IOX2-mediated PHD2 targeting enhances mesenchymal osteogenesis for critical-sized bone repair

Bone regeneration requires mesenchymal progenitor commitment. Prolyl hydroxylase domain protein 2 (PHD2) influences metabolism and osteogenesis, but its specific role in skeletal repair is undefined. Using a murine critical-sized femoral defect model, dynamic PHD2 expression marked early healing. Single-cell RNA sequencing of PHD2-deficient cells revealed preferential osteogenic activation in mesoderm lineages. Pharmacological PHD2 inhibition (IOX2) significantly enhanced bone regeneration (p < 0.01) and amplified RUNX2 signaling. IOX2 promoted non-cytotoxic osteogenic differentiation in bone marrow stromal cells (BMSCs). Mechanistically, PHD2 suppression led to enhanced expression of osteogenic transcription factors (RUNX2, COL1A1) and their downstream targets. Our findings suggest that PHD2 plays a key role in restricting osteoblast lineage commitment during repair, and that therapeutic PHD2 inhibition may enhance regenerative potential by modulating osteogenic gene expression.