Nanoparticles Targeting Delivery Antagomir-483-5p to Bone Marrow Mesenchymal Stem Cells Treat Osteoporosis by Increasing Bone Formation

Background: Promoting bone marrow mesenchymal stem cell (BMSC) osteoblastic differentiation is a promising therapeutic strategy for osteoporosis (OP). The present study demonstrates that miR- 483-5p inhibits the osteogenic differentiation of BMSCs. Therefore, selectively delivering the nanoparticles carrying antagomir-483-5p (miR-483-5p inhibitor) to BMSCs is expected to become an effective treatment drug for OP. Methods: Real-time PCR assays were used to analyze miR-483-5p, ALP and Bglap levels in BMSCs of ovariectomized and aged osteoporotic mice. Immunoglobulin G and poloxamer-188 encapsulated the functional small molecules, and a BMSC-targeting aptamer was employed to confirm the direction of the nanoparticles to selectively and efficiently deliver antagomir-483-5p to BMSCs in vivo. Luciferase assays were used to determine the target genes of miR-483-5p. Western blot assays and immunohistochemistry staining were used to detect the targets in vitro and in vivo. Results: miR-483-5p levels were increased in BMSCs of ovariectomized and aged osteoporotic mice. Inhibiting miR-483-5p levels in BMSCs by antagomir-483-5p in vitro promoted the expression of bone formation markers, such as ALP and Bglap. The FAM-BMSC-aptamer-nanoparticles carrying antagomir- 483-5p were taken up by BMSCs, resulting in stimulation of BMSC osteoblastic differentiation in vitro and osteoporosis prevention in vivo. Furthermore, our research demonstrated that mitogen-activated protein kinase 1 (MAPK1) and SMAD family member 5 (Smad5) were direct targets of miR-483-5p in regulating BMSC osteoblastic differentiation and osteoporosis pathological processes. Conclusions: The important therapeutic role of FAM-BMSC-aptamer-nanoparticles carrying antagomir- 483-5p in osteoporosis was established in our study. These nanoparticles are a novel candidate for the clinical prevention and treatment of osteoporosis. The optimized, targeted drug delivery platform for small molecules will provide new ideas for treating clinical diseases.