Impact of arginine-modified solid lipid nanoparticles on the membrane charge of human brain-microvascular endothelial cells

Targeting nevirapine delivery across human brain microvascular endothelial cells using transferrin-grafted poly(lactide-co-glycolide) nanoparticles

Aims: Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) were grafted with transferrin (Tf) to enhance the transport of nevirapine (NVP) across human brain microvascular endothelial cells (HBMECs). Methods: NVP-loaded PLGA NPs with surface-grafting Tf (Tf/NVP–PLGA NPs) were incubated with HBMECs and immunochemical staining characterized Tf receptors (TfRs). Results: The polydispersity index of Tf/NVP–PLGA NPs was lower than 0.008. The entrapment efficiency of NVP and loading efficiency of Tf was 20–75% and 15–80%, respectively. Tf slightly retarded the release of NVP from PLGA. Dioctadecyldimethylammonium bromide (DODAB)-stabilized Tf/NVP–PLGA NPs reduced the viability of HBMECs to 70–75%. The secretion of TNF-α was inhibited by Tf and stimulated by DODAB. The permeability of NVP across HBMECs reached maxima at 67% DODAB and 0.1–0.2% Tf. An increase in the concentration of Tf enhanced the uptake of Tf/NVP–PLGA NPs via a TfR-mediated mechanism. Conclusion: Tf/NVP–PLGA NPs are efficacious carriers in targeting delivery across HBMECs for viral therapy.

Effect of human astrocytes on the characteristics of human brain-microvascular endothelial cells in the blood-brain barrier

A blood-brain barrier (BBB) model in vitro was established by cultivating human brain-microvascular endothelial cells (HBMECs) with the regulation of human astrocytes (HAs) (HBMEC/HA). Astrocyte-conditioned medium (ACM) was employed to constitute a confluent monolayer of HBMECs without directly conjugated HAs. HBMECs exhibited an orientated multiplication on the supporting membrane; while HAs grew in an overlapping fashion. In addition, HBMECs could propagate over the membrane pore, and the end-feet of HAs extended into the membrane pore to improve the integral feature of the BBB. HBMEC/HA demonstrated a high transendothelial electrical resistance (TEER) about 230 Ω cm² and low permeability of propidium iodide (PI) about 4 × 10⁻⁶ cm/s. The order in TEER was HBMEC/HA>HBMECs with 100% ACM>HBMECs with 50% ACM > HBMECs. The reverse order was valid for the permeability of PI and uptake of calcein-AM by HBMECs. The tranwell culture of HBMECs and HAs displays appropriate characteristics of the BBB and can be applied to estimate the delivery efficiency of therapeutic chemicals for the brain-related disease.

Capillary electrophoresis characterization of molecularly imprinted polymer particles in fast binding with 17β-estradiol

Molecularly imprinted polymer (MIP) submicron particles were synthesized, using either ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate as a cross-linker, specifically for recognition of 17β-estradiol (E2). HPLC with fluorescence detection (HPLC-FD) results showed that 90(±5)% of E2 bound onto these particles after 2 min of incubation, and 96(±3)% after long equilibrium. The binding capacity was 8(±3) μmol/g for MIP particles prepared using ethylene glycol dimethacrylate, and 33-43(±8) μmol/g for using trimethylolpropane trimethacrylate. CE separation of MIP and non-imprinted polymer particles was successful when 50 mM borate buffer (pH 8.5) containing 0.005% w/v EOTrol™ LN in reverse polarity (-30 kV) was used. The electrophoretic mobilities of MIP and non-imprinted polymer particles, together with dynamic light scattering measurement of particle sizes, allowed for an estimation of their surface charges. Automated injection of E2 and particles in mixture set a lower limit of 20(±1) s on incubation time for the study of fast binding kinetics. The presence of E2 and bisphenol A (BPA) together tested the selectivity of MIP particles, when the two compounds competed for available binding cavities or sites. Addition of E2 after BPA confirmed E2 occupation of the specific binding cavities, via displacement of BPA.

Capillary electrophoresis of bone marrow stromal cells with uptake of heparin-functionalized poly(lactide-co-glycolide) nanoparticles during differentiation towards neurons

This study analyzes the varying electrophoretic mobility and zeta potential of bone marrow stromal cells (BMSCs) during their differentiation towards neurons. Electrophoresis of primary BMSCs and neuron growth factor (NGF)-induced neuron-like cells with the uptake of heparin-functionalized poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) are also investigated. Immunofluorescent images revealed that a high concentration of NGF accelerated the differentiation of BMSCs into neurons. When the concentration of NGF increased, the absolute values of electrophoretic mobility and zeta potential of the differentiating BMSCs increased. In addition, a longer inductive period yielded higher charge of the differentiating BMSCs and a smaller uptake amount of heparin-functionalized PLGA NPs. However, an increase in the loading efficiency of heparin on PLGA NPs enhanced the uptake and reduced the electrical characteristics of the primary and differentiating BMSCs. Hence, a general rule is drawn that an increase in the uptake of heparin-functionalized PLGA NPs decreased the electrophoretic mobility and zeta potential of BMSCs during differentiation towards neurons.