Bone-Targeted Biomimetic Nanogels Re-Establish Osteoblast/Osteoclast Balance to Treat Postmenopausal Osteoporosis.

Insufficient bone formation and excessive bone resorption caused by estrogen deficiency are the major factors resulting in the incidence of postmenopausal osteoporosis (PMOP). The existing drugs usually fail to re-establish the osteoblast/osteoclast balance from both sides and generate side-effects owing to the lack of bone-targeting ability. Here, engineered cell-membrane-coated nanogels PNG@mR&C capable of scavenging receptor activator of nuclear factor-κB ligand (RANKL) and responsively releasing therapeutic PTH 1-34 in the bone microenvironment are prepared from RANK and CXCR4 overexpressed bone mesenchymal stem cell (BMSC) membrane-coated chitosan biopolymers. The CXCR4 on the coated-membranes confer bone-targeting ability, and abundant RANK effectively absorb RANKL to inhibit osteoclastogenesis. Meanwhile, the release of PTH 1-34 triggered by osteoclast-mediated acid microenvironment promote osteogenesis. In addition, the dose and frequency are greatly reduced due to the smart release property, prolonged circulation time, and bone-specific accumulation. Thus, PNG@mR&C exhibits satisfactory therapeutic effects in the ovariectomized (OVX) mouse model. This study provides a new paradigm re-establishing the bone metabolic homeostasis from multitargets and shows great promise for the treatment of PMOP.