Increased efficacy of aphidicolin killing of human neuroblastoma cells in vitro by encapsulation in liposomes

Aphidicolin is a tetracyclic diterpene antibiotic which kills human neuroblastoma cells (NB) in vitro while it has no significant effect on the viability of different human cell types including normal embryonal cells. In the present study, we tested whether aphidicolin encapsulated in liposomes kills NB cells with the efficacy superior to that of unencapsulated aphidicolin. The drug was entrapped in vesicles composed of phosphatidylcholine, phosphatidylserine and cholesterol in a molar ratio of 83:5:12. The treatment with encapsulated aphidicolin at a concentration of 200 nmol for 5 days killed all cells of three human NB cell lines. In contrast, at least 30% of the cells survived 5 days of treatment with 200 nmol unencapsulated aphidicolin. The results showed that aphidicolin killing of human NB cells may be increased by encapsulation in liposomes.

In vitro anti-human cytomegalovirus activity of liposome-encapsulated foscarnet

Foscarnet is a pyrophosphate analogue that possesses substantial activity against human cytomegalovirus (HCMV) in patients with CMV retinitis. In this in vitro study we tested whether liposome encapsulation of foscarnet would provide the drug with anti-HCMV activity comparable with that of nonencapsulated foscarnet. The drug was entrapped in large unilamellar vesicles of homogeneous size at a concentration of 10 mg/ml. The vesicles were prepared by the method of fast and controlled dialysis of mixed detergent-lipid micelles using N-Octyl--D-glucopyranoside as the detergent. The activity of drugs against two laboratory HCMV strains (AD169 and Towne) was tested in a plaque-reduction assay using monolayers of human foreskin fibroblasts. The dose of encapsulated or nonencapsulated foscarnet required for a 50% reduction in the number of plaques (IC50) for the AD169 strain was 106 and 113 mumol/l, respectively. For the HCMV Towne strain the dose was 112 and 109 mumol/l, respectively. Treatment with concentrations of up to 400 mumol/l (maximal concentration tested) demonstrated that foscarnet is released at efficient doses from liposomes and that it is not toxic in the range of concentrations tested.