Abstract
BACKGROUND: Osteoporosis is a chronic condition affecting patients' morbidity and mortality and represents a big socioeconomic burden. Because stem cells can proliferate and differentiate into bone-forming cells, stem cell therapy for osteoporosis has been widely studied. However, cells as a live drug face multiple challenges because of their instability during preservation and transportation. In addition, cell therapy has potential adverse effects such as embolism, tumorigenicity, and immunogenicity. RESULTS: Herein, we sought to use cell-mimicking and targeted therapeutic nanoparticles to replace stem cells. We fabricated nanoparticles (NPs) using polylactic-co-glycolic acid (PLGA) loaded with the secretome (Sec) from mesenchymal stem cells (MSCs) to form MSC-Sec NPs. Furthermore, we cloaked the nanoparticles with the membranes from C-X-C chemokine receptor type 4 (CXCR4)-expressing human microvascular endothelial cells (HMECs) to generate MSC-Sec/CXCR4 NP. CXCR4 can target the nanoparticles to the bone microenvironment under osteoporosis based on the CXCR4/SDF-1 axis. CONCLUSIONS: In a rat model of osteoporosis, MSC-Sec/CXCR4 NP were found to accumulate in bone, and such treatment inhibited osteoclast differentiation while promoting osteogenic proliferation. In addition, our results showed that MSC-Sec/CXCR4 NPs reduce OVX-induced bone mass attenuation in OVX rats.