(676c) Cholesterol Content Mediates Tumor Cell Uptake of Targeted Liposomes

Authors: 
Kong, S. M., University at Buffalo, The State University of New York (SUNY)
Effective design of nanocarriers is incumbent upon thorough understanding of material properties and their interactions at biological interfaces. Within this context, the role of nanoparticle mechanical properties on cellular uptake is poorly understood. By altering membrane fluidity via cholesterol composition, we show that liposome cholesterol content controls particle uptake kinetics of CD44-overexpressing high grade serous ovarian cancer cells. Hyaluronic acid-coated liposomes were synthesized with membrane cholesterol mole compositions ranging from 0% to 40%. Liposome bilayers were fluorescently tagged with NBD and the core was loaded with calcein blue to differentiate uptake of lipophilic and hydrophilic cargo respectively. Uptake kinetics of the NBD-calcein blue nanoparticles was assessed via fluorescence-activated cell sorting (FACS). At early time points (4hr), particle accumulation of layered liposomes containing no cholesterol was found to be significantly higher than layered liposomes containing 8%, 30% and 40% cholesterol (P < 0.001). These differences in particle uptake kinetics were confirmed via fluorescence confocal microscopy. Uptake mechanisms were probed using a panel of inhibitors. ATP-depletion and inhibition of receptor-mediated endocytosis prevented uptake of layered liposomes comprised of 40 mol% cholesterol, but did not prevent uptake of layered liposomes containing 0 mol% cholesterol. This work demonstrates that cholesterol composition can be used to control the uptake kinetics and uptake mechanism of targeted liposomes.