title: Macrophage depletion induced by clodronate-loaded erythrocytes.
abstract: Given the important role of macrophages in various disorders, the transient and organ specific suppression of their functions may benefit some patients. Until now, liposome-encapsulated bisphosphonate clodronate has been extensively proposed to this end. In this paper, we demonstrate that erythrocytes loaded with clodronate can also be effective in macrophage depletion. Here, clodronate was encapsulated in erythrocytes through hypotonic dialysis, isotonic resealing and reannealing to final concentrations of 4.1 +/- 0.4 and 10.1 +/- 0.8 micromol/ml of human and murine erythrocytes, respectively. The ability of clodronate-loaded erythrocytes to deplete macrophages was evaluated both in vitro and in vivo. In vitro studies on human macrophages showed that a single administration of engineered erythrocytes was able to reduce cell adherence capacity in a time-dependent manner, reaching 50 +/- 4% reduction, 13 days post treatment. The administration of loaded erythrocytes to cultures of murine peritoneal macrophages was able to reduce macrophage adhesion 67 +/- 3%, 48 h post treatment. In vivo, the ability of clodronate-loaded erythrocytes to deplete macrophages was evaluated both in Swiss and C57BL/6 mice. Swiss mice received 125 microg of clodronate through erythrocytes and 6 days post treatment 69 +/- 7% reduction in the number of adherent peritoneal macrophages and 75 +/- 5% reduction in number of spleen macrophages were observed. C57BL/6 mice received 220 microg clodronate by RBC and 3 and 8 days post treatment 65 +/- 7% reduction in the number of spleen macrophages and the complete depletion of liver macrophages were obtained. In summary, our results indicate that clodronate selectively targeted to the phagocytic cells by a single administration of engineered erythrocytes is able to deplete macrophages, even if not completely. The transient suppression of macrophage functions through clodronate-loaded erythrocytes can be used in many biomedical phenomena and research applications.
authors.affiliation: Institute of Biochemistry G. Fornaini, University of Urbino, 61029 Urbino (PU), Italy.
authors.forename: Luigia
authors.initials: L
authors.lastname: Rossi
authors.forename: Sonja
authors.initials: S
authors.lastname: Serafini
authors.forename: Antonella
authors.initials: A
authors.lastname: Antonelli
authors.forename: Francesca
authors.initials: F
authors.lastname: Pierigé
authors.forename: Andrea
authors.initials: A
authors.lastname: Carnevali
authors.forename: Valeria
authors.initials: V
authors.lastname: Battistelli
authors.forename: Manuela
authors.initials: M
authors.lastname: Malatesta
authors.forename: Emanuela
authors.initials: E
authors.lastname: Balestra
authors.forename: Raffaele
authors.initials: R
authors.lastname: Caliò
authors.forename: Carlo-Federico
authors.initials: CF
authors.lastname: Perno
authors.forename: Mauro
authors.initials: M
authors.lastname: Magnani
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D004002:Clodronic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D004337:Drug Carriers / Q000737:chemistry; D004355:Drug Stability; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007274:Injections, Intraperitoneal; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000187:drug effects / Q000276:immunology
chemical_list: D004337:Drug Carriers; D004002:Clodronic Acid