Cyclodextrins (CDs) can be envisaged to cure some diseases related to the brain, but the behavior of these compounds toward the blood-brain barrier (BBB) remains largely unexplored to envisage such clinical applications. To fulfill this gap, the toxicity and endothelial permeability for native, methylated, and hydroxypropylated ␣-, ␤-, and ␥-CDs have been studied on an in vitro model of BBB. As shown by the endothelial permeability for sucrose and immunofluorescence stainings, the native CDs are the most toxic CDs (␣-Ͼ ␤-Ͼ ␥-CD). Whereas the chemical modification of ␤-CD did not affect the toxicity of this CD, differences are observed for the ␣-and ␥-CD. To determine the origin of toxicity, lipid effluxes on the brain capillary endothelial cells were performed in the presence of native CDs. It was found that ␣-CD removed phospholipids and that ␤-CD extracted phospholipids and cholesterol. ␥-CD was less lipidselective than the other CDs. Finally, the endothelial permeability of each CD has been determined. Surprisingly, no structure/ permeability relationship has been observed according to the nature and chemical modifications of CDs.Cyclodextrins (CDs) are cyclic oligosaccharides composed of 6, 7, or 8 glucose units named ␣-, ␤-, or ␥-cyclodextrin, respectively. These compounds are widely used in the pharmaceutical field to improve the dissolution rate,

Association between doxorubicin (DOX) and ␥-cyclodextrin (␥-CD) or hydroxypropyl-␥-CD (HP-␥-CD) has been examined to increase the delivery of this antitumoral agent to the brain. The stoichiometry and the stability constant of ␥-CD or HP-␥-CD and DOX complexes were determined in physiological medium by UV-visible spectroscopy. By using an in vitro model of the blood-brain barrier (BBB), endothelial permeability and toxicity toward the brain capillary endothelial cells of DOX, ␥-CD, and HP-␥-CD were performed. For each CD, endothelial permeability was relatively low and a disruption of the BBB occurred at 20 M, 20 mM, and 50 mM DOX, ␥-CD, and HP-␥-CD, respectively. Increasing amounts of CDs were added to a fixed DOX concentration. Addition of ␥-CD or HP-␥-CD, up to 15 and 35 mM, respectively, decreased the DOX delivery, probably due to the low complex penetration across the BBB and the decrease in free DOX concentration. Higher CD concentrations increased the DOX delivery to the brain, but this effect is due to a loss of BBB integrity. In contrast to what was observed on Caco-2 cell model with various drugs, CDs are not able to increase the delivery of DOX across our in vitro model of BBB.

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