Comparison of osteogenesis of bovine bone xenografts between true bone ceramics and decalcified bone matrix

Xenograft bone scaffolds have certain advantages such as mechanical strength, osteoinductive properties, sufficient source and safety. This study aimed to compare osteogenesis of the two main bovine bone xenografts namely true bone ceramics (TBC) and decalcified bone matrix (DBM), and TBC or DBM combined with bone morphogenetic protein (BMP)-2 (TBC&BMP-2 and DBM&BMP-2). The characteristics of TBC and DBM were investigated by observing the appearance and scanning electron microscopic images, examining mechanical strength, evaluating cytotoxicity and detecting BMP-2 release after being combined with BMP-2 in vitro. The femoral condyle defect and radial defect models were successively established to evaluate the performance of the proposed scaffolds in repairing cortical and cancellous bone defects. General observation, hematoxylin and eosin (HE) staining, mirco-CT scanning, calcein double labeling, X-ray film observation, three-point bending test in vivo were then performed. It indicated that the repair with xenograft bone scaffolds of 8 weeks were needed and the repair results were better than those of 4 weeks whatever the type of defects. To femoral condyle defect, TBC and TBC&BMP-2 were better than DBM and DBM&BMP-2, and TBC&BMP-2 was better than TBC alone; to radial defect, DBM and DBM&BMP-2 were better than TBC and TBC&BMP-2, and DBM&BMP-2 was better than DBM alone. This study has shown that TBC and DBM xenograft scaffolds can be more suitable for the repair of cancellous bone and cortical bone defects for 8 weeks in rats, respectively. We also have exhibited the use of BMP-2 in combination with DBM or TBC provides the possibility to treat bone defects more effectively. We thus believe that we probably need to select the more suitable scaffold according to bone defect types, and both TBC and DBM are promising xenograft materials for bone tissue engineering and regenerative medicine. Graphical abstract.