A novel fluorescently-labeled long-chain fatty acid analog for the study of fatty acid metabolism in cultured cells

Abstract 123 I-15-(p-iodophenyl)-( R,S )-methyl pentadecanoic acid (BMIPP) is a long-chain fatty acid (LCFA) analog developed to examine myocardial LCFA metabolism and has been used as a tracer for nuclear cardiology. However, its use is limited because of the specialized features of cardiac scintigraphy. In this study, a novel BMIPP-based probe was utilized, in which iodine-123 was replaced with a fluorescent compound, to extend the use of 123 I-BMIPP to a wider variety of cells ex vivo . To confirm that this fluorescent LCFA analog (fluorescent BMPP) was imported into cells, fluorescence-activated cell sorting (FACS) analysis and fluorescent cell imaging were performed using cultured cells. The analysis showed that the import of fluorescent BMPP into the cells occurred in a concentration-dependent manner. This import into cells was inhibited by Sulfosuccinimidyl Oleate in a dose-dependent manner, which is an inhibitor of CD36, a well-known LCFA transporter, suggesting that fluorescent BMPP could be imported into cells via the same pathway as LCFA. FACS and cell imaging intensities of the cells importing fluorescent BMPP were attenuated after incubation in the non-Alexa680-BMPP medium. These results suggest that fluorescent BMPP can be transported into and from cells, reflecting the metabolism of LCFA. Fluorescently-labeled BMPP has the potential to be used as a probe for studying LCFA metabolism in various cells.