Icariin: A promising osteoinductive compound for repairing bone defect and osteonecrosis.

Icariin (Ica), the main active component of Herba Epimedii, has been identified as an osteogenic and angiogenic phytomolecule. To develop a bioactive scaffold for enhancing bone repair, Ica was loaded into porous tricalcium phosphate (TCP) scaffolds, and the obtained porous Ica/TCP composites were investigated for treating osteonecrosis of the femoral head (ONFH) in a rabbit model. ONFH was histopathologically confirmed at two weeks after methylprednisolone acetate injection, and the rabbits were treated with porous Ica/TCP scaffolds (group A), porous TCP scaffolds (group B), and autogenous cancellous bone graft (group C). At 12 weeks, the amount of newly formed bone in group A increased significantly compared with that in group B (P = 0.003). The mean histological and radiological scores for repaired defects in group A were significantly higher than those in group B (P = 0.007, P = 0.029, respectively), but were lower than those in group C (P = 0.032, P = 0.046, respectively). In addition, the expression of vascular endothelial growth factor by immunohistochemical testing and real-time polymerase chain reaction in group A was significantly higher than that in group B (P = 0.002, P = 0.001, respectively), but was lower than that in group C (P = 0.034, P = 0.005, respectively). Therefore, Ica can be a promising osteogenic and angiogenic compound for repairing bone defects and preventing the collapse of the femoral head in ONFH.