Synthesis, properties, and intratumoral evaluation of mitoxantrone-loaded casein microspheres in Lewis lung carcinoma.

Smooth, round, uniform bovine casein microspheres of 1-5 and 10-20 microns size were readily prepared by a steric stabilization technique previously developed in this laboratory for synthesis of albumin microspheres. The avid phagocytic uptake of casein and albumin microspheres was demonstrated with fluorescein-labelled microspheres using a macrophage-like mouse myelomonocytic leukaemia cell line. Post-synthesis loading of 25% mitoxantrone was achieved for casein microspheres containing 20% polyglutamic acid. Preliminary intratumoural chemotherapy experiments with a mouse Lewis lung carcinoma indicated that mitoxantrone and mitoxantrone-loaded casein-polyglutamic acid microspheres exhibited lower toxicity when administered intratumorally.