Studies on the use of antimitotic drugs entrapped within liposomes and of their action on a human glioma cell line

The optimal conditions have been determined for producing the maximum incorporation within liposomes of two cell cycle-specific antimitotic drugs (bleomycin and vincristine) used in the treatment of human cerebral gliomas. Under these conditions the subsequent rate of release of these two drugs was studied in vitro. Neither cell fusion nor endocytosis could be demonstrated between liposomes of the size distribution used in these experiments (0.1-15 micron) and a human glioma cell line (U.251-MG) using a variety of marker techniques. Dose-response curves were similar for the two drugs whether free or entrapped within liposomes when applied to this cell line. These results suggest that drugs entrapped within liposomes may be useful as a potential depot preparation in the treatment of human gliomas.