Physiological function and inflamed-brain migration of mouse monocyte-derived macrophages following cellular uptake of superparamagnetic iron oxide nanoparticles—Implication of macrophage-based drug delivery into the central nervous system

This study was designed to use superparamagnetic iron oxide nanoparticles (SPIONs) as evaluating tools to study monocyte-derived macrophages (MDM)-mediated delivery of small molecular agents into the diseased brains. MDM were tested with different-configured SPIONs at selected concentrations for their impacts on carrier cells’ physiological and migratory properties, which were found to depend largely on particle size, coating, and treatment concentrations. SHP30, a SPION of 30-nm core size with oleic acids plus amphiphilic polymer coating, was identified to have high cellular uptake efficiency and cause little cytotoxic effects on MDM. At lower incubation dose (25 μg/mL), few alteration was observed in carrier cells’ physiological and in vivo migratory functions, as tested in a lipopolysaccharide-induced acute neuroinflammation mouse model. Nevertheless, significant increase in monocyte-to-macrophage differentiation, and decrease in in vivo carrier MDM inflamed-brain homing ability were found in groups treated with a higher dose of SHP30 at 100 μg/mL. Overall, our results have identified MDM treatment at 25 μg/mL SHP30 resulted in little functional changes, provided valuable parameters for using SPIONs as evaluating tools to study MDM-mediated therapeutics carriage and delivery, and supported the concepts of using monocytes-macrophages as cellular vehicles to transport small molecular agents to the brain.

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