RESUMEN
<p><b>BACKGROUND</b>Repair of large bone defects remains a challenge for clinicians. The present study investigated the ability of mesenchymal stem cells (MSCs) and/or periosteum-loaded poly (lactic-co-glycolic acid) (PLGA) to promote new bone formation within rabbit ulnar segmental bone defects.</p><p><b>METHODS</b>Rabbit bone marrow-derived MSCs (passage 3) were seeded onto porous PLGA scaffolds. Forty segmental bone defects, each 15 mm in length, were created in the rabbit ulna, from which periosteum was obtained. Bone defects were treated with either PLGA alone (group A), PLGA + MSCs (group B), periosteum-wrapped PLGA (group C) or periosteum-wrapped PLGA/MSCs (group D). At 6 and 12 weeks post-surgery, samples were detected by gross observation, radiological examination (X-ray and micro-CT) and histological analyses.</p><p><b>RESULTS</b>Group D, comprising both periosteum and MSCs, showed better bone quality, higher X-ray scores and a greater amount of bone volume compared with the other three groups at each time point (P < 0.05). No significant differences in radiological scores and amount of bone volume were found between groups B and C (P > 0.05), both of which were significantly higher than group A (P < 0.05).</p><p><b>CONCLUSIONS</b>Implanted MSCs combined with periosteum have a synergistic effect on segmental bone regeneration and that periosteum plays a critical role in the process. Fabrication of angiogenic and osteogenic cellular constructs or tissue-engineered periosteum will have broad applications in bone tissue engineering.</p>