Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.31.230136v1?rss=1 Authors: Carradori, D., Chen, H., Werner, B., Shah, A., Leonardi, C., Usuelli, M., Mezzenga, R., Platt, F. M., Leroux, J.-C. Abstract: Niemann-Pick Disease Type C (NPC) is a severe neurovisceral disorder that is pathophysiologically characterized by intracellular transport abnormalities leading to cytoplasmic accumulation of lipids such as cholesterol and multiple sphingolipids, including sphingosine. The compound 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) is a compound with high cholesterol complexation capacity and is currently under clinical investigation for the treatment of NPC. However, due to its short blood half-life, high doses are required to produce a therapeutic effect. It has been reported in mice that HPbetaCD's circulation time and efficacy can be improved by increasing its size via polymerization, but the biodegradable nature of these systems did not allow the contribution of the macromolecule to the activity to be determined. In this work, stable forms of polymerized HPbetaCD were generated (via epichlorohydrin crosslinking) to investigate their in vitro mechanisms of action and in vivo effects. Crosslinked CDs (8-312 kDa) displayed a 10-fold greater complexation capacity towards cholesterol than monomeric HPbetaCD but were taken up by cells to a lower extent (in a size-dependent fashion), resulting in an overall comparable in vitro effect on intracellular cholesterol accumulation that was dependent on cholesterol complexation. When tested in vivo, the crosslinked 19.3 kDa HPbetaCD exhibited a longer terminal half-life than the monomeric HPbetaCD. However, it did not increase the life span of Npc1 mice, possibly due to reduced organ penetration and brain diffusion consequence of its large molecular weight. This could be circumvented by the application of magnetic resonance imaging-guided low intensity-pulsed focused ultrasound (MRIg-FUS), which increased the brain penetration of the CD. In conclusion, stable forms of polymerized HPbetaCD constitute valuable tools to elucidate CDs' mechanism of action. Moreover, the use of MRIg-FUS to maximize CDs tissue penetration warrants further investigation, as it may be key to harnessing CDs full therapeutic potential in the treatment of NPC. Copy rights belong to original authors. Visit the link for more info