SF-deferoxamine, a bone-seeking angiogenic drug, prevents bone loss in estrogen-deficient mice

Deferoxamine (DFO) possesses a good chelating capability and is therefore used for the clinical treatment of ion deposition diseases. Increasing evidence shows that DFO can inhibit the activity of proline hydroxylase (PHD) by chelating iron, resulting in hypoxia-induced factor (HIF) signaling activation and angiogenesis promotion. However, clinical evidence indicates that a high concentration of DFO could be biotoxic due to its enrichment in related organs. Thus, we established a new compound by conjugating DFO with the bone-seeking agent iminodiacetic acid (IDA); the new agent is called SF-DFO, and we verified its promotion of HIF activation and tube formation in vivo. After confirming the bone-seeking property of SF-DFO in the femur and vertebra of both male and female mice and comparing it to that of DFO, we analyzed the protective effect of DFO and SF-DFO in an ovariectomized (OVX) mouse model. The serum CTX-I level revealed no influence of DFO and SF-DFO on osteoclast activity, but the blood vessels and osteoblasts in the metaphysis were more abundant after SF-DFO treatment, which resulted in a greater protective effect against trabecular bone loss compared to the DFO group. Additionally, the cortical parameters and bone strength performance were identical between the DFO and SF-DFO groups. However, the diffuse inflammatory response in the liver and spleen that occurred after DFO injection was not observed in the SF-DFO group. Thus, with reduced biotoxicity and an equivalent bone-seeking capability, SF-DFO may be a better choice for the prevention of vascular degradation-induced osteoporosis.