title: ICAM-1 recycling in endothelial cells: a novel pathway for sustained intracellular delivery and prolonged effects of drugs.
abstract: Intercellular adhesion molecule-1 (ICAM-1) is a target for drug delivery to endothelial cells (ECs), which internalize multivalent anti-ICAM nanocarriers (anti-ICAM/NCs) within 15 to 30 minutes. The concomitant ICAM-1 disappearance from the EC surface transiently inhibited subsequent binding and uptake of anti-ICAM/NCs. Within 1 hour, internalized ICAM-1 diverged from anti-ICAM/NCs into prelysosomal vesicles, resurfaced, and enabled uptake of a subsequent anti-ICAM/NC dose. Thus, internalized ICAM-1 was able to recycle back to the plasma membrane. In vivo pulmonary targeting of a second anti-ICAM/NC dose injected 15 minutes after the first dose was decreased by 50% but recovered between 30 minutes and 2.5 hours, comparable to cultured ECs. Anti-ICAM/NCs affected neither EC viability nor fluid-phase endocytosis and traffic to lysosomes. However, lysosomal trafficking of the second dose of anti-ICAM/NCs was decelerated at least 2-fold versus the first dose; hence the major fraction of anti-ICAM/NCs resided in prelysosomal vesicles for at least 5 hours without degradation. Two successive doses of anti-ICAM/NC/catalase protected ECs against H2O2 for at least 8 hours versus 2 hours afforded by a single dose, suggesting that recurrent targeting to ICAM-1 affords longer effects. ICAM-1 recycling and inhibited lysosomal traffic/degradation of subsequent doses may help to prolong activity of therapeutic agents delivered into ECs by anti-ICAM/NCs.
authors.affiliation: Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6068, USA. silvia@mail.med.upenn.edu
authors.forename: Silvia
authors.initials: S
authors.lastname: Muro
authors.forename: Christine
authors.initials: C
authors.lastname: Gajewski
authors.forename: Michael
authors.initials: M
authors.lastname: Koval
authors.forename: Vladimir R
authors.initials: VR
authors.lastname: Muzykantov
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D016503:Drug Delivery Systems / Q000379:methods*; D004705:Endocytosis; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008863:Microspheres; D018384:Oxidative Stress; D021381:Protein Transport; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D007457:Iodine Radioisotopes; D018799:Intercellular Adhesion Molecule-1; D002374:Catalase