Iranian Red Crescent Medical Journal Iran Red Crescent Med J 2012; 14(2):96-103 ©Iranian Red Crescent Medical Journal ORIGINAL ARTICLE

Background: Bone healing and its reconstruction in fractures, especially in long bones are of particular im-portance in regenerative medicine. This study compares the bone healing rate after a human xenograft of miner-alized bone and together with an allograft of bone marrow mesenchymal stem cells (MSCs) in an experimental tibial bone fracture rabbit model. Methods: In fall 2009, twenty New Zealand white rabbits were randomly divided into 2 equal groups. In both groups, a 5 mm segmental defect was created in the right tibia. In group A, a scaffold pin was seeded with allo-genic rabbit MSCs and was placed in the defect area and in group B, the defect was filled with an unseeded pin human mineralized bone xenograft. An untreated defect was induced in the left tibia of all animals serving as the control. After 4-8 weeks, the segmental defects were histologically evaluated and also by a compressive test. Results: In groups A and B, healing and formation of new bony tissue were significantly more than the control group and with a significant less inflammation. Conclusion: Tissue engineering of mineralized bone xenograft and MSCs allograft may be significant steps i