The efficacy of allogeneic mesenchymal precursor cells for the repair of an ovine tibial segmental defect.

Introduction: Synthetic void-fillers offer an alternative to autograft or allograft bone in the repair of segmental defects. However, the reparative process is delayed as only osteoconductive elements are present. The inclusion of pluripotential cells may resolve this limitation, and the use of allogeneic tissue provides the opportunity for an off-the-shelf remedy. The current study evaluated the utilisation of mesenchymal precursor cells (MPC) for the repair of an ovine critical-size tibial segmental defect. Methods: Twenty-four, mature female sheep underwent surgery for the creation of a 3 cm tibial diaphyseal defect. In one group of 12 sheep the scaffold was used alone, and in the second group the scaffold was seeded with MPC. The defect was stabilised using a locking intramedullary nail and allowed to heal over a nine-month-period. Outcome assessments of healing included radiology of callus formation, computed tomography, assessment of new-bone volume, mechanical attributes, and histological evaluation of linear bone apposition rate and tissue response. Results: The MPC-treated group displayed a significantly greater level of callus formation and rate of bone apposition in the defect. Discussion: The incorporation of allogeneic MPC to a synthetic void filler stimulated early repair of critical-size diaphyseal segmental defects and holds potential as an off-the-shelf therapy for augmenting bone regeneration.