Local Retention and Combination Effects of Biocompatible Doxorubicin-Loaded and Radioiodine-Labeled Microhydrogels in Cancer Therapy.

I-131-labeled chitosan microhydrogels (I-131-CMH) that are retained at an injection site without leaking free I-131 into normal tissue can provide opportunities to improve cancer therapy. This study focuses on the development of doxorubicin-loaded I-131-CMH (Dox-I-131-CMH) for use in radiochemotherapy against cancer. The radiolabeling of I-131-CMH was found to be stable over a period of 2 weeks with no disassociation of free I-131, and Dox showed a sustained release from the CMH. When I-131-CMH were injected into the thigh muscle or tumor tissue, in vivo gamma imaging showed a retention at the injection site with no significant leakage of I-131 into other areas of normal tissue, and after an intrahepatic arterial injection, I-131-CMH were selectively retained in the liver. Dox-I-131-CMH had significant synergistic therapeutic effects of radiation and chemotherapy on mouse breast cancer models. In this regard, Dox-I-131-CMH may be a new alternative agent for cancer therapy.