Increased lung uptake of liposomes coated with polysaccharides

Liposomes labeled with [14C]coenzyme Q10 in the lipid bilayer were coated with various polysaccharide derivatives, i.e., palmitoyl conjugates of pullulan, pullulan phosphate, amylopectin, amylopectin phosphate and amylopectin sulfate. The kinetics of disposition and the tissue distribution of [14C]coenzyme Q10 after intravenous injection of the liposomes into guinea pigs were investigated. Lung uptake of radioactivity after injection of the O-palmitoyl amylopectin- and O-palmitoyl amylopectin phosphate-coated liposomes was 5- and 3-times higher, respectively, at 30 min after injection than that of the conventional liposomes. For doubly labeled liposomes with [3H]inulin and [14C]coenzyme Q10, the 3H/14C ratios in the lung, spleen and heart were similar to one another. Urinary excretion of [3H]inulin encapsulated in O-palmitoyl amylopectin-coated liposomes was much lower than that of unencapsulated [3H]inulin. These observations suggest that the O-palmitoyl amylopectin-coated liposomes are rather stable in vivo and are taken up into tissues in the intact form.