Magnetite nanoparticles were used for their ability to be heated when they are put in an oscillating magnetic field. When they are located inside tumors they can eradicate the tumor cells by heating. We have developed a biomaterial constituted by a mineral degradable matrix containing magnetite nanoparticles. This material can be injected into bone metastasis in which it sets and releases magnetite particles uptaked inside the cancer cells. We have implanted this material inside rabbit bone to check by histology the fate of the nanoparticles in bone. The implant matrix was degraded within a few days releasing the nanoparticles. They were found inside monocytes and fibroblasts having ingrown the material. The nanoparticles could form aggregates which then were fragmented in micro/nanoparticles penetrating the surrounding cells. This study showed that the nanoparticles are released from the mineral matrix within a few days and penetrate the cells in their close proximity.