Lactose-appended β-cyclodextrin as an effective nanocarrier for brain delivery

The blood-brain barrier (BBB) prevents the permeability of drugs into the brain, and as such limits the management of various brain diseases. To overcome this barrier, drug-encapsulating nanoparticles or vesicles, drug conjugates, and other types of drug delivery systems (DDSs) have been developed. However, the brain-targeting ability of nanoparticles or vesicles is still insufficient. Recently, among the various brain-targeting ligands previously studied for facilitating transcellular BBB transport, several sugar-appended nanocarriers for brain delivery were identified. Meanwhile, cyclodextrins (CyDs) have been used as nanocarriers for drug delivery since they can encapsulate hydrophobic compounds with high biocompatibility. Therefore, in this study, we created various sugar-appended β-cyclodextrins (β-CyDs) to discover novel brain-targeting ligands. As a result, of the six sugar-appended CyDs, lactose-appended β-CyD (Lac-β-CyD) showed greater cellular uptake in hCMEC/D3 cells, human brain microvascular endothelial cells, than other sugar-appended β-CyDs did. In addition, the permeability of Lac-β-CyD within the in vitro human BBB model was greater than that of other sugar-appended β-CyDs. Moreover, Lac-β-CyD significantly accumulated in the mouse brain after intravenous administration. Thus, Lac-β-CyD efficiently facilitated the accumulation of the model drug into the mouse brain. These findings suggest that Lac-β-CyD has the potential to be a novel carrier for drugs across the BBB.