The promotion of bone regeneration through positive regulation of angiogenic-osteogenic coupling using microRNA-26a.

Bone is highly vascularized tissue reliant on coordinated coupling between angiogenesis and osteogenesis to regenerate. Delivery of a combination of growth factors involved in the coupling has to some extent enhanced bone regeneration. However, the stimulation may interrupt the balance of bone and vessel remodeling leading to the excessive bone formation or vascular leakage. MicroRNAs function as potent molecular managers that may simultaneously regulate multiple endogenous signaling pathways. Delivery of microRNA may provide a way to maximally mimic the native bone development environment. In this work, we identified an miRNA, miR-26a in vitro assays that positively regulates angiogenesis-osteogenesis coupling. This resulted in enhanced bone formation coordinated with vascularization in mouse subcutaneous assay. Furthermore, we constructed an miRNA enhancer delivery system to enhance miR-26a expression in a localized and sustained manner in vivo. We found that the system led to complete repair of the critical-size calvarial bone defect and increased vascularization accordingly. Host specific real-time PCR test of the neo-formed bone demonstrated that miR-26a optimized bone regeneration mainly due to simultaneously regulating endogenous angiogenesis-osteogenesis coupling. We anticipated our assay providing evidence that miRNA-based therapy can be a valuable tool to promote bone regeneration.