Repair of rabbit femoral head necrosis by release of alendronate and growth differentiation factor-5 from injectable alginate/calcium phosphate carriers

Osteonecrosis of the femoral head (ONFH) is a common disease with limited options of treatment. In this study, we prepared self-setting nano-sized hydroxyapatite carriers incorporating microspheres for controlled release of growth differentiation factor-5 (GDF-5) and/or alendronate (ALN). GDF-5 release enhanced the proliferation of rabbit bone mesenchymal stem cells (BMSCs), and ALN release inhibited the proliferation of macrophages. A rabbit ONFH model was created by liquid nitrogen infusion, and the carriers were implanted into the channel-shaped defects and harvested at 12 weeks. Imaging examination and histological analyses found that all carriers increased new bone formation in the defects, with the group simultaneously incorporating GDF-5 and ALN yielding the greatest improvement. The synergistic release of ALN and GDF-5 from the carrier may offer a promising option for the treatment of ONFH after surgical decompression.