Modifying cationic liposomes with cholesteryl-PEG prevents their aggregation in human urine and enhances cellular uptake by bladder cancer cells

Intravesical drug delivery by cationic liposomes (Cat-LPs) represents a potent nanotechnology for enhancing therapeutic effects against bladder disorders. However, preventing the aggregation of Cat-LPs in urine poses a significant barrier. We report on an examination of the effect of modifying liposomes with polyethylene glycol (PEG) lipids to prevent Cat-LPs from aggregating in human urine. Although Cat-LPs underwent significant aggregation in human urine, introducing 5 mol% of PEG2k lipid or 2 mol% of PEG5k lipid completely inhibited the aggregation of the Cat-LPs. When 2 mol% of PEG2k lipids were introduced, the lipid structures of 1,2-distearoly-sn-glycero-3-phosphoethanolamine (DSPE) and 1,2-distearoyl-sn-glycerol (DSG) greatly prevented aggregation compared with cholesterol. By contrast, when Cat-LPs, after incubation in urine, were exposed to bladder cancer cells, only introducing cholesteryl-PEG into the Cat-LPs showed a significant enhancement in cellular uptake. These results offer the potential for incorporating cholesteryl-PEG into Cat-LPs for achieving both stability in urine and effective cellular uptake.