Bone targeting antioxidative nano-iron oxide for treating postmenopausal osteoporosis.

Osteoporosis is the most common degenerative orthopedic disease in the elderly. Recently, the therapeutic methods for osteoporosis have shifted towards the regulation of local immunity in bone tissues, which could provide a suitable environment for the positive regulation of bone metabolism, promoting osteogenic differentiation and inhibiting osteoclast differentiation. Our previous work demonstrated that iron oxide nanoparticles (IONPs) could positively regulate bone metabolism in vitro. In this study, we further demonstrated that daily administration of IONPs relieved estrogen deficiency-induced osteoporosis via scavenging reactive oxygen species in vivo. Meanwhile, IONPs promoted the osteogenic differentiation of bone marrow mesenchymal stem cells and inhibited the osteoclast differentiation of monocytes from IONPs treated mice. Besides, alendronate, a clinically used anti-osteoporosis bisphosphate, was employed to precisely deliver the IONPs to the bone tissues and played a synergically therapeutic role. Eventually, we verified the bone targeting ability, therapeutic efficiency, and biocompatibility of the novel bone target iron oxides in ovariectomy-induced osteoporotic mice. By applying BTNPs, the OVX-induced osteoporosis was significantly revised in mice models via the positive regulation of bone metabolism.