Bone-Seeking Albumin-Nanomedicine for In Vivo Imaging and Therapeutic Monitoring.

Malignant osteolysis associated with irreversible primary bone tumors and bone metastases remains a clinically urgent problem. Exploiting the imaging and therapy function of flexible nanomedicine can provide an alternative for therapeutic navigation and monitoring of malignant osteolysis. Here, we report the development of albumin-based gadolinium oxide nanoparticles loaded with doxorubicin and conjugated with bone-seeking alendronate for targeted delivery and therapeutic monitoring. Compared with nontargeted nanomedicine, bone-seeking accumulation and retention can be proven by MRI in a rat model of focal malignant osteolysis. Meanwhile, we observed a whole-body distribution in the consecutive SPECT imaging after radiolabeling with 125I, SPECT imaging also indicated the enhanced bone tumor accumulation and prolonged retention. Resulting from the high drug loading and 131I labeling efficiency, the targeted nanomedicine exhibited significant chemotherapy and inter-radiotherapy capacity. Ultimately, the tumor burden of rats was obviously decreased except for the nontargeted group and the empty carrier group. In vivo CT imaging and pathological analysis revealed that the combined therapy was an efficient measure for antiosteolysis. Our findings suggest that albumin-based nanomedicine can provide a platform for bone-seeking diagnosis and therapeutic monitoring.