Nanoparticulate Transport of Oximes over an In Vitro Blood-Brain Barrier Model

Background: Due to the use of organophosphates (OP) as pesticides and the availability of OP-type nerve agents, an effective medical treatment for OP poisonings is still a challenging problem. The acute toxicity of an OP poisoning is mainly due to the inhibition of acetylcholinesterase (AChE) in the peripheral and central nervous systems (CNS). This results in an increase in the synaptic concentration of the neurotransmitter acetylcholine, overstimulation of cholinergic receptors and disorder of numerous body functions up to death. The standard treatment of OP poisoning includes a combination of a muscarinic antagonist and an AChE reactivator (oxime). However, these oximes can not cross the blood-brain barrier (BBB) sufficiently. Therefore, new strategies are needed to transport oximes over the BBB. Methodology/Principal Findings: In this study, we combined different oximes (obidoxime dichloride and two different HI 6 salts, HI 6 dichloride monohydrate and HI 6 dimethanesulfonate) with human serum albumin nanoparticles and could show an oxime transport over an in vitro BBB model. In general, the nanoparticulate transported oximes achieved a better reactivation of OP-inhibited AChE than free oximes. Conclusions/Significance: With these nanoparticles, for the first time, a tool exists that could enable a transport of oximes over the BBB. This is very important for survival after severe OP intoxication. Therefore, these nanoparticulate formulation

Transport study of adsorptively HI 6 dichloride monohydrate-loaded nanoparticles on an <i>in vitro</i> BBB model.

<p>Transport study of adsorptively HI 6 dichloride monohydrate-loaded nanoparticles on an <i>in vitro</i> BBB model.</p

Transport study of adsorptively obidoxime-loaded nanoparticles on an <i>in vitro</i> BBB model.

<p>Transport study of adsorptively obidoxime-loaded nanoparticles on an <i>in vitro</i> BBB model.</p

Long time measurement of transendothelial electrical resistance (TER) after nanoparticle addition.

<p>pBCEC were seeded on collagen IV-coated Transwell inserts and incubated with the free drug or 0.26 mg nanoparticles per cm² growth area of the ApoE-modified (NP-ApoE) as well as the PEGylated (NP-PEG) nanoparticulate formulations, which were loaded with 1000 µM of HI 6 dichloride monohydrate (HI 6-DCL) at 37°C by adding the nanoparticles into the upper/apical compartment of the Transwell system. The TER was measured automatically every hour by impedance measurement. A magnification of the area of interest is highlighted in the red quadrangle. As control the measurement of the TER of a Transwell insert without cells is shown.</p

Transport study of adsorptively HI 6 dimethanesulfonate-loaded nanoparticles on an <i>in vitro</i> BBB model.

<p>*Mann-Whitney U Test: significant difference between NP-ApoE and free HI 6-DMS (P<0.05).</p

Cellular uptake and intracellular distribution of the nanoparticles studied by CLSM.

<p>bEnd3 cells were cultured on collagen IV-coated glass slides and were treated with a) PEGylated HI 6 dichloride monohydrate-loaded nanoparticles or b) ApoE-modified HI 6 dichloride monohydrate-loaded nanoparticles for 4 h at 37°C. The green autofluorescence of the nanoparticles was used for detection. Red: cytosol stained with CellTracker™ Red CMTPX, blue: nucleus stained with DAPI. Pictures were taken within inner sections of the cells.</p

Measurement of transendothelial electrical resistance (TER) and the capacitance (C_cl).

<p>pBCEC were seeded on collagen IV-coated Transwell inserts, which were placed in the cellZscope. The transendothelial electrical resistance (TER) and the capacitance (C_cl) of the pBCEC were measured automatically every hour by impedance measurement. As control the measurement of the transendothelial electrical resistance (TER) of a Transwell insert without cells is shown.</p