Fisiologia, Departament de Bioquímica i Fisiologia, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Av. Joan XXIII 27-31, 08028, Barcelona, Spain.|Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Augé
authors.affiliation: Unitat de Microscòpia Òptica Avançada, Centres Científics i Tecnològics de la Universitat de Barcelona (CCiTUB), Barcelona, Spain.
authors.forename: Manel
authors.initials: M
authors.lastname: Bosch
authors.affiliation: Division of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Beckett
authors.affiliation: Division of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Prior
authors.affiliation: Secció de Fisiologia, Departament de Bioquímica i Fisiologia, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Av. Joan XXIII 27-31, 08028, Barcelona, Spain.|Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.|CIBERNED Centros de Biomedicina en Red de Enfermedades Neurodegenerativas, Madrid, Spain.
authors.forename: Carme
authors.initials: C
authors.lastname: Pelegrí
authors.affiliation: Secció de Fisiologia, Departament de Bioquímica i Fisiologia, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Av. Joan XXIII 27-31, 08028, Barcelona, Spain. vilaplana@ub.edu.|Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain. vilaplana@ub.edu.|CIBERNED Centros de Biomedicina en Red de Enfermedades Neurodegenerativas, Madrid, Spain. vilaplana@ub.edu.
authors.forename: Jordi
authors.identifier: http://orcid.org/0000-0003-2113-238X
authors.initials: J
authors.lastname: Vilaplana
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics; D001812:Blood-Brain Barrier / Q000378:metabolism* / Q000648:ultrastructure*; D006046:Gold / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007275:Injections, Intravenous; D008297:Male; D053768:Metal Nanoparticles / Q000008:administration & dosage / Q000032:analysis*; D051379:Mice; D008813:Mice, Inbred ICR; D008855:Microscopy, Electron, Scanning
chemical_list: D000911:Antibodies, Monoclonal; D006046:Gold
keywords: 3D electron microscopy; Blood-brain barrier; Drug delivery; Monoclonal antibodies; Receptor-mediated transport; SBF-SEM; Transferrin receptor