Immune-Derived THBS1-CD47 Axis Induces Cellular Senescence and Suppresses Osteogenesis in Diabetic Periosteum

Type 2 diabetes mellitus (T2DM) weakens bone repair and increases fracture risk, but how the periosteal environment contributes to this problem is not fully understood. We found that diabetic mice showed thinning of the periosteum, reduced bone mass, and poor function of bone-forming cells. Using single-cell RNA sequencing, we discovered that immune cells and bone-lineage cells interact more strongly in diabetes through the THBS1-CD47 pathway. THBS1 was mainly produced by macrophages, while its receptor CD47 was abundant in osteogenic cells. Laboratory experiments showed that THBS1 blocked bone gene activity, increased inflammation and cell death, and damaged mitochondria, leading to higher oxidative stress. Knocking down CD47 reversed these effects, restoring bone cell activity and energy balance. In diabetic fracture models, blocking THBS1 improved callus formation and bone healing. These findings identify THBS1-CD47 as a key driver of periosteal dysfunction in T2DM and highlight it as a potential target to improve skeletal repair in diabetic patients.