Permeation of PEO-PBLA-FITC polymeric micelles in aortic endothelial cells

Purpose. To determine aortic endothelial cells permeation ability and mechanisms of the aqueous block copolymeric micelles, poly(ethylene oxide)- poly (β-benzyl L-aspartate) (PEO-PBLA) chemically conjugated with fluorescein isothiocyanate (FITC) by transport study and confocal laser scanning microscopy. Methods. The block copolymers' PEO-PBLA-FITC was first synthesized and characterized by gel permeation chromatography (GPC) reflect index, UV, fluorescence detectors, and critical micelles concentrations (CMC), and atomic force microscopy (AFM). Permeation ability and mechanisms of polymeric micelles in aortic endothelial cells were evaluated by incubating with NaF, NaN₃, wortmannin, cytochalasin B inhibitors, at 20°C, and under reverse conditions. FITC and latex particles (40 nm) were also used for comparison of transport ability. The extent of localization of uptake polymeric micelles was established by confocal laser scanning microscopy. Results. The size of the aqueous PEO-PBLA-FITC polymeric micelles was detected at around 56 nm with unimodal distribution by AFM. The CMC test revealed the fluorescence intensity increased to around 0.01 ~ 0.05 mg/ml. NaF, NAN₃, wortmannin, cytochalasin B, 20°C, and reverse experiments inhibited the absorption of polymeric micelles through aortic endothelial cells with apparent permeability coefficients (P) of 18.07 ± 1.03 to 12.98 ± 0.93, 11.31 ± 0.77, 12.44 ± 1.23, 6.40 ± 0.23, 11.11 ± 0.46, and 10.22 ± 1.09 x 10^-7 cm/sec, respectively. Also, the permeation of FITC and latex on aortic endothelial cells was 70.02 ± 4,71, and 2.05 ± 0.41 x 10^-7 cm/sec, respectively. Confocal laser microscopy showed that fluorescent compounds were distributed in the intracellular cytoplasm and nucleus. Conclusions. PEO-PBLA-FITC copolymeric micelles in an aqueous system were transported by energy-dependent endocytosis with 18.07 x 10^-7 cm/sec penetrated range and were localized on intracellular and nucleus endothelial cells.