title: The polyoxyethylene/polyoxypropylene block co-polymer poloxamer-407 selectively redirects intravenously injected microspheres to sinusoidal endothelial cells of rabbit bone marrow.
abstract: Small colloidal particulates (150 nm and below, in diameter) can be redirected specifically to the rabbit bone marrow following intravenous administration by coating their surface with the block co-polymer poloxamer-407, a non-ionic surfactant. The coated colloids are sequestered by the sinusoidal endothelial cells of the bone marrow and are accumulated in dense bodies within these cells. The uptake of poloxamer-407-coated colloids by marrow endothelial cells suggests that the steric repulsive barrier, imposed by the polyoxyethylene segment of the polymer, to particle-cell interaction can apparently be overcome by a specific interaction mechanism(s) with the cell surface. Such a dramatic uptake cannot be achieved with other block co-polymers of similar structure to poloxamer-407. The application of the current model for the site-specific targeting of drug carriers to bone marrow and the prevention of the adherence of metastases of tumours which selectively colonize the bone marrow endothelium is discussed.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nottingham, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Porter
authors.forename: S M
authors.initials: SM
authors.lastname: Moghimi
authors.forename: L
authors.initials: L
authors.lastname: Illum
authors.forename: S S
authors.initials: SS
authors.lastname: Davis
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000648:ultrastructure; D001854:Bone Marrow Cells; D004337:Drug Carriers; D004727:Endothelium / Q000166:cytology / Q000648:ultrastructure; D007275:Injections, Intravenous; D008854:Microscopy, Electron; D008863:Microspheres; D011060:Poloxalene / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D004337:Drug Carriers; D011060:Poloxalene